Detecting an Air Leak - efficiently

jmerring · Post by **jmerring** » Mon Apr 30, 2007 11:55 pm

While I am waiting for my new horn, I have been playing my band's POS Jupiter 3 valve 3/4 size (changeable leadpipe for marching *&(^%)(*!!). I feel that it must have a leak in it, somewhere as I am almost hypervenitilating when trying to play anywhere near FF. This should not be happening!

What would be an efficient way of finding the leak - assuming, as I do - that one exists? Putting it in a tub of water and blowing through it? I have tried pulling out each slide and re-inserting them in reversed position and playing the horn, but this lead me nowhere, due to the fact that the third slide only goes in one way.

Any ideas/insights provided would be appreciated.

Chuck(G) · Post by **Chuck(G)** » Tue May 01, 2007 12:00 am

jmerring wrote:Any ideas/insights provided would be appreciated.

The easiest way I know of is to find a great big vat of water sufficient to completely immerse your horn. Plug the leadpipe with a cork and immerse the tuba, bell down, in the water until it's completely covered. Look for bubbles.

iiipopes · Post by **iiipopes** » Tue May 01, 2007 9:03 am

I also took one of my young son's smooth plastic playballs, had my wife hold it firm in the bell, then blew through the receiver listening for hisses. Oh, Boy! My poor old Besson hissed like a snake! It needs some work, especially around the bottom bow on the off side, as it has suffered at several points in its 35 years before I got it from being improperly stood on its bell, then knocked over, leaving the flat on the opposite outer lower bow which so many of them have.

Dan Schultz · Post by **Dan Schultz** » Tue May 01, 2007 9:13 am

Leaks that cause the biggest problems are usually confined to the smaller tubing... before, in, or immediately after the valve section. Pull out your main tuning slide, reinsert the slide into the branch that comes off the valveset, and plug the open end of the main slide with a wine bottle cork. Now you can submerge the horn without having to stand on it or having three friends hold it down. Put a piece of vinyl tubing over the receiver and blow. Don't use compressed air or you might have tuba pieces all over! I'll bet that you'll find that the problem is in the leadpipe, the valves, or a waterkey.

If you don't find any substantial leaks (ALL horns leak a LITTLE)... you might have a look at the valve alignment. Minor obstructions can cause BIG problems.

Alex C · Post by **Alex C** » Tue May 01, 2007 9:14 am

Water immersion is the only way you can find out where the leaks are. I have used a swimming pool on several occassions, works great.

A friend had an old Miraphone that "just wasn't playing like it used to," we took the tuba to a swimming pool and dunked it as described above. This pinpointed leaks at worn centerposts and under a brace flange. All leaks were able to be addressed and they lived happily ever after.

I would disagree that leaks in the large tubing have little effect on the tuba. I have found that leaks in large tubing affect low register response and intonation. The large tubing is often the source of large air leaks.

Fixing leaks will not make a horn perfect. It the physics are wrong, the horn is going to be wrong. Fixing leaks will bring the horn closer to it's potential.

Yeah, dunking a tuba kind of nutty. The best way to approach it is to bring beer and brats and make an event out of it.

Chuck(G) · Post by **Chuck(G)** » Tue May 01, 2007 12:27 pm

iiipopes wrote: It needs some work, especially around the bottom bow on the off side, as it has suffered at several points in its 35 years before I got it from being improperly stood on its bell, then knocked over, leaving the flat on the opposite outer lower bow which so many of them have.

That's what I call the "Honest, it just fell right over!" dent.

iiipopes · Post by **iiipopes** » Tue May 01, 2007 12:44 pm

Hey, Alex C -- can I be invited to your next find a tuba leak party?

Tubaguy56 · Post by **Tubaguy56** » Tue May 01, 2007 3:13 pm

I actually had a tuba "just fall over" due to a crappy tuba stand....

windshieldbug · Post by **windshieldbug** » Tue May 01, 2007 3:45 pm

Alex C wrote:The best way to approach it is to bring beer and brats and make an event out of it.

Well, that's pretty much the best way to make ANY event tolerable...

Art Hovey · Post by **Art Hovey** » Tue May 01, 2007 11:42 pm

Put an old mouthpiece in, stick a garden hose into the mouthpiece, and turn it on while holding the tuba upright on your lawn. When the tuba fills up you'll see water squirting out from the leaks. This is best done on a warm day.

sloan · Post by **sloan** » Wed May 02, 2007 1:44 am

Art Hovey wrote:Put an old mouthpiece in, stick a garden hose into the mouthpiece, and turn it on while holding the tuba upright on your lawn. When the tuba fills up you'll see water squirting out from the leaks. This is best done on a warm day.

And...with great respect for the physics involved. A tuba full of water can quickly develop a mind of its own...

runelk · Post by **runelk** » Thu May 03, 2007 7:51 pm

After plugging up the large end of the tuning slide, find a friend who smokes, have him take a big long drag on his cig. and have him blow into the horn.

You'll find the leak plus you'll have to wash the horn afterward, unless you like that smoky aftertaste.

Leland · Post by **Leland** » Thu May 03, 2007 8:41 pm

runelk wrote:After plugging up the large end of the tuning slide, find a friend who smokes, have him take a big long drag on his cig. and have him blow into the horn.

You'll find the leak plus you'll have to wash the horn afterward, unless you like that smoky aftertaste.

That was going to be my suggestion, too. Never did it myself, but I've known a couple who did.

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Detecting an Air Leak - efficiently

Detecting an Air Leak - efficiently

Re: Detecting an Air Leak - efficiently