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OK, so I got to thinking...

Assuming that the bell of a horn has virtually no effect on intonation,
The leadpipe has a relatively minimal effect (if at all, per Joe) on intonation*
And the taper of the branches are the primary influence of intonation....

Why would a mouthpiece within reasonable size constraints have a dramatic effect on intonation???

* I do believe this, as I have had both a tuba and a trombone with multiple leadpipes. The response changed noticeably between leadpipes, and the timbre changed slightly, but there was virtually no effect on the relative intonation of the instrument (the overall pitch may have varied slightly).

MartyNeilan wrote:Why would a mouthpiece within reasonable size constraints have a dramatic effect on intonation???

Taking your statement of remaining within the context of a reasonable size:

The pitch of the final sound is the result of navigating through the impedance of the embouchure, mouthpiece, and tuba. Each contributes its influence.

But the mouthpiece is relatively broadbanded, meaning that it's resonance peak is a broad hill over the whole range of the instrument. A bigger backbore and a smaller cup each shift that hill to the right and raise the general pitch tendency. That affects the upper notes more than the lower notes. Benade found that as the popping frequency of the mouthpiece increased, the tendency to go sharp in the upper notes on the instrument moved faster than the tendency to go sharp down low.

And Benade also found that a larger throat actually increased the bandwidth of the mouthpiece, reducing its tendency to affect the pitch. So a large throat makes it easier to bend pitches (and the downside is that it doesn't filter out as much unresonant noise from the buzz).

As far as making a significant change on pitch, I don't think that's a resonance issue with the mouthpeice itself. But I do see how it can interact with the impedance curve of the player and cause a general tendency. But that's just a theory.

Chuck can check me on my electrical analogy: Mouthpieces have very low Q, the embouchure also has relatively low Q, and the tuba has high Q. Q is the quality of the resonance. Higher Q means more resonance, but over a narrower band of frequencies. That means that the mouthpiece and emchochure are broadbanded and depend on the tuba for lot of filtering of unresonant noise.

The basic intonation of the instrument is defined by the taper design. Added to that are about 1,365,859.4 additional influences, so it's hard to insist that everyone will have the same experiences or the same perceptions of those experiences.

Rick "not sure about the .4" Denney

Personal experience has provided some insight to this for me.


1. The faster the instrument tapers, the more "mouthpiece sensitive" the horn is.

2. The slower the instrument tapers, the LESS mouthpiece sensitive the horn is.


I find that generally horns lacking fast taper and having little bell flare "slot" well. This makes them more difficult to tune (or bend), but more "secure" feeling. Horns that taper quickly, slot less, and are more sensitive to what mouthpiece you are using. I liken this to playing a piece of flexible tubing with no taper at all, or playing a "practice" attachment with immediate flare. The longer the horn is cylindrical, generally the more it influences what you are doing at the mouthpiece.


Wes "can only cite personal experience, not claiming to be a physicist" pendergrass

Some good comments, but nothing form the bloke???

MartyNeilan wrote:Some good comments, but nothing form the bloke???

Maybe he has to work today. I think he's on record on this topic anyway -- see if you think his post, number 6 in Another mouthpiece question addresses your question?

Love the Guy Smiley avatar, BTW.

Eric "Muppet fan" L.

Rick Denney wrote:

Marty Neilan wrote:... (mouthpiece question) ...

... (over Tom's head) ... (uhhhhhmmm, yeah) ... (might as well be Greek) ... (eyes burning) ... (over Tom's head) ...

Rick "verbal Chuck Norris" Denney

Dude, you friggin' amaze me. I am pwn3d. Off to eBay I go!

Rick Denney wrote:A bigger backbore and a smaller cup each shift that hill to the right and raise the general pitch tendency. That affects the upper notes more than the lower notes. Benade found that as the popping frequency of the mouthpiece increased, the tendency to go sharp in the upper notes on the instrument moved faster than the tendency to go sharp down low. And Benade also found that a larger throat actually increased the bandwidth of the mouthpiece, reducing its tendency to affect the pitch. So a large throat makes it easier to bend pitches (and the downside is that it doesn't filter out as much unresonant noise from the buzz).

On both the YFB-621 and the MW 2141 (the latter being my present axe), I've had some trouble with the high notes (6th partial and up) being flat. All else being equal (i.e. assuming I'm not the problem, or only part of the problem), is it possible that switching to a mouthpiece with a bigger backbore and a smaller cup (and/or a higher popping frequency if that's also possible?) may help balance this out?

For the record, I consider myself non-mouthpiece sensitive simply because I've never bothered to experiment. I'm presently using the mouthpiece that came with my horn.

Stefan Kac wrote:On both the YFB-621 and the MW 2141 (the latter being my present axe), I've had some trouble with the high notes (6th partial and up) being flat. All else being equal (i.e. assuming I'm not the problem, or only part of the problem), is it possible that switching to a mouthpiece with a bigger backbore and a smaller cup (and/or a higher popping frequency if that's also possible?) may help balance this out?

That was Benade's theory. It seems to bear out to some extent with me, though I could play a toilet bowl with a pinhole throat and I would still tend sharp up high. It probably has to do with using pressure to compensate for my weak-*** embouchure.

Rick "who can't possibly imagine how Tom knows which note to play next in a Dixieland riff" Denney