75 RPM is 75 RPM irrespective of the line frequency. 75 also happens to be
a speed attainable “on the nose” on either 50 Hz with 80 bands on the
strobe disc, or 60 Hz with 96 bands.
Kurt Nauck has a legacy page for a DOS based strobe generator, but it
happens to have a valuable table for calculating how many bands are needed
for a given speed reading at a particular frequency. You can also see the
equivalent variations between the two, with what we know as 78 being 77.92
at 50 Hz but 78.26 at 60 Hz.
On Sun, 20 Jan 2019 at 15:55, Steve Smolian <[log in to unmask]> wrote:
> Is there a formula to covert a specified playing speed at 50 cycles to the
> playing speed at 60 cycles? Example: 75 rpm at 50 cycles, what speed at 60
> Steve Smolian