On 1/25/2011 12:14 PM, Alan Eder wrote: > > It's really noticeable with seasonal changes, which would be humidity. > > And if the seasonal changes are humidity-caused, and the soundboard is > NOT actually rising and falling (as many of us had thought), what IS the > humidity doing to effect the exaggerated changes in pitch in the low > tenor and lower lower-treble areas? The soundboard does rise and fall some, just not nearly enough to account for what we hear in pitch changes. So what does? We have pinblocks changing dimension as one possibility. That's a more direct line thing than soundboard rising and falling, and only a very small change would make a big difference. We have the bridge cap rising and falling on the slanted bridge pins, which changes the length of the string path. I think this is a big factor, since the tuning is so much more stable with epoxy laminated caps. We also have the lossy termination effect. A less hard termination of a vibrating string will produce a lower effective frequency. As the soundboard panel expands in wet seasons, it compresses and gets stiffer. In dry seasons, it gets less stiff. At the same tension, a string will sound at a higher pitch on this board in summer humidity than in winter dry heat. So it isn't any one thing, or probably even any five things. No two people agree on anything except soundboard rise and fall. What it's not is the soundboard rising and falling. Ron N
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