On 11-22-94, Tom Seay wrote: >But if you did turn it off and adjust the capstans or whatever, wouldn't it >go right out of tune the minute you turned it back on? Seems to me to be >another good reason not to install the things in the first place, unless >it's absolutely necessary. I wonder how many Dampp-Chasers are mistakenly >installed to correct real problems such as tight key bushings or action >centers, rather than correcting the problems themselves? Yes you're right that there will be a pitch change each time the bar turns on or off, but as long as the pitch is stable during the tuning you have a fighting chance of getting a reasonable tuning pattern onto the piano. If after that the pitch cycles up and down a few cents with the heating and cooling cycles of the Dampp Chaser rod, the tuning will distort somewhat, but will average around a reasonable pattern. Overall, you're trading a temperature-caused deviation of a few cents for moderation of perhaps a 15 - 25 cent humidity-caused variation (in areas where wide humidity swings occur). It's a small price to pay, but it would be better yet to have no temperature effect. It's not surprising that a 25 watt rod can affect pitch when just touching one unison string with a fingertip for 30 seconds will throw the unison out of tune. The Dampp Chaser heat transfers to the plate and strings by convection (air currents) and by radiation, so closeness of the rod to the strings is not really a factor. I agree that Dampp Chasers are sometimes stuck into pianos in lieu of easing keys or action centers. If there's not a humidity variation problem, friction problems should be corrected by easing, not heating up the piano. The rod under the pinblock is the worst -- like treating cold stiff fingers by lighting your hair on fire! Creates a lot of pinblock replacement jobs. Bill Spurlock
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