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?
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I suppose using a strobe disk and the Timeline laser then comparing the results. I don't lose much sleep over it...I use a strobe disk and that is good enough.
I like and use a digital tachometer for checking speed accuracy. I've tried strobe discs but like the tach more.
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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 :^)
What Viridian said and Halcro hinted at. More important is stable speed regardless of groove modulation, as opposed to bang on 33.33 rpm. If a table can stay at 32 rpm whilst tracking any and all passages, then it could probably be adjusted to run stably at 33 rpm, so absolute speed is less of an issue, IMO. I read a very insightful piece somewhere on the internet last week which pointed out that the turntable provides fully "half" the music, as its speed past the stylus provides the horizontal axis of the complex sine waves that represent music, if it were graphically displayed for example with an oscilloscope. The cartridge can only give us the other half, the vertical or amplitude direction. All musical timing must come from the tt. Pretty sobering, eh? Well, I knew that, but I had never thought of it that way.
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 :^(
The turntable speed should be at least as accurate as the tape recorders used to record, master, and playback the tape.

Constant speed is "much more" important than absolute speed.

Just buy a strobe disc and illuminate it with a light bulb.

The 60 Hz AC frequency does not fluctuate enough to worry over.

Adjust the speed of your turntable, or AC input (if you have a variable frequency supply like VPI SDS) for the lines or dots to appear stationary or slightly vary around a fixed position.

This is simple and more than sufficient. Tape decks are not all that accurate, and do go out of spec.

On my VPI TNT the SDS AC line frequency is set within .01 Hz.

If your platter is heavy, playing a record will not affect the speed.
If your platter is heavy, playing a record will not affect the speed
Written by a man who has no verifiable proof.

Sutherland designs "CRAP" cold sounding phono stages!

They sound similar to HALCO amps!

The turntable in the video has a wimpy low torque motor drive system!!

Needle drag does not slow down well designed turntables!

Sutherland designs "CRAP" cold sounding phono stages!

They sound similar to HALCO amps!

The turntable in the video has a wimpy low torque motor drive system!!

Needle drag does not slow down "Properly Designed" turntables!
Don_c55, try comparing a carefully tensioned cotton poly thread to the stock elastic band on your TNT. This will demonstrate the clearly audible difference between absolute and transient speed stability.

You are simply wrong. Stylus drag will slow down any turntable, regardless of platter weight; it merely changes the period over which it occurs due to inertia. And yes, the 60Hz mains supply does fluctuate enough to be completely problematic.
Then again, if you can't hear it, more power to you.
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 :-)
I used to own a VPI TNT-V hot rod and a HRX.

EVERY time a pulled out the kab strobe the speed was different.

This had nothing to do with stylus drag.

Yup, that will irk you. Alas, that's a fine example of a poorly designed drive system; there's a reason the SDS was developed and that goes back to the AC mains. Trying to accurately derive 33.3 RPM using a crude phase shifting capacitor and hoping that the frequency of the incoming AC is stable enough to do the job is bad engineering. While frequency accuracy (and adjustablity) is one issue, it doesn't begin to address waveform shape, harmonic distortion, phase amplitude and shift, and all the other interesting things that go into generating a waveform suitable for driving a synchronous AC motor.

DC motors have their own set of problems...
Peter I forgot drive method. I have a Walker Ultimate motor controller plugged into an Exact Power 15 putting out a constant 120V, this combination keeps the speed as constant as I'm able to check.

Don_c55: "Just buy a strobe disc and illuminate it with a light bulb. The 60 Hz AC frequency does not fluctuate enough to worry over."
I wish that's true but using your method and comparing to a KAB strobe, there is a noticeable visual difference, even when your turntable is accurate the light bulb frequency will drift and you end up adjusting to the wrong speed.

Not only the speed should be accurate but, more importantly, no wavering or no intermittent irregularity. To me cogging or analog jitter has the worst effect on the sound of playing a record. DD gets the speed accurate but often suffers from motor cogging. When done right then DD sounds great. Belt is good at filtering the jitters but the elasticity on the belt creates another set of problem. Sigh, what a circle jerk of a hobby!

