Has anyone had trouble with speed on their tt

The OP suggests that there was an actual malfunction that was speed related.

I would get some good days and then the temperamental thing would drift or even radically switch speeds ending my listening session

Two areas of difficulty here that can cause intermittent speed problems: the speed selector switch, which might need cleaning, also if the 'table uses any kind of servos to control motor speed, there are often potentiometers that are used to set the range. If they develop corrosion it can result in intermittent behavior. A simple cleaning (using a $5.00 can of contact cleaner from Radio Shack) can correct the problem in either case.

Some turntables do not have accessible servo circuitry outside of the motor, in which case the motor itself will have to be replaced.

In belt drive machines if the belt is perishing, it can settle at the wrong spot on the motor shaft, causing the 'table to be off speed. In some cases the motor shaft angle can be adjusted to allow the belt to set itself to the correct position on the shaft; if the adjustment is off this may cause the belt to have difficulties doing so.

Google cog free , Ironless rotor , encoder with absolute Position,,, http://www.aeroflex.com/ams/motion/datasheets/motion-motors-zerocogging.pdf

Mosin You might be onto something about the platter being so important to speed control.

But thanks to everyone for the thoughts. I had bought Origin Live's best tranny/motor DC200/and motor controller and had problems so I bought a second complete O.L.system and had them both turning a heavy steel Aerex flywheel. The VPI tt was updated to the super platter that is now defunct. It was driven with belts and I tweaked them for just the right tension and everything lubed and leveled and was always unhappy with my speed. My McIntosh 831MVP blu ray player with Upgrade Co mods cannot touch Expressimo's turntable and motor. Plus Mac had trouble with the transports and it took a long time to get mine back after owning it less than a year. Digital does have excellent speed and if you get a good modder like David Schulte to shield it properly you can take the jitter out of the digital system. My vinyl still bests it by a good margin.

Omsed.
If you are observing dynamic speed changes, greater than 1% in a closed loop system, I would suggest that the TT is poorly designed or malfunctioning.

Technically whatever it is the proof is in the play back, one outstanding example that will shock anyone that thinks they are familiar with this outstanding RCA Living Stereo recording is Belafonte at Carnegie Hall, Belafonte's vocals are much different, it will stop you in your tracks.
I'm not claiming that I have any answers why this Lp sounds the way it does including others that I thought I knew well, but I think this goes beyond having a table that is capable of precise speed no matter what is going on in the music.

Correct, Tony.

Except...

System inertia is key here, and certainly not platter flywheel effect like some turntable designers would have you think. I like high mass platters, but where the mass is located is critical, in my opinion. If properly done, the platter can be an extremely important component toward reaching the goal of optimal system inertia. I realize that my view goes against conventional thought on the subject, but I am convinced that the location of platter mass is a big deal.

One day maybe people will see that a platter should be more than a big round chunk of whatever, but right now there seems to be little thought put into platter design. Guys use a lot of different materials in lots of different combinations, but in the end they are still nothing more than big chunks of whatever for the most part. Isolation and tone seem to be the only concerns. That and marketing hype.

The motor provides torque to hold speed. Platter mass is a component of the drivetrain system and affects how the system responds to changes in load and torque. A high mass platter does more for isolation of the record than the inertia effect. That's because more platter mass requires more motor torque. I have said before that if a motor can bring the platter up to speed in under one rotation, then it probably has sufficient torque. An undersized motor will struggle with the micro dynamics. The motor and platter are part of a system. Any one of the two out of balance results in poor performance.

Richard, very easy to read with a frequency counter and test record with steady tone. In a fraction of a second I've seen servos change 30 hz when playing a 2150 hertz tone.

Read Doug Deacon's last post again. He gets it.

Zavato said, "stick with a design that has an AC synchronous motor and a platter heavy enough to have some flywheel effect."

I could not disagree more. Flywheel effect caused by the platter is the reason many turntables lack micro dynamics, or sound lackluster in more general ways. It is a simple case of letting the platter control the speed, rather than the device assigned the job, the motor. That doesn't work, if you want a turntable that is truly precise.

Dougdeacon said...

"No strobe (Timeline or otherwise) operates in short enough increments of time to detect micro-/pico-/nano-second variations. Knowing that a TT is speed stable across a time span of minutes tells us nothing about how stable or unstable it may be across a few thousandths or millionths of a second. Such short-period variations are just as audible and musically important, arguably more so."

Brilliant. This is so true.

Tonywinsc also touched on the same point.

IMO it is the reduction of these tiny speed changes that is one key to a TTs performance. Do we have a way to objectively measure this? Maybe, with some of the new optical speed sensors capable of measuring greater than 1x10^6 counts per rev, but I sure know that we can hear it.

