Effects of mouthpieces on intonation?

[bort]

Maybe not exactly what you mean... but I've found that for "lipping" notes, some mouthpieces are easier than others to bend a note into tune.

[Roger Lewis]

In my experience, going from the Miraphone TU23 (old C4) to the Miraphone TU27 Rose Solo model, quite a number of intonation improvements occurred. Even though these mouthpieces are somewhat similar I was impressed with the intonation improvements that were noticeable when played the same way. Specifically the D in the staff on a CC tuba, which tends to be on the low side and needs to be raised - this mouthpiece put that note perfectly in tune without affecting other notes that need to be manipulated a bit. It also has a sweeter sound that the TU23 and is my "go to" mouthpiece on the 188.

Just what I've seen. YMMV.

Roger

[iiipopes]

Yes, indeed. With the replacement detachable upright St Pete Bell, my 186 is very sensitive to mouthpiece intonation. With my Curry, it is generally great, with the extreme lows going a little sharp but lippable down, and the extreme highs going a little flat, but lippable up, not related to the general 5th partial tendencies. The same characteristics with a Kelly 18. With a Wick 1L, it was really, really good and broad on the low end, mid was fine, top end wouldn't center. With a PT34, top end was really responsive and in tune, midrange intonation wobbled, low end was grainy. With my particular Bach 18, top end is particularly secure and right on pitch. With the Bloke symphony, intonation was very inconsistent from note to note and register to register, with some notes sharp, others flat, with no discernable pattern.

[Wyvern]

I have noticed that shallower cup mouthpieces tend to make the tuba play sharper (need to pull out tuning slide more).

Also I find that deeper cup mouthpieces tend to easier allow lipping of notes into tune. As I am not a slide puller, this together with tone, means I usually prefer deep cup mouthpieces.

[iiipopes]

What does all of that gobbledygook above mean? I honestly don't know. I typed it out before I was really awake. I think it means that I believe mouthpieces really don't fix intonation problems all that much.

Absolutely. The player fixes the intonation. All the above points to the benefit of reasonable efforts to match a mouthpiece to a player/horn/repertoire combination to make playing a little more straightforward.

[windshieldbug]

I have 2 immediate reactions (which you have to take in context because evidently my reaction time when compared to racetrack walls could evidently stand some improvement);

1. Mouthpiece depth affects tone color more, throat size affects intonation more.

2. When you find something that works well for you, you are better off applying that mouthpiece to other horns for different situations than you would be applying several mouthpieces to the same horn for different situations.

[Rick Denney]

When the air-resonant frequency of a mouthpiece rises, so does its pitch tendency. You can hear that resonance by popping the open cup-rim flat against your palm (obviously with the mouthpiece off the tuba).

According to the literature, a larger throat raises this pitch tendency, as does a smaller cup.

More cup volume increases the breadth of the sound, which can also increases the pitch flexibility. But it can also add woofiness if one's embouchure is not really strong. A shallower cup adds clarity, but at the expense of depth. Ditto funnel vs. cup, up to a point. A larger throat also adds pitch flexibility, but buzzing away from the instrument's resonant pitch will undermine tonal color. Some instruments are more tolerant of this than others.

So, there are tendencies, but they still have to be steered by someone in control.

Rick "who hears what Joe is saying, but who still can't make his Miraphone 186 sound like his Holton" Denney

[Rick Denney]

2/ when I'm sick in the bed with the flu for the entire month of December, my more 186-like tuba is coming with me to the gigs, rather than the more Holton-like tuba.

That's why I keep my tubas around.

Rick "sometimes you feel like a nut...sometimes you don't" Denney

[Dan Schultz]

..... Do you think this might be due to receiver gap differences or something else?

The short answer is 'yes'.... on both counts.

There's been a lot of discussion regarding the 'gap'. Exactly what it IS can be quite easily understood. Exactly what it DOES is a little more difficult to comprehend.

The fact is... you horn may not even have what most consider to be a 'gap'. Many European horns just have a mouthpipe that's deformed at the small end to make a receiver. The leadpipe has it's own taper and then there is another taper where the mouthpiece is inserted. Where the two opposite tapers meet and where the end of the mouthpiece shank is I suppose can be considered the 'gap'. This point will vary with the manufacturing tolerances of the mouthpiece shank and the taper. Two seemingly identical mouthpieces can have two different 'gaps'.

