Turntable speed accuracy

Sorry Dover,
I'm confused?
Are you saying that turntable link by Hiho is the Fat Bob?

I have the Kab strobe disc and laser pointer which I have used reliably for the last two years and I have now just obtained the Sutherland Timeline laser weight.
The Timeline demonstrates that the Kab strode is merely an 'approximation' of correct speed.....or at least is not capable of detecting instantaneous 'stylus drag' which is clearly visible with the Timeline.
I can assure anyone......that once you have heard a record played without stylus drag.......speed constancy will become an important factor in your vinyl experience :^)

Quite right Lew.
It really doesn't matter if your TT is revolving at 32.4rpm or 33.3rpm (other than pitch)......as long as it it is unwavering!
And that article you read was the one I posted by Peter Moncreif of the IAR. It was like a thunderbolt for me. The man is a real thinker :^)......in a field where there are some stinkers :^(

If your platter is heavy, playing a record will not affect the speed

Written by a man who has no verifiable proof.
TIMELINE

If your platter is heavy, playing a record will not affect the speed.

That was the first quote from Don.

Needle drag does not slow down "Properly Designed" turntables!

That was the second quote from Don.
I guess I can agree with the second. it seems like a logical imperative :-)

Oh....OK.
You mean it was the Fat Bob in the video of the Timeline?
I agree.......not a very impressive performance for a turntable?
But it makes the point about 'stylus drag' very convincingly?

Now D and Syntax,
That photo just needs more explaining?
Are those speakers available at Audio Connection? :^)

Nice shot Hiho,
Never seen that turntable before?
Intrigued by the armpod cylinder. Seems like it may revolve for different length arms and has multi-way fixing options?

For the record Raul.....the Victor TT-81 was $300.00 but I doubt that it was able to 'burn' a hole in the wall like the TT-101 which cost the princely sum of $1500.00..........the best money spent on my system other than my speakers :^)

Dear Nicola,
You disappoint me. I thought you were such a thorough compatriot who lets nothing escape him and now I discover that you did not even 'click' on the video Link I previously attached for the Timeline?
In it, you would have seen.......about half way through the video......where he drops the cartridge on the record and immediately.....the speed decreases?
And this is only the beginning of the record. Not a heavily modulated passage?
Can you imagine what happens with a really heavily modulated passage? And that turntable in the video has a very heavy platter.

So here once again.....for your benefit Nicola....I attach the Timeline video for you to study. Please don't disappoint me :-)
TIMELINE

Atmasphere is quite correct about constant speed and soundstage.
There are many audible benefits with a turntable which does maintain constant unwavering speed which are unrelated to pitch.
With most turntables.......when the music becomes loud, and complex......the soundstage narrows and flattens, the transparency disappears and the sound becomes brittle.
This is caused by the auto modulation distortion of the soundwave in the time domain.
It is no different to a distortion in the amplitude of the soundwave which we simply would refuse to tolerate.
Those with tape decks have a better understanding of this phenomena and unfortunately........the majority of turntable listeners have not really experienced the liberation that accompanies constant speed control.
Once you do.......there's no going back:^)

I didn't count the screws on the Timeline Thuchan because I thought.......although they supply a Hex bolt with it.........someone is really saying "don't open this!" :^)

How does the Criterion stack up with the Timeline? That would be interesting to know?

Tonywinsc,
Your explanation makes a lot of sense to me....especially with my experiences with DD turntables compared to belt drive.
I'll try your experiment with the one revolution......although I'm not quite sure what it proves?

on all my TTs I experience a change in speed when the needle hits the record.

Thuchan,
On my TT-101 there is zero speed change when the cartridge hits the record. Even with the low compliance heavy tracking XV-1s and FR-7f.

Dear Thuchan,
The Victor TT-101 is quartz controlled direct drive and automatically runs at a true 33.3rpm or 45rpm.
It has pitch adjustment in 6hz increments in both positive and negative direction.....but I never use this feature.
The servo control is bi-lateral........it works to speed up AND slow down.
Most other servos only are capable of speeding up and then rely on natural friction (or stylus drag) to be detected as 'too slow'.......for it to 'then 'speed up'.
This natural time delay is too slow with too much speed variance to really be critically effective IMHO?
Do you notice this slow-down when the stylus lands.........on your Nakamichi as well as your belt drives?

My point is that inertia has to be addressed at the outset of a turntable's design, and that electronic speed control merely augments it.

