[pianotech] Downbearing on RC&S designs was RE: Steingraeber

Ron Nossaman rnossaman at cox.net
Wed Jul 7 23:20:33 MDT 2010


jimialeggio wrote:
> 
>>
>>> That could be (backscale) the issue.
> 
> Could you guys define "short" backscale?

It depends on where in the scale it is. The low bass needs 
more back scale length than the high treble because the board 
has to move with so much more amplitude to produce anything 
remotely resembling a fundamental. If I can get over 120mm in 
the bass, I'm a happy guy. If not, as much as I can manage. 
The high treble 50mm is enough. It's not an absolute number 
sort of thing. You usually have to settle for what you can 
get, but try to get what you can. I've seen a piano with a 
treble back scale of about 8mm. The bridge pins stuck up out 
of the bridge taller than that. I have no idea what sort of 
bearing was there. I'm not sure how I'd try to measure it.
Ron N


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