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Turntable speed accuracy

There is another thread (about the NVS table) which has a subordinate discussion about turntable speed accuracy and different methods of checking. Some suggest using the Timeline laser, others use a strobe disk.

I assume everyone agrees that speed accuracy is of utmost importance. What is the best way to verify results? What is the most speed-accurate drive method? And is speed accuracy really the most important consideration for proper turntable design or are there some compromises with certain drive types that make others still viable?
peterayer
lewm
13,057 posts
 
Dear Dover, I don't. But I am surprised you were even able to perceive (visually) a 2-mm displacement, although I guess over time you could measure a larger distance and then extrapolate backwards to determine 2mm per revolution.
dover
2,243 posts
 
Lewm - I positioned vertically a silver metal marker, about 25mm wide, on the wall - it was quite easy to check the moving distance from the leading edge.
atmasphere's avatar
atmasphere
11,807 posts
 
Dover, it has been sitting for some decades, I suspect.

The trust bearings are interesting. They are a set of polished platforms that reside beneath the platter. The drive shaft comes through the center and has nothing to do with them!
rockitman's avatar
rockitman
417 posts
 
I almost bought the timeline. Glad I didn't. using a Fluke digital multimeter is a more accurate way to set your speed, rather than trying to look at a laser being somewhat stationary on a wall. Use a test record at 1000Hz and connecting the Fluke to the output of the phono stage. For 45 rpm, the same 1000 Hz tone should read 1.35k Hz. The Fluke cost about $125.00.
dgad
782 posts
 
Rockitman,

I have been doing almost the same. Card as test LP 1khz tone through my Prism Orpheus into my MAC Mini. I see it on the screen. You can see the stability of the signal and all. And I can hear the differences as well.
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