>Hi Ron > >Would you mind explaining to me what you mean by "semi-log" as I am >unfamiliar with this term. How is a "semi-log" bridge calculated and what >are the pros/cons re results? > >Thanks in advance! > >Stephen You'll want to check out Theory and Practice of Piano Construction, by William B. White for better detail, but essentially, speaking length progressions in pianos are based on logarithmic progressions - sort of. Suppose you wanted a C-8 length of 52mm, with a (semi) logarithmic progression to 186mm at C-6. EXP(LN(52)+((88-present unison)*0.0531) will get you there. Increasing the 0.0531 figure will make the scale longer, and decreasing it will make it shorter. This can be done anywhere in the scale with your choice of starting and ending lengths, depending on what sort of room you have and the string tensions you want. Note that the last octave+ of a cheap little spinet can have speaking lengths identical to the last octave+ of a 9' grand, but the length progression rates change rather dramatically from there on down. I hope than makes some sense. Ron N
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