Mouthpiece Work / Reflection on Mouthpiece Theory Discourse
FROM: perksjim (perksjim)
SUBJECT: Reflection on Mouthpiece Theory Discourse
Hi Team!
I have really found your discussion of mouthpiece theory to be
interesting
and informative. I think we all agree that there is more
information/speculation
and less real understanding about the mouthpiece than any other part of
the
instrument. Here is a layman's cent and a half.
HELMHOLTZ
Characterizing the mouthpiece as a Helmholtz resonator is unproductive.
The saxophone is not an air-column with a Helmholtz jug stuck on top.
The saxophone is a truncated-cone air-column with functional
perturbations. ***
The effect of adding a constriction ring depends on where it is relative
to the W-curves, and not depended on its effect on an imaginary
Helmholtz
resonator.
--- lancelotburt <lancelotburt@...
<mailto:lancelotburt%40yahoo.com> > wrote:
" Additionally, Bernoulli effects aside, it is still an air column,
with a compression anti-node, an irregular bore, and a displacement
anti-node at the other end, and as such, the effects of bore
irregularities on the pitch of the different modes of different notes,
each with a different wave length, still apply - even more so, since it
all starts here. Given accurate cross-sectional volume information along
the entire length of the truncation, one could make a W curve chart that
would assist greatly in analysis of which shape where does what to which
resonance mode, of which note, pitch-wise, in every register, and how to
align resonances for optimal harmonic regime formation. I'm surprised
that such mouthpiece design/analysis software is not abound yet - W
Curve Chart excel sheets anyway."
YES!
Speaking of W-curves, it would be nice to have an Excel version.
Somebody should dig out Benade's paper. I use the curves he shows
for an oboe in his "Acoustic Evolution of Wind Instruments".
Question:
He shows the curves starting at the missing apex. Do I need to start
them at the physical MP tip and shorten the waves according to length
proportional to volume?
THEORY/PRACTICE TUNING DISCREPANCY
Most of you subscribe to the following:
"Yes, tuning in the low register is by volume,
tuning of the high register is by length."
However, theory indicates that volume has little effect on low notes
and great effect on high notes.
Benade: FMA page 471 and page 502
Nederveen: Figure 27.4
What is the basis for this discrepancy?
Changing the mouthpiece position affects the relationship of the
low bore notes to the high bore notes, but moving the MP also changes
the volume. Hence, moving the mouthpiece should have different effects
on the registers.
Since volume affects frequency response, I set my chamber volume
for best partial alignment to harmonics, determined mostly by the sound,
strength and stability of the notes throughout the full range of the
instrument.
NECK CYLINDER
The cylindrical end of the neck made to accept the MP may not be
a problem. In fact, it may be acoustically necessary to compensate
for high frequency partial compression due to big tone-hole length
correction at high frequencies.
Benade: FMA, Page 432
Benade: Horns, Strings, and Harmony, Page 213
Frs
All of the tone holes occur below the neck, so one wants the geometry
above this point to provide an acoustic quasi-cone. The bore is nearly
conic and the conicity easy to measure; the neck is not. Therefore,
Benade, as usual, is correct.
Would like some feedback on my:
http://f1.grp.yahoofs.com/v1/INfMSt-Qukoz8pAdlxU8oo9qNH5J29qtN7UTPFtr9Ia\
4GFN3VXZ5zz2JP3oOnODgkhf36HG8ahy1F7CJIHRm2COwjHjXvQ/Methods/C_melody%20B\
uescher%20TT%20117549_2.xls
<http://f1.grp.yahoofs.com/v1/INfMSt-Qukoz8pAdlxU8oo9qNH5J29qtN7UTPFtr9I\
a4GFN3VXZ5zz2JP3oOnODgkhf36HG8ahy1F7CJIHRm2COwjHjXvQ/Methods/C_melody%20\
Buescher%20TT%20117549_2.xls>
<http://launch.groups.yahoo.com/group/MouthpieceWork/C_melody%20Buescher\
%20TT%20117549_2.xls>
<http://f1.grp.yahoofs.com/v1/YGzKStcKT64zaxZxoHRcUjXQJ6UK0fCgilGw_ahVuN\
wfxvp9cpJdXTApLasyP2IfkuMj39dkLxq-8f7IH3UQeZm0QRHJqA/Methods/Missing%20V\
olume.xls> CUTOFF FREQUENCY (Fc)
An alto Fc is about 850 Hz. This means, that above about midway in the
2nd
register, the tone has no harmonic support, only the fundamental. So,
above Fc
the frequency is unaffected by shape. So we don't need to talk about
high
frequencies in the MP, except for turbulence. Of course, the MP or MP
and neck alone have no cutoff frequency because there is no tone-hole
lattice.
By the way, turbulence degrades motion, DC or AC.
Benade suggests that a harmonic above Fc should be provided by player
adjustments to set the reed frequency (Fr). Isn't this technique the
opposite of
those that say the embouchure should remain fixed? Has anybody cut open
a
mouthpiece so as to measure Fr?
IMPEDANCE MATCHING
I have seen no discussion about matching the acoustic impedance of the
narrow MP
tip with the big chamber. The audio profession does it with
Bessel curves, such
as an audio horn loudspeaker. Does a rollover baffle imply a
quasi-bessel curve?
What is a MP S-curve?
***
Fletcher refers to brass mouthpiece measurements. He shows that changing
a brass MP size has little effect on frequency. It mostly changes the
frequency of amplitude enhancement. We know that changing the sax MP
size does change the frequency. Also the Q of the sax MP Helmholtz is
very
low compared to a brass MP (Q is proportional to the square root of the
volume divided by the cube power of the constriction cross section).
Plus
the reed elastic boundary also degrades the Q. I think Fletcher is
mistaken
about the sax MP being analogous to the brass MP Helmholtz jug.
jim
FROM: lancelotburt (MartinMods)
SUBJECT: Re: Reflection on Mouthpiece Theory Discourse
JPerks Wrote:
"Speaking of W-curves, it would be nice to have an Excel version.
Somebody should dig out Benade's paper. I use the curves he shows
for an oboe in his "Acoustic Evolution of Wind Instruments" .
MartinMods Wrote: When I have time, I'm going to plug them into Comsol and make an interactive/animated W-Curves Chart.
JPerks Wrote: "
Question:
He shows the curves starting at the missing apex. Do I need to start
them at the physical MP tip and shorten the waves according to length
proportional to volume?"
MartinMods Wrote: Go with the physical reality described by your measurements.
JPerks Wrote:
"Most of you subscribe to the following:
"Yes, tuning in the low register is by volume,
tuning of the high register is by length."
However, theory indicates that volume has little effect on low notes
and great effect on high notes.
Benade: FMA page 471 and page 502
Nederveen: Figure 27.4
What is the basis for this discrepancy?"
MartinMods Wrote: Tuning is affected by length and also diameter of the air column at the compression anti-nodes/displacement anti-nodes of the particular mode in question. This equates to volume more or less. The mouthpiece chamber at the reed is the compression anti-node for every resonance on the instrument. Giving the mouthpiece chamber in the vicinity of the reed, more volume is the same as enlarging the bore, and the pitch of all modes will be lowered. Bore perturbations have more effect on the fundamental and lower modes, than the higher modes, so one tunes lower frequencies by volume at the compression anti-node.
The higher frequencies, being of shorter wave lengths, are more affected by tube length than are lower frequencies. It's a matter of proportion, so the high frequencies are tuned most effectively by adjusting tube length.
As one can not adjust length without changing volume, both must be taken into account. One tunes then the saxophone as a whole.
JPerks Wrote: "
An alto Fc is about 850 Hz. This means, that above about midway in the 2nd register, the tone has no harmonic support, only the fundamental."
MartinMods Wrote: First - your link is full of spaces and does not work. Use the "create hyperlink" button to insert a web link.
The higher harmonic resonances above Fc, which one clearly sees in a spectral analysis, are still present and they are audible. That they lie above Fc merely means that they do not supply energy to the harmonic regime.
________________________________
From: perksjim <mcbop@...>
To: MouthpieceWork@yahoogroups.com
Sent: Mon, October 12, 2009 6:58:29 PM
Subject: [MouthpieceWork] Reflection on Mouthpiece Theory Discourse
Hi Team!
I have really found your discussion of mouthpiece theory to be interesting
and informative. I think we all agree that there is more information/ speculation
and less real understanding about the mouthpiece than any other part of the
instrument. Here is a layman's cent and a half.
HELMHOLTZ
Characterizing the mouthpiece as a Helmholtz resonator is unproductive.
The saxophone is not an air-column with a Helmholtz jug stuck on top.
The saxophone is a truncated-cone air-column with functional
perturbations. ***
The effect of adding a constriction ring depends on where it is relative
to the W-curves, and not depended on its effect on an imaginary Helmholtz
resonator.
--- lancelotburt <lancelotburt@ yahoo.com> wrote:
" Additionally, Bernoulli effects aside, it is still an air column, with a compression anti-node, an irregular bore, and a displacement anti-node at the other end, and as such, the effects of bore irregularities on the pitch of the different modes of different notes, each with a different wave length, still apply - even more so, since it all starts here. Given accurate cross-sectional volume information along the entire length of the truncation, one could make a W curve chart that would assist greatly in analysis of which shape where does what to which resonance mode, of which note, pitch-wise, in every register, and how to align resonances for optimal harmonic regime formation. I'm surprised that such mouthpiece design/analysis software is not abound yet - W Curve Chart excel sheets anyway."
YES!
Speaking of W-curves, it would be nice to have an Excel version.
Somebody should dig out Benade's paper. I use the curves he shows
for an oboe in his "Acoustic Evolution of Wind Instruments" .
Question:
He shows the curves starting at the missing apex. Do I need to start
them at the physical MP tip and shorten the waves according to length
proportional to volume?
THEORY/PRACTICE TUNING DISCREPANCY
Most of you subscribe to the following:
"Yes, tuning in the low register is by volume,
tuning of the high register is by length."
However, theory indicates that volume has little effect on low notes
and great effect on high notes.
Benade: FMA page 471 and page 502
Nederveen: Figure 27.4
What is the basis for this discrepancy?
Changing the mouthpiece position affects the relationship of the
low bore notes to the high bore notes, but moving the MP also changes
the volume. Hence, moving the mouthpiece should have different effects
on the registers.
Since volume affects frequency response, I set my chamber volume
for best partial alignment to harmonics, determined mostly by the sound,
strength and stability of the notes throughout the full range of the instrument.
NECK CYLINDER
The cylindrical end of the neck made to accept the MP may not be
a problem. In fact, it may be acoustically necessary to compensate
for high frequency partial compression due to big tone-hole length
correction at high frequencies.
Benade: FMA, Page 432
Benade: Horns, Strings, and Harmony, Page 213
Frs
All of the tone holes occur below the neck, so one wants the geometry
above this point to provide an acoustic quasi-cone. The bore is nearly
conic and the conicity easy to measure; the neck is not. Therefore,
Benade, as usual, is correct.
Would like some feedback on my:
http://f1.grp. yahoofs.com/ v1/INfMSt- Qukoz8pAdlxU8oo9 qNH5J29qtN7UTPFt r9Ia4GFN3VXZ5zz2 JP3oOnODgkhf36HG 8ahy1F7CJIHRm2CO wjHjXvQ/Methods/ C_melody% 20Buescher% 20TT%20117549_ 2.xls
CUTOFF FREQUENCY (Fc)
An alto Fc is about 850 Hz. This means, that above about midway in the 2nd
register, the tone has no harmonic support, only the fundamental. So, above Fc
the frequency is unaffected by shape. So we don't need to talk about high
frequencies in the MP, except for turbulence. Of course, the MP or MP
and neck alone have no cutoff frequency because there is no tone-hole lattice.
By the way, turbulence degrades motion, DC or AC.
Benade suggests that a harmonic above Fc should be provided by player
adjustments to set the reed frequency (Fr). Isn't this technique the opposite of
those that say the embouchure should remain fixed? Has anybody cut open a
mouthpiece so as to measure Fr?
IMPEDANCE MATCHING
I have seen no discussion about matching the acoustic impedance of the narrow MP
tip with the big chamber. The audio profession does it with Bessel curves, such
as an audio horn loudspeaker. Does a rollover baffle imply a quasi-bessel curve?
What is a MP S-curve?
***
Fletcher refers to brass mouthpiece measurements. He shows that changing
a brass MP size has little effect on frequency. It mostly changes the
frequency of amplitude enhancement. We know that changing the sax MP
size does change the frequency. Also the Q of the sax MP Helmholtz is very
low compared to a brass MP (Q is proportional to the square root of the
volume divided by the cube power of the constriction cross section). Plus
the reed elastic boundary also degrades the Q. I think Fletcher is mistaken
about the sax MP being analogous to the brass MP Helmholtz jug.
jim
FROM: lancelotburt (MartinMods)
SUBJECT: Re: Reflection on Mouthpiece Theory Discourse
Jperks wrote:
"Benade: FMA page 471 and page 502
Nederveen: Figure 27.4
What is the basis for this discrepancy?"
MartinMods wrote:
Benade, in both instances refers specifically to very complete conical air columns (bassoon), and states that for less complete cones (saxophones) the tuning effect is less pronounced.
Nederveen's chart is based entirely upon computations using a theoretical formula, again, as regards specifically the bassoon. In the next paragraph, he qualifies this result with, "As a matter of fact, no such deviations are experienced in reality. Therefore, mechanisms must exist which provide compensations."
________________________________
From: perksjim <mcbop@...>
To: MouthpieceWork@yahoogroups.com
Sent: Mon, October 12, 2009 6:58:29 PM
Subject: [MouthpieceWork] Reflection on Mouthpiece Theory Discourse
THEORY/PRACTICE TUNING DISCREPANCY
Most of you subscribe to the following:
"Yes, tuning in the low register is by volume,
tuning of the high register is by length."
However, theory indicates that volume has little effect on low notes
and great effect on high notes.
Benade: FMA page 471 and page 502
Nederveen: Figure 27.4
What is the basis for this discrepancy?
FROM: perksjim (Jim West)
SUBJECT: Re: Reflection on Mouthpiece Theory Discourse
jim:
"However, theory indicates that volume has little effect on low notes
and great effect on high notes.
Benade: FMA page 471 and page 502
Nederveen: Figure 27.4"
MartinMods wrote:
Benade, in both instances refers specifically to very complete conical air columns (bassoon), and states that for less complete cones (saxophones) the tuning effect is less pronounced.
Nederveen's chart is based entirely upon computations using a theoretical formula, again, as regards specifically the bassoon. In the next paragraph, he qualifies this result with, "As a matter of fact, no such deviations are experienced in reality. Therefore, mechanisms must exist which provide compensations."
jim responds:
I am surprised that the bassoon has a lesser truncation ratio than the sax. The angle of
conicity for the bassoon is 4 times shallower than the sax. That should put the bassoon
missing apex way out there.
Read the Nederveen again, his writing is not always easy to follow. His "As a matter of fact, no such deviations are experienced in reality." refers to the chamber volume being zero. He then shows in the graft how that deviation is affected by increasing chamber volume. It indicates that high frequencies are much more sensitive to volume than low frequencies.
JPerks Wrote: "
Question: {Regarding the use of W-curves.}
He shows the curves starting at the missing apex. Do I need to start
them at the physical MP tip and shorten the waves according to length
proportional to volume?"
MartinMods Wrote: Go with the physical reality described by your measurements.
jim asks:
What/how physical measurements? Do I move a ring (inside) around with a magnet (outside)
and try to ascertain peaks and valleys?
MartinMods Wrote:
The higher harmonic resonances above Fc, which one clearly sees in a spectral analysis, are still present and they are audible. That they lie above Fc merely means that they do not supply energy to the harmonic regime.
jim sez:
Yes they are produced by the reed harmonics. Do you agree, that above Fc, shape isn't as
important?
Sorry about my link. Does it open in "Files>Methods?
jim
----- Original Message -----
From: MartinMods
To: MouthpieceWork@yahoogroups.com
Sent: Monday, October 12, 2009 5:23 PM
Subject: Re: [MouthpieceWork] Reflection on Mouthpiece Theory Discourse
JPerks Wrote:
"Speaking of W-curves, it would be nice to have an Excel version.
Somebody should dig out Benade's paper. I use the curves he shows
for an oboe in his "Acoustic Evolution of Wind Instruments" .
MartinMods Wrote: When I have time, I'm going to plug them into Comsol and make an interactive/animated W-Curves Chart.
JPerks Wrote: "
Question:
He shows the curves starting at the missing apex. Do I need to start
them at the physical MP tip and shorten the waves according to length
proportional to volume?"
MartinMods Wrote: Go with the physical reality described by your measurements.
JPerks Wrote:
"Most of you subscribe to the following:
"Yes, tuning in the low register is by volume,
tuning of the high register is by length."
However, theory indicates that volume has little effect on low notes
and great effect on high notes.
Benade: FMA page 471 and page 502
Nederveen: Figure 27.4
What is the basis for this discrepancy?"
