Damper Thump Noise

[Overs Pianos]

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Terry,

>1950-ish Baldwin L grand, all original. Raise dampers with pedal and 
>then release pedal. Dampers make quite an audible thump. Remove 
>action and manually lift a dozen or so dampers and you get a similar 
>thump - it is especially prominent with the bicords - very little 
>noise from the flat dampers.
>
>Is this nothing more than the sound that 55 year-old grand dampers 
>make? That is my strong suspicion.

Certainly old and hardened dampers will increase the propensity for 
any damper system to thump on sudden return. However, another factor 
about which some piano manufacturers seem oblivious is the 
damper/pedal lift ratio.

We rebuilt a Baldwin SD-10 around 1989 and a Grotrian 275 concert 
piano in 1995. Complaints were received about the sustain pedal 
mechanism of both pianos. The Baldwin system had the thump which 
Terry described, while some pianists complained of a lack of control 
with the Grotrian. I looked at both pianos to find the difference 
between their damper lift systems, since we had rebuilt both pianos 
similarly, yet they had quite different characteristics.

The difference turned out to be the damper/sustain-pedal lift ratio. 
The Grotrian had 5 mm of pedal travel for every 1 mm of damper lift, 
while the Baldwin had around 2 mm of pedal travel for each mm of 
damper lift. After discovering the lift ratio to be a factor worthy 
of consideration, I examined a few other pianos from different 
manufacturers, concluding that the ratio should be no lower than 
3.5:1 and no higher than 2.5. Our 225 piano has a ratio of 3.2.

I altered the trap-work levers on both pianos so that the 
damper/sustain lever ratio was adjusted to 2.5:1. I haven't had a 
damper complaint from either piano since. The Grotrian 275 is the 
broadcast and recording piano at Sydney FM radio station 2MBS FM. The 
Baldwin was used by us as a hire piano for many years. We sold it two 
years ago to a piano enthusiast here in Sydney. It is coming back to 
the workshop very soon for a minor overhaul which will include a 
re-string, and finally a proper fix for the action, which has always 
been heavy. Rick Wheeler has just completed a making a new keyboard 
and key-frame which I designed for fitting an Overs action to the 
Baldwin. I'm really looking forward to doing this refit, since I 
regard the Baldwin SD-10 as one of the very best contemporary concert 
grand piano designs (action and keyboard excepted). The major problem 
which held these pianos back from trumping their opposition (aside 
from poor action geometry) was sloppy workmanship and a complete lack 
of attention to detail. What a shame.

Ron O.
-- 
OVERS PIANOS - SYDNEY
    Grand Piano Manufacturers
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Web http://overspianos.com.au
mailto:ron@overspianos.com.au
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