mem@sii.UUCP (Mark Mallett) (02/06/84)
b
Greetings.
I spent some time this weekend looking at turntables. An interesting
observation I made- I could not find any "linear tracking" turntable which
sports a pitch control. No salesperson I talked to could explain this (or
even express any interest in it, actually). I theorized that it has to
do with stylus/groove pressure feedback to the tracking motor, but-
is this so? answers to this question, as well as comments regarding
linear/radial tracking in general, are welcome (I've been reading this
group for a long time, and haven't seen too much on this).
Mark Mallett
{ittvax|decvax}!sii!memrentsch@unc.UUCP (Tim Rentsch) (02/07/84)
I own a Revox linear tracking turntable, and it works great. I'm all in favor of linear tracking. And the revox does have variable speed, complete with digital readout (for those that like that sort of ting). One interesting thing -- when varying the sppeed (and you can switch off the variable speed if you want) the speed never seems to be quite as constant as for the "fixed" (33.33 and 45.00) speeds. The speed varies by one, two, or three hundreths of a rev/minute. Why? I don't know. Maybe temperature variation in the setting resistor?! cheers, Tim
spoo@utcsrgv.UUCP (Suk Lee) (02/10/84)
I would suspect that the variable pitch
"feature" was thrown away for two
reasons: I don't think that many
people actually use it, and it was a
"bug" turned into a "feature" that
turned back into a "bug" when quartz
locked oscillators became common in DD
turntables. In the beginning...
direct drive turntables used an
internal oscillator to lock the drive
speed (not necessary with the
synchronous motors typically used in
belt-drive turntables). However, these
oscillators drift with temperature,
which prevented the manufacturers from
factory-setting the speed. So, they
slapped a cheap strobe on the platter,
stuck in a pot in the oscillator
circuit, and hey presto, we now have
a "feature". With the advent of
quartz locked oscillators, it became
difficult to offer a quartz-locked
variable speed feature (most DD's with
quartz-lock turn it off when you turn
on the variable spead "feature"--
Technics being an exception), and I
suspect that manufacturers threw this
"feature" away since they don't need
it anymore.
--
From the pooped paws of:
Suk Lee
..!{decvax,linus,allegra,ihnp4}!utcsrgv!spoo