Mosin, as inertia is directly related to mass and friction.....are you saying that heavy platters have inherently greater inertia than light ones?
If you are?.........how do you explain that the turntable in the Timeline video features the Fat Bob platter with a massive weight and slows down alarmingly when the the stylus hits the record?
Yet my TT-101 has a puny 2.0 Kg cast aluminium platter which has zero deviation in speed with one, two or three cartridges lowered onto the same record?
All speed control is via the direct drive with servo control.
This instantaneous speed control I believe, is far more critical than inertia?

Thank you In_shore,
But what happens if the orchestra being recorded is already tuned 12Hz lower than 440Hz which means that at 33.33rpm......we are getting 428Hz for the note A?
If our turntables are then running slow by....say 12Hz.....it can't really be good?
The aim should really be....to be as close as possible to an accurate and consistent 33.33rpm?
Cheers
Henry

Chris,
Your wish is my command :-)
Please forgive the amateurish state of the movie but it was taken on my iphone4.....my first film..... and my first upload to utube!
TT-101

Your accent doesn't come through in the posts here.

Accent??........I have an accent??!

Thanks Dover, Chris, Thuchan & Banquo,
I appreciate your encouragement :^)...... John Gielgud (blush).
Dover is from New Zealand.....so of course I sound like an orator to him:^)

I was going to follow up with a video of the Raven AC-3 under test.......but I don't think it's fair?
Everyone can test his own turntable once armed with the Timeline.
There will be some shocks?

Tony,
The TT-101 does in fact reach its correct speed within a revolution as seen on the Timeline.
The actual specification states that 'starting time' is within 0.6sec.
Starting torque: 1.2Kg/cm
Speed deviation: 0.002%
Drift: 0.0004%

There appears to be some confusion about the functioning of the quartz locked positive and negative servo control of the TT-101?
It does not compensate for a speed deviation over a complete 'revolution' or series of 'revolutions'.
In other words......if there is a slowing down due to stylus drag........the servo does NOT speed up to 'compensate' for that 'lost' time and thus keep an 'average' continuum?
The servo does not know how many revolutions it is completing in any listening session....nor does it care.
It cares only about 'instantaneous' micro speed control.
What this means, is that if there were a slow-down due to stylus drag at any point of a record's playing cycle......that error would be permanently imprinted on the Timeline 'Blutak' marker on the wall. And any extra deviations would be accumulative so that the laser line of the Timeline would 'drift' further to the left with every revolution.
This you will appreciate if you ever use your own Timeline on your own turntable?
It truly puts into perspective the performance of the TT-101 which you have witnessed on the video?

Sometimes threads do accidentally get 'wiped' by an administrator.
It's happened to me twice and when I contacted A'Gon ........they retrieved them.
Have you tried that?

I discovered that removing one of the three motors of the Raven AC-3 (aka Raven AC-2)......the turntable was able to maintain far more accurate speed control than with the three motors.
Perhaps the belt stretch or slippage is increased with the three motors?......or the greater contact of the belt on the platter with two motors is the reason?
I can't wait to try a Bavarian thread in place of the rubber belt?
Are you listening D? :^)

From what I can see and read about the Speednic......it seems no different to a Kab strobe?
Can anyone explain to me how the Speednic competes in any way with the Timeline?

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 :^)

Dear Thuchan,
I don't use the Timeline as a record weight as I find it too light.
Therefore I use it from one turntable to the other only if I want reassurance? :^)
Cheers
Henry

Thanks Rugyboogie,
The video was very amateurish but I think....made its point.
Hollywood has not been ringing though which is puzzling?
You are one of the 'brave' ones amongst us....having purchased the Timeline only to find disillusionment with the macro accuracy of most belt-drive turntables.
However I believe the truth can help you.....and you happily have plans to correct the situation with the Verdier.
I certainly wish you luck.

Pryso,
Yes you are misunderstanding the principle of the Timeline as also Lew continues to do despite me trying to explain it on 2 or 3 occasions?
A turntable......any turntable......will not 'make up' for lost speed.
If a turntable did this......it would simply be unlistenable as it would never be revolving at the correct speed. This is a common misconception about servo-controlled DD motors.
A turntable must revolve at a 'constant' speed. If that 'constant speed is not exactly 33.3rpm......it is only a matter of 'pitch'.
When something occurs to 'alter' that speed momentarily.......it will almost always slow it down (stylus drag). When the motor detects that 'slow-down'....it will compensate to regain its 'correct' speed. It will NOT 'correct' that slow speed to another 'incorrect' FAST speed?
Thus the original 'altered' speed (due to stylus drag)....is a historical event that the turntable motor does not 'remember'.
The Timeline however.......will keep the record of that altered speed as long as it keeps revolving and thus the laser line will NEVER 'recover' to once again hit the mark on the wall.
This is the difference between a strobe and the Timeline. With a strobe....any speed change is so quick that a blink of your eye will simply miss it and the strobe has regained its 'correct' speed before you ever see it. With a strobe....there is no 'record' of the speed change.
With the Timeline.......a 'running' record is automatically kept and cannot be erased.
I hope this is somehow clearer........but the way many here are discussing the accuracy of different strobes to the way the Timeline is designed to function......simply leaves me open-mouthed :^O

