Mouthpiece characteristics that affect partials

[afugate]

I'm curious about what aspects of the mouthpiece affect how the partials line up on a horn? I assume insertion depth is one.

--Andy in OKC

[BGuttman]

There is an interaction between embouchure and rim size. Generally a mouthpiece that has too wide a rim for a particular embouchure will have flat partials in the upper register. I would assume there are effects from too small a rim as well; Doug or Dave would probably be able to describe them.

[harrisonreed]

I have found the following to be true for me:

The backbore and throat are what affect the partials the most, if you have a mouthpiece that otherwise fits into the leadpipe properly. A backbore that is too tight will have more upper harmonics in the tone and will crunch the partials in towards middle Bb. So you end up with a sharp lower resister and a flat upper register. A larger throat and backbore gives you more volume and lower harmonics in the sound, but has the opposite affect for intonation -- sharp upper register and flat lower resister. They also kill your endurance. I have a mouthpiece from Griego called the O3 that has about .75" of a cylindrical section within the backbore, and doesn't seem to have ANY intonation issues between octaves. The 15CL had the same thing and also lined up octave to octave. Don't know if that is intentional but I think it's related.

[imsevimse]

This is one of the reasons mouthpiece is important but what is most important to me is to find a mouthpiece that helps me get the sound I'm after.

I have played strange mouthpieces that have been "cut". I do not know the reason why but such an operation can completely ruin a mouthpiece. It makes the horn play fuzzy.

What about characteristics?

I don't know the physical reason why, but a deep mouthpiece Hammond makes my horn play flat so I have to adjust by pushing the tuningslide. If the mouthpiece is my deepest tenor mouthpiece I push it all the way in and will still be a little on the flat side for A=442. With a more shallow mouthpiece such as a Bach 11C I have the tuning slide pulled about 2 cm. The horn can be played without much problems after that adjustment.

When it comes to rim I have not noticed intonation issues, but I have not experimented much with different rims on the same cup. Some think the rim is of no importance other than for personal comfort. To me the rim has an impact on the endurance and the register and also seam to add something to the overall experience of my playing abilities. I think it puts me in the right context and help me get a neater smaller sound if the rim is small and helps a "beefier" sound if the rim is wider. It makes me treat the horn with different approaches more easy. It could be psychological, because other may think of it differently. In that case it is fine with me. Do what works best.

What I've noticed is if the mouthpiece is "wrong" then strange intonation issues happens. If I put a bass trombone mouthpiece in one of my .547 bore tenors the partials will not line up very well. Equally strange when I put a large shank tenor mouthpiece in my bass trombone.

It's a lot of talk about mouthpiece. What I think is of most importance is the sound needs to be in my head first. I need to imagine the sound I want without the instrument. I need to have that clear picture of my sound before the sound starts. I can then strive for that sound on any mouthpiece. Then again what I hear is not what other hear because I hear my sound also through bones and tissues. The sound that reach my ears is a different mix than what the person hears who listens in front.

/Tom

[Basbasun]

This is to complicated for a simple answer. In general a mothpieces with a larger volume makes the higher partials flatt, smaller volume the higher partials sharp and the lower partials flatt.
If the rim is to large for what the embouchure can manage the high partials will come out flatt, but if the embouchure is strong enogh the partials will come out better.
There is to many factors, backbore, bore, shape, lips, mouth cavety an so on. Try different mputhpices and see what what happens. Play what works.

[afugate]

This is one of the reasons mouthpiece is important but what is most important to me is to find a mouthpiece that helps me get the sound I'm after.

That's always been my approach, too.

--Andy in OKC

[afugate]

This is too complicated for a simple answer. In general a mouthpieces with a larger volume makes the higher partials flat, smaller volume the higher partials sharp and the lower partials flat.
If the rim is too large for what the embouchure can manage the high partials will come out flat, but if the embouchure is strong enough the partials will come out better.
There is too many factors, backbore, bore, shape, lips, mouth cavity an so on. Try different mouthpieces and see what what happens. Play what works.

What made me curious was a recent thread where someone mentioned that the partials lined up better on a horn with a different mouthpiece. On my Eastman Shires with Thayer, I find that the 6th partial is extremely sharp. I generally must play about 3/4 inch off the bumpers. But it hadn't occurred to me to check that partial with other mouthpieces. I found a mouthpiece that makes it easier to produce the sound in my head, so I stopped trying mouthpieces. I may go back and experiment some with mouthpieces just to check the partials (especially the 6th one).

--Andy in OKC

[BGuttman]

I think the appropiate sound trumps partial alignment.

Yes, the Conn 7C provided with my 36H alto aligns the partials but I prefer the characteristics of my 4C and I adjust my positions to humor it.

[LeTromboniste]

It's all about balance actually, and not any single parameter. What affects the tuning of the partials is the balance/ratio between the volume of air in the the backbore(which is affected by the size and shape of the throat and the length and taper profile of the backbore) vs the volume of air in the cup (which can be affected by depth, rim diameter, shape of cup, etc).

