[pianotech] GH-1s

[Ron Nossaman]

On 12/17/2012 8:40 PM, Jim Ialeggio wrote:
> David wrote:
> <Lowering the tension in the bass artificially because the piano is
> smaller will just create something that is unpleasant or out of balance,
> in my opinion. Avoiding gnarliness can result is a bass that sounds like
> a rubber band.
>
> I agree, that while we start with a string scale, the design of the the
> whole system determines whether the "string scale" works or not. Its not
> just a string scale or a belly structure or an action setup, or a hammer
> choice but a whole interdependent system.
>
> But my question to you regarding the above quote would be, how do you
> know the alternative to gnarliness is rubberband-iness.  There are no
> modern pianos that I know of, save my experiments,  which have pushed
> the lower limits of the low tension bass scale to see what would happen.
> Mainly I think because the tensile strength of modern wire didn't allow
> the experiment.  How do you know the alternative is rubberband-iness???

you and I have discussed this, so you know I can't give you a "this 
number makes this sound" map. But I do have some criteria for 
establishing the low bass. Using that S&S M mentioned earlier, I have an 
original scale showing A-0 at 1250mm long, with a 0.063" core, a 0.189" 
wrap diameter (single wrapped), at 189lbs tension and 19% break on a 
cantilevered bridge. I find a whole lot wrong with this that can be 
improved. Since the 19% break doesn't work all that swimmingly in either 
the GH-1 or the S&S B in the low tenor, I don't really want it that low 
at A-0 either. First, I eliminate the bridge cantilever and move the 
bridge location (new bridge) forward to get a longer back scale. This 
adds flexibility and allows higher amplitude of movement - patience, 
there's more. On this new bridge location, I measured a 1192mm revised 
length, which then got a 0.051" core, replacing the rebar of the 
original with something that will actually flex, and a 257mm double 
outer wrap, double for added flexibility, for a tension of 227 lbs and a 
34% break. That's better. The soundboard tail also got a bass float, 
cutting the soundboard loose from the rim centered along the panel grain 
at the low end of the bass bridge for yet more flexibility and 
amplitude. You might get the impression I want the low bass bridge to 
MOVE when the low bass is played. This would be an accurate impression. 
I use an 8mm panel all over for pianos this size, with no tapering 
anywhere. I haven't really found it to be necessary by my criteria and 
with my layouts, string scales, and rib scales. I've also never doped a 
low bass in one of these, though I hear from others that they do. Again, 
I never found it to be necessary, nor is the bass overly loud. Power 
(without noise) is there if you want it, but the pianissimo is clear 
quiet, and clean, and can be voiced down if you like without losing it. 
My overall bass tensions are typically somewhat lower than the original, 
but A-0 is typically built to get the break% up into the 30s.

High basses typically BOOM, as low tenors quack like ducks. I try to 
angle bass bridges out with foot extensions to get the high end closer 
to the rim for a little added stiffness to minimize the boom. The low 
tenor transition is at some angle to the long bridge because making it 
like an extension of the tenor gets it too close to the low end of the 
bass bridge, making the low bass stiffer than I want it, and the longer 
low tenor strings require too small a wrap for my liking. I also move 
the agraffes in the transition back to correct the strike ratio that I 
screwed up by shortening the low tenor lengths to install the 
transition. Typically, with very little voicing required, I can get 
those two transitions aurally invisible, or very nearly so, and worlds 
better than the original.

Now, what else?
Ron N