[CAUT] sympathetic vibration in non damper section

Susan Kline skline@peak.org
Sat, 30 Apr 2005 19:14:09 -0700


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At 08:48 PM 4/30/2005 -0400, you wrote:
>I'm having a tough time with an SD Baldwin at Colby College (in 
>Maine).  E6 (the first note above the dampers) rings quite noticeably 
>after playing loud chords.  It took me a while before I figured out it was 
>the speaking length causing the problem.  (I muted all the duplex sections 
>hoping they were also affecting the ring, but they are not the problem.)
>
>Any ideas on how to eliminate the ring without negatively affecting the 
>sound of E6 when it is needed?  I'm stumped.  One idea I thought of was 
>increasing the downbearing of that one note (it has accu-just hitch pins) 
>figuring more downbearing might lessen ring time.  But I didn't actually 
>do this, because I don't really know what other problems this might cause.

Hi, Gordon

Have you investigated the long waste lengths on the bridge end of the tenor 
section? I've had a few pianos where one (or another) note around the sixth 
octave would ring on too long and too loud. I tried plucking all the 
different waste lengths (especially the ones behind the bridges) that I 
could. Sometimes it seems like a bunch of them are reinforcing (mainly) 
just one note.

Keybushing cloth cut into strips makes effective stringing braid, but one 
has to decide just how much to use. Our SD-10 had the problem, which got me 
very frustrated, and I tightly braided a whole lot of the waste lengths 
from the middle treble right down to the end of the tenor. It was muffled 
up to its eyeballs, and the after-ring (the normal after-ring) of the whole 
instrument was really crummy and dull. I took it all back out again, and 
just used a little bit of extra braiding on the super-long tenor strings. 
They can have the original braid, and still have too much sympathetic 
resonance, because the waste lengths are so long, where they go past that 
round plate opening.

Sometimes just a little fold or two, hidden under the edge of the plate 
down at the tail end, will be enough.

If you have a helper, you can have him or her keep playing E6 while you 
wander around the tail end, muffling this or that place to see what you get.

Why would it suddenly get worse? --- The original braid might have suddenly 
worked loose; or the problem gradually appeared, but nobody paid attention 
till it became really obvious.

Susan Kline
Linfield College,
McMinnville, OR
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