"Big Valve" refers to really large pistons that were initially developed by Warren Deck and Meinl-Weston in order to avoid having the small dimples, or knuckles disturbing the windway in the ports of the valves. These dimples come from adjacent ports; they just put a little dent in the windway to accommodate all the windways. Warren didn't think this was an acceptable compromise, and asked if they wouldn't be willing to avoid this by making larger valves (thus avoiding crowding of the windways). Thus the "big valve" section.
Whether it has any real-world effect is anyone's guess.
Big Valves?
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UDELBR
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You can remove the dimples either by making the valves broader or taller (or both...).PhilW. wrote:What you're talking about sounds like the valve height to me. The holes would be spaced further apart on the piston so that they wouldn't crowd each other.
Or not. Brass players allow themselves many unscientific notions about "resistance" that don't hold water either logically or empirically.This could work to make the horn more free-blowing, like open wrap horns, or Willson's Rotax valves.
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UDELBR
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I'd read once (maybe Scientific American) that a dent of less than 30% of the diameter of a brass instrument windway's cross-section will have a negligible effect on tone / response.
I know it's tempting to think of air rushing through your tuba, although in reality, all you're doing is setting up standing waves in a column of air. "Resistance" plays almost no part. Better to read up on acoustics than hydraulics, as it's far more applicable!
I know it's tempting to think of air rushing through your tuba, although in reality, all you're doing is setting up standing waves in a column of air. "Resistance" plays almost no part. Better to read up on acoustics than hydraulics, as it's far more applicable!