What Elements Determine How Much Air a Horn Needs?

[Z-Tuba Dude]

I recently played a small F tuba which required a surprising amount of air, particularly below the staff. It actually used more air than my 4/4 CC!

It brought to mind the question of what determines how much air a horn needs, in order to produce good tone. I've heard of 6/4 tubas that "suck the air out of you" while others do not.

Is there a known aspect of tuba construction, which effects efficiency of tone production?

[David Richoux]

I am not an acoustic engineer or instrument designer - but as I understand the physics of horns, all tubas of a particular pitch would require the same volume of air inside the pipes. The length and diameter ratio may vary a bit and that is the main factor how the horn "feels," also the number and tightness of bends and pathways through the valves. The F tuba you played might have very large diameter pipes to allow a smaller overall size.

There are others on this list that that might have more specific info, but "The acoustics of any brass instrument are extremely complex, and still not fully understood."(Bevan's "The Tuba Family")

[Jay Bertolet]

Is there a known aspect of tuba construction, which effects efficiency of tone production?

This is the $64000 question. Why does a horn play with a wonderful sound but require far less air than another? I used to think that the bore measurement played a significant role but I've played many horns that performed far different than I expected from knowing the bore size. A common theme among 6/4 instruments is that the last couple of bows and the bell are a massive diameter but the bore is relatively smaller. But even that isn't very telling.

I think Bevan has it right, we have far more work to do to understand how these instruments truly function. Any number of variables of the design could be producing either the good or bad aspects we all know to look for. Considering that the violin community is a few hundred years ahead of us on similar questions without answers, I'm confident our answers will not be known in my lifetime.

[Jess Haney]

Is there a known aspect of tuba construction, which effects efficiency of tone production?

This is the $64000 question. Why does a horn play with a wonderful sound but require far less air than another? I used to think that the bore measurement played a significant role but I've played many horns that performed far different than I expected from knowing the bore size. A common theme among 6/4 instruments is that the last couple of bows and the bell are a massive diameter but the bore is relatively smaller. But even that isn't very telling.

I think Bevan has it right, we have far more work to do to understand how these instruments truly function. Any number of variables of the design could be producing either the good or bad aspects we all know to look for. Considering that the violin community is a few hundred years ahead of us on similar questions without answers, I'm confident our answers will not be known in my lifetime.

My thoughts exactly. Every different variable can determine how a horn feels when you play it. Even when changing something as simple as mouthpiece or altitude can effect how a horn reponds and how hard you work to produce the sound you want. A thousand variables stand between the question and the answer with this one. Bore demensions, as well as leadpipes, and bows, and key, and wrap design can all effect playability with air use. Even having missallignments in the valves can change air consumption. If someone is working on a thesis or a dissertation this would be a fun project.

[bort]

what was the F tuba?

[Z-Tuba Dude]

It was an older German style, rotary F tuba.

[windshieldbug]

You do not blow air through a horn, you do, however, need enough air to sustain a large enough embochure opening to make an acceptable sound with the standing wave excited in the horn.

The acoustic characteristics of some horns require a large opening to maintain a wave and so the traditional description of such horns is "needing a lot of air".

Because this is acoustic phenomenon, sometimes a change in mouthpiece is all that is needed to dramatically improve this effect. Sometimes nothing will.

YMMV

[Tuba-G Bass]

My observation for what is is worth.....

I feel my Miraphone BBb Contrabass Trombone is an Airhog,
and my 5/4 BBb Rudy Meinl is the most efficient with air tuba I have ever played.
The Rudy is much easier to play softly and louder.
The CBT has a .670 bore and the Rudy is around .870.

So there was mention of Buzzing, I think that is where it makes the difference,
A large bore Tuba has a lot of volume regardless of the fact it is the
same length as a CBT of the same key, the mass of air in my Rudy offers
better resistance, so it's easier to get a buzz from the embouchure.
In the CBT, it's most cylindrical rather than conical, and the small bore
has less air mass, so the effect is the air moves easier, and makes it tougher
to buzz the lips.
An argument/reason for more BAT's if there ever was one...

[Rick Denney]

Resonance.

Rick "not that resonance is particularly easy to quantify" Denney

[Tuba-G Bass]

Ian,
That's right,
I compared two very different instruments because
in my experience of playing they were the polar opposites of air efficiency.

I also own a M&M 4RV 4/4 tuba, the Rudy plays rings around it,
the Conn 24-J Piston Bat I have also is inferior to the Rudy.
The Miraphone is the only CBT I've played,
with Bass Trombones the mouthpiece is smaller,
so the resistance is "on the other side", [so maybe I should switch to a smaller mouthpiece.]
if I ever get a chance to play my Trombone Choir's "off-line" Minick CBT,
I will report back.