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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
halcro's avatar
halcro
2,664 posts
 
Dear Swampwalker,
Please look HERE
lewm
13,300 posts
 
Dear Swampy, Halcro may be trying to tell you that we have covered the territory of your query, and "we" tend to agree with you, I think. I certainly do.
in_shore's avatar
in_shore
596 posts
 
Halcro Good work and thank you for your time spent on this.

I know that I am pitch sensitive and I believe it is most important perceptual feature in music.
Which is why I have never been satisfied with any of the belt drive turntables that I have owned so far.
atmasphere's avatar
atmasphere
11,953 posts
 
But in general, a good direct-drive motor WiLL have more torque than a good belt-drive motor.

As a generalization that is incorrect. A DD drive has to spin at 33 1/3 rpm. In a belt drive, there is a tremendus amplification of torque of the motor afforded by the ratio between the motor diameter and that of the platter diameter. Add to that the possibility of a powerful motor, and you see what I mean. By no means is this an excuse to use a weenie little motor to drive a 20 pound platter though.

As an example the Atma-Sphere 208 is up to speed in 1/2 a revolution- not that far off from the SP-10, which gets there in 1/4 of a turn. Most of the delay on the 208 is the belt slipping on the motor, as it is up to speed before you can take your finger off of the 'On' button.

However the platter of the SP-10 is about triple that of the 208 in weight. The SP-10 in particular is an exceptional turntable, and thoroughly disproves that old idea that DD was somehow flawed. But it is the exception rather than the rule regarding DD, IOW the SP-10 motor has more torque than most any other motor in use in turntables. I am sure that is a large part of why it works so well. A robust drive is really important in a good turntable!
swampwalker's avatar
swampwalker
5,138 posts
 
A robust drive is really important in a good turntable!
Very interesting comment. Jibes with the idea that the quality of the power supply is v. impt in amp and pre-amps as well. Not sure why, maybe its just a co-incidence? But after having my pre-amp's power supply upgraded, I am more convinced than ever that it is true for the electronics!
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