Hi from the UK, where the latest issue of the Clarinet & Saxophone 
Society magazine has an interesting article on Lomax clarinet 
mouthpieces. 
 
There is quite a lot about the "Varibore" mouthpiece which seems to be 
a standard piece with a brass screw that can goes from the outside, 
low down into the tone chamber.  This apparently stays airtight, but 
introduces a "perturbation" in the flow and has effects on the tone, 
intonation and feel of the mouthpiece.  The mouthpiece can then be 
tailored to what the player wants or to the acoustics of the room.

Has anyone seen one of these "Varibore" mouthpieces ?  It sounds like 
a fairly easy modification to make to your own piece, but where would 
the threaded hole go on a sax mouthpiece, and what size would work 
best ?

Happy Christmas from a first time poster

Rhys

As I recall, I did not see any of these at the Salt Lake City Utah ICS
ClarinetFest in 2003, but I did see them at the 2004 Washington DC
ClarinetFest. (They may have been available in 2003, but I did not see
them.) In 2004, I watched several players try them out, including some
pretty knowledgable pros. They seemed impressed with them, although
the sound, intonation and response did not seem to be much different
from a listener point of view. Maybe they liked the response. I even
saw a couple of folks buy them. But at least one of the pros that
bought one was not playing it 10 months later. I do not know what that
means. I did not personally try one out. The screw looked like a
1/4-20 brass set screw (just a piece of threaded rod with a slot in
the top) inserted near the tenon. The threads to accept it seemed to
be tapped directly in the material of the piece itself (no insert of
any type). I did not see the shape of the bottom of the screw (that
would have actually been in the chamber). The pieces otherwise looked
normal. In fact, think they offer the mod on any of their standard
clarinet pieces for about $40 extra. I never saw a sax piece with this
mod.

- Brent -
=============--- In MouthpieceWork@yahoogroups.com, "rhysonsax" <rhysonsax@g...> wrote:
>
> Hi from the UK, where the latest issue of the Clarinet & Saxophone 
> Society magazine has an interesting article on Lomax clarinet 
> mouthpieces. 
>  
> There is quite a lot about the "Varibore" mouthpiece which seems to be 
> a standard piece with a brass screw that can goes from the outside, 
> low down into the tone chamber.  This apparently stays airtight, but 
> introduces a "perturbation" in the flow and has effects on the tone, 
> intonation and feel of the mouthpiece.  The mouthpiece can then be 
> tailored to what the player wants or to the acoustics of the room.
> 
> Has anyone seen one of these "Varibore" mouthpieces ?  It sounds like 
> a fairly easy modification to make to your own piece, but where would 
> the threaded hole go on a sax mouthpiece, and what size would work 
> best ?
> 
> Happy Christmas from a first time poster
> 
> Rhys
>

> There is quite a lot about the "Varibore" mouthpiece which seems to be 
> a standard piece with a brass screw that can goes from the outside,
> low down into the tone chamber. This apparently stays airtight, but
> introduces a "perturbation" in the flow and has effects on the tone,
> intonation and feel of the mouthpiece. The mouthpiece can then be
> tailored to what the player wants or to the acoustics of the room.

If you can post a link to a picture of this, that would be interesting.

As far as perturbation of airflow in the mouthpiece, another thing that
comes to mind is the Runyon "spoiler".

FWIW, I've made mouthpiece baffle inserts for myself with and without
spoilers, and the effect of a spoiler was not at all obvious to me. I didn't
try any unusual angles or bends - that would be an interesting experiment.

