Originally Posted by
davewerden
DISCLAIMER: I know nothing about this particular instrument.
In general, I think it would be unusual for a factory to build a horn that had specs for the first valve that were different from the others (clearances, for example). So for a first valve to stick more then others, there would need to be an external factor.
True. Nonetheless, there are several quite distinct reports that the 2nd valves on the Jin Bao EEb tubas seem to exhibit fit/finish problems more than the others. Perhaps there is a "second valve guy" or "second valve apprentice" whose work is being seen.
The ones I have seen in real life are:
Poor bracing. This was a very real problem with Miraphone's first compensating euph, back in the early 1980's. You could push down the 1st valve, press on the 1st valve slide, and release the first valve without having it return to its up position. Obviously the maker fixed that in later production. A clone maker could stumble into that trap in early production, but that would be the type of thing I'd expect the Chinese factories to find and correct relatively soon. (That's my personal expectation, not based on real-world experience with Chinese factories.)
In terms of the Chinese clones it is not exactly poor bracing that is reported at times, but poor solder joints on the braces. Dan Shultz has told me that it isn't just the Chinese who have this problem since the same (fast and easy electro-soldering) technique is now being used by most manufacturers to reduce cost over hand soldering, and it can lead to imperfectly soldered joints. This does not seem to be a terribly wide-spread problem, but I have seen it.
Probably the most likely... DIRT/SLIME! The first valve gets the first taste of whatever you blow down the leadpipe. That could include food particles, sugar from a soft drink, or you may just be pushing down naturally-occurring slime that built up and was never cleaned out of the leadpipe.
Absolutely, and especially with pistons. People don't clean their instruments as frequently as they should. And a very little gunk of any sort can really affect a piston. I've also seen it claimed that synthetic valve oils can "build up" and need to be cleaned off more frequently than "natural" oils. However, I can't say that I've seen this myself. On the other hand, I do clean stuff fairly frequently.
Gary Merrill
Wessex EEb Bass tuba (DW 3XL or 2XL)
Mack Brass Compensating Euph (DE N106, Euph J, J9 euph)
Amati Oval Euph (DE 104, Euph J, J6 euph)
1924 Buescher 3-valve Eb tuba (with std US receiver), Kelly 25
Schiller American Heritage 7B clone bass trombone (DE LB K/K10/112/14 Lexan, Brass Ark MV50R)
1947 Olds "Standard" trombone (Olds #3)