TubeNet

Remove the main tuning slide, block the tube with your hand, blow. If you suspect the 3rd valve tubing be sure to press the 3rd valve.

Andy1100 wrote:I was wondering if anyone has any suggestions on how to track down a 3rd valve leak. It's a Conn 20J, that plays really well, but the F sharp has no volume, and sounds flat. Any ideas on how to track down the problem? Thanks.

The first question I would have is "how do your other notes that are fingered just #3 sound". Could it be that you have a problem in your #2 circuit? While you have your main tuning slide out you might as well check everything out. If you don't find any substantial leaks, check your port alignment. You may have to fiddle with your corks and felts.

You are correct sir, it is vertical alignment. The first quick check is there should be a small groove on your valve stems, and it should line up with the top of the valve cap when the valve is in the up position. If it is above the the cap, there is not enough cork and /or felt on top of the valve, and if you can't see the groove, too much. Most 20J's need about 1/4" of cork and 1/8" of felt. For the down position make sure there is just enough felt under the finger buttons so they don't "clank" when pushed. I do an accurate alignment on my horns with a cheap plastic dental mirror and a flashlight. Remove the adjacent valve and lower the mirror into the valve casing and shine the light down there too. You might have to bend the head of the mirror a bit to get a good viewing angle. Push the valve up and down and you should be able to see if the ports line up in both up and down position. You should see little or no valve in the open ports and no openings (only silver) in the closed ones. It will be difficult to get the mirror, light and and your eye all lined up to see at first, so it might help to get a second set of hands. Use a razor blade or Xacto to trim the cork to get the valves to end up in the correct place. I make my own out of wine corks, so I don't need to have a stack of thinner ones. You also need to check that the new corks and felts don't hang over the edge of the valve and rub on the inside of the casing. Because the the stem is offset (not in the center) some of the commercial tuba corks and felts are too large in diameter and need to be trimmed or they will rub and slow things down. You will need to add or subtract felt or thin cork washers under the the valve button to get the valve to line up in the down position. I don't think it's real difficult to do, but it can be tedious and frustrating the first few times you do it. I hope this helps more than it confuses.

if it is a leak I like to connect my horn to the hose and I just watch where water leaks out. I don't plug mine, the water going through will usually start dripping or spraying from any leaks. That's just how I did it on my horn.

Ben

twoconnguy wrote:. . . . You will need to add or subtract felt or thin cork washers under the the valve button to get the valve to line up in the down position. I don't think it's real difficult to do, but it can be tedious and frustrating the first few times you do it. I hope this helps more than it confuses.

Very good directions. I like the notion of using wine bottle corks. Drill before slicing.

One more detail. Some tubas' piston valves have small, vent-like holes on the tops. The holes are probably important when manufacturing the valves. It might make a small difference in valve speed if the corks and felts' diameters are small enough not to cover the holes.

Concerning valve alignment, there are some more posts worth reading on the rarely used Smartgroups Repair Forum. Look for topics on corks and felts after registering.