Post by BOZCHANNEL 2 WAS RECORDED BY THE GRAY AUDOGRAPH.
The Gray Audograph used a AC motor. To control the speed of an AC motor
you control the frequency of the input power. It was used in both Europe
and the US. In the US the main power supply is 60Hz. In Europe it is 50
Hz. The capacity of the same disc's when used in Europe was about 2
minutes longer than when used in the US, because the machine ran slower in
Europe.
As the machine aged, it also slowed down, owing to the aging of its
components. The Audograph used by the Dallas Police Department was
probably 10 years old and could have been 13 years old at the time of the
assassination. How do we know this? Because the DPD purchased the
Audograph in the "early 1950's". We are not talking integrated circuits.
Here is a picture of the electronics for the Gray Audograph.
https://photos.app.goo.gl/Tw6jJN7jE7C2AWjQ2