With all the discussion about 78 RPM turntables, does anyone know why
the RPM rates for the various record sizes were chosen?  For example,
does 78 RPM represent the best compromise at the time using the
available technology to achieve reasonable frequency response, or was
there another reason?

The same question applies for 45 RPM and 33-1/3 RPM.  Secondary
question: why the big spindle hole in the 45's instead of the same size
as the 78's and 33-1/3's?  Was it marketing or were there technology
issues that drove the design choices?

Richard Brandle

 [ I think RCA chose the large center hole so that a stack of discs
 [ could be supported using only the center spindle, therefore a more
 [ reliable record changing mechanism.  The goal was to improve the
 [ whole technology of the (nominally 3-minute) phonograph disc system.
 [ -- Robbie