> I've been following this discussion with some interest, and don't have any > strong opinions or data on one side or the other of the soundboard/bridge > debate. However, I'd be interested in how the various factions explain the > difference in humidity-related pitch change between the treble and bass > bridges. We've all observed the same sort of difference with both > solid-body and cantilevered bridges, so I don't think it can be explained by > simply saying, "Bass bridges have more wood, so they expand and contract > more." Hi Bob, Tell me, how would having more wood and expanding and contracting more have any reasonable hope of producing better tuning stability? This stuff works by real rules in the real world, so the conceptual model has to make rational sense somewhere. >And how about those Yamaha C3s where the lowest octave of the tenor > bridge has far greater seasonal pitch swings than any other part of the > scale, treble or bass? > > Just wondering > > Bob Hohf Once again. Strings at a tension putting them at a lower percentage of breaking tension change pitch more for a given length change than strings at a higher break%. The low tenor in way too many scales is too low a break% because the less than stellar scaling approach has the speaking lengths foreshortened because the bass/tenor break is too low in the scale to allow adequate speaking length in the lowest tenor note and still fit in the piano. That's it. In most scales, the bass is at a higher break% than the low tenor, often *much* higher, so the mechanism that changes string lengths with humidity changes produces the greatest pitch change in the low tenor - which is typically at a lower break% than everything around it. Using Sanderson's scaling formulae against what we observe in the physical world, it becomes more obvious all the time that there are real cause and effect relationships at work here. Ron N
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