post pitch-raise creep?

[Alan Barnard]

What ETD are you using? Don't they all have a built in PR program nowadays?

I'm using Tunelab and find that the machine-calculated overpulls put pitch right on the money, amazingly so.

In the olden days, I was using a Yamaha PT-100 II which didn't have the calculated overpulls. They recommended pulling it up (or down as the case may be, and I THINK I remember these fractions right, others may need to correct me) of 1/3 the difference in the bass, 1/5 the difference in the low tenor (about 6 unisons), and 1/4 the difference in the upper tenor and treble. So if the bass is averaging 18 cents flat, for example, you'd tune it 6 cents sharp.

Anyway, my point is that that method used to be very accurate, also.

Alan Barnard
Salem, Missouri


----- Original Message ----- 
From: David Nereson 
To: List Pianotech
Sent: 07/07/2006 2:28:36 AM 
Subject: post pitch-raise creep?


    I do many many many pitch raises -- almost every piano I tune, for the last 27 years.  (Almost everybody lets them go too long.)
    I've found that the ideal average overpull is halfway between 1/3 to 1/2 the amount sharp as it was flat.  In other words, a 41% overpull of the amount it was flat.  For an easy-figuring example, say the piano is 18 cents flat.  Half of that is 9 cents and a third of that is 6 cents.  Half-way between 6 and 9 is 7.5, so I pull it 7.5 cents sharp, and almost invariably A4 ends up right on 440 Hz, or very close.  
    However, if the piano is a half-step flat, I don't pull it 41 cents sharp.  That would be too much.  There's some degree of flatness where the usually-ideal 41% overpull has to taper off.  For a half-step pitch raise, I usually overpull so that A4 is beating about 5 beats sharp.  That's approximately 20 cents, I believe.  Sometimes more is required, sometimes less.  It varies.  That's here in Denver -- probably different elsewhere.  
    But what I often experience is:  even though after the pitch raise, A4 is at 440; after I've gone through the fine tuning and      pulled in unisons, when I go back to do the final check and touch up anything that has slipped, I find that the whole middle section is sharp!  Why?
    --David Nereson, RPT
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