Hello!
 I wonder if there is something that affects the tuning of a mouthpiece beyond the shank length?

 A mouthpiece that is tuned in the middle region may be out of tune in the acute region?

 The sound is a frequency and its eighth is a harmonic, is possible the eighth untune?

 

 Thanks!
 

 Sancler

I don't know that it would be possible to affect tuning on one harmonic only.  We've done some tricks on antennas, increasing the frequency of the fundamental without affecting the higher harmonics, but that involved adding a capacitor in the middle and offset feedline, that is, not feeding a dipole in the center, but to one side of center.  I have no idea how to do this acoustically.

Next... the low register tuning of the saxophone is mostly influenced by the volume of the mouthpiece past the end of the neck... and the exposed bore is part of the chamber volume.  

The upper register tuning is influenced somewhat by volume, but mostly by length.  A mouthpiece with a very small chamber must be pulled out excessively in order to obtain the volume needed to tune the low register.  Then palm key notes of the upper register become very flat. 

The volume needed is the missing part of the conical section of the neck.

If the mouthpiece has a very large chamber, then the mouthpiece must be pushed in to make the low register play in tune.  Again, the volume needed is the missing part of the conical section of the neck.  But now it is too short, and the palm key notes are sharp.

This shows up with all sizes of saxophones, from soprano to bass.  Some of the old "large chamber bass sax mouthpieces" many recommend will make the palm key notes unplayable.  They can not be "lipped down" in tune.  

I have a soprano sax mouthpiece that I backbored into the chamber somewhat, and made various lengths of tubes from Delrin, 1/2" (12.7 mm) O.D. x 5/16" (8 mm) ID that could be inserted.  In this way I could change the volume of the chamber, and this affected how far the mouthpiece pushed onto the neck cork to tune the instrument.  By finding the correct length, and thus chamber volume, I was able to adjust the mouthpiece such 
that the upper notes of the upper register played easily in tune without lipping up or down.

The front portion of the baffle has the most effect on tone, so leave that alone.  Changing the back part of the 
chamber has little effect on tone, but will vary the effective volume of the mouthpiece.

Paul C.