2. analog
  3. 151541-486

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 
128x128halcro

Showing 7 responses by uberwaltz

uberwaltz's avatar
uberwaltz
13,381 posts
 
Thx Phoenix
Great post which actually makes sense to myself. I must admit some prior posts have shot right over my head but now I am trying to think in industrial terms which is something I am at least vaguely familiar with.
We rotate, amongst other things, 900 to 1200lb steel rollers with a required very high degree of speed accuracy precision.
Think in terms of  3 phase 5 to 25hp motors for this task.
Current feedback has proven very effective at precise control AND eliminating the pesky noise problem sometimes seen on 0-10vdc and 4-20ma control feedback circuits.
uberwaltz's avatar
uberwaltz
13,381 posts
 
Just some random thoughts and maybe I missed this.

In my industrial world, traditional motor absolute speed control was obtained by either servo motors/ controllers or motors with speed encoder feedback.
However in past few years drive controllers have become so sophisticated that now best speed regulation is obtained by running " open loop" with zero encoder feedback and using current feedback at the controller itself.

Now is this a possibility for TT speed control or is this how some are already controlled?
uberwaltz's avatar
uberwaltz
13,381 posts
 
Hey Chris
You know that really got me thinking.
You are so right as I now remember listening to live tapes of our band from different nights and yes the tempo was different night to night.
I mastered our "sessions" into a tape I considered good enough to sell at venues and/or send off as a demo tape so always chose the best performance of each song whether they were from the same show or not.

We are human beings not machines so a live performance IS going to differ ever so slightly every time.
And probably true that myself (bass ) and our drummer might have ultimately drove that tempo overall.

And here we are with people worrying about 0.001% speed difference.
Lol.
uberwaltz's avatar
uberwaltz
13,381 posts
 
Very nice looking system Mike!

Those platforms are indeed impressive.
uberwaltz's avatar
uberwaltz
13,381 posts
 
Chris
You took the words from my fingers sir!

I routinely run my TT,s and my R2R ever so slightly fast deliberately just for that sense of extra attack, drive and dynamics.
Correct?
No but it's my system and ears and stability is key for me NOT absolute speed being locked at 33.333333 recurring.
Heck if it was good enough for Fleetwood Mac it works for me.
uberwaltz's avatar
uberwaltz
13,381 posts
 
Usefull information here.

https://www.rarewoodsusa.com/product/ebony-gabon/
uberwaltz's avatar
uberwaltz
13,381 posts
 
Rodman.
The Sonus Gold Blue has great reviews and high recommendations.
A while ago a member was going to sell me one from his stash but then he just fell off the face of the Earth so it never happened.

I still peruse eBay and here etc but never see a complete usable one.

Shame...... 
More to discover