A client of mine was asking how to get better low note response from his
mouthpieces.  I told him to make sure his sax is leak free and to consider
using key clamps between pad work.  As for the mouthpiece, I suggested
getting a nice arc to the facing curve and possible lengthening the curve
to favor low note response.  He asked me what I meant by a "nice arc". 
This was my reply:

Most facing curves are based on the arc of a circle.  If they deviate from
this, it is difficult to determine if it is intentional or sloppy
manufacturing.  I think most of the variation is sloppy work since if you
measure several MPs from the same manufacturer marked the same, there is
usually some significant variation.

The rails can be even, but there can still be high and low spots on the
facing curve.  Low spots are flat areas that cause the reed to slap against
it.  This can create some edge to the sound.  Some facings have intentional
flat spots in them to produce more edge.  I've seen this most often near
the tip on hand finished pieces.

Some MPs have high spots on the facing curve.  This creates a hump that the
reed has to pivot over.  The hump creates resistance which makes low notes
harder to get.  A facing curve with a smooth curve plays smooth and
responds easier.

Some pros complain that their refaced MP blows too freely.  Jon Van Wie
mentioned that in his interview with Paul Coats.  Resistance can be added
back in by opening the tip some and/or going to a shorter facing.  There
are usually trade offs with change.  Most people prefer free-er blowing
pieces.  You can get the sound in your head with less effort.  But, If you
like the way a MP plays now, dont mess with it.  I play on some mouthpieces
I wont touch.  They have "defects" in the facing curve that have to be
considered "features" until I find better playing pieces.  Then I will work
on them.


==Hear me at http://www.geocities.com/kwbradbury/MojoCD.html
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1.I recently read an article on the net where Santy Runyon stated 
that all the facing curve should be a part of a perfect circle. 
Is this the golden rule or can success be had by opening up the tip 
in a tighter curve?  
I'm new at this so please forgive my ignorance.

2.  What relatively easy to use programs are available for Pc users 
for plotting curves?

> 1.I recently read an article on the net where Santy Runyon stated 
> that all the facing curve should be a part of a perfect circle. 
> Is this the golden rule or can success be had by opening up the tip 
> in a tighter curve?  

I'd say its a Silver rule.  ;-)  Radial curves play well and are very 
responsive on sax mouthpieces.  Making the curve gradually tighter as 
it approches the tip also works.

First, you need to be able to hand face a precise and even curve on a 
mouthpiece.  If you can not do this well, the subtleties of different 
curve designs gets lost within the implementation error.  

> 
> 2.  What relatively easy to use programs are available for Pc users 
> for plotting curves?

I think spreadsheet programs are the way to go.  Excel, Lotus123, 
even MS Works have plotting capabilities.   See the Files area for 
some sample Excel files.

Many mathematical curves will produce targets for a facing curve that will work.  For me, I was after the simplest curve that would work.  I also wanted it to pass through the desired tip opening, the desired facing length and be exactly mathematically tangent to the table.  A simple radial curve does this with 2 constants. 
 
Later I found I wanted to also play with the curvature.  Adding a 3rd constant by using an elliptical curve does this.  I played with a few other curves, but the ellipse was the most "elegant" and I could visualize the significance of the 3rd constant as the aspect ratio of the ellipse.  
 
The oddest non-elliptical facing curve that I have found that "works" is a 3-segment curve.  It is flat at the table, has a radius, then a flat section in the middle of the "curve", then a radius, and finally a flat section near the tip.  This works well on clarinet mouthpiece.  I'm not sure why but I suspect it adds resistance where players like it with respect to the 3 clarinet registers.  This curve also works well on some lead alto mouthpieces that are not real open.  This would be a very odd curve to fit with a mathematical curve.  I just fit an ellipse through it and look at a plot to deside where I want to deviate from the ellipse to create the flat sections.

--- On Mon, 6/29/09, lcchtt <Letydan@...> wrote:


From: lcchtt <Letydan@...>
Subject: [MouthpieceWork] Re: Elliptical Facing Curves
To: MouthpieceWork@yahoogroups.com
Date: Monday, June 29, 2009, 5:11 AM








Why not a double exponential curve? Something like this one:

y = A1*exp(-x/t1) + A2*exp(-x/t2) + y0

It fits any link I measured, modern and old ones... moreover scientists know that if we use a theoretical curve with a lot of parameters (6, 7, 8...) it will fit even better :) of course the problem is the physical meaning of these parameters. I am writing this because I noticed Link curves are not really radial neither exponential but they play in any case great. What I usually do is to start with an elleptical facing (thanks Mojo 4 sharing your knowledges) and finish it using my ears and my (few) skills as saxophone player to adapt the mouthpiece to the player needs. We should not forget a mouthpiece should play in spite of all the math we are using.

DannyG

















      

I think we do reach a point of diminishing returns as we add more variables.  One thing is that unless you're programing the machine cutting the curve, the numbers are somewhat soft targets.  A radial curve or an elliptical curve of such and such length and eccentricity gets good results, but once it's close, I end up doing the final adjustments to it by testing and adjusting for sound and feel.

--- In MouthpieceWork@yahoogroups.com, Keith Bradbury <kwbradbury@...> wrote:
>
> Many mathematical curves will produce targets for a facing curve that will work.  For me, I was after the simplest curve that would work.  I also wanted it to pass through the desired tip opening, the desired facing length and be exactly mathematically tangent to the table.  A simple radial curve does this with 2 constants. 
>  
> Later I found I wanted to also play with the curvature.  Adding a 3rd constant by using an elliptical curve does this.  I played with a few other curves, but the ellipse was the most "elegant" and I could visualize the significance of the 3rd constant as the aspect ratio of the ellipse.  
>  
> The oddest non-elliptical facing curve that I have found that "works" is a 3-segment curve.  It is flat at the table, has a radius, then a flat section in the middle of the "curve", then a radius, and finally a flat section near the tip.  This works well on clarinet mouthpiece.  I'm not sure why but I suspect it adds resistance where players like it with respect to the 3 clarinet registers.  This curve also works well on some lead alto mouthpieces that are not real open.  This would be a very odd curve to fit with a mathematical curve.  I just fit an ellipse through it and look at a plot to deside where I want to deviate from the ellipse to create the flat sections.
> 
> --- On Mon, 6/29/09, lcchtt <Letydan@...> wrote:
> 
> 
> From: lcchtt <Letydan@...>
> Subject: [MouthpieceWork] Re: Elliptical Facing Curves
> To: MouthpieceWork@yahoogroups.com
> Date: Monday, June 29, 2009, 5:11 AM
> 
> 
> 
> 
> 
> 
> 
> 
> Why not a double exponential curve? Something like this one:
> 
> y = A1*exp(-x/t1) + A2*exp(-x/t2) + y0
> 
> It fits any link I measured, modern and old ones... moreover scientists know that if we use a theoretical curve with a lot of parameters (6, 7, 8...) it will fit even better :) of course the problem is the physical meaning of these parameters. I am writing this because I noticed Link curves are not really radial neither exponential but they play in any case great. What I usually do is to start with an elleptical facing (thanks Mojo 4 sharing your knowledges) and finish it using my ears and my (few) skills as saxophone player to adapt the mouthpiece to the player needs. We should not forget a mouthpiece should play in spite of all the math we are using.
> 
> DannyG
>