What's your SDS setting?

Mark,

Yes, the Classic has a stepped-up pulley with three possible positions for 33 and 45 rpm each. The latest models come with a different, wider pulley, and I'm not entirely sure with how many positions, but I'd think it'd be the same deal.

The different pulley positions are useful if you don't use the SDS as apparently there are differences in speed (Fremer found the top position to be most accurate for 33 rpm when he was reviewing the Classic III). With the SDS however, you just use one pulley position as you can make way more accurate speed adjustments through the SDS. Also, you want to use the same pulley position when setting the speed from 33 to 45; the SDS automatically adjusts to the higher speed (you still have to make small adjustments to dial it in perfectly initially), and if you switch the pulley position the speed would be way off.

Oddly enough 58.79 Hz gives me perfect speed with a KAB strobe on my TNT. Weird huh?

When VPI manufactures or sources components from their suppliers, they are spec’d to an acceptable tolerance. Variations in motor, pulley, belt and platter tolerance will result in slight speed variations.

For 2 tables to have the exact same speed without a SDS, both will need to have identical motor rotation, identical pulley diameter, identical belt tolerance with no stretch, and identical platter diameter without any deviations between the 2 samples.

If there is any deviation in tolerances between the 2 tables, they will have different speeds. It is simple physics. The SDS is designed to fine tune a table and to factor out the fact that each table will not have the exact same manufactured tolerances and be feed with a stable 60 Hz power.

If you believe that a lower frequency sounds better, then put on a motor pulley designed for a 11 ½ inch VPI platter and adjust your SDS to the low 50 HZ.

Wntrmute2
Oddly enough 58.79 Hz gives me perfect speed with a KAB
strobe on my TNT. Weird huh?

My old TNT was very close to this setting as well. And
around 64.50 if I remember with silk thread, dental floss
and fishing line. FWIW - if bypassing the belts, Mike at VPI
had a preference for fishing line when I talked to him a
while back. He said look for the Spider braided version.

Actusreus
but it seems to me that since all VPI tables are fully
functional and quite accurate without the SDS

Actusreus, the TNT was designed to work with a speed
controller. Otherwise it runs way to fast. So as a caution
anyone looking to purchase one used should ensure it is
being sold with a functional SDS. Otherwise budget an extra
$900 – 1000 into the purchase. I would not touch the old
PLC controller. Unless you like to rip out your hair.

Cheers

43°0′40″N
78°38′5″W