Noisy Dampers on Shift

[Paul McCloud]

Hi, Thomas:
    Hard to diagnose damper problems over the 'net.  But, I'll take a stab...  I'd check to see if the dampers ride in the bushings without excess friction.  Remove the action and lift the dampers with your finger.  Do they fall and make a thump on the strings?  If they fall slowly, you might see if they lean too heavily to one side and cause excess friction.  Or the bushings may be swollen.  Are the strings level?  Are the damper heads directly over the strings, and do the damper felts meet the wires simultaneously when the key is released?  Are these trichord dampers with flat pads in front or back?  If the dampers have both trichord and flat felt, see if the flat part is sitting on the strings, or held up with the wedges.  I assume agraffes in this section, no?
    If the action shifts too far, perhaps the key end felt is rubbing adjacent damper underlevers.
    Sometimes buzzing can come from hard, glue-soaked bushing felt.  When the dampers contact the string, the wire buzzes on the hard felt in the bushing.
    More info?

    Paul McCloud
    San Diego  

Paul McCloud
Service Technician for PianoSD.com
www.pianoservsd.com 
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----- Original Message ----- 
From: Thomas Cole 
To: Pianotech
Sent: 07/15/2008 10:04:21 PM 
Subject: Noisy Dampers on Shift


I just acquired a client who bought a new F183 Fazioli. Obviously it's a very nice piano, but the owner is complaining of improper damper function on several notes starting above C4, especially on shift. The hammers all shift off of the first string in Faziolis so I can see that there might be some phase shift between the strings of each unison challenging the dampers, but he's only complaining about a handful of notes in the fourth octave.

The fact that the owner is formerly a synth player is likely why this effect was so noticeable to him, but I must admit the buzzy cutoff on a slow release of the key is not at all subtle. Even the dealer over the phone could hear it.

So far, the trichord wedges are exerting equal pressure on the strings (plucking doesn't reveal any leaks or uneven damping) and the dampers follow when pressing on the strings. The technician who prepped the piano didn't notice a problem but who checks damper function on shift?

Anyone care to take a shot at it?

Tom Cole
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