How bad is it to have a leak in the bottom bow

[Michael Bush]

...under the guard?

When I set the horn on its bell, after a while a little bit of water will leak out from under the guard on the end near the first branch.

I'm thinking it doesn't really matter that much. Right or wrong?

[Dan Schultz]

This is a GREAT question !
The short answer is yes it matters but not as much as a leak in the lead pipe.
Usually if a leak is away from a tonal node, .....

That's a good answer, Brian!

I probably should start a new thread for this. But... although we all have heard of and have ideas of what 'tonal nodes' are.... no one has accurately described them. I'm thinking that 'tonal nodes' move back and forth the length of a horn depending on the frequency of the note.

??

[Michael Bush]

That's a good answer, Brian!

I probably should start a new thread for this. But... although we all have heard of and have ideas of what 'tonal nodes' are.... no one has accurately described them. I'm thinking that 'tonal nodes' move back and forth the length of a horn depending on the frequency of the note.

??

I know in a general way what tonal nodes are, and the reason is a good story related to my undergraduate education and the need to keep big time athletes eligible. (I can say with confidence based on personal experience that Sam Bowie has heard of tonal nodes also.)

This is just reinforcing my intention to get this tuba into your hands over the holidays, if my car will cooperate this time.

[tclements]

I think a bullet hole in that part of the horn wouldn't make much difference. I'll try it and let you know.....

[Michael Bush]

I think a bullet hole in that part of the horn wouldn't make much difference. I'll try it and let you know.....

Looking forward to hearing how that comes out, as long as you're not shooting at my horn!

(At some point, presumably when it was sacrificing itself in the Los Angeles schools, someone took a couple of potshots at it with a BB gun. But the BBs just made distinctive dents, they didn't go all the way through.)

[Dan Schultz]

I think a bullet hole in that part of the horn wouldn't make much difference. I'll try it and let you know.....

Looking forward to hearing how that comes out, as long as you're not shooting at my horn!

Tony's pretty close with that statement. There's very little sound pressure in the larger tubes. I've seen lots of cases where the joints weren't even soldered!

[imperialbari]

A short term fix might be about making sure the bottom bow area being dry also below the cap. Then taking some clear nail polish and applying it along the edge of the cap, where it has become unsoldered. Let the polish run under the cap and apply until it doesn’t take more.

It may however be worthwhile in the longer run to have the area below the cap inspected. Water coming out under the cap indicates corrosion of the bow tubing.

Klaus

[SousaSaver]

If you have a small amount of water coming out of a bow guard, you will be horrified when that bow guard is removed, especially if the Tuba you are talking about is the 1911 Conn.

Are you sure it's coming from the guard? It is possible that the leak could be a hole in the branch itself, and it just happens to let water down the guard.

If there are any solder holes in the guard, get them soldered and that should help. Sometimes guards make unintentional patches.

Do you have pictures?

[Rick Denney]

A short term fix might be about making sure the bottom bow area being dry also below the cap. Then taking some clear nail polish and applying it along the edge of the cap, where it has become unsoldered. Let the polish run under the cap and apply until it doesn’t take more.

It may however be worthwhile in the longer run to have the area below the cap inspected. Water coming out under the cap indicates corrosion of the bow tubing.

Klaus

I wouldn't apply nail polish--it will burn and be annoying when the cap is removed, as it will have to be at some point.

If you just want to test for yourself the effects, apply electrician's tape to the entire guard edge to seal it up, and then see if the instrument plays differently. If it does, hie thee to the repair tech. If it doesn't, you'll still eventually have to fix it, but it won't be as urgent.

I have a leak in a bad solder joint where the bottom bow of my euphonium is attached, and I can hear air pushing in and out of it on some notes. The electrical tape has been on that joint for a couple of years now, heh. I would have fixed it sooner if I used that instrument more than rarely.

On the subject of nodes, here's my "engineer-speak". When your lips part, you send a pulse of air. That pulse is marked by the pressuring being higher. These pressure fronts travel at the speed of sound. When they get to the bell opening, the sudden change in impedance acts like a wall at some frequencies, and they bounce back. The return pulses interact with the outgoing pulses, creating a standing wave. At some points, the pressure fronts are wiggling back and forth vigorously, and at other points, they are canceling each other out causing the air to be still (though waves are still passing through it). Where the air is still is at nodes.