MartinMods Wrote: Tuning is affected by length and also diameter of the air column at the compression anti-nodes/displacement anti-nodes of the particular mode in question. This equates to volume more or less. The mouthpiece chamber at the reed is the compression anti-node for every resonance on the instrument. Giving the mouthpiece chamber in the vicinity of the reed, more volume is the same as enlarging the bore, and the pitch of all modes will be lowered. Bore perturbations have more effect on the fundamental and lower modes, than the higher modes, so one tunes lower frequencies by volume at the compression anti-node.
The higher frequencies, being of shorter wave lengths, are more affected by tube length than are lower frequencies. It's a matter of proportion, so the high frequencies are tuned most effectively by adjusting tube length.
As one can not adjust length without changing volume, both must be taken into account. One tunes then the saxophone as a whole.
JPerks Wrote: "
An alto Fc is about 850 Hz. This means, that above about midway in the 2nd
register, the tone has no harmonic support, only the fundamental."
MartinMods Wrote: First - your link is full of spaces and does not work. Use the "create hyperlink" button to insert a web link.
The higher harmonic resonances above Fc, which one clearly sees in a spectral analysis, are still present and they are audible. That they lie above Fc merely means that they do not supply energy to the harmonic regime.
------------------------------------------------------------------------------
From: perksjim <mcbop@...>
To: MouthpieceWork@yahoogroups.com
Sent: Mon, October 12, 2009 6:58:29 PM
Subject: [MouthpieceWork] Reflection on Mouthpiece Theory Discourse
Hi Team!
I have really found your discussion of mouthpiece theory to be interesting
and informative. I think we all agree that there is more information/ speculation
and less real understanding about the mouthpiece than any other part of the
instrument. Here is a layman's cent and a half.
HELMHOLTZ
Characterizing the mouthpiece as a Helmholtz resonator is unproductive.
The saxophone is not an air-column with a Helmholtz jug stuck on top.
The saxophone is a truncated-cone air-column with functional
perturbations. ***
The effect of adding a constriction ring depends on where it is relative
to the W-curves, and not depended on its effect on an imaginary Helmholtz
resonator.
--- lancelotburt <lancelotburt@ yahoo.com> wrote:
" Additionally, Bernoulli effects aside, it is still an air column, with a compression anti-node, an irregular bore, and a displacement anti-node at the other end, and as such, the effects of bore irregularities on the pitch of the different modes of different notes, each with a different wave length, still apply - even more so, since it all starts here. Given accurate cross-sectional volume information along the entire length of the truncation, one could make a W curve chart that would assist greatly in analysis of which shape where does what to which resonance mode, of which note, pitch-wise, in every register, and how to align resonances for optimal harmonic regime formation. I'm surprised that such mouthpiece design/analysis software is not abound yet - W Curve Chart excel sheets anyway."
YES!
Speaking of W-curves, it would be nice to have an Excel version.
Somebody should dig out Benade's paper. I use the curves he shows
for an oboe in his "Acoustic Evolution of Wind Instruments" .
Question:
He shows the curves starting at the missing apex. Do I need to start
them at the physical MP tip and shorten the waves according to length
proportional to volume?
THEORY/PRACTICE TUNING DISCREPANCY
Most of you subscribe to the following:
"Yes, tuning in the low register is by volume,
tuning of the high register is by length."
However, theory indicates that volume has little effect on low notes
and great effect on high notes.
Benade: FMA page 471 and page 502
Nederveen: Figure 27.4
What is the basis for this discrepancy?
Changing the mouthpiece position affects the relationship of the
low bore notes to the high bore notes, but moving the MP also changes
the volume. Hence, moving the mouthpiece should have different effects
on the registers.
Since volume affects frequency response, I set my chamber volume
for best partial alignment to harmonics, determined mostly by the sound,
strength and stability of the notes throughout the full range of the instrument.
NECK CYLINDER
The cylindrical end of the neck made to accept the MP may not be
a problem. In fact, it may be acoustically necessary to compensate
for high frequency partial compression due to big tone-hole length
correction at high frequencies.
Benade: FMA, Page 432
Benade: Horns, Strings, and Harmony, Page 213
Frs
All of the tone holes occur below the neck, so one wants the geometry
above this point to provide an acoustic quasi-cone. The bore is nearly
conic and the conicity easy to measure; the neck is not. Therefore,
Benade, as usual, is correct.
Would like some feedback on my:
http://f1.grp. yahoofs.com/ v1/INfMSt- Qukoz8pAdlxU8oo9 qNH5J29qtN7UTPFt r9Ia4GFN3VXZ5zz2 JP3oOnODgkhf36HG 8ahy1F7CJIHRm2CO wjHjXvQ/Methods/ C_melody% 20Buescher% 20TT%20117549_ 2.xls
CUTOFF FREQUENCY (Fc)
An alto Fc is about 850 Hz. This means, that above about midway in the 2nd
register, the tone has no harmonic support, only the fundamental. So, above Fc
the frequency is unaffected by shape. So we don't need to talk about high
frequencies in the MP, except for turbulence. Of course, the MP or MP
and neck alone have no cutoff frequency because there is no tone-hole lattice.
By the way, turbulence degrades motion, DC or AC.
Benade suggests that a harmonic above Fc should be provided by player
adjustments to set the reed frequency (Fr). Isn't this technique the opposite of
those that say the embouchure should remain fixed? Has anybody cut open a
mouthpiece so as to measure Fr?
IMPEDANCE MATCHING
I have seen no discussion about matching the acoustic impedance of the narrow MP
tip with the big chamber. The audio profession does it with Bessel curves, such
as an audio horn loudspeaker. Does a rollover baffle imply a quasi-bessel curve?
What is a MP S-curve?
***
Fletcher refers to brass mouthpiece measurements. He shows that changing
a brass MP size has little effect on frequency. It mostly changes the
frequency of amplitude enhancement. We know that changing the sax MP
size does change the frequency. Also the Q of the sax MP Helmholtz is very
low compared to a brass MP (Q is proportional to the square root of the
volume divided by the cube power of the constriction cross section). Plus
the reed elastic boundary also degrades the Q. I think Fletcher is mistaken
about the sax MP being analogous to the brass MP Helmholtz jug.
jim
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FROM: kymarto (kymarto123@...)
SUBJECT: Re: Reflection on Mouthpiece Theory Discourse
perksjim <mcbop@...> wrote: Hi Team! I have really found your discussion of mouthpiece theory to be interesting and informative. I think we all agree that there is more information/speculation and less real understanding about the mouthpiece than any other part of the instrument. Here is a layman's cent and a half. HELMHOLTZ Characterizing the mouthpiece as a Helmholtz resonator is unproductive. The saxophone is not an air-column with a Helmholtz jug stuck on top. The saxophone is a truncated-cone air-column with functional perturbations. *** Toby: Absolutely not! The Helmholtz resonance of the mpc must match the Helmholtz resonance of the missing apical section to align the higher modes when the wavelength is shorter than 1/4 wavelength of the truncated section (in my understanding). Here is an interesting quote from a new entry in the UNSW FAQ: "..... woodwind instruments are not simply truncated cones. The inside the saxophone mouthpiece is not a continuation of the conical bore: there is an extra volume in the mouthpiece. Informally, we could can describe it this way: imagine a wave of air flowing up the bore towards the reed, in both a complete cone and a real saxophone. In the saxophone, the air arrives at the mouthpiece and starts pouring into it, gradually raising the pressure. When the pressure is high enough, it forces the air back, and a reflection has occurred. Of course, the bigger the volume of the mouthpiece, the longer it takes before the pressure builds up and the reflection occurs. Meanwhile, the pulse in the complete cone is completing the longer path to the end of the bore, and then its reflection occurs. (Technically, we would say that this volume is an acoustic compliance and (using a perturbation method due to Helmholtz) this compliance flattens all of the resonances that have a pressure antinode there.) It turns out that, if you make the volume of the mouthpiece equal to the missing volume of the cone, the frequency of the first resonance is about the same, although this approximation only works if the truncation is a reasonably small fraction of the total length." However it is a question of the behavior of the spherical wavefront, as opposed to the planar wavefront in a cylindrical instrument, which complicates matters in a cone (again IMU), in that it depends not only on length but on diameter. Short wavelengths are relatively more disturbed because the mpc with its incorrect shape represent more of their total length. Getting the Helmholtz resonance correct at least allows them to 'see' a better representation of the resonance structure of the missing apex. The effect of adding a constriction ring depends on where it is relative to the W-curves, and not depended on its effect on an imaginary Helmholtz resonator. Toby: Functionally, the entire area under the reed is a pressure antinode. So this already screws up everything at the top of the mpc. If you think of a complete cone, you will see that the very apex of the cone has to be a node, since all waves reflect from there. As you move further from the apex, the position of the nodes begins to spread out as a function of the wavelengths of the harmonics of the fundamental (as determined by total cone length). In the truncated cone, those positions no longer exist, since they are past the truncation point. There is no way to recover the missing resonance structure past the point of truncation, so all the resonances which have a node there are going to be disrupted. Most of those are too high to be of much consequence, and mode locking will pull what's left into correct harmonic alignment with the stronger peaks of lower resonances which will determine basic frequency of the regime of oscillation. But if higher notes have important partials with nodes which lie past the point of truncation, their resonances are affected (all modes are widened in a truncated cone), and this can seriously throw off the tuning, because now important and influential members of the regime of oscillation are no longer at correct integer intervals and exert a lot of pull on the final frequency. However if you match the Helmholtz resonance of the mpc compliance with that of the truncated cone, you at least have gotten the first mode resonance correct, and this is generally enough to be in the ballpark for any note which can be played, although as Dr. Joe Wolfe says, "for higher frequencies, all bets are off." It is interesting to note that Scavone postulates that the long, narrow chambered mpc he tested played with more high harmonic content than a fat, short chambered one because the shape more nearly approximated the shape of the conic apex, preserving its resonance structure and thus not destructively interfering with the high partials. Timing is everything ;-) In terms of W curves, for notes of lower frequency, there is not much difference in the curves in the area of the mpc, at least insofar as the stronger, lower resonances of the regime of oscillation that determine the frequency of the sounding note go.
FROM: lancelotburt (MartinMods)
SUBJECT: Re: Reflection on Mouthpiece Theory Discourse
jim
asks:
What/how physical measurements? Do I move a ring
(inside) around with a magnet (outside)
and
try to ascertain peaks and valleys?
millimeter by millimeter cross sectional volume measurements/calculations, the entire length of the air column container.
________________________________
From: Jim West <mcbop@...>
To: MouthpieceWork@yahoogroups.com
Sent: Tue, October 13, 2009 8:40:31 PM
Subject: Re: [MouthpieceWork] Reflection on Mouthpiece Theory Discourse
jim:
"However, theory indicates that volume has little effect on low
notes
and great effect on high notes.
Benade:
FMA page 471 and page 502
Nederveen: Figure
27.4"
MartinMods
wrote:
Benade, in both instances refers
specifically to very complete conical air columns (bassoon), and states that for
less complete cones (saxophones) the tuning effect is less
pronounced.
Nederveen's chart is based entirely upon
computations using a theoretical formula, again, as regards specifically the
bassoon. In the next paragraph, he qualifies this result with, "As a
matter of fact, no such deviations are experienced in reality. Therefore,
mechanisms must exist which provide
compensations. "
jim responds:
I am surprised that the bassoon has
a lesser truncation ratio than the sax. The angle of
conicity for the bassoon is 4 times
shallower than the sax. That should put the bassoon
missing apex way out
there.
Read the Nederveen again, his writing
is not always easy to follow. His "As a matter of fact, no such deviations are experienced
in reality." refers to the chamber volume being zero. He then shows in the graft how that deviation is affected by increasing chamber
volume. It indicates that high frequencies are much more sensitive to volume than low
frequencies.
JPerks Wrote: "
Question: {Regarding the
use of W-curves.}
He shows the curves
starting at the missing apex. Do I need to start
them at the physical MP
tip and shorten the waves according to length
proportional to
volume?"
MartinMods Wrote: Go with the physical reality
described by your measurements.
jim
asks:
What/how physical measurements? Do I move a ring
(inside) around with a magnet (outside)
and
try to ascertain peaks and valleys?
MartinMods Wrote:
The higher
harmonic resonances above Fc, which one clearly sees in a spectral analysis, are
still present and they are audible. That they lie above Fc merely means
that they do not supply energy to the harmonic
regime.
jim
sez:
Yes they are produced by the reed
harmonics. Do you agree, that above Fc, shape isn't as
important?
Sorry about my link. Does it open in
"Files>Methods?
jim
----- Original Message -----
>From: MartinMods
>To: MouthpieceWork@ yahoogroups. com
>Sent: Monday, October 12, 2009 5:23
> PM
>Subject: Re: [MouthpieceWork] Reflection
> on Mouthpiece Theory Discourse
>
>
>JPerks Wrote:
>
>"Speaking of W-curves,
> it would be nice to have an Excel version.
>Somebody should dig out
> Benade's paper. I use the curves he shows
>for an oboe in his
> "Acoustic Evolution of Wind Instruments" .
>
>
>
>
>MartinMods Wrote: When I have time, I'm going to
> plug them into Comsol and make an interactive/ animated W-Curves Chart.
>
>
>JPerks Wrote: "
>
>Question:
>He shows the curves
> starting at the missing apex. Do I need to start
>them at the physical MP
> tip and shorten the waves according to length
>proportional to
> volume?"
>
>
>MartinMods Wrote: Go with the physical reality
> described by your measurements.
>
>
>JPerks Wrote:
>"Most of you subscribe
> to the following:
>
> "Yes, tuning in the
> low register is by volume,
>
> tuning of the high register is by length."
>
>However, theory indicates that volume has little effect on low
> notes
>and great effect on high notes.
> Benade:
> FMA page 471 and page 502
> Nederveen: Figure
> 27.4
>
>What is the basis for this discrepancy? "
>
>
>MartinMods Wrote: Tuning is
> affected by length and also diameter of the air column at the compression
> anti-nodes/displace ment anti-nodes of the particular mode in
> question. This equates to volume more or less. The mouthpiece
> chamber at the reed is the compression anti-node for every resonance on the
> instrument. Giving the mouthpiece chamber in the vicinity of the reed,
> more volume is the same as enlarging the bore, and the pitch of all modes will
> be lowered. Bore perturbations have more effect on the fundamental and
> lower modes, than the higher modes, so one tunes lower frequencies by volume
> at the compression anti-node.
>
>
>
>The higher frequencies, being of
> shorter wave lengths, are more affected by tube length than are lower
> frequencies. It's a matter of proportion, so the high frequencies are
> tuned most effectively by adjusting tube length.
>
>
>
>
>As one can not adjust length without
> changing volume, both must be taken into account. One tunes then the
> saxophone as a whole.
>
>
>JPerks Wrote: "
>An alto Fc is about 850 Hz. This means, that above about midway in the
> 2nd register, the tone has no
> harmonic support, only the fundamental. "
>
>MartinMods Wrote: First - your link is full
> of spaces and does not work. Use the "create hyperlink" button to insert
> a web link.
>
>The higher harmonic resonances above Fc, which one
> clearly sees in a spectral analysis, are still present and they are
> audible. That they lie above Fc merely means that they do not supply
> energy to the harmonic
> regime.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
________________________________
From: perksjim
> <mcbop@.... com>
>To: > MouthpieceWork@ yahoogroups. com
>Sent: Mon, October 12, 2009 6:58:29
> PM
>Subject: [MouthpieceWork]
> Reflection on Mouthpiece Theory Discourse
>
>
>Hi Team!
>
>I have really found
> your discussion of mouthpiece theory to be interesting
>and informative. I
> think we all agree that there is more information/ speculation
>and less real
> understanding about the mouthpiece than any other part of the
>instrument. Here is a
> layman's cent and a half.
>
>
>HELMHOLTZ
>
>Characterizing the
> mouthpiece as a Helmholtz resonator is unproductive.
>
>The saxophone is not an
> air-column with a Helmholtz jug stuck on top.
>The saxophone is a
> truncated-cone air-column with functional
>perturbations.
> ***
>
>The effect of adding a
> constriction ring depends on where it is relative
>to the W-curves, and
> not depended on its effect on an imaginary Helmholtz
>resonator.
>
>--- lancelotburt
> <lancelotburt@ yahoo.com> wrote:
>
>
>" Additionally,
> Bernoulli effects aside, it is still an air column, with a compression
> anti-node, an irregular bore, and a displacement anti-node at the other end,
> and as such, the effects of bore irregularities on the pitch of the different
> modes of different notes, each with a different wave length, still apply -
> even more so, since it all starts here. Given accurate cross-sectional volume
> information along the entire length of the truncation, one could make a W
> curve chart that would assist greatly in analysis of which shape where does
> what to which resonance mode, of which note, pitch-wise, in every register,
> and how to align resonances for optimal harmonic regime formation. I'm
> surprised that such mouthpiece design/analysis software is not abound yet - W
> Curve Chart excel sheets anyway."
>
>
>YES!
>
>Speaking of W-curves,
> it would be nice to have an Excel version.
>Somebody should dig out
> Benade's paper. I use the curves he shows
>for an oboe in his
> "Acoustic Evolution of Wind Instruments" .
>
>Question:
>He shows the curves
> starting at the missing apex. Do I need to start
>them at the physical MP
> tip and shorten the waves according to length
>proportional to volume?