Don_c55: "If your platter is heavy, playing a record will not affect the speed."
Didn't Halcro just said he tested the TimeLine on the TW Raven, which has a heavy platter?


Below is an excerpt from the long winded and thought provoking piece that Lewm and Halcro was referring to in the below analogy. Good read, if you have time. :-)

Peter Moncrieff in International Audio Review, issue # 80:
Consider the following analogy. Imagine first that you want to draw a music waveform, like the ones you've seen in previous IAR articles. Draw it on a square piece of graph paper. Note that you can freely move your hand in two dimensions on the graph paper, so you can simultaneously draw both the varying amplitude (height) and progressing time (horizontal axis) of the waveform on the graph paper. Next, imagine that you're doing the same thing, but you've turned the piece of graph paper sideways, so that your wrist moves from side to side (instead of up and down) as you're charting the waveform's amplitude variations.

Now, imagine that you can only move your wrist from side to side, and can't move your hand up and down at all. Your hand holding the drawing stylus has now become just like a phono cartridge holding a stylus that can only read the side to side variations in a record groove. Your hand holding the waveform drawing stylus is mounted on your arm, the same way that a cartridge holding the waveform reading stylus is mounted on the pickup arm of the record player.

If you were to try drawing a music waveform, while limiting your hand to only this side to side motion, you couldn't do it. There would have to be a further mechanism for moving the drawing stylus in your hand along the time axis of the graph paper where you want to draw the complete music waveform. You could for example rely on a strip chart recorder, which could dispense the graph paper in strip form at a fixed time rate (you've probably seen strip chart recorders in the form of earthquake recorders, where the side to side needle motion indicates earthquake amplitude, on a steadily unrolling strip of graph paper; if you're unacquainted with this, imagine a roll of toilet paper unrolling at a steady rate). The strip chart recorder makes the graph paper move along under your hand at a constant speed, thus creating a steady time axis for the waveform you wish to draw. And the strip chart literally creates this time axis. Your hand is limited to reproducing (accurately we hope) only the amplitude axis of the music waveform, since you are now limited to side to side motion.

That's exactly what a turntable does. It literally creates the time axis half of your music waveform, while the cartridge, which is restricted to side to side motion, reproduces (accurately we hope) the amplitude information that the grove contains.

Speed accuracy is important for me since I jam with guitar while record is playing and that's one of my ways to realize how precise the speed is. If it's faster or slower by small fraction of rpm I'll hear the difference in tunes.
I haven't got perfect pitch and my friends tell me my timing aint that good, but I find piano recordings fantastic for laying bare speed and VTA issues. The words clangy and compressed come to mind when things aren't well, assuming the recording is ok to start with.
Regenerated ac supplies are quite cheap and accessible today and possibly an easy upgrade for tt's with simple supplies.
Love the US$6000 VPI Classic III - Fremer says its one of the most speed stable belt drives he has heard - the supply consists of 1 cap and 1 resistor. Be interesting to run the timeline on one.

The drive system on the TW Raven just is not perfect, that's all.

Does the TW raven have any "measurable" wow and flutter, or rumble?

The VPI TNT III and IV with SDS and their motor, flyweel, and belt system have "UNMEASURABLE" wow and flutter and rumble. The accuracy and consistency, is better than "ANY" tape deck or disk cutter. That is "ALL" that is necessary or maters! VPI has not improved since, or has anyone else as far as speed, end of story! Do not worry or leave sleep over this.

The strobe lines on a strobe disk are not "exactly" spaced, and the flashing bulb has ever so slight time delays, which leads to a very slight jitter of the image.

As far as the KAB strobe goes, I agree it is a better way of measuring speed inconsistencies, that "only mater" to neurotic audiophiles! Sane, intelligent, knowledgeable people just do not need it!

You and Moncrief are splitting hairs here, and hung up on "unaudible absolutes"!

How many years was it before side one of Kind of blue was found to be 1/3 of a semitone fast? Maybe Miles knew, but who else? Speed variation "is" noticeable on classical piano "IF" you have played a piano, but typically the audience could care less.