Barry

It seems to me that the main effect would be the variation in the
interior volume of the piece, not any disruption ("perturbation") of
the flow of the air itself. This is because, as I figure it (roughly),
the opening of a typical clarinet piece at the tip is 1.10 mm
(undisplaced reed) by 14.0 mm, which gives an opening area about 0.15
square centimeters. On the other hand, the crossection of the back
bore of the clarinet (where the screw would be) is about 14.65 mm or a
crossection area of about 1.69 square centimeters. I guess a player
(guess based on the human lung capacity being partially emptied in
about half a minute) might supply perhaps 1000 cubic centimeters per
minute of air into the clarinet. This converts to a flow velocity of
about 65 meters per minute as the air passes through the tip opening
at the reed. That would likely be very turbulent. On the other hand,
the air flow in the back bore of the piece is only about 6 meters per
minute, due to the larger area of the crossection through which the
air passes, compared  to the tip opening. Compare this to the speed of
sound at 20 degrees Celsius, which is over 20,000 meters per minute. I
think it is pretty unlikely that a small round obstruction would
produce much "perturbation" in the flow of the air itself at 6 meters
per minute. I did not calculate a Reynolds number for it, but I think
that flow would be pretty laminar (not turbulent). On the other hand,
the standing sound wave itself could be slightly/partially reflected
by an obstruction, and of course changing the interior volume of the
back bore of the piece would have significant effect on its tuning and
other characteristics. These latter two effects are (as I guess at it)
more likely to have an effect than any "perturbation" in the flow of
the air itself. I have never actually measured any of this, so it's
all a guess.






--- In MouthpieceWork@yahoogroups.com, "Barry Levine"
<barrylevine@n...> wrote:
>
> > There is quite a lot about the "Varibore" mouthpiece which seems
to be 
> > a standard piece with a brass screw that can goes from the outside,
> > low down into the tone chamber. This apparently stays airtight, but
> > introduces a "perturbation" in the flow and has effects on the tone,
> > intonation and feel of the mouthpiece. The mouthpiece can then be
> > tailored to what the player wants or to the acoustics of the room.
> 
> If you can post a link to a picture of this, that would be interesting.
> 
> As far as perturbation of airflow in the mouthpiece, another thing that
> comes to mind is the Runyon "spoiler".
> 
> FWIW, I've made mouthpiece baffle inserts for myself with and without
> spoilers, and the effect of a spoiler was not at all obvious to me.
I didn't
> try any unusual angles or bends - that would be an interesting
experiment.
> 
> Barry
>

--- In MouthpieceWork@yahoogroups.com, "ko4py" <brent_smith@n...> 
wrote:
>
> It seems to me that the main effect would be the variation in the
> interior volume of the piece, not any disruption ("perturbation") of
> the flow of the air itself. This is because, as I figure it 
(roughly),
> the opening of a typical clarinet piece at the tip is 1.10 mm
> (undisplaced reed) by 14.0 mm, which gives an opening area about 
0.15
> square centimeters. On the other hand, the crossection of the back
> bore of the clarinet (where the screw would be) is about 14.65 mm 
or a
> crossection area of about 1.69 square centimeters. I guess a player
> (guess based on the human lung capacity being partially emptied in
> about half a minute) might supply perhaps 1000 cubic centimeters per
> minute of air into the clarinet. This converts to a flow velocity of
> about 65 meters per minute as the air passes through the tip opening
> at the reed. That would likely be very turbulent. On the other hand,
> the air flow in the back bore of the piece is only about 6 meters 
per
> minute, due to the larger area of the crossection through which the
> air passes, compared  to the tip opening. Compare this to the speed 
of
> sound at 20 degrees Celsius, which is over 20,000 meters per 
minute. I
> think it is pretty unlikely that a small round obstruction would
> produce much "perturbation" in the flow of the air itself at 6 
meters
> per minute. I did not calculate a Reynolds number for it, but I 
think
> that flow would be pretty laminar (not turbulent). On the other 
hand,
> the standing sound wave itself could be slightly/partially reflected
> by an obstruction, and of course changing the interior volume of the
> back bore of the piece would have significant effect on its tuning 
and
> other characteristics. These latter two effects are (as I guess at 
it)
> more likely to have an effect than any "perturbation" in the flow of
> the air itself. I have never actually measured any of this, so it's
> all a guess.
> 

I did a similar rough guess about air velocities at different points 
in the mouthpiece (for sax) and came up with similar results, though 
I didn't know how to take air temperature into account.  It seemed to 
indicate that turbulence effects are only happening at the tip and 
maybe 1cm or so into the mouthpiece, and not much if any turbulence 
at the entrance of the neck.  I think there are boundary effects that 
can affect the tone even down into the horn, depending on surface 
roughness of the bore (Toby can probably help here!) but I think 
that's different. In my mouthpiece development I haven't noticed any 
differences in playability with roughness down into the chamber.

