I fixed a bell-problem on my bass trombone

[imsevimse]

I fixed the bass I bought during Corona isolation.

When it arrived it had a very vibrant bell. The playability was good and it gave a good sound but when I played notes on the third position - actually right between second and third position - a tone rang. It was a strong sounding Eb in the staff.

I have never had a trombone with a problem like this before, at least not as obvious and I wonder what technically in manufacturing causes the error. I googled and found very little information. I have a few horns that have a little touch of this on ANY note and when it is little and very high in frequency it passes as just a part of the sound and character of the horn. This ring on the contrary stays about a second after I stop playing and that is a problem, but again only if I hit the notes while playing in between the second and third position. It does not happen much. It is obvious in glissandos of course. It is to annoying to just leave it like this.

I made a "tone-ring" out of a velcro to take care of the ringing E-flat temporarily. I'm very pleased with the result, it even looks good enough to show in public. Later I want one that is made of brass and I will let my tech make me one.

Is it good or bad to have a bell that is as resonant as this? This is something I have started to experiment with using the velcro in different places. How is this phenom usually avoided when they make bells? It must be something that every maker knows kan happen when they make a bell and I guess they do everything they can in the design process to avoid and in this case it is a mistake that no one discovered. It is a big error. The question is if it acctually can be good the bell vibrates as much as possible? If the construction of the bell removes vibrations it could also mean it can be dampened to much. In this case the bell is not dampened enough, that's obvious. At the moment I think it is rather good it is very vibrant and that I can change this. I notice I can slide the velcro down the bell and reduce vibrations even more but then I think the trombone is to dampened. If I move it higher the ringing starts to appear again (but less of it than without the velcro). I have now found the perfect spot just to dampen enough. At the picture it is as high as if goes. The ideal spot is a few mm down the bell. The perfect spot made this bass real good.

Have anyone had experience with ringing bells like this, and what can be done besides letting a tech make a removable tone-ring? I think I want a nice looking ring out of brass with damping material under that can be moved slightly. Maybe the ring can be fastened with a scew that tightens the ring in a way the placement can be altered, and also to vary how much force that is used to fasten the ring. I could also have the tech add to the construction a possibility to add weights to the ring. I could ask for an ability to slide in pillars to see what that does to the result. The material that dampens might also be something to experiment with. It could be corks or rubber or linen as I have in my home made tone-ring of velcro. Everything just to find the optimal spot for placement and weight. My speculation is I also could ask the tech to replace the brace that is closest to the velcro (see the picture) and make a curved, to have one that anchors further down the bell, but who knows what other side affects this will have on the bass trombone?

/Tom

[harrisonreed]

Way to go Christian Lindberg!

I use a much larger version that I made myself on the bell there nearly 100% of the time I play. I think it improves the way most horns respond, and I can project better with less effort. Here is a picture of it in action in Palau a few weeks ago:

214118936_10157709517575728_8721421455767531436_n.png

This is a known issue with some bells and people have done what you did to solve it in the past. I had the issue on my Conn and fixed it by having a brace resoldered.

[elmsandr]

Could always go with the old Shires/Osmun style “tone tumor”; a big chunk of brass soldered on in that position. Or some duct tape, that was common for a bit.

Yeah, this is not uncommon. Also not uncommon is doing absolutely nothing, as most of the issues can’t be heard from 4’ in front of the bell. I’ve got one that rings like all get out, but nobody other than me hears it when I play.

Cheers,
Andy

[baileyman]

I think I recall makers try to move the typical resonance near A to be between A and Ab top of staff. It's interesting not to see any historical bell-tuning devices.

[biggiesmalls]

A piece of wine cork, cut a bit oversized and pressure fit very tightly into the gap between the bell/bell brace/F-tubing, will sometimes do the trick.

[hornbuilder]

I think I recall makers try to move the typical resonance near A to be between A and Ab top of staff. It's interesting not to see any historical bell-tuning devices.

