15 Cents Flat

[Robert Scott]

Sy Zabrocki wrote:

>I was clicking through some piano tuner web pages. One page linked to a
>A-440 WAV File which would play a sound at A-440.  It just didn't sound
>right so I checked it with my Accu-Tuner. IT WAS 15 CENTS FLAT!!!
>Maybe my tired old sound card just couldn't handle A-440.

Sy, you are right to suspect your sound card.  The wav file that you
downloaded may very well have been right on A-440 if played back on a
sound card with a precisely correct crystal frequency.  Unfortunately the 
makers of sound cards do not attempt to control their crystals accurately
enough for piano tuning applications.  That is why Dean and I must supply
calibration procedures for the RCT and TuneLab.  Once the sound card
error has been compensated for, the error is very constant, and will
probably not need recalibration for the life of the sound card.  But
the regular Windows WAV playback functions do not provide for any
calibration.  Actually, 15 cents is quite good.  I've seen sound cards
that were off by more than that.

-Robert Scott
 Real-Time Specialties