I have read the IAR and Moncrief is a very good "theoretical" technical BSer. You should read his BS about "audible goodness curves", or the Oracle having 377 times lower distortion than a Linn, or his "Wonder" caps. He can weave a technical tale as good as anyone, but he is no Richard Heyser!

I recently bought a Vibraplane isolation platform for under my turntable. It replaced the Townshend Seismic Sink which I then put under my SME motor controller. Isolating the motor controller from vibrations made a remarkable change to the sound of the system.

I understand why isolation under the tt would improve the sound, but I was surprised by the improvement under the motor controller. Could someone explain to me what is going on there?

Also, does anyone have any experience with replacing the rubber belt with a thread on an SME table? Thanks.
Peterayer alludes to interesting questions:

Is speed stability THE most important turntable parameter?

Is there a degree of speed stability below which variations become inaudible?

Is this something that could be tested with reproducible results?

How does a turntable's immunity to outside vibration and ability to dissipate internally generated noise and vibration impact performance relative to speed stability?
In absolute terms there is no such thing as perfect speed stability. There is always a finite amount of instability. It's like saying a surface is smooth. A smooth surface looks like a mountain range under a microscope.

So the right question is what level of speed instability is audible? It is a fact that uneven drag from a stylus will affect platter speed. But is it enough to be audible?

To the novice it would seem that a good motor and a heavy platter will push instability into the in-audible range. Early work with digital encoding fell into the same trap. Who would have imagined that infinitesimally small timing errors in the tens of pico seconds would be audible. Well, it is clearly documented fact that these microscopic errors are audible. This tells us that our ears are far more sensitive to errors in the time domain than anyone would have imagined.

In my opinion achieving speed stability such that there are no audible artifacts is something that state of the art turntables approach but never quite meet. My experience has shown that there is always room for improvement when it comes to speed stability.

All I know is that the wavering on the decaying note of a piano is REALLY annoying and that usually happens on belt-drive suspended turntables with stretchy belt. I may not know what I like but I know what I don't like.

AC line frequency in the US is adjusted within .02% and accurate within .033%, the KAB strobe is accurate within .03%.

AC from the power line is as accurate. The KAB website info is WRONG! A light bulb and strobe disk is as accurate. END OF STORY!!!

From Wikipedia

Regulation of power system frequency for timekeeping accuracy was not commonplace until after 1926 and the invention of the electric clock driven by a synchronous motor. Network operators will regulate the daily average frequency so that clocks stay within a few seconds of correct time. In practice the nominal frequency is raised or lowered by a specific percentage to maintain synchronization. Over the course of a day, the average frequency is maintained at the nominal value within a few hundred parts per million.[19] In the synchronous grid of Continental Europe, the deviation between network phase time and UTC (based on International Atomic Time) is calculated at 08:00 each day in a control center in Switzerland, and the target frequency is then adjusted by up to ±0.01 Hz (±0.02%) from 50 Hz as needed, to ensure a long-term frequency average of exactly 24×3600×50 cycles per day is maintained.[20] In North America, whenever the error exceeds 10 seconds for the east, 3 seconds for Texas, or 2 seconds for the west, a correction of ±0.02 Hz (0.033%) is applied. Time error corrections start and end either on the hour or on the half hour.[21][22]
My last post should end this thread.

The VPI SDS adjustment, a strobe and light bulb, or a $100 KAB strobe, "are all" about as accurate as your AC line frequency!

How do all you "SUCKERS" feel, that payed $100 for the KAB BS!
When I am playing Vladimir Horowitz on my turntable should I ask him to stop on the half hour Eastern Standard Time so I dont have to listen to the speed corrections ?

Seriously though when I was selling Elite Rock Townsend turntables which used an AC motor, when I corrected the operating voltages from 69.9 to 70 volts, even though AC motors are supposedly dependent of frequency not voltage, the sonic presentation changed from that of a Van den Hul to a Koetsu without changing the cartridge. Something was going on - motor resonance, optimum torque, minute speed changes - who knows.