If you draw a picture of what goes on inside the section of a mouthpipe where the mouthpiece inserts... the dynamics are the same whether the leadpipe has a separate receiver or not. This is always a point where the taper of the mouthpiece shank and the leadpipe converge.

[sloan]

When the air-resonant frequency of a mouthpiece rises, so does its pitch tendency. You can hear that resonance by popping the open cup-rim flat against your palm (obviously with the mouthpiece off the tuba).

According to the literature, a larger throat raises this pitch tendency, as does a smaller cup.

Can you please provide a citation to this literature?

I haven't been able to find this in print.

What I read says that changing the popping frequency raises the ENVELOPE of pitches which resonate. The individual slots don't move - but a higher-pitched mouthpiece allows for an extra slot or three on the high end (and a lower-pitched mouthpiece loses those high slots but provides extra slots at the low end). So, switching to a smaller mouthpiece (holding the bore constant) will allow you to extend your range up some - but should not change the pitch of any of the notes you can already play.

I think that the math supports the claims made here that some mouthpieces provide wider slots, thereby allowing a player (perhaps unconsciously) to lip pitches up or down. Here, what is important is the ratio between cup volume and bore. A big cup with a big bore will match pitch range (what slots are available) with a small cup and a small bore - but the big/big combination will be more steerable (wider slots).

but, that's just my reading of the math - I'm really interested in a pointer to literature that provides a model for how mouthpiece size or geometry affects intonation. So...please educate me.

Now...I *have* seen explanations of how changing a mouthpiece can move HALF of the pitches - but not all of them. The cartoon version of this is that you start with a very strange set of resonances and compress one end of them with the bell and the other end with the mouthpiece - and with a lot of luck and engineering end up with something resembling the harmonic series we want. (if memory serves, you start with just the odd(?) harmonics wrt one fundamental and end up with (almost) all the harmonics of a completely different fundamental - by compressing the series on both ends towards the middle.) I suppose if all the "problem pitches" are at one end, then one might get the impression that changing the mouthpiece moves ALL of the slots - but I think that's not supported by the math.

[swillafew]

Yes I do use a mouthpiece that was picked to improve the intonation on the horn. I was provided several to try on one horn (same brand as the horn) and I spent the trial time figuring out which combination worked. One model surpassed the others.

I don't know about the construction of the receivers etc., but I did observe the mouthpieces to have different dimensions in the cup.

[Rick Denney]

When the air-resonant frequency of a mouthpiece rises, so does its pitch tendency. You can hear that resonance by popping the open cup-rim flat against your palm (obviously with the mouthpiece off the tuba).

According to the literature, a larger throat raises this pitch tendency, as does a smaller cup.

Can you please provide a citation to this literature?

You know very well what literature I'm drawing this from. I never claimed what I said to be mathematically supported, however. Even Fletcher and Rossing are not that clear.

Yes, the change is in the impedance curve, which for mouthpieces is broad, which provide little filtering. That's why a mouthpiece buzz includes many noise components. The instrument filters out more. You end up with a superposition of the embouchure's impedance curve, the mouthpiece's impedance curve, and the instrument's impedance curve. The combinations are hard to predict, which is why I used the word "tendency"--it could be negated by other factors in any given situation. And yes, the effect is reported to be more pronounced at the upper end of the register.

There is also an effect of the size of the mouthpiece in relation to the strength of the embouchure. It takes a stronger embouchure to maintain a buzz at the proper pitch when more lip is exposed inside the mouthpiece. I've heard lots of players (including myself) with weaker embouchures overcome that weakness using pressure, with a resulting loss of resonance and tone. Pitch rises as a result of pinching off a big chunk of the embouchure's impedance curve. I've also heard lots of players (also including myself) who have overcome some of the pressure problem only to find that their weaker embouchures and too-large mouthpieces are now causing their pitch to sag. A smaller mouthpiece, and one with more resistance (in the frequency domain), helps in both cases, it seems to me, though if it is too small it pinches the impedance curve at the bottom end.

The common mistake is to evaluate pitch using a tuner instead of finding the best resonance of the instrument and seeing where that is. And the question is whether a mouthpiece can affect the frequency of the best resonance of the instrument, but many players don't have the skills and embouchure strength for that question to be relevant. For them, mouthpiece effects, slide-pulling, and all the rest of it are just window dressing.

Rick "ref: Benade" Denney