>
>
>
>
>THEORY/PRACTICE TUNING
> DISCREPANCY
>
>Most of you subscribe
> to the following:
>
> "Yes, tuning in the
> low register is by volume,
>
> tuning of the high register is by length."
>
>However, theory indicates that volume has little effect on low
> notes
>and great effect on high notes.
> Benade:
> FMA page 471 and page 502
> Nederveen: Figure
> 27.4
>
>What is the basis for this discrepancy?
>
>Changing the mouthpiece position affects the relationship of
> the
>low bore notes to the high bore notes, but moving the MP also
> changes
>the volume. Hence, moving the mouthpiece should have different
> effects
>on the registers.
>
>Since volume affects frequency response, I set my chamber
> volume
>for best partial alignment to harmonics, determined mostly by the
> sound,
>strength and stability of the notes throughout the full range of the
> instrument.
>
>
>NECK CYLINDER
>
>The cylindrical end of the neck made to accept the MP may not be
>
>a problem. In fact, it may be acoustically necessary to
> compensate
>for high frequency partial compression due to big tone-hole length
>
>correction at high frequencies.
> Benade: FMA, Page 432
>
> Benade: Horns,
> Strings, and Harmony, Page 213
>
>
>Frs
>
>All of the tone holes occur below the neck, so one wants the
> geometry
>above this point to provide an acoustic quasi-cone. The bore is
> nearly
>conic and the conicity easy to measure; the neck is not. Therefore,
>
>Benade, as usual, is correct.
>
>Would like some feedback on my:
>
>http://f1.grp.
> yahoofs.com/ v1/INfMSt- Qukoz8pAdlxU8oo9 qNH5J29qtN7UTPFt r9Ia4GFN3VXZ5zz2
> JP3oOnODgkhf36HG 8ahy1F7CJIHRm2CO wjHjXvQ/Methods/ C_melody% 20Buescher%
> 20TT%20117549_ 2.xls
>
>
>
> CUTOFF
> FREQUENCY (Fc)
>
>An alto Fc is about 850 Hz. This means, that above about midway in the
> 2nd
>register, the tone has no harmonic support, only the fundamental. So,
> above Fc
>the frequency is unaffected by shape. So we don't need to talk about
> high
>frequencies in the MP, except for turbulence. Of course, the MP or
> MP
>and neck alone have no cutoff frequency because there is no tone-hole
> lattice.
>
>By the way, turbulence degrades motion, DC or AC.
>
>
>Benade suggests that a harmonic above Fc should be provided by
> player
>adjustments to set the reed frequency (Fr). Isn't this technique the
> opposite of
>those that say the embouchure should remain fixed? Has anybody cut open
> a
>mouthpiece so as to measure Fr?
>
>
>
>IMPEDANCE MATCHING
>
>I have seen no discussion about matching the acoustic impedance of the
> narrow MP
>tip with the big chamber. The audio profession does it with
> Bessel curves,
> such
>as an audio horn loudspeaker. Does a rollover baffle imply a
> quasi-bessel curve?
>What is a MP S-curve?
>
>
>
>***
>Fletcher refers to
> brass mouthpiece measurements. He shows that changing
>a brass MP size has
> little effect on frequency. It mostly changes the
>frequency of amplitude
> enhancement. We know that changing the sax MP
>size does change the
> frequency. Also the Q of the sax MP Helmholtz is very
>low compared to a brass
> MP (Q is proportional to the square root of the
>volume divided by the
> cube power of the constriction cross section). Plus
>the reed elastic
> boundary also degrades the Q. I think Fletcher is mistaken
>about the sax MP being
> analogous to the brass MP Helmholtz jug.
>
>
> jim
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
________________________________
>
>No virus found in this incoming message.
>Checked by AVG -
> www.avg.com
>Version: 8.5.421 / Virus Database: 270.14.12/2431 - Release
> Date: 10/12/09 13:01:00
>
FROM: kymarto (Toby)
SUBJECT: Re: Reflection on Mouthpiece Theory Discourse
Since the metal thickness is pretty much going to be consistent, how about outside measurements minus the metal thickness? I think you can pretty well extrapolate between points if they are not too far apart (not ideal, but...). A good set of calipers should get you going. In FMA Benade has a handy-dandy formula for calculating the effective widening at closed tone holes, which is NOT the same as if the widening were at the walls.
Toby
----- Original Message -----
From: MartinMods
To: MouthpieceWork@yahoogroups.com
Sent: Wednesday, October 14, 2009 1:22 PM
Subject: Re: [MouthpieceWork] Reflection on Mouthpiece Theory Discourse
jim asks:
What/how physical measurements? Do I move a ring (inside) around with a magnet (outside)
and try to ascertain peaks and valleys?
millimeter by millimeter cross sectional volume measurements/calculations, the entire length of the air column container.
------------------------------------------------------------------------------
From: Jim West <mcbop@...>
To: MouthpieceWork@yahoogroups.com
Sent: Tue, October 13, 2009 8:40:31 PM
Subject: Re: [MouthpieceWork] Reflection on Mouthpiece Theory Discourse
jim:
"However, theory indicates that volume has little effect on low notes
and great effect on high notes.
Benade: FMA page 471 and page 502
Nederveen: Figure 27.4"
MartinMods wrote:
Benade, in both instances refers specifically to very complete conical air columns (bassoon), and states that for less complete cones (saxophones) the tuning effect is less pronounced.
Nederveen's chart is based entirely upon computations using a theoretical formula, again, as regards specifically the bassoon. In the next paragraph, he qualifies this result with, "As a matter of fact, no such deviations are experienced in reality. Therefore, mechanisms must exist which provide compensations. "
jim responds:
I am surprised that the bassoon has a lesser truncation ratio than the sax. The angle of
conicity for the bassoon is 4 times shallower than the sax. That should put the bassoon
missing apex way out there.
Read the Nederveen again, his writing is not always easy to follow. His "As a matter of fact, no such deviations are experienced in reality." refers to the chamber volume being zero. He then shows in the graft how that deviation is affected by increasing chamber volume. It indicates that high frequencies are much more sensitive to volume than low frequencies.
JPerks Wrote: "
Question: {Regarding the use of W-curves.}
He shows the curves starting at the missing apex. Do I need to start
them at the physical MP tip and shorten the waves according to length
proportional to volume?"
MartinMods Wrote: Go with the physical reality described by your measurements.
jim asks:
What/how physical measurements? Do I move a ring (inside) around with a magnet (outside)
and try to ascertain peaks and valleys?
MartinMods Wrote:
The higher harmonic resonances above Fc, which one clearly sees in a spectral analysis, are still present and they are audible. That they lie above Fc merely means that they do not supply energy to the harmonic regime.
jim sez:
Yes they are produced by the reed harmonics. Do you agree, that above Fc, shape isn't as
important?
Sorry about my link. Does it open in "Files>Methods?
jim
----- Original Message -----
From: MartinMods
To: MouthpieceWork@ yahoogroups. com
Sent: Monday, October 12, 2009 5:23 PM
Subject: Re: [MouthpieceWork] Reflection on Mouthpiece Theory Discourse
JPerks Wrote:
"Speaking of W-curves, it would be nice to have an Excel version.
Somebody should dig out Benade's paper. I use the curves he shows
for an oboe in his "Acoustic Evolution of Wind Instruments" .
MartinMods Wrote: When I have time, I'm going to plug them into Comsol and make an interactive/ animated W-Curves Chart.
JPerks Wrote: "
Question:
He shows the curves starting at the missing apex. Do I need to start
them at the physical MP tip and shorten the waves according to length
proportional to volume?"
MartinMods Wrote: Go with the physical reality described by your measurements.
JPerks Wrote:
"Most of you subscribe to the following:
"Yes, tuning in the low register is by volume,
tuning of the high register is by length."
However, theory indicates that volume has little effect on low notes
and great effect on high notes.
Benade: FMA page 471 and page 502
Nederveen: Figure 27.4
What is the basis for this discrepancy? "
MartinMods Wrote: Tuning is affected by length and also diameter of the air column at the compression anti-nodes/displace ment anti-nodes of the particular mode in question. This equates to volume more or less. The mouthpiece chamber at the reed is the compression anti-node for every resonance on the instrument. Giving the mouthpiece chamber in the vicinity of the reed, more volume is the same as enlarging the bore, and the pitch of all modes will be lowered. Bore perturbations have more effect on the fundamental and lower modes, than the higher modes, so one tunes lower frequencies by volume at the compression anti-node.
The higher frequencies, being of shorter wave lengths, are more affected by tube length than are lower frequencies. It's a matter of proportion, so the high frequencies are tuned most effectively by adjusting tube length.
As one can not adjust length without changing volume, both must be taken into account. One tunes then the saxophone as a whole.
JPerks Wrote: "
An alto Fc is about 850 Hz. This means, that above about midway in the 2nd
register, the tone has no harmonic support, only the fundamental. "
MartinMods Wrote: First - your link is full of spaces and does not work. Use the "create hyperlink" button to insert a web link.
The higher harmonic resonances above Fc, which one clearly sees in a spectral analysis, are still present and they are audible. That they lie above Fc merely means that they do not supply energy to the harmonic regime.
----------------------------------------------------------------------------
From: perksjim <mcbop@.... com>
To: MouthpieceWork@ yahoogroups. com
Sent: Mon, October 12, 2009 6:58:29 PM
Subject: [MouthpieceWork] Reflection on Mouthpiece Theory Discourse
Hi Team!
I have really found your discussion of mouthpiece theory to be interesting
and informative. I think we all agree that there is more information/ speculation
and less real understanding about the mouthpiece than any other part of the
instrument. Here is a layman's cent and a half.
HELMHOLTZ
Characterizing the mouthpiece as a Helmholtz resonator is unproductive.
The saxophone is not an air-column with a Helmholtz jug stuck on top.
The saxophone is a truncated-cone air-column with functional
perturbations. ***
The effect of adding a constriction ring depends on where it is relative
to the W-curves, and not depended on its effect on an imaginary Helmholtz
resonator.
--- lancelotburt <lancelotburt@ yahoo.com> wrote:
" Additionally, Bernoulli effects aside, it is still an air column, with a compression anti-node, an irregular bore, and a displacement anti-node at the other end, and as such, the effects of bore irregularities on the pitch of the different modes of different notes, each with a different wave length, still apply - even more so, since it all starts here. Given accurate cross-sectional volume information along the entire length of the truncation, one could make a W curve chart that would assist greatly in analysis of which shape where does what to which resonance mode, of which note, pitch-wise, in every register, and how to align resonances for optimal harmonic regime formation. I'm surprised that such mouthpiece design/analysis software is not abound yet - W Curve Chart excel sheets anyway."
YES!
Speaking of W-curves, it would be nice to have an Excel version.
Somebody should dig out Benade's paper. I use the curves he shows
for an oboe in his "Acoustic Evolution of Wind Instruments" .
Question:
He shows the curves starting at the missing apex. Do I need to start
them at the physical MP tip and shorten the waves according to length
proportional to volume?
THEORY/PRACTICE TUNING DISCREPANCY
Most of you subscribe to the following:
"Yes, tuning in the low register is by volume,
tuning of the high register is by length."
However, theory indicates that volume has little effect on low notes
and great effect on high notes.
Benade: FMA page 471 and page 502
Nederveen: Figure 27.4
What is the basis for this discrepancy?
Changing the mouthpiece position affects the relationship of the
low bore notes to the high bore notes, but moving the MP also changes
the volume. Hence, moving the mouthpiece should have different effects
on the registers.
Since volume affects frequency response, I set my chamber volume
for best partial alignment to harmonics, determined mostly by the sound,
strength and stability of the notes throughout the full range of the instrument.
NECK CYLINDER
The cylindrical end of the neck made to accept the MP may not be
a problem. In fact, it may be acoustically necessary to compensate
for high frequency partial compression due to big tone-hole length
correction at high frequencies.
Benade: FMA, Page 432
Benade: Horns, Strings, and Harmony, Page 213
Frs
All of the tone holes occur below the neck, so one wants the geometry
above this point to provide an acoustic quasi-cone. The bore is nearly
conic and the conicity easy to measure; the neck is not. Therefore,
Benade, as usual, is correct.
Would like some feedback on my:
http://f1.grp. yahoofs.com/ v1/INfMSt- Qukoz8pAdlxU8oo9 qNH5J29qtN7UTPFt r9Ia4GFN3VXZ5zz2 JP3oOnODgkhf36HG 8ahy1F7CJIHRm2CO wjHjXvQ/Methods/ C_melody% 20Buescher% 20TT%20117549_ 2.xls
CUTOFF FREQUENCY (Fc)
An alto Fc is about 850 Hz. This means, that above about midway in the 2nd
register, the tone has no harmonic support, only the fundamental. So, above Fc
the frequency is unaffected by shape. So we don't need to talk about high
frequencies in the MP, except for turbulence. Of course, the MP or MP
and neck alone have no cutoff frequency because there is no tone-hole lattice.
By the way, turbulence degrades motion, DC or AC.
Benade suggests that a harmonic above Fc should be provided by player
adjustments to set the reed frequency (Fr). Isn't this technique the opposite of
those that say the embouchure should remain fixed? Has anybody cut open a
mouthpiece so as to measure Fr?
IMPEDANCE MATCHING
I have seen no discussion about matching the acoustic impedance of the narrow MP
tip with the big chamber. The audio profession does it with Bessel curves, such
as an audio horn loudspeaker. Does a rollover baffle imply a quasi-bessel curve?
What is a MP S-curve?
***
Fletcher refers to brass mouthpiece measurements. He shows that changing
a brass MP size has little effect on frequency. It mostly changes the
frequency of amplitude enhancement. We know that changing the sax MP
size does change the frequency. Also the Q of the sax MP Helmholtz is very
low compared to a brass MP (Q is proportional to the square root of the
volume divided by the cube power of the constriction cross section). Plus
the reed elastic boundary also degrades the Q. I think Fletcher is mistaken
about the sax MP being analogous to the brass MP Helmholtz jug.
jim
----------------------------------------------------------------------------
No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 8.5.421 / Virus Database: 270.14.12/2431 - Release Date: 10/12/09 13:01:00
FROM: lancelotburt (MartinMods)
SUBJECT: Re: Reflection on Mouthpiece Theory Discourse
Just like with impedance measurements, they aren't complete unless you inclued the mouthpiece - it's part of the bore too, and as Benade points out in:
https://ccrma.stanford.edu/marl/Benade/documents/Benade-Perturbation-1985.pdf
In underlined text: "End modifications not only stretch and shrink Pn in the main air column, they also can slide it lengthwise along it. For this reason, end perts alter middle bore perts."
You can't measure the mouthpiece from the outside. Neither can one measure other important bore perturbations like tube couplings, which have steps in bore diameter, gaps, ridges, etc. Further, many vintage instruments (and it is these instruments which hold the most interest for this analysis) have been subject to years of use, abuse, and repair. More often than not, the body tube is no longer perfectly round.
External measurments would suffice to satisfy the curious, I'm sure, but to do serious alignment work a little more precision would probably be needed.
________________________________
From: Toby <kymarto123@...>
To: MouthpieceWork@yahoogroups.com
Sent: Wed, October 14, 2009 8:12:29 AM
Subject: Re: [MouthpieceWork] Reflection on Mouthpiece Theory Discourse
Since the metal thickness is pretty much going to
be consistent, how about outside measurements minus the metal thickness? I think
you can pretty well extrapolate between points if they are not too far apart
(not ideal, but...). A good set of calipers should get you going. In FMA Benade
has a handy-dandy formula for calculating the effective widening at closed tone
holes, which is NOT the same as if the widening were at the walls.
Toby
----- Original Message -----
>From: MartinMods
>To: MouthpieceWork@ yahoogroups. com
>Sent: Wednesday, October 14, 2009 1:22
> PM
>Subject: Re: [MouthpieceWork] Reflection
> on Mouthpiece Theory Discourse
>
>
>jim asks:
>What/how physical measurements? Do I move a ring
> (inside) around with a magnet (outside)
>and try to ascertain peaks and
> valleys?
>
>
>millimeter by millimeter
> cross sectional volume measurements/ calculations, the entire length of
> the air column container.
>
>
>
>
________________________________
From: Jim West <mcbop@.... com>
>To: MouthpieceWork@ yahoogroups. com
>Sent: Tue, October 13, 2009 8:40:31
> PM
>Subject: Re:
> [MouthpieceWork] Reflection on Mouthpiece Theory
> Discourse
>
>
>jim:
>"However, theory indicates that volume has little effect on low
> notes
>and great effect on high notes.
> Benade:
> FMA page 471 and page 502
> Nederveen: Figure
> 27.4"
> MartinMods
> wrote:
>
>
>Benade, in both instances refers
> specifically to very complete conical air columns (bassoon), and states that
> for less complete cones (saxophones) the tuning effect is less
> pronounced.
>
>
>Nederveen's chart is based entirely
> upon computations using a theoretical formula, again, as regards specifically
> the bassoon. In the next paragraph, he qualifies this result with, "As a
> matter of fact, no such deviations are experienced in reality.
> Therefore, mechanisms must exist which provide compensations.