The frequency at which a bell resonates is dictated by the bell's weight/thickness of metal. So, 2 bells made on the same mandrel to the same diameter, but different thickness will have different resonant frequencies. Tenor bells resonate at different frequencies to bass bells, or alto bells, or small tenor bells, etc.

There are no manufacturers that I know of that make bells with the resonant frequency of that bell in mind. (If we only played "one" note, then it would make sense to do so, but that isn't the case.) Bell parameters are chosen for their overall performance qualities, with the resonant frequency being "way" down the list in importance.

[WGWTR180]

Duct tape was the fix for some decades back.

[hornbuilder]

PS. Having a horn that displays an obvious resonant frequency is a huge pain in the butt for "every" manufacturer. (If I may be so bold as to speak for them all!) It is not always an easy fix. In fact it most often is not.

[btone]

I' ve had 2 like that. Your solution was good. To get more efficient dampening, I affixed a short piece of leather belt using a black velro strap to the bell. Right in front or behind the main bell brace; don't remember which. When I removed the two diamond braces from under the bell stem of a Bach 50b, it started ringing on high A. Fixed that with a brace from the upper tuning slide receiver to the F tubing; like the upper and lower braces seen on old Conns and Holtons.

[harrisonreed]

Screenshot_20191219-171055.png

[harrisonreed]

FWIW, Tom, they make what you're thinking about already, but I don't know if it will fit a bass trombone:

https://www.wwbw.com/Amrein-Tone-Enhanc ... 28973.wwbw

[baileyman]

I think I recall makers try to move the typical resonance near A to be between A and Ab top of staff. It's interesting not to see any historical bell-tuning devices.

... Tenor bells resonate at different frequencies to bass bells, or alto bells, or small tenor bells, etc.

...

Interesting. My collection of 480s to 509s all fit that A-Ab scheme, but what you say makes sense. The makers do try to put the resonance in between semitones, don't they?

[elmsandr]

A piece of wine cork, cut a bit oversized and pressure fit very tightly into the gap between the bell/bell brace/F-tubing, will sometimes do the trick.

/cuts to scene from my shop

"Nope, this wine cork won't do... need to try another."

/Take one down, pass it around, 99 bottles of wine for the 'bone...

Cheers,
Andy

[biggiesmalls]

A piece of wine cork, cut a bit oversized and pressure fit very tightly into the gap between the bell/bell brace/F-tubing, will sometimes do the trick.

/cuts to scene from my shop

"Nope, this wine cork won't do... need to try another."

/Take one down, pass it around, 99 bottles of wine for the 'bone...

Cheers,
Andy

[trombonedemon]

I always thought that was a perfect thing to happen. I went the deadening direction. Effected the chops negatively.

[harrisonreed]

Tom did you ever get the tone ring you wanted?

[imsevimse]

Tom did you ever get the tone ring you wanted?

I've talked to the tech. They have just opened after vaccation. I was there with another problem, a Hagmann valve that had stuck during Corona. I will collect that horn on Friday and then I will show him the bass.

As I talked about the problem he suggested he could move the first brace that holds the bell. He also said he could not guarantee the result. He said the ringing could be due to tensions. He also said he had bad experience with repairing Chinese made horns; tubes that crack open and seams that opens up when worked at but I doubt he has seen many Thomann horns. I also know there are reputable brands that let the Chinese make them their student line horns. I wonder what his experience is with those horns?

I have not yet suggested he make me a tone-ring. I just asked him if he had thoughts on how to fix it without suggesting my own sulotion. After he sees the horn I will probably ask for a tone-ring because I don't know what will happen to the horn if he starts to use a torch on it.
What I do know is the lacquer will be destroyed and since he said other unexpected things might happen and after that the ringing might not even go away I think a tone-ring will be what I want. I just want it to look nice or else I keep my velcro.

I will update here after I know what we will do.

