[pianotech] SSM evaluation

[Ron Nossaman]

PAULREVENKOJONES at aol.com wrote:
> In balance, I agree, but in reality, it makes no difference. The 
> discovery of the overborne backscale was the primary problem. The 
> lessening of the back bearing and the net lessening of overall bearing 
> are in this instance just differing perspectives on the bearing 
> condition as a whole. The front bearing condition may marginally change 
> with the change in back bearing and both components need to be watched 
> as changes are made. Has this been your experience?

My experience has been that, short of rather dramatic negative 
front bearing, the balance of bearing front and back has very 
little affect on tone. Net bearing changes are by far the more 
significant tonally. I try to come close to balancing front 
and back bearing when I set a piano up, just as a place to 
start, but I've found plenty of pianos with anywhere from 
slightly negative, to excessive bearing either front or rear 
that didn't seem to adversely affect tone. In every case I can 
remember where I've checked bearing and crown in response to 
tonal complaints, net bearing against crown answered the 
necessary questions.

No, I just remembered one. A newish grand, under warranty, 
nasty WHANG in the high tenor, next to the plate strut, on a 
hard blow. Local techs baffled, so they gave me a shot. After 
whanging around for a while, I found slight positive crown 
there, and slight positive net bearing. The problem was a 
combination of front bridge pins drilled too near vertical, 
only about a 5° offset, and slightly negative front bearing. 
The strike pulse was making the string move on the bridge pin. 
Had the pin been at a 15° or more angle with a 10° or so 
offset, it wouldn't have been noticeable, as I've seen these 
bearing conditions in pianos that didn't make noises.

Ron N