[ARSCLIST] Power line frequency and phonograph record speed...

[Graham Newton <gn@xxxxxxxxxxxxxxxxxxxxx>]

As the AC power supply evolved, there were many instances of recordings that
were made at the wrong speed, simply because the power line frequency was
off the 60 cycles per second, or Hertz (Hz) as we now call it.

Once the power grid came into being, every power company had to tow the
60 Hz line and make sure it was dead on where it was supposed to be.

Now, in the earlier times, many of the recordings had power line hum recorded
along with the music and this can be used as a marker to determine what the
correct speed of the record SHOULD be, in order to correctly play and sound
the way it was heard in the studio the day the recording was made.

Generally, this idea works well, but like anything else, there are variations
that could make the marker wrong, and tying the marker to 60 Hz would make
the music sound wrong and at the wrong pitch, or off key.

Recordings made with portable equipment tied to a local generator could
easily have been a few Hz off the 60 Hz that the motors were designed to
operate at, resulting in a faster speed if over 60 Hz and a slower speed
if below 60 Hz.  Clearly, placing the hum at 60 Hz doesn't work in these
cases and the adjustment has to be made for the music to play in the
correct key and not somewhere between notes!


Here's where some knowledge of the power system in various parts of the
USA and Canada would be useful.

Does any one have accurate knowledge of areas of the country that WERE NOT
operating at 60 Hz power line frequency?

It is known that parts of the city of Toronto operated on 25 Hz until around
1954 when it was changed to conform to the 60 Hz standard.




... Graham Newton

--
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