Posted by Rick Denney on November 28, 2003 at 09:43:56:
In Reply to: Re: Re: Question about 3 vs 4 valve Compensators posted by Statman on November 27, 2003 at 18:38:21:
I think you'd run into practical limitations attempting to add a fourth compensated valve onto a three-valve compensation system. You could do it, but instead of each valve having two complete sets of ports, it would have to have three, and the valves would be about a foot long. That would lead to difficult manufacturing and maintenance issues, it seems to me.
You could put a plain fourth valve on a three-valve compensator. You could tune the fourth valve to a perfect low F, since you wouldn't use that valve for anything else. But you'd still have to make some adjustments for pitch below that F. In practical terms, I can't see the limitation here. I think that making the fourth valve the control valve on a BBb compensator is giving up the best advantages of compensation.
But don't depend too much on compensation. Dr. Young's analysis is based on tubing length, but taper design and mouthpiece volume both affect the location of resonance peaks in the spectral response nearly as much as length. Thus, it is possible to have a three-valve compensator with wretched intonation, which I have personally experienced. Good design and execution in other aspects of the tuba are required to bring out the advantages of compensation. And good execution in performance is still required to get good pitch in an ensemble--ensembles don't always follow pitch rules (or the rules they follow aren't the same as those assumed by the compensation system designer), but their members have to stay together to sound good even so.
Rick "who has played a three-valve compensating euphonium that he just loved" Denney