Setting Pitch

[Robert Scott]

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)