Atmosphere is right there are many things we hear that are not measurable.

A sinewave doesn't tell you whether the pianist was happy or sad when they hit the note.

By the way the 0.02 is the correction of the AVERAGE fequency deviation - that is quite different from the real deviations in frequency.

My Dual turntable has a built in AC light bulb to check the strobe marks on the platter rim. It drifts over time while the KAB strobe light is stationary. So there is a discrepancy between using AC line frequency and quartz locked frequency. Jeez, I am such a KAB sucker.
From the Dual manual:
"It can happen that the stroboscope lines appear to move slightly although the exact speed setting with stroboscope lines stationary has not been altered. This apparent contradiction is explained by the fact that the electronic central drive motor operates fully independently of the line frequency whilst the only relatively accurate line freqency of the AC current supply is used for speed measurement with the light stroboscope."
I am happy that some people found their perfect turntable without worrying about these things. Us neurotics just have to suffer.

Your 60Hz line freq, may no longer be sacred! This COULD POSSIBLY become an issue soon. A copy/paste, from a previous thread: Something that got me thinking more about speed accuracy lately, as both of my tables are equipped with AC synchronous motors: (http://wattsupwiththat.com/2011/06/25/it-hertz-when-you-do-that-power-grid-to-stop-regulating-60-hz-frequency/) (http://radiomagonline.com/infrastructure/power/60hz-stability-going-away-0627/) If you are using a strobe disc, that depends on your house lighting's 60Hz flicker, or your table has a motor, dependent on your AC's 60Hz for speed regulation; take note. This may soon become a concern. (Note: They were NOT simply referring to the nightime correction, in these articles)
when i compare various turntables to the same recording on my Studer A820 it's easy to hear which turntables get the closest to matching the soliditiy of the music on the Studer.

Nojima Plays Listz is a very good recording of Piano on Lp, and is a Tape Project tape too; in theory the solidity and speed accuracy of that tape is the reference for the Lp as we know it's the actual source. on that recording there is no place to hide any speed variations as well as inaccuracies. and there are plenty of peaks to hear also.

i do have the KAB strobe and use it. however, it's limitation is the accuracy of the printed strobe and the perfection of the center hole of the strobe.

i think the tape-Lp comparison has more value to me.
Palasr wrote: "While frequency accuracy (and adjustablity) is one issue, it doesn't begin to address waveform shape, harmonic distortion, phase amplitude and shift, and all the other interesting things that go into generating a waveform suitable for driving a synchronous AC motor."

I have a Mark Kelly AC-1 drive controller on my VPI TNT that features separate manipulation of several of these parameters, while deriving an AC waveform from a 12V battery independent of the power grid. Unlike a VPI SDS, the AC-1 is a true two-phase controller-- it eliminates the phasing capacitor from the motor tower. Varying the separate effects independent of frequency is easily audible, as are differences between belts of varying compliance-- yet the strobe disk doesn't move a whit.
No one seems to set the speed as I do. I adjust speed while playing same known track on CD as well as TT. I measure with stopwatch and play simultaneously going back and forth such that the song start and ends at exactly the same time on both CD and TT. I change source back and forth, each note sounding exactly same that you can hardly tell diff. It helps that my main CD source and TT are set pretty much to same tonal balance. It takes few iterations, but then I listen without worrying about speed. Makes sense?
Don, I think you underestimate the situation.

"Speed variation "is" noticeable on classical piano "IF" you have played a piano, but typically the audience could care less. "

I cannot play piano, or any other instrument, or read music. I'm certain I do not possess perfect pitch. But when I listen to piano recordings I am quickly aware if the sound becomes either sour or cartoonish. That tells me something slowed down or sped up. It could be my turntable, it could be the power line, it could be someplace in the recording chain. But it is not difficult to hear when a recording does not sound like a live instrument. (And yes I understand there are multiple other factors in the "sounds live" experience.)
What is the best way to verify results?
It depends on what results you're trying to verify.

