Instead of sharpening this area would lengthening the window achieve the same effect?   What are the negatives of a very long window.  I forget the name of the existing sax mouthpiece with the window going to the bottom of the table.  

No "negatives" as such to a long window, apart from more possibility of leakage around a warped reed. Cutting out the window has basically the same effect as lowering the baffle  at the point where the window is cut. You are mostly looking at the volume at all points in the mpc. You can take it
 off from under the table, or on the sides or at the baffle. It doesn't really matter AFAIK.

Toby 

John <john_w_price33@...> wrote:                                           Instead of sharpening this area would lengthening the window achieve the same effect?   What are the negatives of a very long window.  I forget the name of the existing sax mouthpiece with the window going to the
 bottom of the table.  
 
 
      
                 
                 
 

Has anyone here radically extended the window of a mpc and noted any obvious
changes, or lack thereof? I have not tried this mod.

If I extend the window, I'm exposing more of the reed to Bernoulli forces -
in particular, more of the reed under the base of the vamp.

Scraping a reed at the base of the vamp tends to free up the lower register
a bit.  Would extending the window further in this area might apply more
Bernoulli forces at this area, perhaps improving low register response?

Possibly related to this, I see that Johannes Gerber creates squared windows
with rounded corners, which exposes more of the underside of the reed in
this region to air movement than a window that terminates in a semicircle.

Considering the opposite,  a short window would be concentrating the
Bernoulli forces more at the slender end of the reed. In terms of flexing
the reed down, there would seem to be better leverage.

It's not clear how all these factors interact.

Barry
>  
> No "negatives" as such to a long window, apart from more possibility of
> leakage around a warped reed. Cutting out the window has basically the same
> effect as lowering the baffle  at the point where the window is cut. You are
> mostly looking at the volume at all points in the mpc. You can take it off
> from under the table, or on the sides or at the baffle. It doesn't really
> matter AFAIK.
> 
> Toby 
> 
> John <john_w_price33@...> wrote:
>                  
>                  
>> Instead of sharpening this area would lengthening the window achieve the same
>> effect?   What are the negatives of a very long window.  I forget the name of
>> the existing sax mouthpiece with the window going to the bottom of the table.
>> 
>>       
>>                 
>> 
>>  
>> 
> 
> 

--- In MouthpieceWork@yahoogroups.com, Barry Levine <barrylevine@...> wrote:
>
> Has anyone here radically extended the window of a mpc and noted any obvious
> changes, or lack thereof? I have not tried this mod.

I did not notice anything major.  But I added a large epoxy baffle at the same time so it compensated for the volume change and made the sound brighter.

> 
> If I extend the window, I'm exposing more of the reed to Bernoulli forces -
> in particular, more of the reed under the base of the vamp.
> 
> Scraping a reed at the base of the vamp tends to free up the lower register
> a bit.  Would extending the window further in this area might apply more
> Bernoulli forces at this area, perhaps improving low register response?

The Bernoulli forces are only strong near the reed tip where the cross-sectional area the air is passing through is small and so the velocity is high.  A high baffle helps to keep the velocity high a little longer, but after a 1/2" or so it is really weak and the reed is getting stiffer.  By the time the air gets to the larger chamber under the table, its velocity is too slow to be significant.  

--- In MouthpieceWork@yahoogroups.com, Barry Levine <barrylevine@...> wrote:

(trimmed)
> 
> If I extend the window, I'm exposing more of the reed to Bernoulli forces -
> in particular, more of the reed under the base of the vamp.


Hardly.  The Bernoulli Effect would dissipate quickly after the tip rail and first few mm's of the baffle.  As the bore opens there is very little air velocity.

Also, the portion of the reed exposed by lengthening the window is very thick and does not vibrate in a way that exites the standing wave.  It is essentially motionless.

What is really gained by a long window, such as one of the Rovner models, is some additional chamber volume.

Paul C.

One negative is that it takes a long time with a file.  A power tool is 
fast but dangerous.  I don't usually extend the window unless it has 
become visibly too short.  This happens when the tip gets filed down a 
lot.  It's a modification that doesn't have much of a payoff.
There is one mouthpiece now that has a window going all the way back.  I 
don't remember what kind.

--- In MouthpieceWork@yahoogroups.com, "John" <john_w_price33@...> wrote:
>
> Instead of sharpening this area would lengthening the window achieve the same effect?   What are the negatives of a very long window.  I forget the name of the existing sax mouthpiece with the window going to the bottom of the table.
>

In addition to enlarging the chamber, a longer window will tend to make a piece less resistant.  To what extent that is a negative or positive is a matter of taste.