> "
>
>jim responds:
>
>I am surprised that the bassoon has
> a lesser truncation ratio than the sax. The angle of
>conicity for the bassoon is 4 times
> shallower than the sax. That should put the bassoon
>missing apex way out
> there.
>Read the Nederveen again, his
> writing is not always easy to follow. His "As a matter of fact, no such deviations are
> experienced in reality." refers to the chamber
> volume being zero. He then shows in the graft
> how that deviation is affected by increasing chamber volume. It indicates that
> high frequencies are much more sensitive to volume than low frequencies.
>
>
>JPerks Wrote: "
>
>Question: {Regarding
> the use of W-curves.}
>He shows the curves
> starting at the missing apex. Do I need to start
>them at the physical MP
> tip and shorten the waves according to length
>proportional to
> volume?"
>
>
>MartinMods Wrote: Go with the physical reality
> described by your measurements.
>
>jim asks:
>What/how physical measurements? Do I move a ring
> (inside) around with a magnet (outside)
>and try to ascertain peaks and
> valleys?
>
>MartinMods Wrote:
>The higher
> harmonic resonances above Fc, which one clearly sees in a spectral analysis,
> are still present and they are audible. That they lie above Fc merely
> means that they do not supply energy to the harmonic
> regime.
>
>jim
> sez:
>Yes they are produced by the reed
> harmonics. Do you agree, that above Fc, shape isn't as
>
>important?
>
>Sorry about my link. Does it open
> in "Files>Methods?
>
>jim
>
>
>
>
>-----
>> Original Message -----
>>From: MartinMods
>>To: MouthpieceWork@ yahoogroups.
>> com
>>Sent: >> Monday, October 12, 2009 5:23 PM
>>Subject: >> Re: [MouthpieceWork] Reflection on Mouthpiece Theory Discourse
>>
>>
>>JPerks Wrote:
>>
>>"Speaking of
>> W-curves, it would be nice to have an Excel version.
>>Somebody should dig
>> out Benade's paper. I use the curves he shows
>>for an oboe in his
>> "Acoustic Evolution of Wind Instruments" .
>>
>>
>>
>>
>>MartinMods Wrote: When I have time, I'm going to
>> plug them into Comsol and make an interactive/ animated W-Curves Chart.
>>
>>
>>JPerks Wrote: "
>>
>>Question:
>>He shows the curves
>> starting at the missing apex. Do I need to start
>>them at the physical
>> MP tip and shorten the waves according to length
>>proportional to
>> volume?"
>>
>>
>>MartinMods Wrote: Go with the physical reality
>> described by your measurements.
>>
>>
>>JPerks Wrote:
>>"Most of you
>> subscribe to the following:
>>
>> "Yes, tuning in the
>> low register is by volume,
>>
>> tuning of the high register is by
>> length."
>>
>>However, theory indicates that volume has little effect on low
>> notes
>>and great effect on high notes.
>>
>> Benade: FMA page 471 and page
>> 502
>> Nederveen: Figure
>> 27.4
>>
>>What is the basis for this discrepancy? "
>>
>>
>>MartinMods Wrote: Tuning is
>> affected by length and also diameter of the air column at the compression
>> anti-nodes/displace ment anti-nodes of the particular mode in
>> question. This equates to volume more or less. The mouthpiece
>> chamber at the reed is the compression anti-node for every resonance on the
>> instrument. Giving the mouthpiece chamber in the vicinity of the reed,
>> more volume is the same as enlarging the bore, and the pitch of all modes
>> will be lowered. Bore perturbations have more effect on the
>> fundamental and lower modes, than the higher modes, so one tunes lower
>> frequencies by volume at the compression anti-node.
>>
>>
>>
>>
>>The higher frequencies, being of
>> shorter wave lengths, are more affected by tube length than are lower
>> frequencies. It's a matter of proportion, so the high frequencies are
>> tuned most effectively by adjusting tube length.
>>
>>
>>
>>
>>As one can not adjust length without
>> changing volume, both must be taken into account. One tunes then the
>> saxophone as a whole.
>>
>>
>>JPerks Wrote: "
>>An alto Fc is about 850 Hz. This means, that above about midway in
>> the 2nd register, the tone has
>> no harmonic support, only the fundamental. "
>>
>>MartinMods Wrote: First - your link is full
>> of spaces and does not work. Use the "create hyperlink" button to
>> insert a web link.
>>
>>The higher harmonic resonances above Fc,
>> which one clearly sees in a spectral analysis, are still present and they
>> are audible. That they lie above Fc merely means that they do not
>> supply energy to the harmonic
>> regime.
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
________________________________
From: perksjim
>> <mcbop@.... com>
>>To: MouthpieceWork@ yahoogroups.
>> com
>>Sent: Mon, October 12,
>> 2009 6:58:29 PM
>>Subject: >> [MouthpieceWork] Reflection on Mouthpiece Theory
>> Discourse
>>
>>
>>Hi Team!
>>
>>I have really found
>> your discussion of mouthpiece theory to be interesting
>>and informative. I
>> think we all agree that there is more information/ speculation
>>and less real
>> understanding about the mouthpiece than any other part of the
>>instrument. Here is a
>> layman's cent and a half.
>>
>>
>>HELMHOLTZ
>>
>>Characterizing the
>> mouthpiece as a Helmholtz resonator is unproductive.
>>
>>The saxophone is not
>> an air-column with a Helmholtz jug stuck on top.
>>The saxophone is a
>> truncated-cone air-column with functional
>>perturbations.
>> ***
>>
>>The effect of adding
>> a constriction ring depends on where it is relative
>>to the W-curves, and
>> not depended on its effect on an imaginary Helmholtz
>>resonator.
>>
>>--- lancelotburt
>> <lancelotburt@ yahoo.com> wrote:
>>
>>
>>" Additionally,
>> Bernoulli effects aside, it is still an air column, with a compression
>> anti-node, an irregular bore, and a displacement anti-node at the other end,
>> and as such, the effects of bore irregularities on the pitch of the
>> different modes of different notes, each with a different wave length, still
>> apply - even more so, since it all starts here. Given accurate
>> cross-sectional volume information along the entire length of the
>> truncation, one could make a W curve chart that would assist greatly in
>> analysis of which shape where does what to which resonance mode, of which
>> note, pitch-wise, in every register, and how to align resonances for optimal
>> harmonic regime formation. I'm surprised that such mouthpiece
>> design/analysis software is not abound yet - W Curve Chart excel sheets
>> anyway."
>>
>>
>>YES!
>>
>>Speaking of W-curves,
>> it would be nice to have an Excel version.
>>Somebody should dig
>> out Benade's paper. I use the curves he shows
>>for an oboe in his
>> "Acoustic Evolution of Wind Instruments" .
>>
>>Question:
>>He shows the curves
>> starting at the missing apex. Do I need to start
>>them at the physical
>> MP tip and shorten the waves according to length
>>proportional to
>> volume?
>>
>>
>>
>>THEORY/PRACTICE
>> TUNING DISCREPANCY
>>
>>Most of you subscribe
>> to the following:
>>
>> "Yes, tuning in the
>> low register is by volume,
>>
>> tuning of the high register is by
>> length."
>>
>>However, theory indicates that volume has little effect on low
>> notes
>>and great effect on high notes.
>>
>> Benade: FMA page 471 and page
>> 502
>> Nederveen: Figure
>> 27.4
>>
>>What is the basis for this discrepancy?
>>
>>Changing the mouthpiece position affects the relationship of
>> the
>>low bore notes to the high bore notes, but moving the MP also
>> changes
>>the volume. Hence, moving the mouthpiece should have different
>> effects
>>on the registers.
>>
>>Since volume affects frequency response, I set my chamber
>> volume
>>for best partial alignment to harmonics, determined mostly by the
>> sound,
>>strength and stability of the notes throughout the full range of the
>> instrument.
>>
>>
>>NECK CYLINDER
>>
>>The cylindrical end of the neck made to accept the MP may not be
>>
>>a problem. In fact, it may be acoustically necessary to
>> compensate
>>for high frequency partial compression due to big tone-hole length
>>
>>correction at high frequencies.
>> Benade: FMA, Page
>> 432
>> Benade: Horns,
>> Strings, and Harmony, Page 213
>>
>>
>>Frs
>>
>>All of the tone holes occur below the neck, so one wants the
>> geometry
>>above this point to provide an acoustic quasi-cone. The bore is
>> nearly
>>conic and the conicity easy to measure; the neck is not. Therefore,
>>
>>Benade, as usual, is correct.
>>
>>Would like some feedback on my:
>>
>>http://f1.grp.
>> yahoofs.com/ v1/INfMSt- Qukoz8pAdlxU8oo9 qNH5J29qtN7UTPFt r9Ia4GFN3VXZ5zz2
>> JP3oOnODgkhf36HG 8ahy1F7CJIHRm2CO wjHjXvQ/Methods/ C_melody% 20Buescher%
>> 20TT%20117549_ 2.xls
>>
>>
>>
>> CUTOFF
>> FREQUENCY (Fc)
>>
>>An alto Fc is about 850 Hz. This means, that above about midway in
>> the 2nd
>>register, the tone has no harmonic support, only the fundamental. So,
>> above Fc
>>the frequency is unaffected by shape. So we don't need to talk about
>> high
>>frequencies in the MP, except for turbulence. Of course, the MP or
>> MP
>>and neck alone have no cutoff frequency because there is no tone-hole
>> lattice.
>>
>>By the way, turbulence degrades motion, DC or AC.
>>
>>
>>Benade suggests that a harmonic above Fc should be provided by
>> player
>>adjustments to set the reed frequency (Fr). Isn't this technique the
>> opposite of
>>those that say the embouchure should remain fixed? Has anybody cut
>> open a
>>mouthpiece so as to measure Fr?
>>
>>
>>
>>IMPEDANCE MATCHING
>>
>>I have seen no discussion about matching the acoustic impedance of
>> the narrow MP
>>tip with the big chamber. The audio profession does it with
>> Bessel curves,
>> such
>>as an audio horn loudspeaker. Does a rollover baffle imply a
>> quasi-bessel curve?
>>What is a MP S-curve?
>>
>>
>>
>>***
>>Fletcher refers to
>> brass mouthpiece measurements. He shows that changing
>>a brass MP size has
>> little effect on frequency. It mostly changes the
>>frequency of
>> amplitude enhancement. We know that changing the sax MP
>>size does change the
>> frequency. Also the Q of the sax MP Helmholtz is very
>>low compared to a
>> brass MP (Q is proportional to the square root of the
>>volume divided by the
>> cube power of the constriction cross section). Plus
>>the reed elastic
>> boundary also degrades the Q. I think Fletcher is mistaken
>>about the sax MP
>> being analogous to the brass MP Helmholtz jug.
>>
>>
>> jim
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
________________________________
>>
>>No virus found in this incoming message.
>>Checked by AVG
>> - www.avg.com
>>Version: 8.5.421 / Virus Database: 270.14.12/2431 - Release Date:
>> 10/12/09 13:01:00
>>
>
FROM: tenorman1952 (tenorman1952)
SUBJECT: Re: Reflection on Mouthpiece Theory Discourse
--- In MouthpieceWork@yahoogroups.com, MartinMods <lancelotburt@...> wrote: > > Just like with impedance measurements, they aren't complete unless you inclued the mouthpiece - it's part of the bore too, and as Benade points out in: > > https://ccrma.stanford.edu/marl/Benade/documents/Benade-Perturbation-1985.pdf First, guys, please trim your replies, quoting only what is necessary. Back to impedance... in the real world, how does one measure impedance of the mouthpiece? or rather, the mouthpiece/reed? And if you know the impedance, what do you do with it? Paul C.
FROM: lancelotburt (MartinMods)
SUBJECT: Re: Reflection on Mouthpiece Theory Discourse
"Back to impedance... in the real world, how does one measure impedance of the mouthpiece? or rather, the mouthpiece/reed?
And if you know the impedance, what do you do with it?
Paul C."
Basically, it's a way to measure the resonance peaks of an air column, for any given fingered tone. That tells you a lot about how the instrument will play and how to adjust resonance alignment to improve things.
Just do a search for "woodwind impedance measurement". There are numerous publications on the different methods used, with diagrams, charts, etc. One version used a special attachement that fit on the mouthpiece table and sealed, as if the reed were closed.
Some guys use pulse reflectometry, to reconstruct a model of the air column.
None of the methods are perfect.
FROM: saxgourmet (STEVE GOODSON)
SUBJECT: Re: Reflection on Mouthpiece Theory Discourse
What is the practical application? From: MouthpieceWork@yahoogroups.com [mailto:MouthpieceWork@yahoogroups.com] On Behalf Of MartinMods Sent: Wednesday, October 14, 2009 1:55 PM To: MouthpieceWork@yahoogroups.com Subject: Re: [MouthpieceWork] Re: Reflection on Mouthpiece Theory Discourse "Back to impedance... in the real world, how does one measure impedance of the mouthpiece? or rather, the mouthpiece/reed? And if you know the impedance, what do you do with it? Paul C." Basically, it's a way to measure the resonance peaks of an air column, for any given fingered tone. That tells you a lot about how the instrument will play and how to adjust resonance alignment to improve things. Just do a search for "woodwind impedance measurement". There are numerous publications on the different methods used, with diagrams, charts, etc. One version used a special attachement that fit on the mouthpiece table and sealed, as if the reed were closed. Some guys use pulse reflectometry, to reconstruct a model of the air column. None of the methods are perfect.
FROM: lancelotburt (MartinMods)
SUBJECT: Re: Reflection on Mouthpiece Theory Discourse
....talking about impedance (resonance peak) analysis of a saxophone.
________________________________
From: STEVE GOODSON <saxgourmet@...>
To: MouthpieceWork@yahoogroups.com
Sent: Wed, October 14, 2009 3:30:14 PM
Subject: RE: [MouthpieceWork] Re: Reflection on Mouthpiece Theory Discourse
What is the practical application?
I find a good map to be of assistance occasionally.
FROM: perksjim (Jim West)
SUBJECT: Re: Reflection on Mouthpiece Theory Discourse
Toby writes:
"Toby: Absolutely not! The Helmholtz resonance of the mpc must match the Helmholtz resonance of the missing apical section to align the higher modes when the wavelength is shorter than 1/4 wavelength of the truncated section (in my understanding)."
"
jim responds:
Hi Toby!
This stuff is difficult to talk about without having a common nomenclature.
What is your definition of "Helmholtz resonance"? Helmholtz has his fingerprints over
most of acoustic theory, including both lumped and distributed systems. If you are
talking about a "Helmholtz Resonator", then, I would tend to understand that you are talking
lumped, and we have the basis for a heated debate. If you are talking about Helmholtz
resonances involved in distributed systems, then I agree with you. Frs?
Our friends at UNSW do some good research and teaching. But remember they are
colleagues of Fletcher. Do you know of a source for the lumped MP outside of that
clique?
STEVE GOODSON wrote:
"What is the practical application?"
jim responds:
From my original:
"Since volume affects frequency response, I set my chamber volume
for best partial alignment to harmonics, determined mostly by the sound,
strength and stability of the notes throughout the full range of the instrument."
Without paying any attention to pitch and using my preferred embouchure,
I find a MP place on my neck that gives the best sound/stability over the full
note range. I then check the tuning. If I can move the MP to tune to 440 without
degrading the sound, I am done. If this doesn't work, I try a different horn.
This is a "practical application" for me. Other examples available.
jim
----- Original Message -----
From: kymarto123@....jp
To: MouthpieceWork@yahoogroups.com
Sent: Tuesday, October 13, 2009 6:41 PM
Subject: Re: [MouthpieceWork] Reflection on Mouthpiece Theory Discourse
perksjim <mcbop@...> wrote:
Hi Team!
I have really found your discussion of mouthpiece theory to be interesting
and informative. I think we all agree that there is more information/speculation
and less real understanding about the mouthpiece than any other part of the
instrument. Here is a layman's cent and a half.
HELMHOLTZ
Characterizing the mouthpiece as a Helmholtz resonator is unproductive.
The saxophone is not an air-column with a Helmholtz jug stuck on top.
The saxophone is a truncated-cone air-column with functional
perturbations. ***
Toby: Absolutely not! The Helmholtz resonance of the mpc must match the Helmholtz resonance of the missing apical section to align the higher modes when the wavelength is shorter than 1/4 wavelength of the truncated section (in my understanding).
Here is an interesting quote from a new entry in the UNSW FAQ:
"..... woodwind instruments are not simply truncated cones. The inside the saxophone mouthpiece is not a continuation of the conical bore: there is an extra volume in the mouthpiece. Informally, we could can describe it this way: imagine a wave of air flowing up the bore towards the reed, in both a complete cone and a real saxophone. In the saxophone, the air arrives at the mouthpiece and starts pouring into it, gradually raising the pressure. When the pressure is high enough, it forces the air back, and a reflection has occurred. Of course, the bigger the volume of the mouthpiece, the longer it takes before the pressure builds up and the reflection occurs. Meanwhile, the pulse in the complete cone is completing the longer path to the end of the bore, and then its reflection occurs. (Technically, we would say that this volume is an acoustic compliance and (using a perturbation method due to Helmholtz) this compliance flattens all of the resonances that have a pressure antinode there.) It turns out that, if you make the volume of the mouthpiece equal to the missing volume of the cone, the frequency of the first resonance is about the same, although this approximation only works if the truncation is a reasonably small fraction of the total length."