You're right of course Decibell.
The 'correction' to any stylus drag speed reduction is so instantaneous...that we cannot see it on the Timeline.
What I really meant to say was........once a speed shift has occurred....without any instaneous correction.....no turntable motor will 'speed up' to 'remove' that abberation over the course of a few revolutions and thus restore the Timeline laser to its mark on the wall?
Yet with a strobe.......all will seem to be runnIng perfectly immediately after a speed shift (or even during if you blink).

I have just fitted a thread drive to replace the rubber belt on the Raven AC-2 (thank you Daniel for the Bavarian thread)........and apart from the increased accuracy in speed constancy over the original rubber.......the actual improvement in sound is astonishing?
The bass appears to have added a half octave in depth, the clarity and dynamics have improved and the sense of excitement and realism on every track is palpable.
Is there more to this than speed consistency?

Incidentally......I had to reset the speed on the Raven motor controller because of the differences in force transfer between the rubber and the thread and I used the KAB Strobe initially to find the 'ball-park' setting.
I then set the 'correct' speed using the Timeline and the adjustments to the controller were quite severe. I'm not talking fine adjustment here.........it required about 7 or 8 presses of the 'faster' button to reach 'correct' speed over that settled by the KAB.This is rather a serious indictment of the KAB which simply cannot be correct?
I don't know if it's just my strobe or whether this is endemic to the functioning of the KAB?
I know that the Timeline is exact as it agrees 100% with the speed indication on my Victor TT-101 DD turntable which is quartz locked.
So the question to those relying on the KAB or other versions of a strobe to set the speed of their turntables........you may wrongly believe your speed is correct.
And to those who state that it doesn't matter......how do you know when you haven't heard?

I have just replaced the rubber belt on my Raven AC-2 with the Bavarian thread sent to me by Dertonarm ( thanks Daniel).
The speed consistency is slightly improved with this thread drive but the sound of the turntable has been somewhat transformed.
There appears to be a half octave of added bass together with an increased level of excitement and realism to each and every track and record.
Is there more to the drive method than pure speed accuracy?
When I changed to the thread drive, I needed to adjust the Raven motor controller to correct for the differing characteristics and I used the KAB Strobe to quickly get me to the 'ballpark'.
I then installed the Timeline and was shocked to find how inaccurately the platter was now running? I needed to press the 'UP' button about 7 times to reach the correct speed on both 33.33rpm and 45rpm.
When the speeds were corrected with the Timeline......the KAB Strobe indicated incorrect speeds!?
I know the Timeline is correct as it agrees exactly with the speeds on my Victor TT-101 which are quartz-locked.
Perhaps it is only my KAB Strobe which is faulty?.......but I urge caution for all those relying on strobes to set their speeds?
And for those who claim that speed accuracy does not matter.........how do you know if you haven't heard it? :^)

Hi Dev,
I am using only two motors instead of the three. I found that with the standard Raven belt......the speed consistency was better than with the three.
I assume that the extra belt contact on the platter has something to do with it?
The same principle should apply to the thread and yes.....Daniel did warn me about possible marking and wear on the side of the platter with the thread because of the soft Delcrin material.....but I'm prepared to accept this for the increased performance.

Hi Lew,
The Timeline is dead-on accurate as I have proved using the TT-101.
The KAB Strobe must be wrong/faulty?
I haven't listened to the Raven set up according to the strobe since I received the Timeline. All I can tell you is that the TT-101 initially blew the Raven away (sound-wise) when the Raven was set up using the KAB.
With the Raven running the thread drive on two motors and set up according to the Timeline.......the differences to the Victor are not that great.
In other words.....I can happily listen to both decks.

Dear Solong,
Thanks for the hints.
Unfortunately......my cantilevered wall shelf slopes alarmingly to the front due to the weight of the Raven....and the motors require the utmost levelling of the feet to maintain their horizontality. Feet of some sort....are a prerequisite?

