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Speed Control

I've had a Classic 3 for about 1 1/2 years. When I first bought it, I used the KAB strobe to determine it was running spot on 33 1/3 RPM.

Recently I added an SDS. At 60hz it was running fast. With the SDS adjusted to 59.81hz, it runs at 33 1/3 RPM. Any ideas on the impact of -.19hz difference in speed?

At the correct speed it has a much wider soundstage. It sounds like it is playing in a room much larger than my actual room. I have a lot of acoustical room treatment (absorption and diffusion) so that my contribute to the difference.

My system is Benz LP (re-tipped) > Classic 3 > Sutherland Hubble > VK32SE > VK75SE > Eggleston Rosa. I use the record clamp and ring.
bigby
jmcgrogan2's avatar
jmcgrogan2
6,346 posts
 
06-09-14: Brf
A SDS is a great unit for equalizing the variances in pulley, platter and belt machine tolerances.

Not to mention variances in household voltages too.

I thought the speed was supposed to be slightly faster than 33 1/3 when setting the speed using the KAB though, to offset the slight drag from the stylus. Not much for sure, but just so the dots appear to be ever so slightly moving fast under no load so that it would be spot on under load. Is this incorrect or misinformation?

I have tried it both ways and can't really say that I hear much of a difference. Nothing like the differences I hear in overhang, VTA, VTF or azimuth. I'm surprised to read that you are hearing that much of a difference.
brf
1,715 posts
 
AC motors are sync to the line frequency not the voltage. Line frequency in the US is highly regulated and controlled and does not deviate as much as line voltage.

If you use the Platter Speed test record and associated mobile app, you can set you table's speed compensated for stylus drag.
rodman99999
6,121 posts
 
Interesting points, under subheading #5, here: (http://tf.nist.gov/timefreq/general/pdf/2125.pdf) How they accomplish it? A decent analogy, in the third post, here: (http://boards.straightdope.com/sdmb/showthread.php?t=446800)
jmcgrogan2's avatar
jmcgrogan2
6,346 posts
 
Thanks for the clarification and the tip on Platter Speed Brf!
riffer
362 posts
 
The KAB is smaller than a 12" LP, so you can just run the test with the KAB on top of a playing LP.
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