Ken Barry
Saxscape Mouthpieces 
http://www.saxscape.com

  ----- Original Message ----- 
  From: Kenneth Barry 
  To: MouthpieceWork@yahoogroups.com 
  Sent: Monday, December 26, 2005 3:14 PM
  Subject: [MouthpieceWork] Re: Lomax "Varibore" Mouthpiece


  --- In MouthpieceWork@yahoogroups.com, "ko4py" <brent_smith@n...> 
  wrote:
  >
  > It seems to me that the main effect would be the variation in the
  > interior volume of the piece, not any disruption ("perturbation") of
  > the flow of the air itself. This is because, as I figure it 
  (roughly),
  > the opening of a typical clarinet piece at the tip is 1.10 mm
  > (undisplaced reed) by 14.0 mm, which gives an opening area about 
  0.15
  > square centimeters. On the other hand, the crossection of the back
  > bore of the clarinet (where the screw would be) is about 14.65 mm 
  or a
  > crossection area of about 1.69 square centimeters. I guess a player
  > (guess based on the human lung capacity being partially emptied in
  > about half a minute) might supply perhaps 1000 cubic centimeters per
  > minute of air into the clarinet. This converts to a flow velocity of
  > about 65 meters per minute as the air passes through the tip opening
  > at the reed. That would likely be very turbulent. On the other hand,
  > the air flow in the back bore of the piece is only about 6 meters 
  per
  > minute, due to the larger area of the crossection through which the
  > air passes, compared  to the tip opening. Compare this to the speed 
  of
  > sound at 20 degrees Celsius, which is over 20,000 meters per 
  minute. I
  > think it is pretty unlikely that a small round obstruction would
  > produce much "perturbation" in the flow of the air itself at 6 
  meters
  > per minute. I did not calculate a Reynolds number for it, but I 
  think
  > that flow would be pretty laminar (not turbulent). On the other 
  hand,
  > the standing sound wave itself could be slightly/partially reflected
  > by an obstruction, and of course changing the interior volume of the
  > back bore of the piece would have significant effect on its tuning 
  and
  > other characteristics. These latter two effects are (as I guess at 
  it)
  > more likely to have an effect than any "perturbation" in the flow of
  > the air itself. I have never actually measured any of this, so it's
  > all a guess.
  > 

  I did a similar rough guess about air velocities at different points 
  in the mouthpiece (for sax) and came up with similar results, though 
  I didn't know how to take air temperature into account.  It seemed to 
  indicate that turbulence effects are only happening at the tip and 
  maybe 1cm or so into the mouthpiece, and not much if any turbulence 
  at the entrance of the neck.  I think there are boundary effects that 
  can affect the tone even down into the horn, depending on surface 
  roughness of the bore (Toby can probably help here!) but I think 
  that's different. In my mouthpiece development I haven't noticed any 
  differences in playability with roughness down into the chamber.

  Ken Barry
  Saxscape Mouthpieces 
  http://www.saxscape.com

  An interesting thread! Boundary effects, as I understand them, are really only viscous losses very close to the walls as roughness slows the motion of air molecules within .1mm of walls and converts their energy to heat. You wouldn't get much in the way of boundary effects due to a screw sticking down into the chamber of a mpc, I don't think.

  One thing to keep in mind is that the air movement in a musical tube is not anything like a laminar flow--essentially it consists of a bunch of standing waves with nodes and antinodes. At the former the air moves quite a lot, with little change in pressure; at the latter there is hardly any actual movement of air molecules--but large changes in pressure. So you can get turbulence effects around any antinode, and the antinodes change depending on the length of the air column. Not only that, there are nodes and antinodes for the harmonics as well.