Hi Dover,
The Raven motor pulleys do not seem to allow the thread to move visually up and down.
I also have some French silk thread which I can try as well. Some sexy colours also :-)

Ahhh the vagaries of the Audiophile mentality?
Rather than question the accuracy of their calculators ( because they can't go to infinity 33.333333333333333333333....) or the accuracy of a Strobe which needs to flash at constant and repeatable frequency whilst aimed at a disc with lines printed by machines to an order of indeterminate accuracy......or question the actual speed of their turntables with sometimes primitive electro/mechanical interfaces......the majority seem to question the accuracy of a scientific instrument whose accuracy can be definitively proven?
And those appearing to do this are invariably those who do not have the Timeline nor have used it on their turntables?

There appears to be an element of fear and trepidation about these 'doubters' with 'denial' being the protection of choice?

What does everyone expect from their turntables when using the Timline device? Absolute zero drift of the laser mark?

It's not an impossible expectation?
Have you not seen my video of the Victor TT-101 with the Timeline and three arms being lowered and raised with "absolute zero drift"?

Hi Tony,
I have left the Timeline running for an entire album side with zero drift.
If you go to YouTube and look up the Timeline video (not mine).....you will notice on the demonstration that his turntable.........demonstrates a significant drift when the tonearm is lowered.
The Timeline is the scientific device that conclusively proved that 'stylus drag' is a reality rather than a theory.
I cannot believe that my Victor TT-101 is the only turntable which can maintain this kind of speed accuracy?
There must be many other brands.......perhaps mostly of the quartz-controlled direct drive type......which are similarly capable?
If this is the case.......then we should have the right to expect this kind of accuracy from our turntables.
Even with my Raven AC-2 with thread drive.........the drift with a stylus in play is only 0.5mm per revolution from the wall mark. If I adjust the speed on the motor controller one step UP.....it then runs fast by 1mm per revolution. But these are both constant deviations which indicate that the turntable is maintaining consistent speed.......just not exactly 33.33rpm. If the motor controller had a finer adjustment......I could get it spot-on.

The Timeline is a wonderful instrument IMHO and it is not correct to believe that turntables cannot match its accuracy?
I await the day when you actually try one on your turntable.......it can only help you :^)

Hi Tony,
Yes....I think speed accuracy was indeed mastered over 30 years ago but as I mentioned elsewhere......with the dominance of belt-drive over DD turntables due in large part to the Linn propaganda and the reviewers who championed it.....'speed accuracy/consistency'.......never was mentioned as a critical factor in their design philosophy?
How do we get back to it?........I think discussions such as this is certainly one of the ways and thanks to the Timeline......I hope more designers and manufacturers will be able to judge their successes or failures and hopefully make some corrections?
'Awareness'.....is our best hope?
The .5mm speed drift I am seeing on the Raven AC-2 is almost negligible.
For instance.......the Victor TT-101 allows me to speed up or slow down, the actual speed of the platter in 6Hz increments.
33.33rpm apparently gives a pitch of 440Hz which is the de-facto standard
pitch for orchestras.
However many of the world's orchestras use a pitch either 6Hz or 12Hz up or down from this?
When I adjust the speed on the TT-101 to 6Hz lower (33.25rpm).....the drift from the wallmark is 5mm every revolution and when the speed is increased to 33.40rpm (6Hz higher).....again the drift is 5mm per revolution.
So the Raven.....running at 0.5mm per revolution could really be called...'spot-on'?

And Lew is right Tony......the Timeline is not so valuable in terms of 'cumulative' drift or speed error (as even a 6Hz pitch deviation will add or subtract 5mm drift to each and every revolution which will appear quite dire over the full side of a record).....rather it is the instantaneous speed drift due to stylus drag which is valuable for us to know about our turntable's performance?
Instead of 'fear' governing our apprehension of the Timeline and what it will reveal about our turntables.......we should really welcome this information.
Knowledge is power....and ultimately the more we know about our system's objective performance.....the more equipped we are to effect improvements?

Hi Chris,

The DD is only at a correct 33.3 “in transition” between the time the motor kicks in to speed up and shuts off to slow down. At all other times it is not at 33.3.

