Uh, well, yeah. It's easy enough to test this out (I've done it) with a water manometer and a low-pressure air supply (a big tank compressor with the outlet regulator set down to a couple of PSI will do). Hook the output of the supply with a tee to the manometer to the leadpipe of whatever you're testing.Rick Denney wrote:Stuffiness is a lack of resonance, not flow.
You won't see much of a variation in back pressure at all, even on those "stuffy" valve combinations. Curiously, some of the "stuffier" ones can exhibit less back pressure than the more open ones.
What I haven't done (and need to do one of these days when I'm occupied with nothing more than studying my navel) is to couple a sound source and transducer to measure SWR (standing wave ratio) when a horn is excited at various frequencies. I suspect that will tell the story behind "stuffiness". A high SWR should result in the least "stuffy" feeling.
In the electronics world, one generally strives for a low SWR (as close to 1:1 as possible), since higher reflected power results in transmission line inefficiencies. But in a brass instrument, being a good transmission line is what you don't need--you could hook your mouthpiece to a 6" diameter length of drainpipe and have a very low SWR indeed.
One of these days...




