[pianotech] Interesting find

[Roger Gable]

Et at,
I agree with Terry, the wedges or springs do not add to sustain or volume. While studying electrical engineering it was noted that restricting the movement of a magnetically activated diaphragm would reduce the volume and reduce the frequency spectrum -- especially the low end. I believe this applies here as well. It is important that the soundboard have the ability to "store" the energy between cycles. The wedges and springs "short circuit" this ability.
Roger Gable
  ----- Original Message ----- 
  From: Susan Kline 
  To: pianotech at ptg.org 
  Sent: Tuesday, October 19, 2010 11:10 AM
  Subject: Re: [pianotech] Interesting find


  On 10/19/2010 9:21 AM, David Love wrote: 
    I don't think the wedge will kill sustain, though it might make it softer. Hold a tuning fork on a rigid steel table and it will continue to vibrate for a long time.
  It looks like a felt mute, so it probably wouldn't couple the beam and the soundboard much. The springs might add stiffness, but the board could still vibrate because of their flexibility. (At least, I imagine that it could.)

  I've been known to resort to measures like this, except I did such stuff on pianos much worse off that this one. Open cracks, big noises, no money, that kind of short crummy grand.

  Haddorff ... I've liked the ones I've seen. Also I have a sense of connection because my grandmother, aunts, and cousins lived in Rockford, IL where Haddorffs were built. In fact, my uncle's grandfather worked in that factory. 

  Susan Kline 
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