Direct drive vs belt vs rim vs idler arm

Tony,

I'm not totally sure what you're trying to say. There is no problem or error with the pencil marks. You make one mark on the wall at the beginning of the record and you make another mark on the wall at the end of the record and measure between them. If the two marks are 3.25" apart after 20 minutes and your turntable's spindle is 31" from the wall, your total speed error over those 20 minutes is 0.0025%.

I haven't even tried aftermarket power cords. We both use Thiels, solid state power amps, and ARC tube preamps. Can you recommend a "cheap" aftermarket power cord for one of my components that will make me think I'm even more abnormal? Sorry for the diversion. Back to speed stability...

Off the deep end will be when someone here says that a power cord made a difference in turntable speed accuracy. Which is both on- and off-topic.

Hi Ketchup,
I'm not sure how else to say it. If you have a timeline or someone who has a timeline could do that test- measure after 20 minutes and then do a 2 hour measurement. See if the per rotation error calculates out the same or not. That would dispel my notion about too few data points.
I have a MIT powercord on my CD player. It made a difference; but I would not call it a cheap powercord. btw- seems like I saw a thread somewhere once that claimed a better powercord on their VPI controller, maybe, made a difference?

One of the downsides of having a turntable that uses an oscillator preamplifier and power amplifier to drive the motor means I have to run 2 MIT power cables/MIT Magnum MA interconnect/custom MIT speaker cable just to run the turntable. It was worse when I drove the TT with monoblocks.

I noticed that my LPs sounded cleaner after I upgraded the power cord to my Loricraft PRC 4. Just kidding. It's a mad world.

All of this serious writing about turntable speed and measuring devices had me wanting to contribute some levity to the discussion. Sorry.

Back to the topic and hand and thanks to those of you who are really thinking about this and sharing your results.