Posted by Frederick J. Young on March 24, 2002 at 09:21:16:
In Reply to: Ascending valve posted by Sam Gnagey on March 21, 2002 at 13:32:05:
Many of the French tubas have ascending third valves. They normally subtract enough cylindrical tubing when depressed to ascend one whole tone. If you had one on a CC tuba, you would descend in half steps from C by using 0, 2, 1. Now you have arrived at Bb which is a lowering of C due to the added cylindrical tubing. Next one would normally use the descending 3rd valve to add more tubing to lower the open C to A. However, the use of the ascending 3rd valve raises the instrument 1 whole tone making it a DD tuba. The to get A one uses the open tone (namely A) which is closer to the fundamental than was the case for the descending 3rd valve.
Your proposal would add an identical whole step 5th valve which you could also use as a third valve. It should work nicely if you put it some place where it can have the right amount of cylindrical and tapered tubing so as to not disturb the CC tuba too much.
In 1993 I published "The Optimal Design and Fair Comparison of Valve Systems for Horn" in the HORN CALL ANNUAL, No. 5, pp. 7 - 15 (1993). This is the refereed journal of the International Horn Society. The conclusion was that horns using the ascending third valve rather than the descending third valve, even when optimized, exhibited poor intonation and were not completely chromatic. Mixing them with descending horns would be especially bad because intonation-wise ascending horns are sharp when descending horns are flat and vice versa.
I have not thought about optimizing your five valve system including an ascending whole tone 5th valve. It could be done following the methods detailed in the aforementioned paper. Your idea is good and there may be some as yet undisclosed benefits to it!
Best of Lick