With regard to general speed accuracy, a good strobe like the KAB or the Timeline both work well.

With regard to stylus drag or other very short-term transient events, my ears are far more sensitive than such tools, which lack a sampling rate capable of measuring variations which occur over mere nano-seconds. YMMV.

What is the most speed-accurate drive method?
A car on cruise control, which will transport you to the venue of your choice to hear real music. All TT drive methods are compromised, each in its own ways, so there's no answer to this overly simplified question.

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?
Whaaat? That's like asking if a red car is best or should we shovel snow or plow it. ;)

1. Is speed accuracy really the most important consideration for proper TT design?

It depends on the sensibilities of the listener. Some posters on this thread and very many TT designers seem oblivious to speed variations that drive me up the wall. I in turn am only just able to hear speed variations that drive my partner out of the room, screaming. OTOH, neither of us has absolute pitch to the extent necessary to identify a TT that's running 1% fast or slow but effectively resists stylus drag, yet my mother's absolute pitch can. What's important depends on who's listening.

2. Are there some compromises with certain drive types that make others still viable?

There are compromises with all drive types. Which ones are viable depends on the effects they have and how audible those effects are to you. Nothing about one design makes any other design more or less viable. Independent phenomena must be judged on their own merits.
Thanks Doug. I have heard three turntables with you and your partner and none drove Paul out of the room screaming. I guess that means the two Teres turntables and the VPI Aries we all listened to together had absolutely no speed variations. I believe two were tape drive and one was a belt drive.

A red car is more likely to be seen in a snow storm than is a white car, and if either has four wheel drive, it is less likely to get stuck.
Dear friends: I'm really surprised on almost all your answers on the overall subject.

Why surprised?, if there is true that some of us has no perfect pitch and can't detect " minute/tiny " speed deviations it is true too that other persons are way better in this regard and very sensitive about.
But, why that " no perfect pitch " or " I can't hear that minute deviations " or even " I don't care what I can't hear " where all these kind of opiniuons are only excuses to " protect " the TT already owned.

I'm not a designer of TT but if someday I take that road my very first and main target will be: no excuse, " perfect pitch " design: period.

If the customers can or can not detect it is does not matters, if during the recording proccess ( including those " great " R2R units. ) does not existed that " perfect pitch " it does not matters either even if the customers do not cares about IMHO any TT designer must look for that " perfect pitch " even absolute speed.

Dear audiophiles, please don't take it away the TT designers responsability. A TT exist because the LP needs to spin for we can listen and has to spin always at 331/3rpm or 45rpm: period.

We as a customers IMHO have to ask for excellence design level and not where almost everyone belongs: mediocrity/average level like the excuses that we don't have perfect pitch or that the electrical supply at home is non-adequate or that today is alittle " cold ".

How our hobby could improve when we are not asking for " more " for excellence but given reasons for the audio device designers does not cares about or at least does not cares enough about.

Halcro experiences with his Victor DD is not alone but several of us already experienced the same with some one of those DD vintage TT samples: exist a difference a difference that any one could hear.

Of course that if I own one of those BD dinosaur/mammoth we " accept " those minute/tiny speed deviations with no other explanation that " I can't hear " even if the timeline put in evidence the problem in our BD units.

Years ago and before the Timeline was in the market I posted several times that with heavy mass BD TT did not exist speed deviations due to stylus friction. Not easy to detect it but this fact does not means that I ask to TT designers : perfect pitch.

Our analog hobby is maybe the most imperfect reproduction medium where IMHO we have to take care in any single and " simple " stage where the cartridge signal must pass and where always suffer a degradation. As lower degradation on each one of those steps/links the cartridge signal suffer as better will be the sound that comes from our speakers and the higher the music enjoyment.

TT perfect pitch is one of those steps/links that degrade the cartridge signal even if we can't detect it or if " we don't care ".

As Teres pointed out: there is land for improvement about TT speed stability.

In this specific regard the DD experiences on many of us already showed that are a head to the BD ones.

