double striking hammers

[John Musselwhite]

>We have a C-7 (Yamaha) that double strikes on certain pianissimo
...
>we try hard.  It is well regulated.  The latest thing I tried was to
>increase let-off to 1/8th of an inch.  I am thinking that the jack

I've run into the same thing and the only advice I can give is to make sure
you DO have 1/8" letoff and a further 1/8" drop, that the rep springs aren't
too tight and the rep lever is not too loose in the bushings. I would think
if the letoff was too close because it was checked with literally no blow
that there might be enough flex in the shank to cause problems once all the
parts get moving.

On Asian pianos in general I've found that if the specs say to make the
letoff and drop at 1/8" (or whatever the metric equivalent is... fine thing
for a Canadian to say, eh?) for a total of 1/4" then often it MUST be set
that way to work properly. Perhaps the shanks flex more on them?

That being said, I have an S&S D with exactly the same problem (with some
players). The fix was to set letoff and drop at 1/16" each just as the specs
say and to make sure the springs weren't too strong. I might add on this
1967 instrument the tone improved by backing off the letoff/drop as well.

                John

John Musselwhite, RPT               Calgary, Alberta Canada
musselj@cadvision.com              sysop@67.cambo.cuug.ab.ca