Bracing affects intonation???

[MartyNeilan]

I have recently seen several posts stating as gospel truth that the amount and location of braces affects intonation. Based on the laws of acoustics, as well as the hacking and soldering I have done on instruments, I cannot see any proof of this.
I believe that bracing does have an effect on RESPONSE of a horn. Too much bracing can deaden a horn, and a large unbraced loop vibrating sympathetically can cause a response issue on one or more affected notes.
Tightening up a long unbraced 4th valve loop has slightly helped low C's on one or more F tubas, both on a Cerveny I had and a Rudy that Lee Stofer worked on.
However, pitch is controlled by the taper of the instrument from end to end. Make something wider or narrower, longer or shorter, and pitch can change. How does what goes on OUTSIDE that taper of brass tubing alter the pitch itself?

[Doug Elliott]

Just guessing here, but as I understand it, the different harmonics in the sound of one note are not necessarily in tune with each other, and that's part of what makes the characteristic sound of different instruments, and also what makes a "bad" or out of tune note on an instrument.

The presence of harmonics that are high or low to the fundamental could push the pitch of a note up or down.

If a brace postion emphasizes or dampens a particular harmonic, or range of harmonics in the sound, I think it could change the perceived pitch center as well as changing the response.

[Donn]

Wouldn't it be great to be able to know the form of the standing wave for a particular note in a particular tuba? The location of nodes etc. Then you could use some simple clamps to test theories like this. Without that knowledge, you could still apply some clamps here and there and see if anything happens, but with much less expectation of resolving anything.

I'm so ignorant about this matters that I don't know for sure that these phenomena even exist in a tangible way, i.e., could a physical instrument detect a node? If that is indeed feasible and the required instrument could further be small enough to pass through the insides of a tuba without severely affecting the acoustics itself -- then you could measure actual vs. predicted wave structure and really zero in on problems.

[MartyNeilan]

Scientific experiments have proven that moving braces on brass instruments burns lacquer or messes up silver plating.

If that is indeed feasible and the required instrument could further be small enough to pass through the insides of a tuba without severely affecting the acoustics itself -- then you could measure actual vs. predicted wave structure and really zero in on problems.

My point exactly - what is on the OUTSIDE (way, way on the outside) should not affect the pathway on the INSIDE.

[GC]

Since the comments referred to were mine, I'll chime in.

I'm NOT a repair person. Every statement I've made has been second hand. I totally agree with Bloke's comment about fiddling with braces and messing up finish. Experimenting with braces is not a good thing to do with a pretty horn.

However, a bunch of years ago I was sitting in the local instrument repair shop (when there was a local repair shop) watching a trumpet that had taken some hits be worked on. A friend who worked at the store, and excellent trumpet player was called in to play test the horn. The horn had several issues with response and intonation. The repairman worked out the dents and straightened out the bell. The play tester said that the horn was better, but it still had some problems with a flat D in the staff and some wonky low response. It was easy to tell where the player was having to work harder to get the horn to respond properly.He suggested removing and reattaching the forward bell brace and the brace on the outer tuning slides. The repairman removed the braces and put them back into as close to the same place as possible. Afterward, the play tester was much happier with the horn, and he definitely sounded better in the problem areas.

The repairman's theory was that horns that are improperly assembled or that have taken hits that put pressure on the horn's structure because of bending may not resonate freely until the tension is released. Maybe.

[PMeuph]

I also have a second hand story.

A former chamber music coach of mine related that he had been play testing horns for Yamaha. During the playtest they had several slides. (Different shape, bracing, materials etc.). After trying the main tuning slide, the whole instrument instrument seems out of tune, the harmonics bad, and something was wrong. The technician that was there handed over another slide that had a brace in it. Reportedly, that made a stunning difference and the instrument played very well after that.

I wonder if on some level, an unbraced slide might vibrate to easily as compared to the rest of the instrument and screw the end result. I wonder if it wouldn't be a similar effect as throwing in a slide made up of a different material in a horn...