Regards and enjoy the music,
Greetings from Monterey Bay.
Just watching a spinning Micro Seiki 5000 with HS-80 inertia unit and a Sutherland Timeline which' laser point is so stable, it almost burns a tiny hole in the wall.
I do agree that speed accuracy is a conditio sine qua non with any serious turntable worth feeding a really good system.
There is indeed no excuse.
I too agree that it is quite a task for most any belt driven turntable.
It is however rather easy for most any thread driven high inertia turntable as well as for most every dd or idler wheel drive.
The elastic nature of most any belt - as well as string and tape - however makes it very difficult for mot belt drive tables.
Start measuring the homogenity of a given belt supplied with a bd turntable.
I mean measuring the mechanical quality of the belt.
Ripple and width/diameter constancy.
A very good reference here are the precision belts supplied by Basis Audio.
Belt driven turntables do need more attention here than the other 3 drive principles.
Greetings from beautiful california coast,
4 German Ears for speed Tuning at Monterey Bay, California (Kuzma XL, Airline & Seiki 5000 + HS-80 Inertia unit, Thread Drive, Lyra Olympos, 2xFR-66s...)

Winner is ...

...the Owner.

welcome to the left coast. if you get up here toward Seattle please stop by.

i too have preference for DD and idler, and while i have no experience with thread/high inertia i defer to your perspective about it.

i think that speed is like noise floor; until you hear your system with lower noise, you don't realize what you were missing. until you hear your records with better speed you don't know what you are missing. and i mean your records in your system.

as one climbs the ladder of performance this type thing becomes a bigger and bigger issue.
Now D and Syntax,
That photo just needs more explaining?
Are those speakers available at Audio Connection? :^)
Dear Halcro, just a nice multi-way horn system based set-up in the beautiful Monterey Bay area.
A friend of ours we are visiting to fine-tune the system.
Besides that it is leisure, wine ( some great vintages ..) and song (music ... good music).
Followed next week by another great time in southern Texas.
I agree with Dertonarm on this subject. DD turntables vary due to their designs and construction. Some are very accurate. String drives can indeed be very accurate, as long as the string is fresh. Idler drives, the one I know a little about, have an inherent tracking error of around one part per million, depending on the footprint of the idler wheel itself. Belt drives are not so inherently accurate as the others, although advances have been made to alleviate belt creep through various workarounds and, of course, the recent use of tape.

So, a controller should be pretty accurate, but exactly how much? I believe one part per million accuracy is reasonable, but if we do that, we can easily substitute a standard clock with an OCXO (oven controlled quartz oscillator) with GPS referencing, which can improve the accuracy of a properly designed controller to around one part per trillion, or better. Can anyone hear the difference with such a controller connected to a turntable that is only capable of one part per million accuracy due to mechanical constraints? Certainly, the math doesn't warrant the extra effort, but at least all bases are covered. Would such an accurate controller be warranted with a proper string driven table? I don't know, but virtually anyone can hear a measurable difference with a good controller. That much I do know. If you have the opportunity to compare a turntable without a controller to the same setup, but with a good controller attached, listen for little parts of music that we never typically use as a guide, like small sounds from background reed instruments. You might be surprised.


Most turntable owners believe, they get a Product which is done right, more or less perfect for the money and all they have to do as next step to think about the ultimate technical solution (independent from price).
This is another common wrong way in audiophile existence. When we go back to the basics, lets think about the belt. Most of them are so horrible from quality and specs, it is hard to believe. Basis did a better work but most belts I tried produced so much drift, that any discussion about following Design features were wasted time.
Even with a heavy platter like shown in the picture showed me results, which were amazing ( really depressing what some 'manufacturers' offer us as 'High End'.

Belt comparisons..

These comparisons are even more depressing with light Platters....
The Audiophile gets what he deserves. Marketing and Fangroups can replace a lot today ....anyway...fun counts.
Tomorrow is another day to transform a big orchestra in a lifelike presentation into a owners home who did a lot of things right....
Nice horns. Seems a real shame to produce all of that analog music and then run it through digital time domain processing. Sorry, the purist in me won't shutup. :-)

How can correct turntable speed as well as excellent speed stability possibly NOT matter and be of the utmost importance? Rhythm and time is where the heart and soul of music lies. Any technical considerations that may have an effect on these are of the utmost importance. I am constantly perplexed by how often audiophiles agonize about minute changes in areas that affect the tonal/timbral characteristics of their audio systems, but are willing to forgive much larger deviations from truth in the area of time and rhythm. 

