Posted by Chuck(G) on September 09, 2001 at 13:16:52:
In Reply to: Re: Re: Re: Re: Re: Re: Re: Re: Re: Your ultimate horn collection posted by and.... on September 09, 2001 at 12:54:07:
In short, consider the problem of tuning on an uncompensating Bb instrument as one descends into the lower register. When the 4th valve is depressed, you've just lowered the basic pitch of a Bb instrument to F; the same as an F tuba. However, your first three slides are still proportioned for an instrument in Bb; any progression the descends below F is going to find that those slides are too short. This is not subject to the whim of a manufacturer; it is a simple fact of physical acoustics. It doesn't make any difference if the horn's been assembled by Gabriel himself out of pure duratanium.
To solve the problem on non-compensating instruments, one resorts to slide pulling and alternate fingerings. One also lives with the "hole" between the pitch obtainable with 1234 and the pedal Bb, or has a 5th valve installed or a super-sized 4th slide that can be pulled WAAAAY out.
The compensating system adds extra tubing to slides 1 2 and 3 when the 4th valve is depressed to bring them into accordance with the new pitch of F. Although the low B sounding with 1234 is somewhat sharp, it is usable, where it is nonexistant on a non-comp horn. And all of the other 4th valve fingerings are in tune without excessive "trombonism".
I suspect that the Marzan euph was not made compensating because Besson still owned the primary patents on the system into the 1970s and perhaps also because Mr. Kurath did not have tooling set up yet for the much longer valve bodies and more complex plumbing required by the compensating system. That was remedied in the early 1990s when Willson starting making the 2975/CB30.
Hence, I stand by my statement that the 2975 is essentially an improvement on the original Marzan design. Given a choice between the two, I would unhesitatingly choose the 2975 (Come to think of it, I already have!).