Posted by Frederick J. Young on January 26, 2001 at 10:27:02:
In Reply to: Re: Re: 7 Valve Tuba posted by Matt G on January 25, 2001 at 14:42:29:
You are right about the idea of increasing the fundamental by having the taper increase more rapidily after the valves. That increases the coupling to the room. However, Arnold Jacobs said "I prefer such a large taper and a small mouthpiece". This greatly increases the high harmonic content. It is also a physical fact that the large taper increase can lead to great intonation problems.
As to the "straight ahead" 4 and 5 valve designs there is nothing straight ahead about them. Trace the convoluted path through the numerous valves needed for the low C#, D and D# on the typical "modern straight through" tuba keeping in mind that on a full double tuba (not to be confused with the B&H compensating system) the path for these notes passes through only the switch valves (26 mm in diameter) and one other valve slide (22 mm
diameter).
With regard to CCC pedal note there is no trouble with the audience hearing it. The trouble is with the tone quality. If you wish to evaluate your own tone quallity download from the spectrogram at
www.monumental.com/rshorne/gram.html
to get a spectrum analyser free for your computer. It is free and easy to use and will show you graphically what the harmonic content of your tone is. I think that most tubists would never play a pedal tone again it they realized that the note one octave higher contains much more bass than the pedal tone. Granted it is fun to have your head vibrate at 32 hertz. However, the audience hears nothing but harmonics centered around 256 hertz!
As far as intonation the Besson Compensating 4 valve instruments are still out of tune on
12, 23, 124, 234 and 1234 because the tubing does not add up properly. The compensation works on 14, 24 and 34 only and is stuffy because the air takes two trips through all of the terrible bends in the piston valves. In addition the bore through the piston valves is less than the small 0.75 inches in the antiquated York.
I'm sure you will try to tell me (an engineering professor and fluid mechanics consultant) that 0.75 through piston valves is much greater than 0.85 in rotary valves. I deny this in advance and tell you that measurements of the pressure drop in piston valves greatly exceeds that found in the larger rotary valves.