I hope we can agree that our audio systems exist to be at the service of the music. Musicians, not audio systems, make music; and musicians  give a great  deal of importance to performance considerations that relate to the perceived effects of correct playback speed and speed stability. The changes in pitch as they relate to performance standards are more subtle than what is generally discussed in relation to technical accuracy in turntable systems. These considerations are not arbitrary, but relate to the emotional impact that tuning has on the music. This is not only the players' consideration, but sometimes also the composer's intent. It is well 
documented that many composers chose to compose in a particular key because of the emotional effect of one key versus another. Likewise, orchestras or individual players will often tune their instruments to achieve a particular sound and it's resulting emotional effect. If we are going to worry about the effects things like slightly raising or lowering VTA, why dismiss the effect of these other considerations when these relate much more to the core of the music? 

Speed stability is even more important as it relates to these considerations. Excellent comments have been made above about the importance of these. There is no question that extremely subtle deviations from absolute pitch stability are quite audible. As has been pointed out, even the very best belt drive tables suffer from these distortions. What is really insidious is the effect that these distortions have on the emotional impact of the music, and the ability of the music to engage the listener. As this relates to musicians' performance standards, I would like to point out that the effects from the absence of absolutely stable playback speed on the music is not nearly as subtle as the considerations that musicians give to absolutely stable and accurate time and rhythm during a performance; these can be the effect of anything from simply the mediocre sense of rhythm on the part of a particular musician, to wether a musician had too much coffee that morning (I kid not). If we can agree that these things matter during a performance, how can similar effects not matter a great deal during playback?

Sorry for the hyperbole.

Our own TT's speed stability did go through two periods where it drove us nuts. We heard the first problem yet no commercial strobe showed it. Paul built a custom, higher resolution strobe and we captured many hours of data to demonstrate the problem to Teres. The data helped Teres identify a problem in their motors but it took them three months of testing and measurement to confirm that the redesign/rebuild actually fixed the problem. The other problem was subtler and was addressed by our own experimentation with better belt materials and implementations.

That Aries was a touch soft on transients but much better than most BD's we've heard. In our experience many (mostly less costly) BD's are unlistenably bad due mostly to poor belt materials, as others have said.

OTOH, concluding that idler wheel/rim drive designs are inherently better than BD's would be going too far. We've had such a design in our system, made by Teres, and it was audibly inferior to our carefully worked out BD. Implementation is always critical and individual cases may trump general rules.
Dear Frogman: We have to take care about. Unfortunately no one of us have control over the recording proccess where happen " terrible " things that " disturb " ( for say the least ) not only what you are pointed out but the " original " essence of the music.

We can't restore what already were degraded on that recording proccess but at least we can take care that that degradation be the lowest one and certainly the overall TT speed subject is vita. As I posted:

+++++++++ A TT exist because the LP needs to spin for we can listen it and has to spin always at 33.1/3rpm or 45rpm : period. " +++++ NO excuses here.

Regards and enjoy the music,
Dear Dougdeacon: ++++ " concluding that idler wheel/rim drive designs are inherently better than BD's would be going too far. We've had such a design in our system, made by Teres, and it was audibly inferior to our carefully worked out BD. Implementation is always critical and individual cases may trump general rules. " +++++

what do you mean with this? that Paul and you listened to two TTs bis a bis with similar tonearm/cartridges at the same sessions/comparisons?

I know both of you and I have no doubt on what you posted it is only for I can understand how that comparison was made.

In the other side, implementation as you said is critical on any audio device design or on tests as the one you mentioned.

Regards and enjoy the music,
Doug, what was the nature of the Teres fix? Did they increase sampling or resolution of regulation or something else?