--- In MouthpieceWork@ yahoogroups. com, "John" <john_w_price33@ ...> wrote:
>
> Instead of sharpening this area would lengthening the window
achieve the same effect? What are the negatives of a very long window.
I forget the name of the existing sax mouthpiece with the window going
to the bottom of the table.

As the table is angled in relation to the throat, the table wall becomes thicker the further back from the tip you go.  I would imagine that lengthening the table on any stock mouthpiece to that of a Jody Jazz or Rovner, without compensating for the increase in volume (by say lowering the roof) would result in an excessively large chamber with all it's acoustical problems.


      

--- In MouthpieceWork@yahoogroups.com, Hal Cooper <halcooper79@...> wrote:

(trimmed)

> There is one mouthpiece now that has a window going all the way back.  I 
> don't remember what kind.


Rovner Deep V.

http://www.rovnerproducts.com/deepv.htm

Paul

Hello Hal,

Which modification doesn't have much payoff - the tip getting filed down
alot, or the restoration of the usual window length?

I've not seen any discussion here as to what exactly constitutes a window
that is too short;  nor what the optimal length of the window should be;
nor what actual shortcomings members have associated with shorter windows.

Previous discussions, in which it was pointed out that turbulence and
Bernoulli effects take place mainly just behind the tip and a little ways
in, suggest that a shorter window shouldn't make much of a difference,
except in terms of mouthpiece volume.

I have no experimental data on this.  Anyone else?  It would seem quite a
bit easier to extend windows or modify the bottom of the "U" than it is to
shorten windows.

Barry


> One negative is that it takes a long time with a file.  A power tool is
> fast but dangerous.  I don't usually extend the window unless it has
> become visibly too short.  This happens when the tip gets filed down a
> lot.  It's a modification that doesn't have much of a payoff.
> There is one mouthpiece now that has a window going all the way back.  I
> don't remember what kind.
>

"I've not seen any discussion here as to what exactly constitutes a window
that is too short;  nor what the optimal length of the window should be;
nor what actual shortcomings members have associated with shorter windows.  I have no experimental data on this.  Anyone else"  


I posted test results a few months back.  I found that filling the window in, up to a hair short of the break, with an extension of the ramp improved intonation, reduced resistance, and focused the tone.  The angled extension created a surface parallel to the baffle which then met the reed without obstruction..  The cross sectional view of the mouthpiece then showed a smooth bore, from the tip to the neck entrance, without obstructions and without the significant bore perturbation of the window slot and sudden U wall.  The displaced chamber volume was regained by rounding the side walls.

Extending the ramp parallel to the reed, to the same point just short of the break, and ending with the same height, vertical wall of the original U, made the mouthpiece play very bright and added a great deal of resistance. 


________________________________
From: Barry Levine <barrylevine@...>
To: MouthpieceWork@yahoogroups.com
Sent: Mon, December 14, 2009 1:47:53 PM
Subject: Re: [MouthpieceWork] Negatives of long window?

  
Hello Hal,

Which modification doesn't have much payoff - the tip getting filed down
alot, or the restoration of the usual window length?

I've not seen any discussion here as to what exactly constitutes a window
that is too short;  nor what the optimal length of the window should be;
nor what actual shortcomings members have associated with shorter windows.

Previous discussions, in which it was pointed out that turbulence and
Bernoulli effects take place mainly just behind the tip and a little ways
in, suggest that a shorter window shouldn't make much of a difference,
except in terms of mouthpiece volume.

I have no experimental data on this.  Anyone else?  It would seem quite a
bit easier to extend windows or modify the bottom of the "U" than it is to
shorten windows.

Barry

> One negative is that it takes a long time with a file.  A power tool is
> fast but dangerous.  I don't usually extend the window unless it has
> become visibly too short.  This happens when the tip gets filed down a
> lot.  It's a modification that doesn't have much of a payoff..
> There is one mouthpiece now that has a window going all the way back.  I
> don't remember what kind.
>


 


      

Barry Levine wrote:
>
> Hello Hal,
>
> Which modification doesn't have much payoff - the tip getting filed down
> alot, or the restoration of the usual window length?
>
Hal> There are several modifications that don't have a big pay off.  
Extending the window and working on side rails are the main ones.  The 
width of the tip rail has a big impact.

>
> I've not seen any discussion here as to what exactly constitutes a window
> that is too short; nor what the optimal length of the window should be;
> nor what actual shortcomings members have associated with shorter windows.
>
Hal> It's pretty obvious when you see it.

>
> Previous discussions, in which it was pointed out that turbulence and
> Bernoulli effects take place mainly just behind the tip and a little ways
> in, suggest that a shorter window shouldn't make much of a difference,
> except in terms of mouthpiece volume.
>

Hal>  It may help some.  The vintage Meyers are shorter.