I don't believe this is a fair assessment of the DD motor technology?
There is no difference I believe, to the maintenance of the speed via the motor of a belt-drive or direct drive. Each one has to monitor its speed via a pre-programmed sine-wave algorithm related to the power supply.
The differences between the two drive types I believe, has to do more with the speed of any correction applied once a deviation is detected?
In this.....a belt or thread drive is at a severe disadvantage.
The DD motor....usually with a lot more torque than that of a belt/thread drive....and being directly connected to the platter.....can correct deviations in micro-seconds theoretically inaudible to the human ear.
With some DD turntables like the Victor TT-101......there is instantaneous 'braking' correction as well as speed-up correction...thus not relying on the time lag slowing-down procedure after an increase is applied.
To my ears......this is a more optimum audible solution than the slow speed deviations and corrections allowed by some belt/thread drive decks?

One point not properly addressed so far.....is how idlers or rim-drives perform against the Timeline?
Perhaps Lew will be able to enlighten us on this?

Halcro have you tried the timeline with your TT81?

Unfortunately I didn't have the Timeline when I had the TT-81 set-up.
Now it is too much of a hassle to remove the TT-101..... Install the TT-81....and then re-install the TT-81? Sorry :^)

One red herring: the LP is sitting on a Boston Audio Mat1, which is kind of slippery; the LP itself could be sliding due to stylus drag. I hate when that happens. I hate record weights.

Lew.......please remove the mat. Slippage can be a real problem?

TIMELINE
Here is the video with the Timeline on the Transrotor Fat Bob which has a massive platter.
Watch how the Timeline immediately slows when the stylus is lowered?

The Timeline is also sold as a 'record weight'....although on the light side.
It is fairly easy to see if slippage is causing a problem by using the Timeline without a stylus playing firstly, then with a stylus playing on the mat and then without the mat or a different mat. It's not rocket science but this mentality of assuming the Timeline is somehow wrong and the turntable correct.......is the real problem here?

Regardless of what the speed inaccuracy is due to.......one must find it and correct it as it is distortion of the analogue sine wave...pure and simple.
The Timeline will show it....and you must correct it. Not look for excuses :^)

Hi Chris,
My statement was directed at the 'speed' of any correction performed by the motor controller being felt by the platter?
I don't think there is any doubt that in a DD situation with the platter being attached to the motor......any speed correction will be effected faster than via a belt or thread connected to a motor/s at some distance from the platter?
If you re-read Peter Moncrief's excellent article that I posted several times........he provides a great deal of information regarding this very subject.

I'm not sure what the differences might be in a turntable designed for a string/thread drive over a belt?
Can you or someone provide some further thoughts on this subject?
Regards
Henry

Dear Swampwalker,
Please look HERE

Good news Lew,
But are you sure the Timeline is accurate? :^)

Hi Dover,
It's a running joke between Lew and me.
Albert got it.......so did Hiho :^)

Sometimes there is simply no substitute for the ears?
I had recently switched from the original rubber belt of the Raven AC-2.....to a thread drive.
There was little difference in the speed consistency as shown by the Timeline......but initially....to my ears.....there seemed to be an improvement in the sound?
Yesterday.....I was sitting back comfortably listening to the ballet music fom Le Cid by Massenet conducted by Louis Fremaux on Klavier Records.
In the third movement 'Catalane-Madriene'......when the French horn and the flute begin their delicate interplay........I could clearly hear some 'wow'...particularly with the flute warbling rather frighteningly?
I quickly switched the disc to the Victor TT-101 where there was nothing but pure joyous breathy consistency.
So I placed the Timeline on the Raven and saw that it appeared as consistent as it previously had.
I replayed the Madriene and re-heard the 'warble'.
I switched the rubber belt back in and re-set the speed according to the Timeline.
No more 'warble'.......?
If anyone has some theory to explain this phenomenon........I would love to hear it?
For the moment......the belt is back on the Raven......but my trust is firmly with the TT-101 :^)

Just watching Berdych take the first set against Rafa in a tie-breaker in the Australian Open.
This looks like a possible match to be 'bottled'?
Dear Geoch & Dover,
Thanks for the explanations.
The Raven belt does have a smooth side and a 'coarse' side designed to grip the platter.
The platter also does not keep rotating very far after the motors are switched off indicating perhaps a bearing designed for friction so that the motors have a load against which to pull?
The thread is stretched tight.....but the side of the platter material is smooth and slippery.....although the shiny heavy metal platters of the big Micros would seem to be equally slippery?
So there may not be a satisfactory way to get the Raven to work with a thread drive?
What I still don't understand is.......accepting the thread slippage.......how does the Timeline indicate constant speed?