  I'm not sure what goes on in the mpc, being so near the end of the tube on that score, but turbulence could definitely be happening in the mpc chamber if you were to stick an obstruction in there. OTOH I guess that the main effects would come with a change in volume. I have been playing with clarinet barrels on a new horn I got and am struck with how a minute difference in the shape and volume of that short section of the air column can affect the overall response of the instrument. So small differences in volume do definitely count. Of course clarinet mpcs are quite different in design from sax mpcs--the throat is quite narrow compared to that of a sax mpc and the segue from the throat to the clarinet barrel is seamless, unlike the rather larger throat diameter of the sax mpc as compared to the neck opening: this alone would probably mean that a mechanism such as the Lomax screw would have less effect in a sax mpc than in a clarinet mpc. 

  When I first read this thread I was picturing a screw which dropped a whole section of the mpc down--like a gate in a levee. Just a screw end seems like it would only affect a very local section of the bore, which is not a good recipe for changing the air "flow" much. There is a mod for the flute in which a long rod is screwed into the center of the end cork plate and extends parallel quite a ways down right in the center of the head. Does anyone remember the name of this? Ohler rings or something--some flutists swear by it. It apparently has the effect of reducing the volume of the head joint--people speak about better response, etc. 

  I was thinking that it would be interesting to modify a sax mpc in the same way--with a rod coming off the back of the baffle and sitting in the middle of the chamber/throat. It would be nice to have an adjustable screw for this, threaded right through the back of the beak, but unfortunately I'm sure this would get in the way of playing. I suppose one could have different lengths of screws and screw them flush with the beak to try different effects. All one would need would be a drill and the right sized tap....anybody have some old mpcs to experiment with?...

  Toby

Toby wrote:
>>>I'm not sure what goes on in the mpc, being so near the end of the tube
on that score, but turbulence could definitely be happening in the mpc
chamber if you were to stick an obstruction in there. 

I'm pretty sure there would only be laminar recirculation flow at the
obstruction, not turbulence.  Turbulence is random chaotic flow that occurs
at higher velocities.  As mentioned, the velocities are only high enough at
the tip of the mouthpiece where the flow cross section is small.

Toby make the important distinction between fluids and acoustic standing
waves.  The air flow in a mouthpiece is useful for setting the reed to
vibrate.  Downstream, the air just dissipates to a very low velocity flow
and the standing waves are what makes the sounds (outside an occasional air
hiss). 

Many mouthpiece makers and refacers have been inspired to streamline the
interiors of the mouthpiece.  I think we see the advances in car and
airplane designs and assume there is a benefit to applying the same ideas
to mouthpieces.  Some have tried applying roughness like golf ball dimples.
 I think aerodynamic considerations have almost no application to
mouthpiece design.  However, they have inspired some very good baffle
designs anyhow.  So the mental model is not real important so long as it
motivates you to try something new.  

I think some step edges in a mouthpiece do give some edge to the sound. 
Test result examples of this are presented in the Wyman paper (see the
Links-Literature section).  But this is an acoustic phenomenon with waves
impinging on these edges.


		
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Keith Bradbury wrote:

> The air flow in a mouthpiece is useful for setting the reed to
> vibrate. 

 (snip)

> I think aerodynamic considerations have almost no application to
> mouthpiece design. However, they have inspired some very good baffle
> designs anyhow. So the mental model is not real important so long as it
> motivates you to try something new.

Baffles increase the perceived acoustical power of mouthpieces; and I think
I first saw it mentioned in an interview of Santy Runyon, that the Bernoulli
principle is involved, by increasing the effective air speed under the reed.
(IIRC, he made some of his first baffles out of chewing gum.)

As an example of a particular application, I have a Ponzol M1 tenor mpc
that, for me, felt somewhat unresponsive in the last octave.

To compensate for this, I added a small additional baffle at the rear of the
original baffle, reasoning that if adjusting reeds at the base of the vamp
improves low register response, then increasing airspeed at the underside of
the reed in this region would also be helpful - which I found to be the
case.

Barry