Tuning a Kawai Grand RX-2

[Fenton Murray]

The piano I'm having a problem with is a 30 yr old Kawai KG-6C or something 
like it. The problem is similar to Al's thread with only the capo sections 
going out, the agraffe sections are rock solid. Three years ago I re-strung 
both capo sections because of false beats and hoping to help the tuning 
stability. At that time I redressed the capos. The piano was much better, 
with frequent tuning for a while but now has slipped back to it's old 
problem. The piano is in a church and gets heavy use but I think the treble 
sections would need to be tuned twice a week to be stable. I may try that.
Fenton
----- Original Message ----- 
From: "Ron Nossaman" <rnossaman at cox.net>
To: "Pianotech List" <pianotech at ptg.org>
Sent: Saturday, July 12, 2008 11:07 AM
Subject: Re: Tuning a Kawai Grand RX-2


>
>> I'm interested in this thread because I've a similar problem with a 
>> Kawai.
>> Ron,
>> Backscale, sounds reasonable then to stretch and settle the back 
>> scale.?.?
>> Fenton
>
> I don't think so, because the back scale isn't unstretched or unsettled. 
> The line of thought that, in thirty years, has gotten me to this point is 
> this: When the slightest movement of tuning pin by the hammer results in a 
> detectable change in speaking length pitch, and you can easily control the 
> thing, by speaking length pitch and the feel of what's happening in the 
> hammer, and it survives whatever test blow(s) you're fondest of, your 
> problem isn't from the speaking length bridge pin forward. Why? Because 
> you've moved all that, felt it move, heard the results, and being a 
> competent tech with some years' experience, left it in a stable state. 
> What you don't know, and what no amount of magic hammer technique will 
> EVER tell you is the condition of the segments behind the front bridge pin 
> row. You have no way of ascertaining what's waiting for you back there - 
> NONE. You can't feel what's there because you likely haven't made a big 
> enough tension difference during tuning (unless you raised pitch 
> substantially), to overcome the bridge pin friction points and detect the 
> resulting movement. So you basically take what you can get. If you pound 
> too hard during tuning, you can pull some of that back scale through the 
> bridge, leaving the rear segment tensions higher than what you settle the 
> front lengths to by listening to the speaking length. Later, with the tiny 
> movements of temperature and later humidity changes, the tensions will 
> tend to equalize some and the speaking length will go sharp. If the back 
> lengths are of lower tension when you tune it (which you can't know) and 
> you can't manage to pull the string through the bridge with test blows, 
> the speaking length pitch will drop later either by those same temperature 
> changes, or by someone hitting it harder in play than you did tuning it. 
> Where do you suppose the pitch drop comes from when a test blow knocks the 
> tuning out? Being a competent tuner, you left the front segments in good 
> shape, so what happened. The back scale happened. The back lengths are a 
> real crap shoot. Sure, you can push on them massage them, stretch them, 
> yell at them, or anything else you want to try to drive out the evil 
> spirits, but the bottom line is that when you have no way to directly 
> compare the front and back length tensions, you have no way of know if 
> you're improving the situation or making it worse. The only way I know of 
> to produce a dependably stable tuning is to tune often, on a piano that is 
> under rigidly controlled temperature and humidity conditions, and move 
> things as little as possible doing it.
>
> I'm, on the way out the door, so won't take the time to proof this for 
> psychotic sentence structure or strange inside out disconnections. If 
> there are any, sorry.
>
> That's essentially it.
> Ron N
>
>