/Tom

[timothy42b]

I wrapped the whole bell in self vulcanizing tape once. (I had this idea I could hear more room sound and less bell sound, and hear my own playing better. Didn't work.)

I couldn't hear any difference.

[BaritoneJack]

A piece of wine cork, cut a bit oversized and pressure fit very tightly into the gap between the bell/bell brace/F-tubing, will sometimes do the trick.

/cuts to scene from my shop

"Nope, this wine cork won't do... need to try another."

/Take one down, pass it around, 99 bottles of wine for the 'bone...

Cheers,
Andy

The torments and trials we suffer for the sake of our art, eh?
Jack

[imsevimse]

I had my first big band rehearsal with the Thomann bass trombone yesterday.

My conclusion is it is not the best and easiest bass for big band music. The problem I have is it has a sound that is too big. To play real short and articulated notes and to fit articulatiions with the small bore trombones was really hard work. This is not something I have noticed as a problem when I played at home. At home I have not had need to play super short and articulated (in bucket even more difficult). It is not a problem I have experienced with the single valved basses I usually play or the (commercial) Kanstul 1662 which is my favourite double valved bass for big band. I have a couple of large basses with 10" that I never have tried. I should try them too just to see if they give me the same problems.

I use a Hammond 20BL on the bass. When I got home I experimented with a skeletonized Hammond 20BL and that lightens up the horn a bit. The skeletonized version responds faster and gives (me) a lighter sound and articulations is a bit faster and easier too. On other basses the normal 20BL mouthpiece is what I favour. I will give a shot again next week and see if a mouthpiece change helps.

My home made tone-ring still works, and I think I will settle with that until I've tried the mouthpiece change or else no point to fix this. But of course a real tone ring in metal might change the tesponse too, maybe to the better (less but faster).

My experience with this bass is about the same as if I play a large bore .547 on the top part and 2:nd and 3:rd are small bores. With those conditions to adjust 1:st to match articulation and sound of the small bores is hard. Usually 2:nd and 3:rd are the ones responsible to adjust to 1:st and change instrument size or change mouthpiece or/and playing style to blend with whatever sound first bone may have. This is my opinion and how I do it if I'm on second and third anyhow. Others may DISCUSS how to make the section blend better and decide what instruments to use and others probably not bother at all. Since I have a myriad of horns I use something that blends when I'm in the section regardless of what part I play. When I'm on this Thomann bass and want to blend with the small tenors it gives me the same problem as to be responsible with a .547 on first to be able to play like if I had a small bore. Bad feeling. The colleges have to put up with me on this bass once more. They did not think the bass sound was bad, but noticed I did not sound like I usually do.

/Tom

[Sander]

I remember when owning my King 2104b over 15 years ago, I found a large version of the Christian Lindberg Resistance Balancer, with the added "counter"-weights.
The insertable metal rods were to increase or decrease the tension and mass of the balancer, adding onto a (as they said then) richer darker tone without resonance from the brass.
Sadly I threw it away when swapping horns to my new orchestral bone, and regretted it ever since.

[harrisonreed]

I suspect those weights are shelf pegs from IKEA. I still have my heavy resistance balancer and I love it.

[conn88Hagmann]

I’m always messing about with this:

Amrein tone ring, or something similar. Came to me in a job lot. It’s changes things for sure. Not sure if it makes it better or worse though!

Anyone got any experience?

image.jpg

[hyperbolica]

I've had at least a couple horns that ring. 88h famously ring at about F#. My 79h rings at I think an A. Resonant frequency of an object is


where K is stiffness and m is mass. When you solder a bell into the rest of a horn, it changes the response. Also when you cut the bell and put a collar on it.

I've been able to stop the ringing by putting an elastic wrist band around the engraving, but I've played the 88h as it is since 1976, and it doesn't bother me. In fact, I had a Bach 42 that didn't ring like the 88h. Clicking it with your fingernail gave a galvanized trash can kind of thunk instead of a ring, so that horn always made me suspicious. I would always do things that mattered how I sounded on the 88h, and saved the 42 for things that were simply loud (Navy ceremonies and marching).

