Re: Re: compensating system


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Posted by Small Correction... on November 25, 2002 at 11:31:07:

In Reply to: Re: compensating system posted by Rick Denney on November 25, 2002 at 11:02:09:

"...But a 1-2-3 combination on a three-valve compensator is in tune...

Well, no it's not. Consider a BBb 3-valve compensator. The 3rd valve adjusts the lengths of the tubing so that 1 and 2 are extended to be in tune for a tuba pitched in GG. But 1+3 gives an in-tune FF and the 2nd branch is still too short, being adjusted for GG. So, while the tuning is yards better than an uncompensated 3-valve instrument, it's not strictly in tune and will be somewhat sharp.

The same applies in spades for a 4-valve compensator. Consider a 4-valve tuba in Eb (probably more common than one in BBb). The 4th valve adjusts branches 1-3 to be in tune for a pitch of BBb. But 134, 1234 and 234 will be no more in tune than they would be on an uncompensated 3-valve BBb. Really, the only fully compensated valve combinations are 4, 24, 14 and 34--and this at the expense of the 23 combination being uncompensated. The other 4th valve combinations theoretically will require adjustment by the player.





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