[pianotech] Regulating drop and controlling semantic drift

Israel Stein custos3 at comcast.net
Thu Nov 26 16:51:32 MST 2009


Thu, 26 Nov 2009 14:14:31 -0700 Cy Shuster <cy at shusterpiano.com>
> After letoff, with aftertouch the hammer rises a second time.  Doesn't 
> the amount of drop keep the hammer out of the string's vibration on 
> second rise?
>
> --Cy--
Cy,

I think that Will Truitt explained that rather well in his excellent 
post. But then, what is this "second rise" that you write about? It 
doesn't happen when you play the piano - the hammer goes into check. We 
only make it happen when we regulate - in order to clearly see the 
relationship between letoff and drop (and, I suppose, check on 
aftertouch). But the piano isn't played that way... But, you say, what 
about on a very soft blow, when the hammer might not check? Again there 
is no issue. If you regulate the letoff to be outside that string 
vibration envelope (which is the absolute minimum allowable letoff 
distance - otherwise some very weird things will happen on quickly 
repeated hard blows) then the tiniest drop position that is below letoff 
will automatically take care of that problem. That is, if the rest of 
the regulation is correct.

As Will explained so well,  the hammer will get into the  strings a 
second time (when the piano is played) if there is a problem with the 
repetition spring being too strong vis-a-vis rep lever pinning.or if you 
have excessive aftertouch. To this list  I add poorly functioning 
backchecks (misregulated or worn) which might be a contributing 
factor... In a properly regulated, well-functioning piano the only 
reason to increase drop distance over the bare minimum, as Will wrote, 
is as a safety factor for weather changes in actions that do not receive 
frequent attention - as is true for  most pianos that aren't on concert 
stages or in music departments of universities, conservatories and 
colleges with regular piano technicians on staff or on contract. I 
suppose that when doing a Q & D (Quick and Dirty) regulation on a PSO 
(Piano Shaped Object) with bobbling hammers and a mile keydip one might 
crank the drop down to keep the bobbling hammers away from the strings 
if one does not want to spend the time dealing with such niceties as 
proper aftertouch and rep lever pinning. But I really don't recommend 
this...

By the way, that line about drop distance being dependent on "how close 
you live to the piano"  should be attributed to its rightful author - 
Susan Kline of Oregon, who posted it during a discussion of the 
advisability of "hair trigger" regulations in home pianos. It's a great 
line, and it has become quite widespread...

Israel Stein


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