Pianotech

Hi. Today, a Kawai K-15E, new this year... on several notes B2-D#4 when the damper came back to rest on the strings, the 6th partial would continue to ring for a bit while the rest of the tone was damped pretty immediately. Damper regulation looks good. The customer can hear it and is complaining about it. Why does this happen, and only on the notes in that range, and what can be done about it? Thanks.

Hi Jonathan:

Two thoughts.  First, if you press on the strings, do the dampers move along with the strings?  That would confirm if the dampers are pressing on the strings.  Check the damper pedal to see if it's got enough free play when it's not being used.  The pedal should move about 1/4" inch before any damper movement.  Do the hammers go halfway to the strings before damper movement?  You said the regulation is good, but you know I have to ask specifics.

If all of this is good, pluck the individual strings involved.  Are some of the strings ringing while the others don't?  Or is it a consistent ringing for all the strings?  

The second thought is that the dampers are not sufficient to dampen the strings.  Either they are too short or they're sitting on nodes of the strings.  You've seen some pianos that have an extra piece of felt on a wire above the damper line to suppress any ringing.  Old Steinway uprights have them.  If all of these notes are similar in their ringing, it may be a design problem.  You might visit the dealer where they bought it and see if it happens on other pianos of that model.  You might also call Kawai and ask their service department if they are aware of the problem, and have suggestions to fix it.

Good luck.

I have found that, typically the ringing is from another string.  With clean hands press on sections of the strings and see if you can find the loose damper (often in the bass) and tweak that one.