bobbling hammers on Yamaha upright (P-22)

[Richard Brekne]

In my experience, bobbling hammers that <<wont regulate away>> in 
uprights are almost exclusively either because of jack springs being too 
strong or the stop rail being too close in.... mostly the former.  The 
problem nearly always equates to the hammer butt bouncing off the top of 
the jack... ergo the jack isnt getting out far enough to begin with, 
and/or cant get easily pushed away by the butt as it follows the hammers 
rebound off the strings.

The jack spring simply doesnt need to be any stronger then is neccessary 
to get the jack quickly back into fireing position with usual centerpin 
tolerances. Any stronger and it becomes an impediment to good touch.

Cheers
RicB

Aps322@aol.com wrote:

> I have noticed for many years that many yamaha verticals, even brand 
> new ones, have bobbling hammers, around the bass break, both sides of 
> it, when played softly. Yamahas are certainly great pianos in all 
> other respects, but for some reason this is a pervasive problem. It is 
> quite consistent, and not a consistent issue on any other brand that I 
> have come across in 20 years of servicing pianos.
>
> I am curious if anyone else has noticed this?
>
> Yamaha tech people told me, a long time ago, to weaken the damper 
> springs. That's alot of dampers to weaken! I wonder if there other 
> reasons for this on specifically new yamahas? (could be lots of 
> reasons on older pianos)
>
> Peter
> RPT