So, stop spending big money on TTs which may or may not hold an accurate speed. I stand by vintage tables with Quartz Lock. I can live without the extraneous info regarding arms, platters, etc. Just give me a consistent 33.3 speed and much of the other takes care of itself.

I count three speed related issues with turntables.
1) Absolute speed- this is what the timeline device can measure with utmost
accuracy. This is the least important of the speed issues with regards to how the
music sounds. If the platter speed is off 1% or less, who cares? You will not
know it unless you have a tuning fork near one ear while playing a record with
the same frequency tone for comparison.
2) Slow variation in speed. I'll define this as Wow&Flutter; which could also
include speed variation beyond the 1.8 second period if a motor controller has
an issue or if line voltage is an issue. The record itself is usually the biggest
contributor, (if you have even a decent level of turntable), to Wow&Flutter due to
center hole tolerances. If bad enough, piano notes sound sour. This is a more
critical issue than absolute speed.
3) Fast variation in speed. This is the big one. Take a look at my system page
for more detail about this. This was an eye opener for me. A lot of potential
contributors to this issue. The biggest problem here is that you may not hear it
or notice it directly; but once this type of issue is resolved you will be amazed at
the difference in sound. My contributor to fast speed variation was my
turntable's suspension system. It was causing high frequency oscillations in the
platter. Other contributors to fast variation in speed could be due to cycling of
closed loop controllers about the speed set point, speed controllers that
constantly adjust speed, motors with too little torque to overcome stylus drag
during loud passages, or motors with too much torque and also belt problems.

I believe that listening is the final test in evaluating a system; but I also believe in
using measurement tools to reduce time and trials in getting to that final
listening test. I put a lot of stock into Dr. Feickert's iPhone app. Use it as a
relative tool. I think the frequency measurements are dead on because the app
uses the iPhone's internal clock.

We have yet to define speed stability.

Glad to see someone acknowledging the complexity. The definition is actually simple. What's infinitely complex is the number of different time periods across which speed stability must be maintained - simultaneously - to assure musically accurate reproduction. This is routinely glossed over in discussions of speed stability.

No strobe (Timeline or otherwise) operates in short enough increments of time to detect micro-/pico-/nano-second variations. Knowing that a TT is speed stable across a time span of minutes tells us nothing about how stable or unstable it may be across a few thousandths or millionths of a second. Such short-period variations are just as audible and musically important, arguably more so.

The Timeline whoopla only considers speed stability across relatively lengthy time periods. While not insignificant, this ignores short-period speed stability issues that are more significant - at least to my ears. Its a bit of a tempest in a teacup.

stick with a design that has an AC synchronous motor and a platter heavy enough to have some flywheel effect.

The only time I had serious issues with my table's speed was in the week immediately after Hurricane Sandy. Once my home had power restored things were better.

Syntex has some good insight on the subject , but first ill ask, is it no wonder some have gravitated back to using the very best of vintage tables.
Syntax's comment which also crossed my mind , he said "Some inexperience manufactures simply did not do their research and home work, how true.
My $17,000.00 up front turned into 10 months of frustration , two motor controllers later including a check of both motors themselves just to end taking a hit when I sold it, inconsistent speeds were not the only issue , that was evident with my favourite Lps.
However I must take blame of course for believing owner testimonials which convinced me to jump in with both feet,..

Reliability issues are more common then some think however there are other forces at work.

Drubin,

It's a vicious circle. We have yet to define speed stability. There seem to be various camps when it comes to the finer points of that definition.

I'll say this much; I believe it is a relatively narrow field.

Kiddman says:

Everyone thinks they have great speed stability in their turntables until they hear one that does, then they wonder why the stable one is so clear, so natural, so right.

Which tables have great speed stability -- which are the best out there?

Dougdeacon is right.

_______

Thanks Mosin but I’m not dismissing any turntable. If users are happy with their Timeline compliant TT that’s great news.
You’ve indirectly summed up my feelings : Everyone should be happy with their TT choice because they chose it. (Timeline notwithstanding).
Let's just say I'm encouraging a little less automatic blanket demonisation of the turntable designing community, which seems to have been an unfortunate consequence of the Timeline Thread.
These issues appear to be taking over the OP’s Thread when it is clear his past/present problems go beyond simple +/-0.02% deviations between turntables or regular and repeatable behaviour of a fully functional power supply?

As an aside, the Rockport Treatise on turntable design was written over a decade ago (and it is wonderful reading). It’s likely that others, apart from us, have read it.
It would be foolish to think that being able to comprehensively describe design problems automatically implies the power to solve all of those problems.
I believe Rockport had a good stab at it (although you'd be struggling to get one now unless you are a millionaire). The new kid on the block – The Beat – is already up to Mk IV/V(?), so it isn’t THAT easy???

