[pianotech] Tuning stability problem

[William Truitt]

So Ron:

How much do you charge for a piano massage?

Will Truitt :-)

-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Ron Overs
Sent: Wednesday, September 22, 2010 6:55 PM
To: pianotech at ptg.org
Subject: Re: [pianotech] Tuning stability problem

Hello all,

Low tension in the back scale is very common, and Ron N's description 
of it rings true with me. When a piano hasn't been tuned for while, 
or when it has been tuned recently but there are a number of unisons 
which are more wild than they should be, it is worth giving a couple 
of unisons a rub on the speaking length with a piece of hammer shank 
to see what happens. If there is more than a little pitch change, I 
rub down the whole piano. This really will help tuning stability. A 
quick rub down takes less than 10 minutes. Its well worth it.

It is also worth doing the rub down check with new pianos as well. It 
seems that today more and more pianos are being built, without any 
attempt being made at the factory to rub down the speaking lengths to 
get the back scale tension up. This is very likely placing huge 
lateral forces on the bridges. You may be surprised as the speaking 
length pitch plummets, when you rub down many new pianos, but it will 
significantly improve stability. If there is a huge drop in pitch 
when you do the rub down, there may be benefit in doing a first rub 
down, then a pitch raise followed by a second rub down.

Furthermore, I suspect that there is a small improvement in tone 
following a rub down, but its often hard to distinguish between 
what's real and what's imagined with some aspects of our work. It 
might be that large lateral forces on the bridge have a slight 
limiting effect on the ability of the down-bearing vector force to 
act on the soundboard panel.

Ron O.

>On 9/21/2010 1:36 PM, jimialeggio wrote:
>>
>>>It is, once again, coming from the back scale. That's why pulling it
>>>sharp and pounding it makes it drop again. The string is pulling
>>>through the bridge. There's no way to "read" what the back scale
>>>tensions are during tuning,
>>>
>>>Ron N
>>>
>>Not familiar with this piano...what is the challenging condition in the
>>back scale?... the length?
>
>
>I have no idea. I notice it in Asian pianos, mostly, usually 
>Yamahas. When I get a call to tune a piano that was tuned a week ago 
>by someone I expect to have done a good job, this is what I find. 
>The pitch responds immediately to anything done at the tuning pin. 
>This indicates that there isn't a friction problem between the 
>bridge and the tuning pin, but on a firm blow, the speaking length 
>pitch will drop a couple of beats. Further hard blows won't do it 
>again. This also will happen on a string that hasn't been touched 
>since it was tuned a year ago, so the pin is undisturbed. That isn't 
>"hammer technique". The string is pulling across the bridge. This 
>same thing will happen on the same piano once a year, year after 
>year, so it's not a one time event like settling the coil. A little 
>more friction at the bridge, or a little less, and we wouldn't 
>notice it. It happens in environments where the piano changes pitch 
>significantly with seasonal humidity changes. I don't find it in 
>climate stable pianos, so it's the seasonal movement that's leaving 
>the back scale low in tension at some part of the cycle. If the 
>piano is tuned at that point in the cycle, this happens. At a 
>different point in the cycle on the same piano, it won't.
>
>The only advice I have is to test for it when you tune, by whacking 
>the bejeebers out of a note in the capo section and see if the pitch 
>drops. If not, good. If so, you're going to have to whack everything 
>from about A-4 on up at least once.
>
>Again, there is no hammer technique that will make this not happen. 
>It has to be hit.
>Ron N


-- 
OVERS PIANOS - SYDNEY
    Grand Piano Manufacturers
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