However it is a question of the behavior of the spherical wavefront, as opposed to the planar wavefront in a cylindrical instrument, which complicates matters in a cone (again IMU), in that it depends not only on length but on diameter. Short wavelengths are relatively more disturbed because the mpc with its incorrect shape represent more of their total length. Getting the Helmholtz resonance correct at least allows them to 'see' a better representation of the resonance structure of the missing apex.
The effect of adding a constriction ring depends on where it is relative to the W-curves, and not depended on its effect on an imaginary Helmholtz resonator.
Toby: Functionally, the entire area under the reed is a pressure antinode. So this already screws up everything at the top of the mpc. If you think of a complete cone, you will see that the very apex of the cone has to be a node, since all waves reflect from there. As you move further from the apex, the position of the nodes begins to spread out as a function of the wavelengths of the harmonics of the fundamental (as determined by total cone length). In the truncated cone, those positions no longer exist, since they are past the truncation point.
There is no way to recover the missing resonance structure past the point of truncation, so all the resonances which have a node there are going to be disrupted. Most of those are too high to be of much consequence, and mode locking will pull what's left into correct harmonic alignment with the stronger peaks of lower resonances which will determine basic frequency of the regime of oscillation.
But if higher notes have important partials with nodes which lie past the point of truncation, their resonances are affected (all modes are widened in a truncated cone), and this can seriously throw off the tuning, because now important and influential members of the regime of oscillation are no longer at correct integer intervals and exert a lot of pull on the final frequency.
However if you match the Helmholtz resonance of the mpc compliance with that of the truncated cone, you at least have gotten the first mode resonance correct, and this is generally enough to be in the ballpark for any note which can be played, although as Dr. Joe Wolfe says, "for higher frequencies, all bets are off."
It is interesting to note that Scavone postulates that the long, narrow chambered mpc he tested played with more high harmonic content than a fat, short chambered one because the shape more nearly approximated the shape of the conic apex, preserving its resonance structure and thus not destructively interfering with the high partials. Timing is everything ;-)
In terms of W curves, for notes of lower frequency, there is not much difference in the curves in the area of the mpc, at least insofar as the stronger, lower resonances of the regime of oscillation that determine the frequency of the sounding note go.
------------------------------------------------------------------------------
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Checked by AVG - www.avg.com
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FROM: kymarto (Toby)
SUBJECT: Re: Reflection on Mouthpiece Theory Discourse
This gives important information about the "slots" in the horn, the impedance maxima for a saxophone (points of highest impedance in the tube) tell you where the horn can most easily set up a standing wave--the frequency where the horn is happiest to play for a given fingering. It also indicates how easily the harmonics can form and add stability to the note being played (there should be maxima at higher frequencies which are integer multiples of the first maximum. If they are not at the correct points, it is harder for the harmonics to sound and contribute stability, color and power to the standing wave).
The theory is that you play a frequency into the tube and see just how much power it takes to get the air moving in the tube. Each frequency will have a characteristic "impedance". In the sax, the frequencies where the impedance is highest are the ones at which the horn tends to set up a standing wave when the reed gets air moving. But this all becomes horribly complicated by the fact that it is not simply the volume of the mpc + horn that matters, but reed characteristics as well. A passive measurement won't really do the trick, although as MartinMods says, it is at least a useful roadmap to the basic characteristics of the tube.
In answer to Paul C., the impedance of the mpc alone doesn't really mean anything until it is connected to the tube, because you really have to measure the whole playing system. Really, you want to measure the whole system with a player sounding a note, but this is really not practical.
The reason that this gets so complex is that the reed itself has a certain compliance--meaning that it effectively adds volume to the mpc, but that is variable depending on the reed strength and the embouchure. So every time you change embouchure or change reed, you are shifting the whole spectrum of tube impedances, and not in a linear manner either. Not only do you change the frequency of the sounding note, but you change the spread of the partials. So the measured impedances of the tube are only a rough guide to how it is going to play.
This is interesting for those wishing to get into this further. The folks at UNSW have posted impedance graphs for each note of the sop and tenor saxes.
http://www.phys.unsw.edu.au/music/saxophone/
There is a link on that page to this page, which explains impedance in much greater detail:
http://www.phys.unsw.edu.au/jw/z.html
And in the top paragraph there is a link to a paper by Dickens relating to techinques of measuing acoustic impedance.
Toby
----- Original Message -----
From: STEVE GOODSON
To: MouthpieceWork@yahoogroups.com
Sent: Thursday, October 15, 2009 4:30 AM
Subject: RE: [MouthpieceWork] Re: Reflection on Mouthpiece Theory Discourse
What is the practical application?
From: MouthpieceWork@yahoogroups.com [mailto:MouthpieceWork@yahoogroups.com] On Behalf Of MartinMods
Sent: Wednesday, October 14, 2009 1:55 PM
To: MouthpieceWork@yahoogroups.com
Subject: Re: [MouthpieceWork] Re: Reflection on Mouthpiece Theory Discourse
"Back to impedance... in the real world, how does one measure impedance of the mouthpiece? or rather, the mouthpiece/reed?
And if you know the impedance, what do you do with it?
Paul C."
Basically, it's a way to measure the resonance peaks of an air column, for any given fingered tone. That tells you a lot about how the instrument will play and how to adjust resonance alignment to improve things.
Just do a search for "woodwind impedance measurement". There are numerous publications on the different methods used, with diagrams, charts, etc. One version used a special attachement that fit on the mouthpiece table and sealed, as if the reed were closed.
Some guys use pulse reflectometry, to reconstruct a model of the air column.
None of the methods are perfect.
FROM: kymarto (Toby)
SUBJECT: Re: Reflection on Mouthpiece Theory Discourse
----- Original Message -----
From: Jim West
To: MouthpieceWork@yahoogroups.com
Sent: Thursday, October 15, 2009 9:57 AM
Subject: Re: [MouthpieceWork] Reflection on Mouthpiece Theory Discourse
Toby writes:
"Toby: Absolutely not! The Helmholtz resonance of the mpc must match the Helmholtz resonance of the missing apical section to align the higher modes when the wavelength is shorter than 1/4 wavelength of the truncated section (in my understanding)."
"
jim responds:
Hi Toby!
This stuff is difficult to talk about without having a common nomenclature.
What is your definition of "Helmholtz resonance"? Helmholtz has his fingerprints over
most of acoustic theory, including both lumped and distributed systems. If you are
talking about a "Helmholtz Resonator", then, I would tend to understand that you are talking
lumped, and we have the basis for a heated debate. If you are talking about Helmholtz
resonances involved in distributed systems, then I agree with you. Frs?
Our friends at UNSW do some good research and teaching. But remember they are
colleagues of Fletcher. Do you know of a source for the lumped MP outside of that
clique?
Toby: Clique? Is Fletcher some sort of demon, plotting to corrupt musical acoustics, and JW and co. his willing henchmen? Where does Thomas Rossing fit into the clique? Is he also guilty because he co-wrote the standard book on the subject with Fletcher?
From their book: "In order that the horn modes be as nearly harmonic as possible, it is desirable that the mouthpiece mimic the acoustic behavior of the missing apex of the cone. This can be done at two frequencies, and then fits reasonably well over the whole range. At low frequencies the matching is achieved if the internal volume of the mouthpiece is equal to that of the missing conical apex, which requires that the mouthpiece have a slightly bulbous internal shape so that it actually constitutes a sort of Helmholtz resonator. The high frequency match can then be achieved by arranging the constriction where it joins the main part of the instrument so that the Helmholtz resonance frequency of the mouthpiece is the same as the first resonance of the missing conical apex, at which it is half a wavelength long."
From Scavone's thesis:
"This requirement is based on the low-frequency behavior of the structure, since a cavity is characterized by its volume in the long-wavelength limit but not by its particular shape. Further, the lowest natural frequency of the assembly should match that of the missing conical tip so that their behaviors are comparable in the vicinity of this frequency."
Yes, this is identical to Benade's Frs.
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FROM: lancelotburt (MartinMods)
SUBJECT: Re: Reflection on Mouthpiece Theory Discourse
....talking about impedance (resonance peak) analysis of a saxophone.
________________________________
From: STEVE GOODSON <saxgourmet@cox. net>
To: MouthpieceWork@ yahoogroups. com
Sent: Wed, October 14, 2009 3:30:14 PM
Subject: RE: [MouthpieceWork] Re: Reflection on Mouthpiece Theory Discourse
What is the practical application?
You discuss to some length, how interesting and/or useful it is to know the location of the pressure nodes in a saxophone neck, on your website. Why would knowing the locations of all the pressure nodes throughout the entire air column be any less so?
FROM: tenorman1952 (tenorman1952)
SUBJECT: Re: Reflection on Mouthpiece Theory Discourse
--- In MouthpieceWork@yahoogroups.com, MartinMods <lancelotburt@...> wrote: > > ....talking about impedance (resonance peak) analysis of a saxophone. > I understand that, just as I do measuring impedance in a speaker system, etc. I know that it must be measured as a system, not just the mouthpiece in isolation. I ask what Goodson asks, too... what is the application? Once you have this number in hand, what can you do with it? In what way does it tell you how to alter a mouthpiece, and is that really want you want to do? I don't understand how knowing this will help you improve a mouthpiece, or design a new mouthpiece. And I've never heard of anyone doing so. Paul
FROM: lancelotburt (MartinMods)
SUBJECT: Re: Reflection on Mouthpiece Theory Discourse
I understand that, just as I do measuring impedance in a speaker
system, etc. I know that it must be measured as a system, not just the
mouthpiece in isolation. I ask what Goodson asks, too... what is the
application?
I don't understand how knowing this will help you improve a mouthpiece, or design a new mouthpiece.
And I've never heard of anyone doing so.
Paul
Unless I misunderstand my own statements in this particular thread, all I said was, that using an impedance analysis to make detailed W-Curves charts of an entire saxophone air column is more accurate if it includes the mouthpiece. I never said anything about using an impedance analysis to design mouthpieces. I can only speak for my own statements however. Maybe someone else addressed this issue.
FROM: kymarto (kymarto123@...)
SUBJECT: Re: Reflection on Mouthpiece Theory Discourse
Measuring mpc impedance alone is AFAIK not only practically impossible, but it wouldn't tell you anything useful. Measuring the system as a whole gives you valuable information about where the tube tends to resonate, which tells you not only about intonation but also indicates to some extent
(based on how far the higher frequency impedance peaks are from the integral multiples of the first peak) the virtual strength of the harmonics--stronger harmonics giving stability and ease of response to the horn. Horns that players like and which seem to play themselves are those with good
resonance alignments.
Nederveen says: "For reed blown instruments with short holes and a sufficiently strong fundamental in the spectrum, it has been shown that the input impedances determined by calculations closely correspond to those 'passively' (without blowing) measured and those actually blown, the latter by
either an artificial mouth or a musician or by both." So this information can help in designing or tweaking a woodwind bore to have a good resonance structure, and having a good resonance structure translates into a horn which has good intonation and feels responsive--which "slots".
A complete cone of any angle (within a certain range determined by the characteristics of air and the need to set up a standing wave which can regenerate) will produce a full set of partials in correct harmonic relationship to the fundamental , but as soon as you truncate that cone, it throws
those partials off: the modes (distances between peaks) are widened, and widened more the higher one goes--the whole string of peaks is "stretched", depending on the amount of truncation and cone angle.
The job of the mpc is to "squeeze" those peaks back into correct integer relationships with the first peak by appearing to be the top of the cone. Doing this completely is impossible, since the resonance structure of the mpc is never going to match that of the missing cone apex--they are of
completely different shape.
But the impedance peaks in the mpc alone are so high that they don't really affect the lower modes which determine intonation (although they do obviously affect the higher modes, which help determine tone color). To do a reasonable job, the mpc must meet two conditions. For lower notes, it is
enough for the volume of the mpc to match that of the missing conic apex. The wavelengths are long enough that the perturbation in shape at the top of the cone don't really affect them.
As one gets higher, with shorter waves to which the mpc perturbation represents an important fraction of their length, it becomes necessary to meet a second condition--that the first resonance of the mpc be the same as that of the missing conic apex. The point where this becomes important seems to
be when the length of the truncation is equal to or greater than 1/4 the wavelength of the sounding frequency.
This is what Benade calls the resonance frequency Frs, and it can be changed by adjusting the diameter of the bottom opening of the mpc where the neck is inserted: making it smaller lowers Frs and squeezes the higher modes together; making it larger widens the higher modes.
It is interesting to note that trumpet mpcs, which are inserted inside the lead pipe (instead of over the neck as in saxes) are adjusted in this way by changing the exit diameter. Unfortunately we don't really have that option--too bad the Conn microtuner did not become the standard!
Theoretically it would be possible to adjust Frs (after making sure that the internal volume is correct) by changing the diameter of the throat--even making it smaller than the diameter of the neck opening if necessary, but the necessity of tuning by moving the mpc on the cork make this
impractical, since that constriction should always be at the end of the neck. If you made a small diameter point in the throat and then pulled the mpc off the cork to tune you would create a nasty wide perturbation at the neck end, and of course the constriction would stop you from moving the mpc
further onto the cork to raise tuning.
Nor is tuning by changing the mpc volume completely practical, since not only does reducing volume make the sax sharper (and vice versa), it makes the higher notes sharper than lower ones (and vice versa).
The saving grace is the fact that the player can vary mpc volume (and thus intonation) by changing the bite on the reed--so actually the player is constantly making adjustments in mpc volume to be able to play the registers in tune. There is no way around this, but the point of the game is to get
the mpc parameters as close as possible under "normal playing conditions" (quite a loaded phrase) so that those adjustments are kept to a minimum.
My two (or perhaps three) cents, though I'm not sure it answers your question.
Toby
tenorman1952 <tenorman1952@...> wrote:
--- In MouthpieceWork@yahoogroups.com, MartinMods <lancelotburt@...> wrote:
>
> ....talking about impedance (resonance peak) analysis of a saxophone.
>
I understand that, just as I do measuring impedance in a speaker system, etc. I know that it must be measured as a system, not just the mouthpiece in isolation. I ask what Goodson asks, too... what is the application?
Once you have this number in hand, what can you do with it? In what way does it tell you how to alter a mouthpiece, and is that really want you want to do?
I don't understand how knowing this will help you improve a mouthpiece, or design a new mouthpiece.
And I've never heard of anyone doing so.
Paul
FROM: kymarto (kymarto123@...)
SUBJECT: Re: Reflection on Mouthpiece Theory Discourse
MartinMods <lancelotburt@...> wrote:
I understand that, just as I do measuring impedance in a speaker system, etc. I know that it must be measured as a system, not just the mouthpiece in isolation. I ask what Goodson asks, too... what is the application?
I don't understand how knowing this will help you improve a mouthpiece, or design a new mouthpiece.
And I've never heard of anyone doing so.
Paul
Unless I misunderstand my own statements in this particular thread, all I said was, that using an impedance analysis to make detailed W-Curves charts of an entire saxophone air column is more accurate if it includes the mouthpiece. I never said anything about using an impedance analysis to design
mouthpieces. I can only speak for my own statements however. Maybe someone else addressed this issue.
I think that no only do you not misunderstand your own statements, they are also completely accurate, and you said it a lot more succinctly than I did.
Toby
FROM: moeaaron (Barry Levine)
SUBJECT: Re: More on taper at bottom of window.
Law of diminishing returns at work: Ponzol M1 had a thick wall at the bottom of the window. I chamfered it a bit, and the piece blew quite a bit more freely, as noted in an earlier post. Wow. Then (after the novelty wore off) I thought to myself, maybe I'll round it off just a wee bit more, it still presents a bump to the airflow, so to speak. Uh uh. The piece became a bit indistinct; notes lost a little bite that I want to hear. Took a fine round file to the bottom of the window and extended the window VERY slightly in order to restore a bit of the wall at the bottom of the "U" Notes got their bite back. These were very slight changes - making a surprising difference. Another variable to contend with... Barry
FROM: lancelotburt (MartinMods)
SUBJECT: Re: More on taper at bottom of window.
Once the air flow gets past the tip of the reed, it really doesn't do
much. The blown air just sort of wanders down the neck, into the body,
and leaks out of the first open holes that it finds. One needn't
concern oneself with "air flow" in the mouthpiece or horn at all
really. The saxophone is not a wind tunnel.
What is of utmost importance of course, is the reed generated sound
wave, which travels through the meandering air molecules in the
mouthpiece,
neck and body tube, at the speed of sound, back and forth, from one end
to the other, the amplitude and alignment of the air column resonances,
which enable
the formation of a harmonic regime for whatever note is fingered. and
the resultant standing wave which is created.
Removing sharp edges eliminates turbulence, and that is always good.
Excessive rounding or beveling, may cause changes in resonance alignment, and that could be good or bad, depending.
________________________________
From: Barry Levine <barrylevine@...>
To: MouthpieceWork@yahoogroups.com
Sent: Tue, December 1, 2009 12:37:47 AM
Subject: Re: [MouthpieceWork] More on taper at bottom of window.
