Bracing affects intonation???

[Ken Herrick]

Less TubeNet, more beer!!

Brace for impact!

[Doug Elliott]

I have no direct experience with the subject, I'm not a repairman... only looking for a potential explanation from how I understand the acoustics of a brass instument, and psychoacoustics.

Many years ago I noticed that if you listen to a recording at a very soft volume, the highest notes sound flat, but if you turn it louder the same notes sound in tune or even sharp. That's not in the horn or in the recording, it's in your ears or your brain.

But I think that harmonics that are high or low can actually influence the fundamental frequency acoustically, not just your perception of the pitch. I'm pretty sure there's more to it than just "length of the tube."

Maybe somebody else with an acoustics background would like to comment?

[Doug Elliott]

No shortage of smartass comments...

[Lee Stofer]

I'm no brilliant acoustician, but I have learned a bit about bracing in the past 18 months.

Marty, if you were working with an instrument that was a straight tube, simple acoustics would most likely be all that is in play. However, when you bend and contort the tubing, add valves, slides and bracing, instrument design then becomes a jungle of potential pitfalls and shortcomings.

I have found that there is a certain pattern of bracing that works, and almost universally well on all instruments of a given pattern of design. in the late winter, I had two Conn monster Eb tubas on the bench simultaneously, one of them incidentally belonging to GC (as pictured in his avatar). These two instruments had serial numbers of 136197 and 136205, so they were basically made very close to each other. GC's tuba, after an Anderson valve plating and reassembly, played like a dream, the best of the Conn monster Eb's I've encountered. However, the other one, after receiving the same treatment, played like a dog, really pretty disappointing. A scientist colleague of mine suggested that I should look at the bracing, and I'm surprised that I hadn't already, because I then noticed that - from the factory - they were braced significantly differently. So, I removed two braces on the poor player, added two braces where they should be, and suddenly this instrument played very much like the other big Conn. This is a breakthrough for me, as I've wracked my brains over the bad low register response of the big Conn Eb's for years, and now it is a simple fix.

[Lee Stofer]

I'm no brilliant acoustician, but I have learned a bit about bracing in the past 18 months.

Marty, if you were working with an instrument that was a straight tube, simple acoustics would most likely be all that is in play. However, when you bend and contort the tubing, add valves, slides and bracing, instrument design then becomes a jungle of potential pitfalls and shortcomings.

I have found that there is a certain pattern of bracing that works, and almost universally well on all instruments of a given pattern of design. in the late winter, I had two Conn monster Eb tubas on the bench simultaneously, one of them incidentally belonging to GC (as pictured in his avatar). These two instruments had serial numbers of 136197 and 136205, so they were basically made very close to each other. GC's tuba, after an Anderson valve plating and reassembly, played like a dream, the best of the Conn monster Eb's I've encountered. However, the other one, after receiving the same treatment, played like a dog, really pretty disappointing. A scientist colleague of mine suggested that I should look at the bracing, and I'm surprised that I hadn't already, because I then noticed that - from the factory - they were braced significantly differently. So, I removed two braces on the poor player, added two braces where they should be, and suddenly this instrument played very much like the other big Conn. This is a breakthrough for me, as I've wracked my brains over the bad low register response of the big Conn Eb's for years, and now it is a simple fix.