Because of how tight the 2nd valve comp loop has to be, yes, the 2+3 combination on all of the Besson/B&H instruments, including Baritone, Euph, and both Eb and BBb tubas does tend to be flat, because of the physical limits of just how short the 2nd valve comp loop can be and still be a loop. Kind of like the 2nd valve on a picc trumpet, it is usually part of the block and must be cleaned, er, um, *very* carefully, if you can get to it at all! So it is a combination of the physical limitations of just how short the comp loop can be made along with the difficulty in keeping it clean is what contributes to 2+3 being slightly flat, even in the best of circumstances. And yes, if 3rd valve is tuned "dead" so that G and D are in tune, 2+3, just like on a non-comp instrument, would be sharp if the 2nd valve comp loop were not there.Mark Finley wrote:It's been years, I don't remember if the d was sharp playing 1-2, but the length of the 3rd slide combined not only with the 2nd slide, AND the extra compensating tubing on the back of the valve, made the 2-3 combination flat. I think that's the weakness of that system. Sure adding the 1st valve or 1st and 2nd to the 3rd valve kicks in extra tubing that is needed, but it also adds extra tubing to the 2+3 combo, which is not needed
Oh - and look again: pressing 1+3 does NOT engage the 2nd valve comp loop. Pressing 2+3 together does not engage the 1st valve comp loop. The second set of ports in the 1st and 2nd valves only engage that particular valve's comp loop when pressed together with the 3rd valve in a 3-valve comp system. Please review Dave Werden's excellent article and applet on the subject:
http://www.dwerden.com/eu-articles-comp.cfm" target="_blank