Setting Pitch

[Dave Nereson]

----- Original Message ----- 
From: "Robert Scott" <robert.scott@tunelab-world.com>
To: <pianotech@ptg.org>
Sent: Sunday, July 18, 2004 10:10 AM
Subject: Re: Setting Pitch


> David Nereson wrote:
>
> > Metal tuning forks are very stable over the years,
> > even decades, as long as they're not dropped or otherwise mistreated.
> > Electronic devices, however, can drift -- capacitors and resistors don't
> > retain their precise values forever;  capacitors can start to leak or
> > transistors can start to "drift" in their characteristics, and extremes
> > of
> > temperature can affect them.  That's why they require re-calibration
> > periodically.
>
> Electronic tuning devices do not rely very much on the stability of
> capacitors and resistors for their pitch stability.  They use a quartz
> crystal, which is much more stable than a tuning fork for both short term
> temperature variations and long term aging variations.  ETDs do not need
> periodic re-calibration under normal circumstances.
>
> Robert Scott
> Real-Time Specialties (TuneLab)
> _______________________________________________
> pianotech list info: https://www.moypiano.com/resources/#archives
>
    OK.  Sorry.  Guess I was thinking of older equipment like audio amps
that get noisy with age because of old or leaky components (this is what a
long-time electronics guy told me).  I suppose ETDs are quite stable, but
some electronic components can change their characteristics with extreme
temperature variations, like overheating, which is common to things like
power supplies and amplifiers.
    But I would still maintain that a tuning fork that is never dropped or
banged too hard should retain its pitch.  Besides variation with
temperature, what would make it change pitch?    --  David Nereson, RPT