Leslie wrote:
Fortunately there WAS a pop.
However, on about three or four of the slides, there was also a hiss
following the pop. Does this mean I need to get my values rebuilt?
When you pull either a F or Bb valve slide, if the other slide on that
value is still installed, it may be that pulling the slide sucks some
air from the closed slide on the other side of the horn. Air sucked
from the main branch of the F or Bb horn would not cause a hiss, since
those branches are open to the outside air.
It is important to realize that there are two kinds of leaks. A worn
valve allows air to leak in both directions. This kind of leak can
cause wolfs or poor definition on various harmonics, making the
instrument difficult and unreliable. Repair requires replating and
relapping and/or all the other very expensive treatments that quality
repair shops like to do. (Don't let your neighborhood guitar/woodwind
repair shop attempt replating your valves. Ship to one of the quality
horn repair shops.)
The other kind of leak is simply a corroded hole in tubing, or a
corroded solder joint. These are common on old horns, or very badly
manufactured not-so-old horns. You can check for this kind of leak by
plugging the bell of the horn and blowing into the mouthpiece end. Use
significant pressure, but be careful not to blow out any loose slides
onto a concrete floor. If you can feel or hear any air escaping, you
have a leak. See if an assistant can locate the leak by sound. This
kind of leak can generally be repaired inexpensively with a glob of
solder, or even temporarily with duct tape, or better by properly by
having a competent repairperson dismantle the horn, clean the joint, and
resolder.
The easiest way I know to run this test is to place a small piece of
kitchen plastic wrap over the wide end of your stopping mute, and
securely inserting the mute into the bell. This seals the bell better
than other methods. This is the most important use I have ever found
for my stopping mute. Plastic wrap, on the other hand, has many
important uses, most others involving food rather than horns.
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