[Dan Schultz]

..... The repairman's theory was that horns that are improperly assembled or that have taken hits that put pressure on the horn's structure because of bending may not resonate freely until the tension is released. Maybe.

This is absolutely correct. When a horn is assembled and the braces are added... care must be taken NEVER to pull a horn together and them apply the braces. The braces should merely take up the space between two components. It's ok to wire the brace flanges as long as the rod between the two flanges floats.

[windshieldbug]

Moreover, I still hold that the effect of most modifications is local (w/in 10') and not out in the hall.

[GC]

That's not exactly what I said, but whatever.

Most kind of you.

[ScottM]

I worked in a repair shop for a while and a local trumpeter came in and complained his flugel didn't resonate the way it should. I got a wild hair and moved the bell so that it was on the other side of the valve section. It made it so his hand did not rest on the bell while he played. It really did seem to make a difference and a couple other locals saw the horn and had us modify thier horns the same way.
ScottM

[MartyNeilan]

I worked in a repair shop for a while and a local trumpeter came in and complained his flugel didn't resonate the way it should. I got a wild hair and moved the bell so that it was on the other side of the valve section. It made it so his hand did not rest on the bell while he played. It really did seem to make a difference and a couple other locals saw the horn and had us modify thier horns the same way.
ScottM

Exacty - resonance. Edwards trombones came out with an elaborate "edge bracing" a few years ago to make their Thayer valved howitzers a little more resonant.
I have seen first hand the pros and cons of adding and removing braces on resonance / response.
I just wonder how it changes PITCH? (In the end, thinking it really doesn't.)

[Matt Walters]

Bracing does NOT change intonation on a horn. But where a brace is put can make it sound more in-tune or out-of-tune. Bracing DOES change resonance and which overtones vibrate more. Doubt me? Put your hand lightly on a ringing bell and tell me you didn't change the sound and pitch. Doubt me? Play enough low notes and on occasion, the tuner will jump between different pitches while you are holding the same note. I see that a lot with weak players testing tubas in the store. The effect of the change in vibrations can change what your ear (and even a digital tuner) hears as the dominant pitch. Therefore if you put a brace where it deadens the overtones that are less in-tune, the instrument can sound more in-tune, etc.
Said another way, the pitches don't change but what you perceive as dominant pitch versus coloring overtones can change so you will think the pitch changed.
A famous Jazz Flugel horn player was in the store complaining that the 4th slide on a new flugel horn was too short but if he moved the 4th slide out, the rest of the horn went flat. He was right. But how can moving the 4th slide change the pitch on the open horn? It only changed what he was perceiving as the dominant pitch because that horn had enough flat overtones that it was easy to nudge them into the the more dominant pitch. His brain registered a flatter pitch that was there previously but not registering with the slide all the way in.
Well that and $5 gets you an expensive coffee.

[Doug Elliott]

Thank you for verifying what I wrote in my earlier post.

Howerver, you said "Bracing does NOT change intonation on a horn."

But it influences the intonation you hear or perceive, what the tuner hears, what the audience hears...

Seems to me it DOES change the intonation.

[Bass Flatulance]

Doug and Matt,
It sounds like ya both agree that braces can change what ya hear. Doug's saying we changed pitches, Matt's saying the same sharp, flat, or on pitch vibrations are there, but that we change the pitch a person's mind concentrates on. Like those funny pictures in the mall that people stared at and supposedly something differnt is there if you look at it just right. Always looked like squigly lines to me. Matt must have been one of the people who saw other stuff in the pictures.
During a polka gig, a brace popped on my sousie and then I didn't like the way the horn played or sound. Had it soldered and I thought I sounded better on the next gig. Then again, there was free beer on that next gig.
Wait.....Beer is more important than a brace to change intonation? The more beer I drink, the more in pitch everyone sounds to me. Wait....I just changed my perception and that changed what I heard was on pitch. Matt might be on to something. Where is one of those stupid squigly pictures? I bet there is a tuba in one of them. Or is there a tuba if I was sober and the squigly lines are cause I have to be drunk or on a gig to walk into a mall? This is making my brain hurt. Less TubeNet, more beer!!

[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.