[pianotech] Buzzing piano puzzler

[Rex Roseman]

Dear List

 

Need some collective help here. A customer has a Shoniger Console piano that
has developed a bad buzzing sound when the notes around C3 and C4 are
played. This piano is sitting over the heat/AC vent for the room. I
explained that this was a bad idea because of drying and that the buzz was
most likely loose soundboard ribs.

 

Diagnosis: The buzz sounded like a loose rib. While playing the notes and
pressing on the soundboard from the front, the buzz stopped. During the
return service call to fix the ribs, the piano was pulled out from the wall
for access. Everything looked tight (ribs to soundboard) and the peripheral
soundboard joint looked good. The buzzing could be stopped by placing a
wedge between one of the ribs and the back post. Only one rib (passing
behind the treble most post) stopped the buzzing sound, so it was thought
that this must be the loose rib. However, when that rib was wedged from the
back, the buzz moved to the C6 area.

 

Repair attempt: ZAP-A-Gap CA glue was used to reattach the rib to the
soundboard by applying glue to the old glue line. The glue never seemed to
wick in except for one spot at the bottom of the piano that didn't seem to
have anything to do with the buzz. All the ribs were treated because the
piano was already cleaned and prepped and just in case the rib that seemed
to be the problem was not. As far as I could tell the glue treatment did not
work this time. The only thing that stopped the buzz was to place a felt
wedge between the harp and the soundboard opposite the rib that seemed to be
the problem. When wedged from the front, the buzz did not move up the piano.
The wedge was left in, but this is not an acceptable long term solution.

 

Obviously either the problem has been missed diagnosed, the wrong glue used
or used the wrong way, or there is something totally different happening
here that I have not discovered.

 

Any suggestions of what to look for and what may have gone wrong?

 

Thank you.

 

Rex Roseman

 

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