These are extremely difficult to measure, because the taper design causes the wavelength to change along the length of the bugle. It would be easier to measure using a sensor on the end of a flexible and thing stick that is inserted from the bell end. But it doesn't really matter: Every note has different nodal locations, and the nodes for the fundamental may not be as important as the (much more numerous) nodes for the upper harmonics. Thus, a leak might only affect a couple of notes, but the effect might be a subtle change in timbre.

Rick "or study Fletcher and Rossing and attempt the rather daunting math" Denney

[Michael Bush]

Thanks to everyone for the suggestions. I'll check to make sure the leak is where I think it is, then use some electrical tape and see how that comes out. It's a fair point that the fact I noticed the water dripping down from the edge of the cap doesn't mean it came from under the cap.

[Dan Schultz]

.... On the subject of nodes, here's my "engineer-speak". ..... These are extremely difficult to measure, because the taper design causes the wavelength to change along the length of the bugle. It would be easier to measure using a sensor on the end of a flexible and thing stick that is inserted from the bell end. But it doesn't really matter: Every note has different nodal locations, and the nodes for the fundamental may not be as important as the (much more numerous) nodes for the upper harmonics. Thus, a leak might only affect a couple of notes, but the effect might be a subtle change in timbre.

Rick "or study Fletcher and Rossing and attempt the rather daunting math" Denney

Thanks, Rick. Having spent a few years doing acoustical research to manufacture automobile horns... I learned a bit of how things work from a very old scientist who actually KNEW Henry Ford and Edison. I understand what is happening inside a horn but cannot explain it as well as you.

Dan 'nodes don't mean much to me since they are a moving target... depending on what note is played' Schultz

[tclements]

Shot a hole in my old E-flat tuba. No change. Not to worry about a leak in bottom bow. After I patched it with duct tape, it played better.

[Dan Schultz]

Shot a hole in my old E-flat tuba. No change. Not to worry about a leak in bottom bow. After I patched it with duct tape, it played better.

That's a good one!

[TubaRay]

I think a bullet hole in that part of the horn wouldn't make much difference. I'll try it and let you know.....

I have little to nothing to add to this thread, however:

If you need a bullet hole, you might plan a trip to the part of Mexico that is just across the Texas border. They apparently are quite willing to provide this. The only problem is that they might prefer a target other than your tuba.

[Casey Tucker]

With water collecting without an easy/easier way out, I would be more afraid of red-rot. Good luck and let us know how everything turns out!

-CT

[Michael Bush]

I've put electrical tape all over the horn. (Not literally, but at the joints.) No leak. Pretty sure now that the water came from the main tuning slide and flowed down the edge of the cap to where I found it running. Thanks for all the help!

[Dan Schultz]

...sounds as if a lot of what's being discussed here about nodes and standing waves relates closely to the antenna theory I studied for my FCC Amateur Radio licenses.

Radio waves are a little more predictable than sound waves!

[Rick Denney]

...sounds as if a lot of what's being discussed here about nodes and standing waves relates closely to the antenna theory I studied for my FCC Amateur Radio licenses.

Radio waves are a little more predictable than sound waves!

Only in air. Running along wire, they are subject to the same velocity factors related to variations that sounds waves face in air.

And, yes, RF lives in the same frequency domain as sound does, so the math will be the same or similar. Instead of pressure fronts, you get magnetic flux fronts, but the Maxwell equations would probably still work.

Tuning electronics is about as finicky as tuning tubas, and finding the resonance likewise.

Rick "KR9D" Denney

[MileMarkerZero]

attempt the rather daunting math" Denney

Just to make sure the significance isn't lost: that quote came from an engineer.

In my case, "rather daunting" means my brain just leaked out of my ear and pooled on the floor.

[imperialbari]

attempt the rather daunting math" Denney

Just to make sure the significance isn't lost: that quote came from an engineer.

In my case, "rather daunting" means my brain just leaked out of my ear and pooled on the floor.

It is the obligation of TubeNetters to take the worries out of the minds of fellow TubeNetters. If possible, that is.

The leak may have happened through your ear, but is still is more likely it was your bladder leaking. Your main worry should be about how a faulty analysis of the pool contents could at all be allowed to confuse you.

K