Does anyone here have a vent hole in the side of their 3rd valve in a compensating Euphonium?
If so, can you feel air escaping from the bottom of the 3rd valve when playing a note involving the 4th valve?
If so, do me a favor, pull your 4th valve slide, plug up the side closest to the bell, push down the 4th valve and blow hard air into the horn. Do you hear air escaping out the bottom cap of the 3rd valve?
thanks