How to find an air leak?

[jacobcasas99]

Hello again fellow euphonium players. I need a bit of help. To begin, our band will be participating in The Festival of Flowers, and we are beginning to practice our marching again. We are getting our marching horns ready but we don't have enough marching horns for the section (5 horns, 6 players). There is a Olds Ambassador with a curved bell that can be used for back up and I've decided to use the Olds (I like American style euphoniums ) and let one of my section mates use my Yamaha YBH 301m. The problem is the Olds sounds and plays as if there is a leak somewhere on the horn. The tone has that "fuzz" in the sound. I would like to know any ways that can help me find the leak. My director won't send the horn out because he hates American style euphoniums so I must do this on my own. I don't care if I have to use electric tape to patch the leak, I just want the horn to really have that true "American" euphonium sound. Any suggestions and/or methods would be greatly appreciated.

[carbogast]

My guess is that the Olds hasn't been used recently or maintained. Brass instrument issues are usually pretty simple and given a quality instrument usually come down to cleaning, new felts and corks, lubricating the slides and oiling the valves. The mouthpiece must fit perfectly. Damage can have an effect, particularly if they affect the lead pipe, slides, or tubing associated with the valves. Look very closely for damage.

You can do much of this work yourself, but if you're a novice, you may want to go to a repairman for corks and felts (the 1st time, then do it yourself from now on)

So... Clean the horn. There are many posts about "really cleaning your horn". Do all that stuff; especially clean all tubing with a snake. Check the spit valves visually. If the corks are deteriorated,replace them(cheap). Pull the slides, clean them with a snake. Put a finger on one end and blow through the other to determine if there is a leak (probably not). Clean the valves and replace the felts... worn felts will cause a slight valve misalignment. Put the horn back together; oil the pistons and put grease on the slides.

To answer your original question: Pull the tuning slide and stop up the open end. Blow into the horn, trying each valve. Oil the valves beforehand.

[jacobcasas99]

I have cleaned the horn in the past and recently have been checking the corks. The corks seem to be in great shape. I'll check each tuning slide like you said and see the results. The horn is in decent shape and really has no major damage on it. I'll probably check the valves and see if they can be the problem. They've always felt weird to me anyway.

[RickF]

Don't forget to check the cork of the water key or spit valve. If it doesn't seal properly you'll hear air or fuzz.

[ghmerrill]

1. Get a role of paper towels that will fit tightly inside the bell.
2. Put the role of paper towels in a plastic garbage bag.
3. Push the bag with the role FIRMLY into the bell so that it creates a seal.
4. Blow into the lead pipe.

If there is a leak, you will hear the air escaping. Have someone identify the location(s) of the leak(s) while you're blowing into the instrument (often difficult to do both by yourself).

That will give you the locations of the leaks. Fixing them will depend on the nature of the particular leak: water key cork leaks, air leaks through worn pistons, air leaks through worn tuning slide, air leaks through degraded solder joint, air leaks through pin hole in tubing.

Don't overlook the possibility that the air is leaking at the mouthpiece as it seats into the receiver. This is fairly unlikely, but it's surprisingly difficult to notice. My Schiller bass trombone had this problem because the receiver was a bit out of round.

One quick way of seeing if it's the valves (or how bad the valves are) is to use vasoline on the valves to ensure a good seal. See if the horn sounds good then. You won't be able to actually play it reasonably, but you will be able to test the sound of the open horn and with each valve depressed. If it sounds bad without the vasoline and sounds good with the vasoline, then your valves probably need to be replated. But you can try heavier oil and see how it works. However, there's only so far you can go with that approach if you value both intonation and the ability to play at an acceptable tempo.

[jervin]

1. Get a role of paper towels that will fit tightly inside the bell.
2. Put the role of paper towels in a plastic garbage bag.
3. Push the bag with the role FIRMLY into the bell so that it creates a seal.
4. Blow into the lead pipe.

If there is a leak, you will hear the air escaping. Have someone identify the location(s) of the leak(s) while you're blowing into the instrument (often difficult to do both by yourself).

Rather than having someone try to watch for a potential leak, I used gas leak detector spray. It's available at any hardware store. You spray it on any places you suspect may be leaking, use Gary's technique above, then look for pea-sized bubbles to form. It's viscous enough that the bubbles will stay around the leak and make it very easy to see where it is.

[LargoBone]

The easiest way I found to test for leaks was just running my hand along the tubing while holding a note. IT'd probably be easier with someone else but I discovered a couple of leaks in a situation very similar to yours using this method.