Law of diminishing returns at work:
Ponzol M1 had a thick wall at the bottom of the window.
I chamfered it a bit, and the piece blew quite a bit more freely, as noted in an earlier post. Wow.
Then (after the novelty wore off) I thought to myself, maybe I'll round it off just a wee bit more, it still presents a bump to the airflow, so to speak.
FROM: kwbradbury (MojoBari)
SUBJECT: Re: More on taper at bottom of window.
--- In MouthpieceWork@yahoogroups.com, MartinMods <lancelotburt@...> wrote: > Once the air flow gets past the tip of the reed, it really doesn't do > much. The blown air just sort of wanders down the neck, into the body, > and leaks out of the first open holes that it finds. One needn't > concern oneself with "air flow" in the mouthpiece or horn at all > really. The saxophone is not a wind tunnel. I totally agree (easy to do because it is fact, not opinion). But this is not intuitive. Nearly all sax players form a mental model that involves aerodynamics. How did Adolph Sax and his contemporaries get so smart about acoustics? > > Removing sharp edges eliminates turbulence, and that is always good. I think so in general. But some players like a stuffy edgy sound that these geometric irregularities provide. > > Excessive rounding or beveling, may cause changes in resonance alignment, and that could be good or bad, depending. > I know a lot more about fluid dynamics than I do about acoustics. Because of my background, this is a semi-rant/question. Turbulence is a fluid dynamics phenomenon. It is also mentioned in acoustic papers, but I'm not sure why. If there is no significant fluid (air) flow, then there can be no turbulence by definition. Not all recirculation of air flows are turbulent. There can be laminar recirculation and transistional (nearly turbulent) recirculation. Perhaps there is a analognous acoustic turbulence around sharp edges that is simply known as "tubulence" in the acoustic field. But I have not come across an acoustic definition of it. Has anyone?
FROM: halcooper79@verizon.net (Hal Cooper)
SUBJECT: Re: More on taper at bottom of window.
MartinMods wrote: > > Once the air flow gets past the tip of the reed, it really doesn't do > much. The blown air just sort of wanders down the neck, into the > body, and leaks out of the first open holes that it finds. One > needn't concern oneself with "air flow" in the mouthpiece or horn at > all really. The saxophone is not a wind tunnel. > > What is of utmost importance of course, is the reed generated sound > wave, which travels through the meandering air molecules in the > mouthpiece, neck and body tube, at the speed of sound, back and forth, > from one end to the other, the amplitude and alignment of the air > column resonances, which enable the formation of a harmonic regime for > whatever note is fingered. and the resultant standing wave which is > created. > > Removing sharp edges eliminates turbulence, and that is always good. > > Excessive rounding or beveling, may cause changes in resonance > alignment, and that could be good or bad, depending. Portallatro>> From a teaching and playing viewpoint, we always talk about "spinning the air forward." There are also issues of placement of the air stream in the mouthpiece, for softer playing. But, it's not a trumpet; Never the less, I would never tell a student to let the air wander down the neck. There is so much material in some of these mouthpieces like the Ponzol and S80. It takes a long time to file this portion down. Unless the customer says the magic words, "more free blowing," I will just smooth those nasty machine edges and call it good.
FROM: lancelotburt (MartinMods)
SUBJECT: Re: More on taper at bottom of window.
The air medium (molecules) does (do) vibrate, back and forth, and it is this air motion that need concern us, as far as motion is concerned. The amount and speed of motion is directly related to the amplitude and the wavelength of any given resonance and how it combines with the other resonances forming a harmonic regime and a standing wave.
Benade gives his formula for figuring the minimal radius of any rounded edge to avoid vibrating air turbulence in: https://ccrma.stanford.edu/marl/Benade/documents/Benade-Physics323-1977.pdf p. 69. and the result is a function of the longest wave length generated by the air column. We discussed this about a year ago on Steve Goodson's repair forum. The amount of rounding needed is a fraction of a mm, generally. He states that microscopic variations are noticeable by the player, and my personal experience would substantiate this.
________________________________
From: Hal Cooper <halcooper79@...>
To: MouthpieceWork@yahoogroups.com
Sent: Tue, December 1, 2009 12:04:24 PM
Subject: Re: [MouthpieceWork] More on taper at bottom of window.
MartinMods wrote:
>
> Once the air flow gets past the tip of the reed, it really doesn't do
> much. The blown air just sort of wanders down the neck, into the
> body, and leaks out of the first open holes that it finds. One
> needn't concern oneself with "air flow" in the mouthpiece or horn at
> all really. The saxophone is not a wind tunnel.
>
> What is of utmost importance of course, is the reed generated sound
> wave, which travels through the meandering air molecules in the
> mouthpiece, neck and body tube, at the speed of sound, back and forth,
> from one end to the other, the amplitude and alignment of the air
> column resonances, which enable the formation of a harmonic regime for
> whatever note is fingered. and the resultant standing wave which is
> created.
>
> Removing sharp edges eliminates turbulence, and that is always good.
>
> Excessive rounding or beveling, may cause changes in resonance
> alignment, and that could be good or bad, depending.
Portallatro> > From a teaching and playing viewpoint, we always talk
about "spinning the air forward." There are also issues of placement of
the air stream in the mouthpiece, for softer playing. But, it's not a
trumpet; Never the less, I would never tell a student to let the air
wander down the neck.
There is so much material in some of these mouthpieces like the Ponzol
and S80. It takes a long time to file this portion down. Unless the
customer says the magic words, "more free blowing," I will just smooth
those nasty machine edges and call it good.
FROM: lancelotburt (MartinMods)
SUBJECT: Re: More on taper at bottom of window.
Hal Wrote: "From a teaching and playing viewpoint, we always talk
about "spinning the air forward." There are also issues of placement of
the air stream in the mouthpiece, for softer playing."
MartinMods wrote: I understand and I was taught similar concepts. The mental imagery may work but it is not at all related to what is actually going on in our physical reality. In reality, all one is doing is manipulating the shape of the vocal tract, our body resonating cavity in order to better align and reinforce specific coupled resonances of the instrument's air column. "Shaping" the note is the most accurate common analogy perhaps.
During actual playing, we still need to simplify our mental concept of what is going on by using mental imagery, but, now that I understand what is going on a little better, the "real world" coupled resonating body cavity (vocal tract) imagery works better for me than the old inaccurate "air stream" thing.
FROM: halcooper79@verizon.net (Hal Cooper)
SUBJECT: Re: Vocal Tract Imagery
> > MartinMods> During actual playing, we still need to simplify our > mental concept of what is going on by using mental imagery, but, now > that I understand what is going on a little better, the "real world" > coupled resonating body cavity (vocal tract) imagery works better for > me than the old inaccurate "air stream" thing. Hal> Most of my teachers come from the Marcel Mule school of playing. I'm a jazz player who does classical for the hell of it. They say it is best to control the instrument from the front. I had to go to a voice teacher to learn anything about the vocal tract. In a sax lesson, bringing up anything involving the throat or vocal tract was essentially off limits. I have had a lot of trouble getting along with most of my teachers too. Is there a teacher or college where this vocal tract idea is more encouraged? I've become rather discouraged with classical sax playing. When playing jazz, I feel like I want to get the throat involved. I have also noticed that clarinet teachers are more into the vocal tract imagery than sax teachers.
FROM: mdc5220 (chedoggy)
SUBJECT: Re: Vocal Tract Imagery
With the risk of participating in an off topic subject, I think Joe Allard and his adherents might be described as vocal tract in approach and Allard studied Mule, so I understand.
I have seen 2 videos of Allard teaching his method and both stressed the throat and the position of the tongue in relation to the players front teeth. (From back to front?) It is fairly well known Allard stressed the harmonic series as a way of developing the throat muscles and keeping your embouchure from choking the reed. So go figure. As phil woods says, "a musician's best friend is his ears."
----- Original Message -----
From: Hal Cooper
To: MouthpieceWork@yahoogroups.com
Sent: Tuesday, December 01, 2009 4:53 PM
Subject: Re: [MouthpieceWork] Vocal Tract Imagery
>
> MartinMods> During actual playing, we still need to simplify our
> mental concept of what is going on by using mental imagery, but, now
> that I understand what is going on a little better, the "real world"
> coupled resonating body cavity (vocal tract) imagery works better for
> me than the old inaccurate "air stream" thing.
Hal> Most of my teachers come from the Marcel Mule school of playing.
I'm a jazz player who does classical for the hell of it. They say it
is best to control the instrument from the front. I had to go to a
voice teacher to learn anything about the vocal tract. In a sax
lesson, bringing up anything involving the throat or vocal tract was
essentially off limits. I have had a lot of trouble getting along with
most of my teachers too. Is there a teacher or college where this
vocal tract idea is more encouraged? I've become rather discouraged
with classical sax playing. When playing jazz, I feel like I want to
get the throat involved.
I have also noticed that clarinet teachers are more into the vocal tract
imagery than sax teachers.
FROM: kymarto (kymarto123@...)
SUBJECT: Re: More on taper at bottom of window.
Any chaotic movement of air molecules counts as turbulence. Don't forget that there is significant local movement of air molecules at displacement antinodes in the standing wave. In woodwinds, fully 99% of the energy input by the player is lost before it can become sound radiating out of the horn,
most of it due to thermal and viscous losses at the walls, where molecules are slowed down by contact with the wall material. Any sharp edge will disrupt the orderly movement of molecules back and forth as well. This is most evident at higher dynamic levels, when the movement is more vigorous,
and turbulence of this kind can effectively limit the maximum playing volume before the losses at the walls do so.
Toby
MojoBari <kwbradbury@...> wrote:
--- In MouthpieceWork@yahoogroups.com, MartinMods <lancelotburt@...> wrote:
> Once the air flow gets past the tip of the reed, it really doesn't do
> much. The blown air just sort of wanders down the neck, into the body,
> and leaks out of the first open holes that it finds. One needn't
> concern oneself with "air flow" in the mouthpiece or horn at all
> really. The saxophone is not a wind tunnel.
I totally agree (easy to do because it is fact, not opinion). But this is not intuitive. Nearly all sax players form a mental model that involves aerodynamics. How did Adolph Sax and his contemporaries get so smart about acoustics?
>
> Removing sharp edges eliminates turbulence, and that is always good.
I think so in general. But some players like a stuffy edgy sound that these geometric irregularities provide.
>
> Excessive rounding or beveling, may cause changes in resonance alignment, and that could be good or bad, depending.
>
I know a lot more about fluid dynamics than I do about acoustics. Because of my background, this is a semi-rant/question. Turbulence is a fluid dynamics phenomenon. It is also mentioned in acoustic papers, but I'm not sure why. If there is no significant fluid (air) flow, then there can be no
turbulence by definition. Not all recirculation of air flows are turbulent. There can be laminar recirculation and transistional (nearly turbulent) recirculation. Perhaps there is a analognous acoustic turbulence around sharp edges that is simply known as "tubulence" in the acoustic field.
But I have not come across an acoustic definition of it. Has anyone?
FROM: kwbradbury (Keith Bradbury)
SUBJECT: Re: More on taper at bottom of window.
>>>Any chaotic movement of air molecules counts as turbulence.
That does seem to be how the term is used in acoustic papers... and in general conversation. I need to be more tolerant...
FROM: moeaaron (Barry Levine)
SUBJECT: Re: More on taper at bottom of window.
I would characterize the change I felt as that the attack for notes got better, easier, once I restored a bit of edge to the bottom of the window. I'm not sure what a "stuffy edgy sound" would be, but it's not how I'd describe what I felt or got. Attack was easier, and notes were less "tubby" perhaps. My sense is that it's a change in the air movement under the reed that's at work, somehow. The feel was similar to the results when adding baffle. The air movement is then closer to the reed, and the transfer of energy to the reed is more efficient. Regarding turbulence: The air between the reed and the baffle has to be quite turbulent. Even with a fairly straight baffle, there's curvature at the very tip of the baffle to set the air roiling; not to mention the motion of the reed slapping the air - which means there is pressure rebound traveling back up at the reed. Perhaps some turbulence at the bottom of the window maintains a certain slap-back-pressure that would dissipate faster otherwise. In any case the effect seemed pretty clear though, on THIS piece. Which doesn't prove it would have the same effect on other pieces with different inner geometries. One could also equally argue that the difference was in extending the window length slightly, since that also changed. I doubt that, however. This requires some more experimentation. A few sharp edges may be a good thing - if one knows where to put them. > From: <kymarto123@...> > Reply-To: MouthpieceWork@yahoogroups.com > Date: Wed, 2 Dec 2009 08:20:49 +0900 (JST) > To: MouthpieceWork@yahoogroups.com > Subject: Re: [MouthpieceWork] Re: More on taper at bottom of window. > >> Removing sharp edges eliminates turbulence, and that is always good. >> >> I think so in general. But some players like a stuffy edgy sound that these >> geometric irregularities provide. >>
FROM: kymarto (kymarto123@...)
SUBJECT: Re: More on taper at bottom of window.
Barry Levine <barrylevine@...> wrote: I would characterize the change I felt as that the attack for notes got better, easier, once I restored a bit of edge to the bottom of the window.
I'm not sure what a "stuffy edgy sound" would be, but it's not how I'd describe what I felt or got. Attack was easier, and notes were less "tubby" perhaps.
My sense is that it's a change in the air movement under the reed that's at work, somehow. The feel was similar to the results when adding baffle. The air movement is then closer to the reed, and the transfer of energy to the reed is more efficient.
--There is no transfer of energy to the reed as such. I'm not sure what you mean by that.
Regarding turbulence: The air between the reed and the baffle has to be quite turbulent. Even with a fairly straight baffle, there's curvature at the very tip of the baffle to set the air roiling; not to mention the motion of the reed slapping the air - which means there is pressure rebound
traveling back up at the reed. Perhaps some turbulence at the bottom of the window maintains a certain slap-back-pressure that would dissipate faster otherwise.
--I don't think this is very accurate. I suggest you read this:
hal.archives-ouvertes.fr/docs/00/25/27/96/PDF/ajp-jp4199404C5120.pdf
In any case the effect seemed pretty clear though, on THIS piece. Which doesn't prove it would have the same effect on other pieces with different inner geometries.
One could also equally argue that the difference was in extending the window length slightly, since that also changed. I doubt that, however.
This requires some more experimentation.
A few sharp edges may be a good thing - if one knows where to put them.
--Never in terms of efficiency, perhaps depending on what you are looking for in terms of response. Some people might prefer more resistance and less dynamic range.
Toby
From: <kymarto123@...>
Reply-To: MouthpieceWork@yahoogroups.com
Date: Wed, 2 Dec 2009 08:20:49 +0900 (JST)
To: MouthpieceWork@yahoogroups.com
Subject: Re: [MouthpieceWork] Re: More on taper at bottom of window.
Removing sharp edges eliminates turbulence, and that is always good.
I think so in general. But some players like a stuffy edgy sound that these geometric irregularities provide.
FROM: lancelotburt (MartinMods)
SUBJECT: Re: More on taper at bottom of window.
________________________________
"Any chaotic movement of air molecules counts as turbulence. Don't forget that there is significant local movement of air molecules at displacement antinodes in the standing wave."
There is significant longitudinal particle movement at displacement anti-nodes of the standing wave. As this flow will enter any bore perturbation to some extent (up to 10% of the diameter of any closed tone hole for example - Nederveen) it is easy to see how sharp edges or a rough, uneven bore wall would result in chaotic particle movement and energy loss at these nodes.
Interestingly, at the compression anti-nodes of the standing wave, the increase in air pressure would appear to cause significant transverse particle motion if the bore provides the opportunity (expansion of a closed tone hole, weak spring on key, gaps at tenons and body couplings), as this experiment clearly demonstrates. (Yahoo Mail insists upon inserting spaces after "." periods, even if the "insert link" button is clicked. You will have to manually remove them for the link to work. It's worth it.)
http://hyperphysics.phy-astr.gsu.edu/Hbase/waves/kundtosc.html#c1
The energy traps for this transverse motion at compression anti-nodes are soft porous wall surfaces (pads) and narrow gaps in the bore (tenons and poorly matched body couplings). The narrower the gap the more the loss.
As far as mouthpieces go, the effect of sharp edges is clear. Narrow gaps between glued-in or adjustable baffle inserts and the mouthpiece wall will cause energy loss. The exposed cork at the end of the neck will dampen resonances as well.
.
FROM: moeaaron (Barry Levine)
SUBJECT: Re: More on taper at bottom of window.