Marketing is a powerful tool and Timelines must be flying off the shelves at the moment.
At the end of the day it is just a strobe. An accurate one but a strobe nevertheless. My strobe gets used once then sits in a cupboard for 3 years. (Ok the Timeline is also a record weight but clamps & weights are not always desirable in all circumstances. Indeed, the designer of The Beat claims he tested most of them and is of the opinion that if the turntable design needs one then it is fundamentally flawed(!!)
Granted, that’s only one opinion - two if you include mine – because I’ve always disfavoured them on the grounds that they “stressed the vinyl”, perhaps not quite the same reason/s as his :)
Of course, the Timeline is removable and storable in the cupboard for 3 years. :)

Digital has a perfect timebase but we prefer the imperfect. That’s my core message. (Timelined or not, still crude)
Never thought I’d see the day I’d be using Digital to strengthen an analogue point. :) :)
Nice to see it’s good for something ;) 

Finally, I think some of my Timeline remarks, although humorously intended, were slightly inflammatory, so I owe the lads an apology if the comments caused them any grief.
(In fact I thought the reactions exceptionally kind and polite, all things considered. Hope I will be welcomed back!
All the best....

Mosin is right, for the second time in the same thread!

Moonglum, You are the one with the agenda. It is possible for turntable to sound great and pass the Timeline test. It is also possible for a turntable to sound awful (or at least less good than some other tt that fails Timeline) and yet pass the Timeline test. The Timeline can only tell about one vital but not exclusive aspect of tt performance; it cannot tell us about resonance control and other more subtle aspects of performance that affect sound; those Timeline guys know that as well as you. However, the main function of the tt is to spin the LP at exact speed at all times and against any frictional drag, so as to re-create the X-axis of music. There's no getting around that. Whether the Timeline test is the sine qua non of that aspect of tt performance, or not, is another matter.

And by the way, I don't think jitter is the digital equivalent of speed inaccuracy in a tt, but you raise an interesting question in that regard.

Moonglum, you are correct, except you dismiss the possibility of a turntable that can pass the Timeline test without servo controls and still involve the listener in the performance.

I just want to know what was the OP's turntable, described as "a very expensive dual DC motor top of the line system of a well known brand from England." Since it's a two motor design, it would have to be a belt drive turntable but I just can't think of a English brand that uses two motors. I know AudioNote UK uses 3 AC motors for their top of the line table. But seems like many commenters are inferring Direct Drive turntable, buzzwords like DC motor, servo, hunting, etc... Are we talking about DC motor or DD turntable here? I'm confused.

_______

“Slow Death by Timeline .”
I’m not a turntable designer but taking servo controls out of context without considering that flywheels and rubber belts influence stability is, to my mind, misleading at best.
To assess a design you need to look at the whole design not just one element of it. Anyone not doing this has an agenda.

In the best of humour, to the Timeline Fanatics, I’ll play one that beats you .
A digital system, when the output is rendered, has a perfectly clocked timeline. It has an accuracy that no analogue system can match and is far better than any Timeline tested example.
The level of jitter is usually, at worst, of the order of hundreds of picoseconds or a nanosecond. This equates to a vanishingly small speed error.
Does this mean that the pitch stability of my digital replay is so good that I instantly comment on it and prefer it to those turntables of “ill-repute” deemed unworthy of merit?
H*LL NO!!!!!!!!!!!!! :D ;D
Those “unworthy” turntables are by far preferable and pass the only test which is important : they involve me in the Performance to the exclusion of all else.
If, as a result of Timeline inspired disillusionment, anyone would care to sell an unworthy turntable of ill-repute at a knockdown price, I’m here. ;)

Of course, Timeline fanatics could, if they wish, dispense with the LP altogether and watch the turntable rotate in preference to listening to music?
The Timeline hype reminds me of the Philips “Perfect Sound Forever” marketing blurb which obsessed about surface noise on LPs. Before you knew it, every listener was holding their breath focussed intently, not on the music, but waiting for the next click or surface imperfection to occur. At a stroke, the marketing changed everyone’s perspective. They had successfully persuaded most of the consumers to stop listening to the music and focus on background noise instead. It took years for the population to re-learn that analogue wasn’t so bad after all.

We don’t really want to go there (again)? (Do we .?)

Syntax, Mosin, and Hiho are correct. What a motley crew.

No i have TW AC3!!

"corrects for drag instantly...."

Not possible. Instant velocity change to the correct velocity would be like a perpetual motion machine.

Fast correction = flutter.

Slower correction = wow.

Slow correction = drift.

