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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
thuchan
1,009 posts
 
The Allnic SpeedNic works pretty well. I have put two images on my page (last two images when scrolling down)

best @ fun only
halcro's avatar
halcro
2,664 posts
 
My KAB strobe works pretty well also.
With it....the Raven keeps perfect speed.
If you want to be happy.....use a strobe.
If you want the truth.....use the Timeline :^)
dertonarm
1,042 posts
 
Halcro put it in the most precisely manner. The Timeline may be frustrating in it's accuracy, but then it is not the Timeline's fault. Very interesting too, to watch the laser beam over the whole record side ( record it with a camera - it is too boring looking there all the time).
On many turntables one may notice shifting back and forth and correction with controlled motors during heavily modulated passages.
A nice lesson in stylus drag and it's not linear nature.
tonywinsc
583 posts
 
I filed the hole in my stereo test record. I improved the runout a bit. According to the iPhone app, I now have the raw Wow down to +/-0.16%. The filtered didn't change, -0.01%/+0.02%. The total spread within the published specs for my tt. With a little more filing of the center hole and more work/patient effort to center the record on the platter, I could improve the raw values even more. I have a feeling that I will be bringing a dial indicator home from the machine shop at work to measure record runout with extreme precision. I will likely be filing the holes on my records now to perfectly center them. My neurosis is ratcheting up a level, I think.
Anyway, this app is nice, you can play the test records 3150Hz track at 45rpm and this app will detect the higher frequency and tracks the speed at 45rpm automatically. I must agree having seen it live with this app. Having the motor via a belt separate from the floating chassis/platter is a deficit. The slightest vibration/movement of the floating chassis causes a speed error. It is a small error, but still there.
thuchan
1,009 posts
 
Dear Halcro, you´re right the Timeline is perfect. The Allinic provides the advantage you may use it as a fixed installation and you do not need to hit the mark at the wall which is a bit of trial and error moving the Timeline forth and back - but of course after a while it works brilliantly.

You have two turntables and only one strobe - this looks like an imbalance :-)

best @ fun only
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