"Serge Auckland" wrote in message
...
I recently was given about 600 LPs, of varying material. After
eliminating Mrs Mills Piano Party, Suddenly it's Des O'Connor and The
Hits from the shows played on the Kazoo, I have got about 150 classical
LPs in pretty good condition, even though many go back to the early 60s
and a few to the late 50s.

Some of the RCA discs have the Dynagroove system, which, if I remember
correctly, involved pre-distorting the recording to compensate for the
tracing distortion of a 0.7thou spherical stylus. The system wasn't
taken up by other labels, and anyway, 0.5thou sphericals soon were
available as were ellipticals, rendering the system unnecessary.

Playing the LPs with my cartridges, all of which have line-contact
styli, I would have expected that the treble would have sounded more
distorted than a non-Dynagroove LP, but in fact, these seem to be
quite clean at the top, certainly no worse than others.

Does anyone know the detail of how the Dynagroove system worked, and
what effect it would have on being played with a modern non-spherical
stylus.


I'm sure I've got a disc or two that claim to be 'Dynagroove System' or
somesuch, but I can't say I've noticed anything out of the ordinary.
Wakipaedia has this on it:

http://en.wikipedia.org/wiki/Dynagroove