post pitch-raise creep?

[David Nereson]

  -----Original Message-----
  From: pianotech-bounces at ptg.org
[mailto:pianotech-bounces at ptg.org]On Behalf Of Farrell
  Sent: Friday, July 07, 2006 6:04 AM
  To: Pianotech List
  Subject: Re: post pitch-raise creep?


  Doesn't sound right. When doing the PR, are you using an ETD?

  Only to measure the amount it's flat and to tune the initial
A4 sharp by 40% of the amount it was flat.

   Unisons as you go?

  No.  All the middle strings, then all the unisons, then the
bass, which sometimes needs very little raising.  I can do it
fastest that way.

   41% is very large percentage for overpull. Most ETDs
recommend between 20% and 35%, depending on the area of the
scale.

  And I say that's usually not enough.  If it's 20 cents flat,
half of that (50%) is 10 cents, and a third of that (33%) is
about 7 cents.  So I pull A4 halfway in between those numbers,
or about 8 1/2 cents sharp, which is roughly 40% of the amount
it was flat.  (I notice in other posts, some tuners use up to
37% in some areas of the piano.)  Then I do the pitch raise, all
the octaves, then all the unisons.  Almost every time, A4 ends
up right on 440, and the rest of the rough tuning is very close.
So I go ahead and do the tuning (fine tuning).  It's after I'm
done with the fine tuning, when I go back to check for anything
that has slipped, that I find the middle of the piano and the
low tenor has crept sharp by a beat or even two.

  Immediately after the PR, do you check the middle section for
pitch?

  Yes, and it's almost always right on 440, so I proceed with
the fine tuning.  It's after the fine tuning that I find it has
crept sharp in the middle.  The low tenor is also quite sharp,
so now I leave that area a bit flat during the pitch raise.  And
during the tuning (fine tuning), the SAT always seems to "tune"
the bass too flat, even if the bass didn't need a pitch raise.

   If it is at or near target, there is no reason for it to
creek up.

  One wouldn't think so.

   How large a pitch gain are you talking about?

  Anywhere from just a few beats flat to a half-step flat.

   I've never noticed such a phenomena.

  That's "phenomenon."  Phenomena is plural.  (Just for your own
info.)
  --David Nereson, RPT

  Terry Farrell

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