All affect the music. Correction (servo circuits) are bad for this application. It's why no master tap machines used them, which is directly addressing the OP's stated problem, his DC turntable's speed problems. DC motors need servo circuits, and those are very compromised for this particular use, high end turntables.

Everyone thinks they have great speed stability in their turntables until they hear one that does, then they wonder why the stable one is so clear, so natural, so right.

Kiddman, there are no motors or turtables with absolute speed stability. Every motor is subject to "kick & coast" - the effects of which cannot be completely removed. It would be nice to think it could be engineered to be 100% non-cogging but it can't.

Even high-tec radical solutions to compensate for inherent issues of suspended chassis tables such as the Kronos which uses counter rotating platters are still flawed because the basic engineering cannot be accurately balanced e.g. weight & tension of materials etc.

To give another example, an Avid Acutus would be one of those poor candidates you mention but I would cheerfully buy one today.

Mosin is right.

_______

Why not just get a speed control? That's what they're made for.

Yup 2 TTWeights TT would not keep accurate speed as told by a Timeline device!

Most turntables of "repute" are not withing very good limits. When you hear a real stable one you realize that. The OP and Syntax are not wrong.

And all DC tables, something that is coming back to be more popular, have servo circuits, and all of them hunt, easily audible when you finally hear something that does not drift and hunt, and easily measurable.

Modern economics in high end audio: give the absolute least you can, don't think of serviceability, get the sale at all cost.

Yes from a new $17,000.00 table purchase back in 2008, after complaints a new motor controller was sent to me which the manufactured called , an upgraded motor controller.
Just a poorly designed controller in the first place and the new one wasn't much better.
My ears were telling me there still were problems with this table however mentioning this on the happy owners group I hurt sensitive egos and was called names, really the joke is on them.

Syntax is right.

I base my speed opinions on sound...if it sounds good (not warble intensive) it's good.

As moonglum says, static buildup can be an issue. I never had stabilty problems, but the controller on my TW Accustic Raven one, suddenly switched to about 300 RPM, luckily, not with a stylus on the record, or that would have been toast. It was indeed due to static build up and the unit was replced, free of charge, with no quibbles, even though it was 3 years old, now that is service. I don't think spending money on kit prevents maintenance issues, perhaps it should, it improves quality and hopefully, after sales service.

One other thing to try, I found using a good, after market power cord, a lessloss, made a big difference to sound quality, which rather suprised me. I thought if one bit of kit would be immune to a better power cord, it would be turntable controller, not so.

just had an issue on a technics 1200, a machine that is supposed to keep perfect time. i swapped mats and was using a leather 45rpm small mat under a cork on cork spot mat. Was hearing sour notes and wowish kind of sonic. turns out the cork mat was slipping on the leather mat. i placed a rubber mat under the cork and all locked in. what would you call that as an issue: mat slippage?

The experience you describe goes beyond simple speed stability issues since most turntables of repute are within reasonable limits.

Your controller switching speeds on a whim is a reliability issue and there have been quite a few cases discussed here and on other forums?
One possibility I would consider carefully is static discharge during handling and operation of the controller. If you have a power block with an external earth binding post nearby, it might be helpful to briefly "ground" yourself as a precaution against damage each time you operate the turntable?
If your supply is already damaged I'd be inclined to get it checked by the manufacturer. No point in suffering any longer! :(
Hope this situation improves.

Well, Syntax, you might be right. I have Expressimo Audio and it is working great as it checks its speed 500 times per revolution and corrects the speed if there is any drag instantly. If it ever needs tweaking at all, a laptop plugs in via USB and it can be calibrated to a strobe to the tenth of a rpm. TTW also has a motor system that has favorable review I have read. Brian of Expressimo also uses very precise machining and a great ceramic bearing on his turntables and they are leveled and balanced precisely. what system do you use?

A very sensitive topic. Most owners don't want to know that. There are a few discussions about drifting Turntables (especially when the Sutherland timeline is used). You find for example for a lot of turntables huge owners "recommendations" but this chapter is completely denied. Based on my information, most of all modern turntables (no matter which pricing) can't hold proper speed. The reason is very simple: Maximum Profit. If you look at it from the pure standpoint of an engineer without any audio perspective – free from audio pre-knowledge and history - learning from scratch about mechanics and static and dynamic behavior in moving objects, you’d find that a lot of designers have simply not done their homework.
Who is interested to tell others "Hey, I spent 35k for a 3 motor unit but it runs wrong each day differently?" It is much more easy to keep the own "reputation" as a "serious, experienced audiophile" and say "Mine is right..."
I think, you won't get much - honest - answers. That experience - or learning - is something you will have to do on your own ...