Thanks Tony,
A perceptive and illuminating commentary :^)

Hi Ralph,

Belt drive turntables differ from one other in belt compliance and platter moment of inertia, so their oscillation wow patterns differ. That explains in part why belt drive turntables sound so different from one another in pace and rhythm, in steadiness of pitch, and in solidity of bass (bass notes last longer, so they require a longer sustain of turntable pitch accuracy to sound straight and massively impactive, rather than warbly, wobbly, and weak).
Can the belt drive designer reduce or damp the unwanted oscillations between platter and belt? In principle yes, but in practice it's tricky to execute. In principle, what's required is simply the addition of some resistive damping. This would damp the reactive LC tank circuit of belt and platter so it would no longer oscillate.
A common form of resistive damping is friction. Thus, if a knowledgeable turntable designer wants better speed constancy, he might well consider intentionally adding some friction to his rotating platter. It's worth noting that some Swiss and German engineers are so justifiably proud of their ability to produce nearly frictionless bearings that they cannot bring themselves to make turntables with high friction. As a result, the Thorens turntables exhibit some of the most spectacularly low friction bearings on the planet, and will spin seemingly forever (with the belt removed); but, at the same time they also exhibit some of the worst audible wow, in part because there is, as a matter of engineering pride, almost no resistive damping for the oscillating reactive tank circuit.
What might be useful ways to introduce friction? The fit and/or finish between platter spindle and well could be made poor, instead of smooth and polished. But this would be causing friction via crude irregularities, like two meshing mountain ranges, rubbing each other. The crude irregularities of these two mountain ranges rubbing together would cause unwanted speed irregularities (snags and letting gos), as well as unwanted vibrational rumble (the earthquake rumble of each letting go after each snag). So that tactic is out.
One useable tactic is to introduce a viscous fluid in the bearing, which provides friction in a liquid hence smooth form. This can be especially effective if the spindle is made in a larger than normal diameter, so that the viscous fluid has a larger moment arm (more leverage) with which to work its resistive magic (as in the Linn Sondek). The use of viscous fluid for resistively damping platter rotation can also be enhanced by various helical screw kinds of arrangements, which force the fluid to do extra work in opposing the rotation of the platter (as in the turntables from Max Townshend). It's no accident that these two brands have the best reputation among belt drive turntables for pace and rhythm, solid bass, and master-tape-like clarity. It's because both these designs recognize that belt drive, far from being a simple Hail Mary solution, brings with it new problems that must be addressed, and that overcoming the problem of speed constancy requires at least the addition of a fourth element, resistive damping, to the three usual elements of a belt drive turntable.

That's a quote from Peter Moncrief's incisive article about turntable speed control.
As also described in his article....is the fact that a 'stretchy' rubber belt can iron out the 'pulses' of a poled motor whereas if a non-compliant tight thread were employed........we're back to transferring that cogging into the platter?

In my experience, belt drive TT's with AC moters with ample torque and low friction fair better than DC motor driven TT's all else being equal.

Perhaps you should listen to a good DD turntable with a coreless DC servo-controlled motor alongside you Raven AC-2 as I have?
No real comparison actually........
Our dear friend Lew wanted a moratorium on discussions of the merits of turntable drive types but I think that's difficult when it comes to the subject of speed consistency and accuracy?
We have heard of the supposedly superb accuracy of some belt-drive turntables according to the Timeline but as yet we have seen no real evidence?
Is someone able to upload a clip of one of these belt-drives with the Timeline....onto YouTube?
Perhaps you Andrew?

And finally, all this chat is still overlooking what I thought was the real issue: speed variation due to stylus drag. None of the above mentioned observations really tell us anything about that. Unless sensitivity to stylus drag is gross, the Timeline may not reveal it.

Lew.......have you not tested the Timeline with and without 'stylus drag' yourself?
I assume all the comments on the Timeline tests are 'with' the stylus playing as demonstrated with 1,2,&3 styli engaged on my YouTube video?
I can assure you that the Timeline is the ONLY device currently available......capable of graphically demonstrating the most marginal of drifts due to stylus drag.

I decided to try another method for the thread drive.
I connected a thread to the platter and one motor (green French silk).....whilst another thread altogether connecting the other motor to the platter (black French silk).
2 THREADS
Re-calibrated the motor-controller using the Timeline (needed to increase the speed due to stylus drag) and listened to the previously warbling flute on the Massenet Le Cid.
No warbling now :-)......and the Timeline is slightly more constant than with the rubber belt.
GREEN BELT
BLACK BELT