What you write is undoubtedly true in terms of *overall efficiency*, i.e. How many watts of breath power and embouchure muscle power can be converted into audio watts via coupling to the reed-mouthpiece-saxophone system But I'm speaking purely from the point of view of perceived effort in order to obtain a desired sound. I think a good example of this is how a baffle insert can heighten the brightness and perceived projection of a mouthpiece, but thin out the bottom. In terms of audio power, the lower frequencies require more power than the higher frequencies, at least as far as what our ears hear. My biamped Peavey keyboard amp has a 40 watt-bass and-midrange amplifier, and a mere 10 watt amplifier for its tweeter. In terms of what the ear hears, you get more bang for your buck from the higher frequencies. So, in this example, a mouthpiece with a baffle insert might be overall less efficient in terms of absolute audio power (putting a sound-level meter out in front of the player), but it is heard and felt as "projecting" better, because it gives us more juice in the upper frequencies, even if at the expense of some lower frequencies. Barry > From: <kymarto123@...> > Reply-To: MouthpieceWork@yahoogroups.com > Date: Wed, 2 Dec 2009 22:19:30 +0900 (JST) > To: MouthpieceWork@yahoogroups.com > Subject: Re: [MouthpieceWork] Re: More on taper at bottom of window. > >> A few sharp edges may be a good thing - if one knows where to put them. >> >> --Never in terms of efficiency, perhaps depending on what you are looking for >> in terms of response. Some people might prefer more resistance and less >> dynamic range. >> Toby >>
FROM: lancelotburt (MartinMods)
SUBJECT: Re: More on taper at bottom of window.
I'm not commenting on the pros an cons of any particular baffle design in any way. All I'm saying is, if your baffle construction is sloppy, leaving a thin gap between the mouthpiece wall and the baffle itself, there will be a significant energy loss - the same baffle design without a gap will play better.
________________________________
From: Barry Levine <barrylevine@...>
To: MouthpieceWork@yahoogroups.com
Sent: Wed, December 2, 2009 10:50:37 AM
Subject: Re: [MouthpieceWork] Re: More on taper at bottom of window.
What you write is undoubtedly true in terms of *overall efficiency*, i.e. How many watts of breath power and embouchure muscle power can be converted into audio watts via coupling to the reed-mouthpiece- saxophone system
But I'm speaking purely from the point of view of perceived effort in order to obtain a desired sound.
I think a good example of this is how a baffle insert can heighten the brightness and perceived projection of a mouthpiece, but thin out the bottom.
In terms of audio power, the lower frequencies require more power than the higher frequencies, at least as far as what our ears hear. My biamped Peavey keyboard amp has a 40 watt-bass and-midrange amplifier, and a mere 10 watt amplifier for its tweeter. In terms of what the ear hears, you get more bang for your buck from the higher frequencies.
So, in this example, a mouthpiece with a baffle insert might be overall less efficient in terms of absolute audio power (putting a sound-level meter out in front of the player), but it is heard and felt as "projecting" better, because it gives us more juice in the upper frequencies, even if at the expense of some lower frequencies.
Barry
>From: <kymarto123@ybb. ne.jp>
>Reply-To: MouthpieceWork@ yahoogroups. com
>Date: Wed, 2 Dec 2009 22:19:30 +0900 (JST)
>To: MouthpieceWork@ yahoogroups. com
>Subject: Re: [MouthpieceWork] Re: More on taper at bottom of window.
>
>
>A few sharp edges may be a good thing - if one knows where to put them.
>>
>>>>--Never in terms of efficiency, perhaps depending on what you are looking for in terms of response. Some people might prefer more resistance and less dynamic range.
>>>>Toby
>>
FROM: lancelotburt (MartinMods)
SUBJECT: Re: More on taper at bottom of window.
Sorry. I see that was a reply to Toby......
________________________________
From: MartinMods <lancelotburt@...>
To: MouthpieceWork@yahoogroups.com
Sent: Wed, December 2, 2009 11:52:04 AM
Subject: Re: [MouthpieceWork] Re: More on taper at bottom of window.
I'm not commenting on the pros an cons of any particular baffle design in any way. All I'm saying is, if your baffle construction is sloppy, leaving a thin gap between the mouthpiece wall and the baffle itself, there will be a significant energy loss - the same baffle design without a gap will play better.
________________________________
From: Barry Levine <barrylevine@ norwoodlight. com>
To: MouthpieceWork@ yahoogroups. com
Sent: Wed, December 2, 2009 10:50:37 AM
Subject: Re: [MouthpieceWork] Re: More on taper at bottom of window.
What you write is undoubtedly true in terms of *overall efficiency*, i.e. How many watts of breath power and embouchure muscle power can be converted into audio watts via coupling to the reed-mouthpiece- saxophone system
But I'm speaking purely from the point of view of perceived effort in order to obtain a desired sound.
I think a good example of this is how a baffle insert can heighten the brightness and perceived projection of a mouthpiece, but thin out the bottom.
In terms of audio power, the lower frequencies require more power than the higher frequencies, at least as far as what our ears hear. My biamped Peavey keyboard amp has a 40 watt-bass and-midrange amplifier, and a mere 10 watt amplifier for its tweeter. In terms of what the ear hears, you get more bang for your buck from the higher frequencies.
So, in this example, a mouthpiece with a baffle insert might be overall less efficient in terms of absolute audio power (putting a sound-level meter out in front of the player), but it is heard and felt as "projecting" better, because it gives us more juice in the upper frequencies, even if at the expense of some lower frequencies.
Barry
>From: <kymarto123@ybb. ne.jp>
>Reply-To: MouthpieceWork@ yahoogroups. com
>Date: Wed, 2 Dec 2009 22:19:30 +0900 (JST)
>To: MouthpieceWork@ yahoogroups. com
>Subject: Re: [MouthpieceWork] Re: More on taper at bottom of window.
>
>
>A few sharp edges may be a good thing - if one knows where to put them.
>>
>>>>--Never in terms of efficiency, perhaps depending on what you are looking for in terms of response. Some people might prefer more resistance and less dynamic range.
>>>>Toby
>>
FROM: dkulcinski (David)
SUBJECT: Re: Vocal Tract Imagery
Being a clarinet newbie, I have noticed that there is a DEFINITE manipulation of the throat/vocal tract needed, especially in the upper registers, in order to sound properly. Having learned sax far too many years ago to recount, I never learned anything except to manipulate tone using the embouchure. Although, I understand that folks like Boots Randolph may have used throat stuff (like growling/ singing) in order to produce their distinctive sounds. To get back on topic, I don't know if there are any features of a mouthpiece that would allow the player to more easily produce the growling tones. Thank you, David --- In MouthpieceWork@yahoogroups.com, Hal Cooper <halcooper79@...> wrote: > > > > > > MartinMods> During actual playing, we still need to simplify our > > mental concept of what is going on by using mental imagery, but, now > > that I understand what is going on a little better, the "real world" > > coupled resonating body cavity (vocal tract) imagery works better for > > me than the old inaccurate "air stream" thing. > > > Hal> Most of my teachers come from the Marcel Mule school of playing. > I'm a jazz player who does classical for the hell of it. They say it > is best to control the instrument from the front. I had to go to a > voice teacher to learn anything about the vocal tract. In a sax > lesson, bringing up anything involving the throat or vocal tract was > essentially off limits. I have had a lot of trouble getting along with > most of my teachers too. Is there a teacher or college where this > vocal tract idea is more encouraged? I've become rather discouraged > with classical sax playing. When playing jazz, I feel like I want to > get the throat involved. > > I have also noticed that clarinet teachers are more into the vocal tract > imagery than sax teachers. >
FROM: lancelotburt (MartinMods)
SUBJECT: Re: Vocal Tract Imagery
Do a search on Youtube for Frank Catalano. He did a multi-part clinic at Saxquest which is full of good info on tone manipulation.
________________________________
From: David <dkulcinski@...>
To: MouthpieceWork@yahoogroups.com
Sent: Wed, December 2, 2009 3:40:12 PM
Subject: [MouthpieceWork] Re: Vocal Tract Imagery
Being a clarinet newbie, I have noticed that there is a DEFINITE manipulation of the throat/vocal tract needed, especially in the upper registers, in order to sound properly. Having learned sax far too many years ago to recount, I never learned anything except to manipulate tone using the embouchure. Although, I understand that folks like Boots Randolph may have used throat stuff (like growling/ singing) in order to produce their distinctive sounds.
To get back on topic, I don't know if there are any features of a mouthpiece that would allow the player to more easily produce the growling tones.
Thank you,
David
--- In MouthpieceWork@ yahoogroups. com, Hal Cooper <halcooper79@ ...> wrote:
>
>
> >
> > MartinMods> During actual playing, we still need to simplify our
> > mental concept of what is going on by using mental imagery, but, now
> > that I understand what is going on a little better, the "real world"
> > coupled resonating body cavity (vocal tract) imagery works better for
> > me than the old inaccurate "air stream" thing.
>
>
> Hal> Most of my teachers come from the Marcel Mule school of playing.
> I'm a jazz player who does classical for the hell of it. They say it
> is best to control the instrument from the front. I had to go to a
> voice teacher to learn anything about the vocal tract. In a sax
> lesson, bringing up anything involving the throat or vocal tract was
> essentially off limits. I have had a lot of trouble getting along with
> most of my teachers too. Is there a teacher or college where this
> vocal tract idea is more encouraged? I've become rather discouraged
> with classical sax playing. When playing jazz, I feel like I want to
> get the throat involved.
>
> I have also noticed that clarinet teachers are more into the vocal tract
> imagery than sax teachers.
>
FROM: jbtsax (John)
SUBJECT: Re: Vocal Tract Imagery
There is also an excellent article on this subject at: http://www.phys.unsw.edu.au/jw/SaxTract.html John --- In MouthpieceWork@yahoogroups.com, MartinMods <lancelotburt@...> wrote: > > Do a search on Youtube for Frank Catalano. He did a multi-part clinic at Saxquest which is full of good info on tone manipulation. > > > > > ________________________________ > From: David <dkulcinski@...> > To: MouthpieceWork@yahoogroups.com > Sent: Wed, December 2, 2009 3:40:12 PM > Subject: [MouthpieceWork] Re: Vocal Tract Imagery > > > Being a clarinet newbie, I have noticed that there is a DEFINITE manipulation of the throat/vocal tract needed, especially in the upper registers, in order to sound properly. Having learned sax far too many years ago to recount, I never learned anything except to manipulate tone using the embouchure. Although, I understand that folks like Boots Randolph may have used throat stuff (like growling/ singing) in order to produce their distinctive sounds. > > To get back on topic, I don't know if there are any features of a mouthpiece that would allow the player to more easily produce the growling tones. > > Thank you, > > David > > --- In MouthpieceWork@ yahoogroups. com, Hal Cooper <halcooper79@ ...> wrote: > > > > > > > > > > MartinMods> During actual playing, we still need to simplify our > > > mental concept of what is going on by using mental imagery, but, now > > > that I understand what is going on a little better, the "real world" > > > coupled resonating body cavity (vocal tract) imagery works better for > > > me than the old inaccurate "air stream" thing. > > > > > > Hal> Most of my teachers come from the Marcel Mule school of playing. > > I'm a jazz player who does classical for the hell of it. They say it > > is best to control the instrument from the front. I had to go to a > > voice teacher to learn anything about the vocal tract. In a sax > > lesson, bringing up anything involving the throat or vocal tract was > > essentially off limits. I have had a lot of trouble getting along with > > most of my teachers too. Is there a teacher or college where this > > vocal tract idea is more encouraged? I've become rather discouraged > > with classical sax playing. When playing jazz, I feel like I want to > > get the throat involved. > > > > I have also noticed that clarinet teachers are more into the vocal tract > > imagery than sax teachers. > > >
FROM: lancelotburt (MartinMods)
SUBJECT: Re: Vocal Tract Imagery
That's a good one. Scavone has published one, as well as a few others. While Frank Catalano still refers to much of what he is doing in terms of "focusing his air flow", he does then give an excellent playing demonstration of what he is talking about, in every case.
________________________________
From: John <jtalcott47@...>
To: MouthpieceWork@yahoogroups.com
Sent: Thu, December 3, 2009 10:44:46 AM
Subject: [MouthpieceWork] Re: Vocal Tract Imagery
There is also an excellent article on this subject at:
http://www.phys. unsw.edu. au/jw/SaxTract. html
John
--- In MouthpieceWork@ yahoogroups. com, MartinMods <lancelotburt@ ...> wrote:
>
> Do a search on Youtube for Frank Catalano. He did a multi-part clinic at Saxquest which is full of good info on tone manipulation.
>
>
>
>
> ____________ _________ _________ __
> From: David <dkulcinski@ ...>
> To: MouthpieceWork@ yahoogroups. com
> Sent: Wed, December 2, 2009 3:40:12 PM
> Subject: [MouthpieceWork] Re: Vocal Tract Imagery
>
>
> Being a clarinet newbie, I have noticed that there is a DEFINITE manipulation of the throat/vocal tract needed, especially in the upper registers, in order to sound properly. Having learned sax far too many years ago to recount, I never learned anything except to manipulate tone using the embouchure. Although, I understand that folks like Boots Randolph may have used throat stuff (like growling/ singing) in order to produce their distinctive sounds.
>
> To get back on topic, I don't know if there are any features of a mouthpiece that would allow the player to more easily produce the growling tones.
>
> Thank you,
>
> David
>
> --- In MouthpieceWork@ yahoogroups. com, Hal Cooper <halcooper79@ ...> wrote:
> >
> >
> > >
> > > MartinMods> During actual playing, we still need to simplify our
> > > mental concept of what is going on by using mental imagery, but, now
> > > that I understand what is going on a little better, the "real world"
> > > coupled resonating body cavity (vocal tract) imagery works better for
> > > me than the old inaccurate "air stream" thing.
> >
> >
> > Hal> Most of my teachers come from the Marcel Mule school of playing.
> > I'm a jazz player who does classical for the hell of it. They say it
> > is best to control the instrument from the front. I had to go to a
> > voice teacher to learn anything about the vocal tract. In a sax
> > lesson, bringing up anything involving the throat or vocal tract was
> > essentially off limits. I have had a lot of trouble getting along with
> > most of my teachers too. Is there a teacher or college where this
> > vocal tract idea is more encouraged? I've become rather discouraged
> > with classical sax playing. When playing jazz, I feel like I want to
> > get the throat involved.
> >
> > I have also noticed that clarinet teachers are more into the vocal tract
> > imagery than sax teachers.
> >
>
FROM: moeaaron (Barry Levine)
SUBJECT: Re: More on taper at bottom of window.
>> I would characterize the change I felt as that the attack for notes got >> better, easier, once I restored a bit of edge to the bottom of the window. >> >> I'm not sure what a "stuffy edgy sound" would be, but it's not how I'd >> describe what I felt or got. Attack was easier, and notes were less "tubby" >> perhaps. >> >> My sense is that it's a change in the air movement under the reed that's at >> work, somehow. The feel was similar to the results when adding baffle. The >> air movement is then closer to the reed, and the transfer of energy to the >> reed is more efficient. >> >>> --There is no transfer of energy to the reed as such. I'm not sure what you >>> mean by that. I'm referring to effort/energy required to set the reed in motion. >> Regarding turbulence: The air between the reed and the baffle has to be quite >> turbulent. Even with a fairly straight baffle, there's curvature at the very >> tip of the baffle to set the air roiling; not to mention the motion of the >> reed slapping the air - which means there is pressure rebound traveling back >> up at the reed. Perhaps some turbulence at the bottom of the window maintains >> a certain slap-back-pressure that would dissipate faster otherwise. >>> --I don't think this is very accurate. I suggest you read this: >>> hal.archives-ouvertes.fr/docs/00/25/27/96/PDF/ajp-jp4199404C5120.pdf >> I've taken a look at this paper... Thanks for locating it. It's quite technical, but some things do seem apparent. Firstly, I don't see anything about pressure rebound (i.e. A wave bouncing back at the reed from the baffle) discussed here. It seems to me that is something that should occur, but I may be wrong. Secondly, though, it appears my assumptions about turbulence under the reed are correct. Have you noted what they had to say on p C5-560, discussing the modulation of the volume flow through the reed channel by the oscillation of the reed? Here they discuss the behavior of the air jet through the mouthpiece: "The intrinsic instability of the free jet results into a chaotic vortical motion called turbulence. Typical for a turbulent flow is that even at high Reynolds numbers [mathematical expression] the kinetic energy of the jet is very efficiently dissipated by energy transfer to small vortical structures." So it is clear that air movement in the mouthpiece is quite turbulent. In discussing how the reed is set in motion, (PC-5-562), which occurs "due to a modulation of the Bernoulli force", they note: "After the curvature of the lay, the geometry of the baffle is the most critical part of mouthpiece design. Not only the spectral distribution of the sound is influenced, but also the emission facility is affected." The paper goes on to report that: "when a SHARP EDGED 'DITCH' [caps mine] is carved just downstream of the reed channel exit one can experience an easier attack transient." [If one refers to illustration "C", we see a cross section of a mouthpiece with said ditch carved just behind what I construe as the tip rail.} I presume that said "ditch" would increase turbulence further. Further regarding turbulence, the paragraph entitled "Turbulence and Chaos" seems to make the point that turbulence is a necessity. "The addition of noise to synthetic sound is necessary to obtain a reasonable naturalness. In speech research this problem has already been recognized, and models of turbulent noise production have been proposed." Furthermore: "As musical instruments are non-linear oscillator[s] they exhibit chaotic behavior. A certain level of non-periodicity is an essentail characteristic of musical sound... Turbulence is an important detail in a clarinet." Beyond my recent experience with my tenor piece's window [I was lucky not to spoil my favorite piece!], I think the fact that many popular saxophones mouthpieces have sharp step baffles (sure to induce a certain amount of turbulence occurring after the reed) supports the notion that turbulence inside the mouthpiece is not necessarily a bad thing, and a few sharp edges are useful, if we know where to put them. This idea that what's going in inside the mouthpiece is primarily some kind of efficient flow (as though oil was flowing through it, and the fewer eddies the better) may be intuitively appealing, but does not appear to be correct. >>> >>>> Removing sharp edges eliminates turbulence, and that is always good. >>>>
FROM: lancelotburt (MartinMods)
SUBJECT: Re: More on taper at bottom of window.