For an equal cup volume, a larger backbore air volume makes the partials wider (low partials are flatter and high partials sharper, octaves are larger), while for an equal backbore volume, a larger cup volume makes the partials narrower.

It's one of the reason I always take comments on certain horns having out-of-tune partials with a grain of salt - a lot of the time that can be fixed easily by using a different mouthpiece that has the right balance for that particular horn.

Strangely it's an aspect of mouthpiece design and fitting that I heard a lot about from makers of historical instruments/mouthpieces and that I had never ever heard about when dealing with modern instruments. Perhaps it's because tuning the partials by getting a correct mouthpiece-instrument fit is much more critical on a natural trumpet where everything has to be otherwise corrected with the lips.

[timothy42b]

Strangely it's an aspect of mouthpiece design and fitting that I heard a lot about from makers of historical instruments/mouthpieces and that I had never ever heard about when dealing with modern instruments. Perhaps it's because tuning the partials by getting a correct mouthpiece-instrument fit is much more critical on a natural trumpet where everything has to be otherwise corrected with the lips.

Benade did discuss it briefly for modern trumpets, in Fundamentals of Musical Acoustics.

[afugate]

It's all about balance actually, and not any single parameter. What affects the tuning of the partials is the balance/ratio between the volume of air in the the backbore(which is affected by the size and affair of the throat and the length and taper profile of the backbore) vs the volume of air in the cup (which can be affected by depth, rim diameter, shape of cup, etc).

For an equal cup volume, a larger backbore air volume makes the partials wider (low partials are flatter and high partials sharper, octaves are larger), while for an equal backbore volume, a larger cup volume makes the partials narrower.

When you say wider/narrower, does this mean that the 6th partial (normally sharp) would be even sharper (wider?) and the 7th partial would be even flatter?

Strangely it's an aspect of mouthpiece design and fitting that I heard a lot about from makers of historical instruments/mouthpieces and that I had never ever heard about when dealing with modern instruments. Perhaps it's because tuning the partials by getting a correct mouthpiece-instrument fit is much more critical on a natural trumpet where everything has to be otherwise corrected with the lips.

That's an interesting bit of historical trivia. Makes sense when I think about it.

Thank you for adding this info, @ Maximilien

--Andy in OKC

[harrisonreed]

No, wider in this case means that as you move away from a center point that's "in tune" (like Bb), the partials get more out of tune in the direction that is away from that central pitch. Ie, low notes are flat and high notes are sharp. And keep getting sharper the higher the partial is. In other words, the octaves don't line up. This is different from intonation issues within partials, where a single partial is shifted linearally.

Think "stretched tuning" like on a real piano.

Mouthpieces with huge backbores like the 2CL or even the Alessi pieces do this, at least to me. Not in a detrimental way, but you have to be aware of it.

[Landok]

I always wondered if there’s a science behind mouthpieces as far as rim size, cup size, and throat. For instants, Bach has a shall shank 4 mouthpiece, which is equivalent to a Bach 4G rim size, but it’s a medium cup/Standard size throat. There’s also a small shank Bach 3 which is equivalent to a bach 3G rim size, which has a medium deep cup, and a smaller throat then the Bach 4. Does anyone know if there’s a reason for that? Is there a such thing of an unbalanced mouthpiece?

[LeTromboniste]

I always wondered if there’s a science behind mouthpieces as far as rim size, cup size, and throat. For instants, Bach has a shall shank 4 mouthpiece, which is equivalent to a Bach 4G rim size, but it’s a medium cup/Standard size throat. There’s also a small shank Bach 3 which is equivalent to a bach 3G rim size, which has a medium deep cup, and a smaller throat then the Bach 4. Does anyone know if there’s a reason for that? Is there a such thing of an unbalanced mouthpiece?

Yes and no. The right balance between different characteristics of mouthpiece will be different when it's used with one instrument or another. I.e. a mouthpiece can be unbalanced on one horn and balanced on another, depending on how the partials want to line up on the instrument itself. Tuning tendencies can be amplified or corrected by the mouthpiece choice. But of course you can go so far off in either direction that it becomes impossible to fit with any instruments. For example if you were to make a bass mouthpiece with the throat size of an alto mouthpiece you'd get something where the partials are so narrow and the octaves so flat that it would be completely unusable.

Generally speaking a smaller cup (either in terms of depth or diameter or because of a narrower V rather than U shape) will need a proportionally smaller throat or tighter backbore, and vice versa, since the throat+backbore size and the cup size counterbalance each other.

[sporto]

Most mouthpieces I've seen have a short cylindrical section right behind the throat before the flare. (vintage Conns do not). I remember reading somewhere that cylindrical section tend to "compress" the scale, making high notes flat and low notes sharp.