[pianotech] PR follow up

[David Love]

What else do you think accounts?  Soundboard compression?  When a string
breaks and the entire section goes out of tune is it the loss of a few
pounds downward pressure on the bridge?  If so, then simply pressing down on
the bridge should put the piano noticeably out of tune.  But it doesn't.
Additionally, when you destring the bass on a piano where the bearing on the
bass bridge is pretty much zero, why does the tenor change so much in pitch?
On the other side, a single string breaking makes a change of over 300 lbs
of tension on the plate.  The removal of the bass strings results in a net
change of 7000 -8000 lbs.  I would assert that it is primarily (if not
exclusively) the change in the way the plate flexes that is responsible for
the change in pitch.  

 

The stability after restringing has other issues including the straightening
of the wire at the terminations, the tightening of the coils, loops and
beckets, etc..  This is not really an issue on a piano that has already
achieved that type of stability.  The net loss the comes about during a
pitch raise is due primarily to progressively added contractual tension to
the plate.  Other factors that affect stability are the ability for the
technician to stabilize the various string segments as Ron outlined in a
previous post, plus getting to a reasonable starting point from which to
start the fine tuning process.  

 

David Love

www.davidlovepianos.com

 

From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of PAULREVENKOJONES at aol.com
Sent: Friday, August 28, 2009 8:00 PM
To: pianotech at ptg.org
Subject: Re: [pianotech] PR follow up

 

Some maybe. But you've tuned a piano immediately after stringing, e.g. and
there are all kinds of things happening that affect stability. A radical
pitch alteration, in smaller part, does much the same thing, don't you
think?

 

P

 

In a message dated 8/28/2009 9:58:14 P.M. Central Daylight Time,
davidlovepianos at comcast.net writes:

What about plate flex.  

 

David Love

www.davidlovepianos.com

 

From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of wimblees at aol.com
Sent: Friday, August 28, 2009 6:33 PM
To: pianotech at ptg.org
Subject: Re: [pianotech] PR follow up

 

The most general phrases that seems appropriate to start the discussion
would be soundboard (de- and re-)compression over both bridges, and the
string segmentation tension differentials. Seems enough. :-)

 

Cheers,

 

Paul

 

 

Paul

 

When I first started tuning 32 years ago, my dad told me that the reason a
piano goes flat after a pitch raise is because strings have memory and want
to "go back where they came from". Then I learned that the reason a piano
goes flat after a pitch raise is because the soundboard compresses. Then
someone told me that the bridge rolls during a pitch raise. 

 

But my question are, how much memory does a string have, how long does it
take for the soundboard to compress, and when does the bridge stop rolling? 

 

I have done some research on this, and my contention is that old strings do
not have memory, (a new one stretches, but not because of memory), the
soundboard stops compressing and the bridge stops rolling as soon as the
strings have been pulled up to pitch. After that, it's just matter of
stabilizing the tuning, just as you would during a "normal" tuning. Is this
the physics you're talking about?

 

Have you done research on this? Have you taken an badly out of tune piano,
lets say 50 cents low, and done a pitch raise and fine tuning in one
setting, then checked it a day later, a week later, a month later? Providing
the environment in which the piano is sitting is stable, what kind of
results did you get? 

 

I ddi this about 10 years ago, and tracked my results, which showed the
pitch didn't alter. And I just did this on a 50 year old Everret Studio
sitting in my office. When it came in two weeks ago, it was 45 cents flat. I
pitch raised and fine tuned it. I just now played it, and it's a little
sour, but then it's sitting in front of an open window and partly opened
patio door. But in general it sounds pretty good.  

 

Wim



-----Original Message-----
From: PAULREVENKOJONES at aol.com
To: pianotech at ptg.org
Sent: Fri, Aug 28, 2009 2:01 pm
Subject: Re: [pianotech] PR follow up

 

In a message dated 8/28/2009 6:36:33 P.M. Central Daylight Time,
davidlovepianos at comcast.net writes:

Please explain the physics as you know it that would account for this.

 


  _____  


 

  _____  

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://ptg.org/pipermail/pianotech.php/attachments/20090828/b8867c21/attachment-0001.htm>