In a message dated 8/28/2009 10:28:20 P.M. Central Daylight Time, davidlovepianos at comcast.net writes: 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. No argument. It was merely an analogy which is demonstrably poor, but has elements of analog. 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. All of which is true. What is still a question is what you call the aim and the result. If the aim is a "fine" tuning after a radical pitch alteration, I suppose degrees of fine can be achieved, indeed, I have done so. But not tunings that I would ever tell a client are "fine", rather adequate to the circumstance. P 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_ (mailto: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/20090828/39dd5b26/attachment.htm>
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