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Stylus-Drag..Fact or Fiction?

Most audiophiles can't seem to believe that a tiny stylus tracking the record groove on a heavy platter could possibly 'slow-down' the rotating speed of a turntable.
I must admit that proving this 'visually' or scientifically has been somewhat difficult until Sutherland brought out the Timeline.
The Timeline sits over the spindle of the rotating disc and flashes a laser signal at precisely the correct timing for either 33.33rpm or 45rpm.
By projecting these 'flashes' onto a nearby wall (with a marker attached)....one can visualise in real-time, whether the platter is 'speed-perfect' (hitting the mark at every revolution), losing speed (moving to the left of the mark) or gaining speed (moving to the right of the mark).

RAVEN BELT-DRIVE TT vs TIMELINE 
Watch here how the laser hits the mark each revolution until the stylus hits the groove and it instantly starts losing speed (moving to the left).
You can track its movement once it leaves the wall by seeing it on the Copperhead Tonearm.
Watch how it then speeds up when the tonearms are removed one by one....and then again, loses speed as the arms are dropped.

RAVEN BELT-DRIVE TT vs TIMELINE
Watch here how the laser is 'spot-on' each revolution with a single stylus in the groove and then loses speed as each additional stylus is added.
Then observe how....with NO styli in the groove.....the speed increases with each revolution (laser moves to the right) until it 'hits' the mark and then continues moving to the right until it has passed the mark.

Here is the 35 year-old Direct Drive Victor TT-81 turntable (with Bi-Directional Servo Control) undergoing the same examination:-
VICTOR TT-81 DD TT vs TIMELINE 
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rodman99999
6,167 posts
 
In my experience, the biggest change in speed of BD tables is caused by the warming of the belt and bearing oil viscosity; it is not uncommon to see speed drift of 0.2~0.3 RPM over a 45 minute playing time which is audible to those with pitch sensitive hearing and if corrected all at once, audible to just about everyone.
That’s why I’ve always turned my SDS on first and had my BD TT spinning, while the system’s electronics/tubes warm up, B+ stabilizes, etc, for about an hour.  Then there’s that 0W-20 Mobile 1, in the VPI’s bearing.  I figure; every little bit helps!
mijostyn's avatar
mijostyn
8,570 posts
 
Phoenixengr, that would involve using a sophisticated solid state 3 phase converter plus the electronics to control speed. I can just see people getting a rotary converter with their Turntable:)
Rodman, use Millers racing oil. It has nano particles in it that reduce friction another 25%.
ct0517's avatar
ct0517
2,041 posts
 
richardkrebs
Is this audible? maybe. What this wonderful hobby has taught me is that pretty much everything is audible, at least in the analogue world where I live.

Hi Richard 
Based on my personal experiences with the Goldilocks adventure, room dimensions,and specifically, the narrow rectangle  - shooting down the short wall, and the type of pickup tonearm/cart used, has "very much" to do with how much is "audible" 8^0

Ag insider logo xs@2x
rauliruegas
13,103 posts
 
Dear friends: I would like to know if each single LP was recorded/cutted at exactly/accurated 33.333..rpm and if for any reasons exist tiny deviations from 33.333..rpm accuracy why or how can we or not detected through an accurate TT that spins at exactly 33.333...rpm during play time of LPs? 

I think that some one can put some light about.

 The stylus-drag is a fact and can be fixed but those tiny differences in speed/pitch always comes by speed non-accurated TTs or by the LP it self?

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.




lewm
13,225 posts
 
Phoenix, Thank you for embellishing on my response to Atma-sphere re my point that operating a motor with 3-phase AC synchronicity does not per se eliminate cogging.  I am a rank amateur on this subject with only a good college level background in physics (and a lifelong habit of thinking like a scientist).  But I was a bit puzzled by your statement: "A 24 pole motor turns at half the speed of 12 pole motor so the frequency of the cogs is identical in both (120Hz)."  In a direct-drive turntable, doesn't the motor have to turn at 33.3333 rpm, regardless of the number of poles?  And therefore might there not be a theoretical advantage to having double the number of poles?

Oh, and thanks for clearing up the many ambiguous on-line websites that don't come right out and say that coreless motors are free of cogging.  It makes perfect sense (and I think I hear the benefits), but you'd be surprised at how poorly this subject is addressed and explained. (Or maybe you wouldn't be surprised.)
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