I guess what I'm saying is that the resonance is natural, and actually shows that the horn doesn't have any built in dampening. Which is a good thing. To me a horn that doesn't ring shows that there is probably something inefficient about how it plays. Learn to ignore the resonance. Adding something to the horn to remove resonance seems counterproductive. Let it ring. The audience can't hear it. You can feel it slightly, but there's no real reason to let it bother you. It's reassuring.

[timothy42b]

I've had at least a couple horns that ring. 88h famously ring at about F#. My 79h rings at I think an A. Resonant frequency of an object is


where K is stiffness and m is mass. When you solder a bell into the rest of a horn, it changes the response. Also when you cut the bell and put a collar on it.

Yup.
However, for real world systems k and m are not single numbers. They are matrices.
(Ever invert a matrix by hand? Probably not, you all have computers. In grad school they made us do it by hand. I don't think anyone did it without error.)
The stiffness matrix in particular is non trivial. It is a combination of the material properties (Young's modulus) and the shape. That may not be obvious but a steel wrench and the same amount made into a steel wire have the same modulus but different stiffness.
The mass matrix is a little easier, provided the thickness doesn't vary too much you can calculate it from the density, but it's still distributed across a matrix.

So the result f of a matrix operation is itself a matrix. You get an eigenvalue and eigenvector, so you have a set of resonant frequencies and a set of relative strengths of each.

I run a handbell choir, and a handbell mostly rings from two places, the change of flare in the bell, and the rim, and mostly in a perceived fundamental and the 12th, although there are more. Beginners when they damp get a whomp sound because they don't cancel both pitches together.

[Kbiggs]

I've been able to stop the ringing by putting an elastic wrist band around the engraving, but I've played the 88h as it is since 1976, and it doesn't bother me. In fact, I had a Bach 42 that didn't ring like the 88h. Clicking it with your fingernail gave a galvanized trash can kind of thunk instead of a ring, so that horn always made me suspicious. I would always do things that mattered how I sounded on the 88h, and saved the 42 for things that were simply loud (Navy ceremonies and marching).

I guess what I'm saying is that the resonance is natural, and actually shows that the horn doesn't have any built in dampening. Which is a good thing. To me a horn that doesn't ring shows that there is probably something inefficient about how it plays. Learn to ignore the resonance. Adding something to the horn to remove resonance seems counterproductive. Let it ring. The audience can't hear it. You can feel it slightly, but there's no real reason to let it bother you. It's reassuring.

Interesting about your 42 bell. I have an old 50 yellow brass bell that had seen a few battles before I bought it. It has the same thunk and trash can klunk to it, even with some good dent work and re-shaping. My gold bell OTOH has a nice ring to it. I find the yellow bell is very stable, and projects very well. The gold bell, like most bells with higher copper content, has a bit more “splash” to it, but I find it’s much more useful in smaller settings and big band work. It’s odd because it’s heavier gauge. No sympathetic ring on either bell, though, and no dampeners on these bells.

I have had some other bells, though, that have had a sympathetic vibration.

[hyperbolica]

The 42 played well enough. It was a Navy issue horn, and I used it in situations where there was some physical danger of damage or i just needed an institutional sort of sound. The 88h cane out for quartet or quintet - more sensitive stuff.

As for the equation - you'd probably never use the math directly, but even from the relationship of k/m you can visualize how the sound is effected by stiff material or a thick bell.

[conn88Hagmann]

So how does silver behave compared to brass? / denser?

[hyperbolica]

So how does silver behave compared to brass? / denser?

If you read up on silver, it can be harder or softer than brass, depending on alloy, working and anneal state. Yes, it's denser than brass, but mass also depends on thickness.

Which is to say that you really can't say anything categorically about silver vs brass bells. Harder bells ring higher, and heavier bells ring lower