"when a SHARP EDGED 'DITCH' [caps mine] is carved just downstream of the reed channel exit one can experience an easier attack transient."
D. Bechert failed to specify exactly what he meant by "sharp" in his personal correspondence to the author of your quoted puplication, as one doing a serious scientific study perhaps ought. We should define "sharp" a little more precisely maybe.
Benade claims that if the edges are sharper than the radius of the curvature .01xSQRT(250/f)mm where f is the frequency of the lowest note of the instrument, there will be undesirable turbulence. The frequency of E3 on the clarinet (as in the quoted example above) is 147hz, so the critical radius of curvature for any edge would be .013mm.
I doubt that one could carve turkey with such an edge, but it would still have the appearance of sharpness to the casual observer.
________________________________
From: Barry Levine <barrylevine@...>
To: MouthpieceWork@yahoogroups.com
Sent: Thu, December 3, 2009 11:48:54 PM
Subject: Re: [MouthpieceWork] Re: More on taper at bottom of window.
>> I would characterize the change I felt as that the attack for notes got
>> better, easier, once I restored a bit of edge to the bottom of the window.
>>
>> I'm not sure what a "stuffy edgy sound" would be, but it's not how I'd
>> describe what I felt or got. Attack was easier, and notes were less "tubby"
>> perhaps.
>>
>> My sense is that it's a change in the air movement under the reed that's at
>> work, somehow. The feel was similar to the results when adding baffle. The
>> air movement is then closer to the reed, and the transfer of energy to the
>> reed is more efficient.
>>
>>> --There is no transfer of energy to the reed as such. I'm not sure what you
>>> mean by that.
I'm referring to effort/energy required to set the reed in motion.
>> Regarding turbulence: The air between the reed and the baffle has to be quite
>> turbulent. Even with a fairly straight baffle, there's curvature at the very
>> tip of the baffle to set the air roiling; not to mention the motion of the
>> reed slapping the air - which means there is pressure rebound traveling back
>> up at the reed. Perhaps some turbulence at the bottom of the window maintains
>> a certain slap-back-pressure that would dissipate faster otherwise.
>>> --I don't think this is very accurate. I suggest you read this:
>>> hal.archives- ouvertes. fr/docs/00/ 25/27/96/ PDF/ajp-jp419940 4C5120.pdf
>>
I've taken a look at this paper... Thanks for locating it. It's quite
technical, but some things do seem apparent.
Firstly, I don't see anything about pressure rebound (i.e. A wave bouncing
back at the reed from the baffle) discussed here. It seems to me that is
something that should occur, but I may be wrong.
Secondly, though, it appears my assumptions about turbulence under the reed
are correct. Have you noted what they had to say on p C5-560, discussing the
modulation of the volume flow through the reed channel by the oscillation of
the reed? Here they discuss the behavior of the air jet through the
mouthpiece:
"The intrinsic instability of the free jet results into a chaotic vortical
motion called turbulence. Typical for a turbulent flow is that even at high
Reynolds numbers [mathematical expression] the kinetic energy of the jet is
very efficiently dissipated by energy transfer to small vortical
structures."
So it is clear that air movement in the mouthpiece is quite turbulent.
In discussing how the reed is set in motion, (PC-5-562), which occurs "due
to a modulation of the Bernoulli force", they note:
"After the curvature of the lay, the geometry of the baffle is the most
critical part of mouthpiece design. Not only the spectral distribution of
the sound is influenced, but also the emission facility is affected."
The paper goes on to report that:
"when a SHARP EDGED 'DITCH' [caps mine] is carved just downstream of the
reed channel exit one can experience an easier attack transient."
[If one refers to illustration "C", we see a cross section of a mouthpiece
with said ditch carved just behind what I construe as the tip rail.}
I presume that said "ditch" would increase turbulence further.
Further regarding turbulence, the paragraph entitled "Turbulence and Chaos"
seems to make the point that turbulence is a necessity.
"The addition of noise to synthetic sound is necessary to obtain a
reasonable naturalness. In speech research this problem has already been
recognized, and models of turbulent noise production have been proposed."
Furthermore: "As musical instruments are non-linear oscillator[s] they
exhibit chaotic behavior. A certain level of non-periodicity is an essentail
characteristic of musical sound... Turbulence is an important detail in a
clarinet."
Beyond my recent experience with my tenor piece's window [I was lucky not to
spoil my favorite piece!], I think the fact that many popular saxophones
mouthpieces have sharp step baffles (sure to induce a certain amount of
turbulence occurring after the reed) supports the notion that turbulence
inside the mouthpiece is not necessarily a bad thing, and a few sharp edges
are useful, if we know where to put them.
This idea that what's going in inside the mouthpiece is primarily some kind
of efficient flow (as though oil was flowing through it, and the fewer
eddies the better) may be intuitively appealing, but does not appear to be
correct.
>>>
>>>> Removing sharp edges eliminates turbulence, and that is always good.
>>>>
FROM: kymarto (kymarto123@...)
SUBJECT: Re: More on taper at bottom of window.
I agree. Also it is important to realize that the turbulence being referred to is simply the dissipation of the jet within the reed channel. Perhaps not generally realized, but there is a free jet formed at the reed, much like the air jet of the flute. Like any jet, it loses focus and dissipates
into small vortices, which is exactly what needs to happen so that it does not interfere with the standing wave in the tube. This definitely does not mean that there is significant turbulence in the mpc generally. The free jet travels some way down the reed channel. The air in the mpc does not
"roil".
The energy/effort to set the reed into motion is a function of the pressure differential across the reed. Ostensibly then, it would be easier to set the reed into motion with a low baffle, rather than a high one.
As regards a "pressure rebound". There is one. It is the reflection of the pressure wave which has hit the end of the tube, inverted, and traveled back up to the top. That is why the reed vibrates at the frequency of the tube. In saxes, there is another reflection from the point where the mpc
meets the neck, which determines the ratio of open/closed. In the clarinet this does not exist, and the ratio is, IIRC 50/50. This is one of the reasons that the clarinet and the sax have such a different blowing feel even using the same design of reed valve.
Toby
MartinMods <lancelotburt@...> wrote:
"when a SHARP EDGED 'DITCH' [caps mine] is carved just downstream of the reed channel exit one can experience an easier attack transient."
D. Bechert failed to specify exactly what he meant by "sharp" in his personal correspondence to the author of your quoted puplication, as one doing a serious scientific study perhaps ought. We should define "sharp" a little more precisely maybe.
Benade claims that if the edges are sharper than the radius of the curvature .01xSQRT(250/f)mm where f is the frequency of thlowest note of the instrument, there will be undesirable turbulence. The frequency of E3 on the clarinet (as in the quoted example above) is 147hz, so the critical radius
of curvature for any edge would be .013mm.
I doubt that one could carve turkey with such an edge, but it would still have the appearance of sharpness to the casual observer.
---------------------------------
From: Barry Levine <barrylevine@...>
To: MouthpieceWork@yahoogroups.com
Sent: Thu, December 3, 2009 11:48:54 PM
Subject: Re: [MouthpieceWork] Re: More on taper at bottom of window.
>> I would characterize the change I felt as that the attack for notes got
>> better, easier, once I restored a bit of edge to the bottom of the window.
>>
>> I'm not sure what a "stuffy edgy sound" would be, but it's not how I'd
>> describe what I felt or got. Attack was easier, and notes were less "tubby"
>> perhaps.
>>
>> My sense is that it's a change in the air movement under the reed that's at
>> work, somehow. The feel was similar to the results when adding baffle. The
>> air movement is then closer to the reed, and the transfer of energy to the
>> reed is more efficient.
>>
>>> --There is no transfer of energy to the reed as such. I'm not sure what you
>>> mean by that.
I'm referring to effort/energy required to set the reed in motion.
>> Regarding turbulence: The air between the reed and the baffle has to be quite
>> turbulent. Even with a fairly straight baffle, there's curvature at the very
>> tip of the baffle to set the air roiling; not to mention the motion of the
>> reed slapping the air - which means there is pressure rebound traveling back
>> up at the reed. Perhaps some turbulence at the bottom of the window maintains
>> a certain slap-back-pressure that would dissipate faster otherwise.
>>> --I don't think this is very accurate. I suggest you read this:
>>> hal.archives- ouvertes. fr/docs/00/ 25/27/96/ PDF/ajp-jp419940 4C5120.pdf
>>
I've taken a look at this paper... Thanks for locating it. It's quite
technical, but some things do seem apparent.
Firstly, I don't see anything about pressure rebound (i.e. A wave bouncing
back at the reed from the baffle) discussed here. It seems to me that is
something that should occur, but I may be wrong.
Secondly, though, it appears my assumptions about turbulence under the reed
are correct. Have you noted what they had to say on p C5-560, discussing the
modulation of the volume flow through the reed channel by the oscillation of
the reed? Here they discuss the behavior of the air jet through the
mouthpiece:
"The intrinsic instability of the free jet results into a chaotic vortical
motion called turbulence. Typical for a turbulent flow is that even at high
Reynolds numbers [mathematical expression] the kinetic energy of the jet is
very efficiently dissipated by energy transfer to small vortical
structures."
So it is clear that air movement in the mouthpiece is quite turbulent.
In discussing how the reed is set in motion, (PC-5-562), which occurs "due
to a modulation of the Bernoulli force", they note:
"After the curvature of the lay, the geometry of the baffle is the most
critical part of mouthpiece design. Not only the spectral distribution of
the sound is influenced, but also the emission facility is affected."
The paper goes on to report that:
"when a SHARP EDGED 'DITCH' [caps mine] is carved just downstream of the
reed channel exit one can experience an easier attack transient."
[If one refers to illustration "C", we see a cross section of a mouthpiece
with said ditch carved just behind what I construe as the tip rail.}
I presume that said "ditch" would increase turbulence further.
Further regarding turbulence, the paragraph entitled "Turbulence and Chaos"
seems to make the point that turbulence is a necessity.
"The addition of noise to synthetic sound is necessary to obtain a
reasonable naturalness. In speech research this problem has already been
recognized, and models of turbulent noise production have been proposed."
Furthermore: "As musical instruments are non-linear oscillator[s] they
exhibit chaotic behavior. A certain level of non-periodicity is an essentail
characteristic of musical sound... Turbulence is an important detail in a
clarinet."
Beyond my recent experience with my tenor piece's window [I was lucky not to
spoil my favorite piece!], I think the fact that many popular saxophones
mouthpieces have sharp step baffles (sure to induce a certain amount of
turbulence occurring after the reed) supports the notion that turbulence
inside the mouthpiece is not necessarily a bad thing, and a few sharp edges
are useful, if we know where to put them.
This idea that what's going in inside the mouthpiece is primarily some kind
of efficient flow (as though oil was flowing through it, and the fewer
eddies the better) may be intuitively appealing, but does not appear to be
correct.
>>>
>>>> Removing sharp edges eliminates turbulence, and that is always good.
>>>>
FROM: kwbradbury (Keith Bradbury)
SUBJECT: Re: More on taper at bottom of window.
>As regards a "pressure rebound". There is one.
He was asking about a rebound off the baffle and back to the reed. Ferron shows some mouthpiece diagrams in his book with sound path reflections off the baffle and the "wall". These may be more artistic than scientific but I think they are based on science.
FROM: kymarto (kymarto123@...)
SUBJECT: Re: More on taper at bottom of window.
Not any science of which I am aware, and I have read the section on mpcs in Scavone pretty carefully as well as Benade's explanation of the function of the baffle in FMA.
C'mon guys, we are talking here about compression waves in a gas and Bernoulli forces, not rubber balls bouncing off of walls...
Toby
Keith Bradbury <kwbradbury@...> wrote:
>As regards a "pressure rebound". There is one.
He was asking about a rebound off the baffle and back to the reed. Ferron shows some mouthpiece diagrams in his book with sound path reflections off the baffle and the "wall". These may be more artistic than scientific but I think they are based on science.
FROM: kwbradbury (Keith Bradbury)
SUBJECT: Re: Baffles
Ferron was/is a pretty bright guy. Have you picked up his book yet? He discusses the vector of the sound wave originating at the reed and perpendicular to it. True it diffuses, but near its origination the reed "spanks" the air and creates a sound wave that bounces off the baffle and back to the reed.
________________________________
From: "kymarto123@..." <kymarto123@...>
To: MouthpieceWork@yahoogroups.com
Sent: Sun, December 6, 2009 7:19:38 AM
Subject: Re: [MouthpieceWork] Re: More on taper at bottom of window.
Not any science of which I am aware, and I have read the section on mpcs in Scavone pretty carefully as well as Benade's explanation of the function of the baffle in FMA.
C'mon guys, we are talking here about compression waves in a gas and Bernoulli forces, not rubber balls bouncing off of walls...
Toby
Keith Bradbury <kwbradbury@yahoo. com> wrote:
>>As regards a "pressure rebound". There is one.
>
>He was asking about a rebound off the baffle and back to the reed. Ferron shows some mouthpiece diagrams in his book with sound path reflections off the baffle and the "wall". These may be more artistic than scientific but I think they are based on science.
>
FROM: lancelotburt (MartinMods)
SUBJECT: Re: Baffles
Ferron's analogy of a vibrating steel bar, clamped at one end, and the sound wave reflecting off a baffle-like surface next to it according to the laws of physics - angle of incidence = angle of reflection, is interesting, but perhaps overly simplistic, being, he left out all the things that other acousticians consider important (and the reverse is also true) - as Toby alludes to.
Obviously the shape and angle of the baffle are of utmost importance. One should keep in mind that the compression waves are traveling in both directions, not only originating from the reed, and that the reed is coupled between two (three on a conical bored instrument - add the mouthpiece Frs generating chamber) resonating air chambers, and forced to vibrate sympathetically with them. The compression waves travel partially, beyond the mouthpiece/reed, into the player's coupled, vocal tract resonator, and back.
I think that if Ferron's analogy has any real significance, it would be between the initial attack of a note, the point where the reed went from "at rest", into motion, and the point where a stable harmonic regime is established.
Ferron does mention how non-harmonic partials formed by mouthpiece surfaces and shapes can interfere with tone production efficiency.
________________________________
From: Keith Bradbury <kwbradbury@yahoo.com>
To: MouthpieceWork@yahoogroups.com
Sent: Sun, December 6, 2009 9:09:29 AM
Subject: Re: [MouthpieceWork] Baffles
Ferron was/is a pretty bright guy. Have you picked up his book yet? He discusses the vector of the sound wave originating at the reed and perpendicular to it. True it diffuses, but near its origination the reed "spanks" the air and creates a sound wave that bounces off the baffle and back to the reed.
________________________________
From: "kymarto123@ ybb.ne.jp" <kymarto123@ybb. ne.jp>
To: MouthpieceWork@ yahoogroups. com
Sent: Sun, December 6, 2009 7:19:38 AM
Subject: Re: [MouthpieceWork] Re: More on taper at bottom of window.
Not any science of which I am aware, and I have read the section on mpcs in Scavone pretty carefully as well as Benade's explanation of the function of the baffle in FMA.
C'mon guys, we are talking here about compression waves in a gas and Bernoulli forces, not rubber balls bouncing off of walls...
Toby
Keith Bradbury <kwbradbury@yahoo. com> wrote:
>>As regards a "pressure rebound". There is one.
>
>He was asking about a rebound off the baffle and back to the reed. Ferron shows some mouthpiece diagrams in his book with sound path reflections off the baffle and the "wall". These may be more artistic than scientific but I think they are based on science.
>
FROM: petesajazzer (Peter M Healey)
SUBJECT: Re: More on taper at bottom of window.
There are also issues of placement of
the air stream in the mouthpiece, for softer playing."
Lance,
I would love to hear you playing like that as it is something that I find quite difficult to do.I have a small collection of mouthpieces most of which do not permit me to play softly with ease---maybe I need a more free-blowing piece?
Peter Healey
----- Original Message -----
From: MartinMods
To: MouthpieceWork@yahoogroups.com
Sent: Tuesday, December 01, 2009 6:20 PM
Subject: Re: [MouthpieceWork] More on taper at bottom of window.
Hal Wrote: "From a teaching and playing viewpoint, we always talk
about "spinning the air forward." There are also issues of placement of
the air stream in the mouthpiece, for softer playing."
MartinMods wrote: I understand and I was taught similar concepts. The mental imagery may work but it is not at all related to what is actually going on in our physical reality. In reality, all one is doing is manipulating the shape of the vocal tract, our body resonating cavity in order to better align and reinforce specific coupled resonances of the instrument's air column. "Shaping" the note is the most accurate common analogy perhaps.
During actual playing, we still need to simplify our mental concept of what is going on by using mental imagery, but, now that I understand what is going on a little better, the "real world" coupled resonating body cavity (vocal tract) imagery works better for me than the old inaccurate "air stream" thing.