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This is something I picked up on eBay a long time ago, because it was missing the 4th valve rotor, and came at a pretty good price. Since then, I tracked down the proper rotor for it, but I would like to know who built it. Does anyone know what horn this was originally built for?

Three valve compensating systems are generally considered complete without the addition of a fourth valve. What is the function of the 4th valve in this setup?

Maybe I am misunderstanding the circuit. Is the fourth valve part of a four valve compensating system? Doesn't look like other 4 valve compensating systems I have seen.


Hup

hup_d_dup wrote: ↑Fri Feb 18, 2022 9:09 am Three valve compensating systems are generally considered complete without the addition of a fourth valve. What is the function of the 4th valve in this setup?

Maybe I am misunderstanding the circuit. Is the fourth valve part of a four valve compensating system? Doesn't look like other 4 valve compensating systems I have seen.

Hup

Look at the double set of valve port knuckles. The third valve does not circle back over to the first valve as would be the case with a 3-valve comp, whether B&H, Besson Enharmonic, or any of the latter manufacturers which have derived their comp systems from either of these two original models. As cheburashka first said, this is a 4-valve comp block with substantial parts of the 4th valve circuits completely missing.

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Look at the double set of valve port knuckles. The third valve does not circle back over to the first valve as would be the case with a 3-valve comp, whether B&H, Besson Enharmonic, or any of the latter manufacturers which have derived their comp systems from either of these two original models. As cheburashka first said, this is a 4-valve comp block with substantial parts of the 4th valve circuits completely missing.
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I've re-thought the idea that there were parts missing, as I originally posted. I hadn't considered that the exit port of the rotary valve was the last point in the valve cluster. The tube that is not connected goes between the third valve, and the curved tube that comes out of the tuning slide for the fourth valve. It's now together and complete. The fourth valve circuit does look short. I guess I'll have to build it up into something interesting to see what it does.

I may be mis-remembering, but I thought Conn had started to do a prototype compensating euphonium with a rotary fourth valve. Possibly Bill Reichenbach played it at a conference? Maybe the Army conference 12ish years ago?

Again, I may be way off the mark, but it looks how I remember that horn.

-T. J.

I have seen an old Meinl-Weston euph with a rotary valve buried in the back like that. I did not bother to see how it was set up, but it looked a lot like this one.

The braces look like Meinl-Weston to me. Compare: https://www.musicarts.com/meinl-weston- ... ain0025016

Assuming that's for 9 ft. Bb, how about a jazz friendly single Bb cimbasso?

Something non-stock looking about the 4th. While the basic 3 look typical for compensating horns.

Is is possible this was a standard piston 4th converted to a rotar.