Strange bell vibrations on specific tone

[Nomsis]

When I play a c my silver hüttl trombone (which went trough a massive undenting process after I bought it for very little money) sucks all my energy and puts it in bell vibrations one can feel and hear clearly when playing it. This behavior happens just in a very specific frequency spot on a well tuned c. This is just like when one sings in resonance with a good wine glass. It is a little annoying because it makes this tone very unresponsive. Since I use this instrument just for marching purposes I could live with it but I would rather not. So if you have some low effort tip to stop the universe sucking my energy on c please give it to me - thanks (:

I tried damping it with a tshirt wrapped around the bell and this works but I feel like this looks uncool and makes the trombone even more front heavy than it is already.

[Doug Elliott]

https://calderpipsmusic.com/tone-halo

[harrisonreed]

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[bassbone1993]

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I wish they still made this, as I have very little skill to make this

[ghmerrill]

As a quick trial, you might try "vet wrap", though it's now not popular to refer to it as that and you might have to look for "self-adhesive bandage" or "self-adherent wrap" or some such. That would at least show you what the effect of a similar sort of "dampener" would have, and you could either stick with it ( ) or try something else. There are various sorts of (smooth flexible plastic) shelf/drawer liners out of which it would be pretty easy to make something (even with using some self-adhesive Velcro strips on the wrap so you could put it on and take it off). The major drug stores carry the self-adhesive bandage or you can get it from Amazon.

[Nomsis]

Thanks for your interesting suggestions. The tone halo looks like a very interesting toy to play around. Where could I buy this (I'm located in Germany) and what is the price ? The problem is that I suspect it costs more than the trombone did, so it might not be a good fit.
I think the leather might not be enough, I tried some lighter cloth already but this wasn't enough. But this gives me another idea I could try for cheap , some black tape could do the trick. Maybe it is to light but maybe not. At least it doesn't cost much.

Another idea I had was giving it a little plastic deformation at the right spot to get rid of the resonance completely (instead of just damping). Problem is I don't know where to hit it and if it would help at all. Although one dent more would be no problem (it still has many although the worst ones are gone) I would not like to dent it pointlessly. Does anyone have experience with such a "modification"?

I really wonder how this strange behaviour comes about in the first place.

[Nomsis]

As a quick trial, you might try "vet wrap", though it's now not popular to refer to it as that and you might have to look for "self-adhesive bandage" or "self-adherent wrap" or some such. That would at least show you what the effect of a similar sort of "dampener" would have, and you could either stick with it ( ) or try something else. There are various sorts of (smooth flexible plastic) shelf/drawer liners out of which it would be pretty easy to make something (even with using some self-adhesive Velcro strips on the wrap so you could put it on and take it off). The major drug stores carry the self-adhesive bandage or you can get it from Amazon.

haha, just had a very similar idea, see post above. I will try some "panzertape"

[ghmerrill]

You sure it isn't a loose solder joint? Or bell wire?

[StephenK]

Thanks for your interesting suggestions. The tone halo looks like a very interesting toy to play around. Where could I buy this (I'm located in Germany) and what is the price ?

I think it's around £100, maybe less. Its from UK. Follow the link in the post.

[Nomsis]

Thanks for your interesting suggestions. The tone halo looks like a very interesting toy to play around. Where could I buy this (I'm located in Germany) and what is the price ?

I think it's around £100, maybe less. Its from UK. Follow the link in the post.

Thanks, I couldn't see any price on the website. So it is as suspected, more than the trombone did cost. I'll save the link, it really looks cool. Maybe I will "need" this in the future for another instrument.

You sure it isn't a loose solder joint? Or bell wire?

I will check it again when I'm at home but I'm pretty sure those are solid.

[timothy42b]

This behavior happens just in a very specific frequency spot on a well tuned c.

This is just like when one sings in resonance with a good wine glass.

It is a little annoying because it makes this tone very unresponsive.

That's exactly as you should expect. A mechanical resonance always sucks energy out of the system, though this one seems unusually extreme. I would not have thought it made that much difference to the wind column vibration.

Out of curiosity, can you tell if it's the middle C fundamental, or some of the overtones? Not that it matters.

Anyway, there are two approaches used in machine design. One is to lower the resonating frequency. Damping won't do that, you have to add mass. You always want to operate above a resonance, preferably way above. Look at a Bode diagram.

The second, and more common when the problem frequency is well defined, is a vibration absorber. That's a simple spring mass system at the problem frequency. It will vibrate instead of the bell. You might get lucky and be able to do it with a counterweight. And if not, a heavier counterweight might just shift the bell frequency low enough.

[Doug Elliott]

I never understand the point when somebody says "it costs more than the horn."
If you got the horn for free you wouldn't spend anything on it?

[harrisonreed]

Screenshot_20191219-171055.png

I wish they still made this, as I have very little skill to make this

It's easy to do. You sew a pattern of suede and Velcro display backing material along three sides (inside out), then pull it "inside out" through the open end, and close it by sewing a Velcro hook strip on. Sewing again around the outer edges and a few lines in the direction of the bell taper eliminates the pocket. The Velcro hook strip adheres to the display backing material.

You can double the layer of the backing material to make a heavier gauge.

[spencercarran]

I never understand the point when somebody says "it costs more than the horn."
If you got the horn for free you wouldn't spend anything on it?

On most of my musical instruments (and all of my bikes) I've spent more on subsequent maintenance/repair/modification than the initial purchase price. If I'm happy with the final total price for the thing I wind up with, all good.

[ssking2b]

I have a vintage 1964 Conn 88H with a similar resonance in rhe
Bell. The G overtone series makes the bell ring. I have used an AMR one on it for years, and the problem was solved. Howerver the AMR company is defunct now. I got the Calder-Pips Halo and it solved the issue, and looks food on the horn.