Hi Joe, > For those of us that use an ETD, I think we've found, (at least I have), > that when you pluck a string it will read flat as opposed to being struck by > the hammer. I don't know why, but this seems to be consistant. Any thoughts > from the Scientific bunch? Can/do you pluck with the same loudness as with a hammer strike? I suspect the phenomenon has to do with the loudness. (For instance a note will slowly flatten as the vibrations dissipate, as observed recently by someone on the list.) Variation of pitch with amplitude has to do with variation in the spring constant as the string is stretched laterally. The increment in pressure required to displace a string from 0 mm to 1 mm is much less than the increment in pressure required to displace it from 10 mm to 11 mm. It's a matter of mechanical advantage and can be understood by examining simple trigometric relationships. There are certainly other contributing nonlinearities at play, both in the steel of the string and in the other vibrating parts, but I don't think these would be as important. The so-what of this is that a string vibrating at a lower spring constant (at lower amplitude) will vibrate at a lower pitch. That's because there's less force to move the string back and forth. At progressively higher amplitudes, associated with higher spring constants, there is a disproportional, extra "tug" that reverses the direction of the string a bit faster, resulting in higher frequency vibration. For the string to vibrate at the same frequency at all amplitudes, the lateral force would need to be directly proportional to the lateral displacement, which it is not. Hope that helps... Peace, Sarah
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