LP12- Power Supply- Need education

I have read a lot about different options to upgrade the analogue power supply.
A phono stage need to amplify micro signal would require very good power supply to ensure there is minimal noise interfere with the signal.
I read about Lingo and other power supply articles, however they never mentioned about the science behind it.
How could a power supply powering a motor will introduce noise to the cartridge especially belt drive?
How do you measure the noise when playing a record?
Or would  the power supply provide a more stable rotational speed, my speed measurement on the turntable shows very consistence rpm once it is playing?
I really do not understand why a Lingo power supply cost so much but cannot provide an improvement with a measurable results.
Could someone educate me.
msnpassion, I think you answered your own question. Having owned two LP 12s, the problems I had with that table had nothing to do with it's power supply. Rotational stability was fine and none of the cartridges I used with the LP12 had a noise issue. I expect you are about to hear all sorts of conflicting opinions all based on razor sharp hearing abilities I obviously do not have. 
If you have a Linn, perhaps you can borrow a Lingo PS and listen to it for yourself.
Suspended tables like the Linn are not my cup of tea. Not at all.

But you didn't ask that. You asked how a turntable motor power supply can make it sound better. Actually quite easy to answer. Should not even be all that hard to understand.

Its really enough to understand the primary component in a power supply, the rectifier diode. These tiny little parts, all they do is convert AC to DC by allowing the AC to flow one way only. Pretty simple. Should hardly even matter really, because the resulting DC power goes straight to a bank of storage capacitors. These things are typically over spec, meaning the caps store enough power to run the unit even sometimes for many seconds even after being turned off and unplugged.

So how could diodes possibly matter? Well, I don't really care. All I care is I know if I swap them out cheap bad ones for expensive good ones it makes a huge improvement. Not subtle hard to hear. Huge. 

But you asked technical and there are technical reasons like switching speed. Looked at microscopically and at high speed nothing goes perfectly on and off. There's always a transition of some kind. Its the speed and slope and nature of that transition that matters. Because yes, in spite of all the capacitance you can throw at it some ripple still gets through.

So technically what you have then is a power supply with less ripple. That's just one reason. But a big one. More than enough. 

But we got more. There's also the way the power supply responds to fluctuations in demand. Because it only looks to us like the motor and platter and all are turning at a perpetually steady constant rate. In reality and viewed up close and microscopically again the whole thing is vibrating like crazy. People use examples like bass notes or drum whacks or orchestral crescendoes, all things with massive groove modulation that makes it easier for us to accept the extra modulation is extra drag that might cause the platter to slow down a tiny amount.

In reality this is happening all the time. Its never enough to hear pitch changes. Nothing like that. You make a change that affects speed like I'm talking about and you will understand. These tiny near instantaneous speed changes are heard as hard, flat, lifeless. Improve the power supply and you hear more sense of ease, more depth, greater drive and life. Its not hard at all. 

If the improvement in the power supply is significant, I mean. With Linn, who knows. I am not a fan of Linn. All the Linn I have heard is overpriced and underperforms. Turntable, phono stage, all of it. To go by my experience then this power supply is probably not going to be much different. Lot of money, might sound a tiny bit better.

Doesn't change a thing about how it is that technically a power supply can make a difference. You asked. No one else got it. So I answered. 
Great reply.
The vibration from power supply 'Ripple" should be measurable. I believed it can be quantified as a frequency rate and the intensity of the ripple.
Why there is no such articles or measurement being published about the ripple effect with Lingo and without Lingo as a comparison?
How much ripple would start to have audible effect? What would be the threshold?
If we use DC- battery power supply, it will eliminate the vibrations generate from AC to DC, am I correct?
How could a Lingo power supply will cost an arm and a leg to make given the technology and parts are now available at a reasonable cost.

One of the major things, if not the major thing, that power supplies like the Lingo, VPI SDS & ADS and other turntable power supplies designed for AC motors do is ramp the voltage down significantly after startup.

The Linn and VPI power supplies, for example, ramp voltage down from about 115-120 (in North America) at startup to between 70-90 volts which results in a fairly significant reduction in motor noise & vibration (which is transferred directly through the belt to the platter).

You can achieve exactly the same thing with a variable output transformer for less than $100, which is what I've been doing with my Michell Gryodec for about the past 8 years. On my Gyrodec, if you start the table at 115 volts and then ramp the voltage down, you can literally feel the motor vibration reducing/falling off if you place your hand on the motor housing when doing so.

Using Audioorigami oil and replacing the steel ball in my Gyro with a Grade 3 silicon nitride ball from Boca Bearings (about $3), I can reduce the voltage to around 50.

Improvements are unquestionably audible; whether it is worth a thousand or two thousand dollars is entirely subjective, of course, like most of this hobby.
Are u implying the start-up of the turntable will generate most of the noise and thereby it will not eliminate as time progress (Newton Law: Conservation of energy)
If this is the case, why can't we manually turn the platter during start and let the low torque take over once it is running which consumed minimal voltage during normal operation.
This is like Nottingham turntable spacedeck, if I remember correctly
Yes, and it is exactly the approach that the Nottingham takes I believe.
Like someone posted above, if you have a chance to hear the various power supplies that Linn has available for their LP12, I am fairly sure you will easily hear the difference each makes. The top of the line Radikal D is not just a power supply upgrade, it is also a whole new motor that runs DC. The Radikal D power supply is the most precise power supply option in the Linn line. As such, the rotational accuracy and ability to keep speed regardless of drag from the cartridge is unsurpassed. The DC motor also is extremely quiet and is controlled with accuracy from the power supply. Having advanced from a Valhalla power supply ...which in itself does a better job than the Majik power supply, or the old Nirvana power supply, I can tell you there are huge gains to be had from going up the chain. Now, as usual there will be naysayers on this thread, typically from folks who haven’t heard a current Linn Klimax, or who used to own a Linn...twenty plus years ago! Today’s new LP12 is absolutely NOTHING like what these posters state...and the ONLY way you can determine this, is to listen to a top end LP12 yourself, preferably one that has been set up by a pro dealer, and not one that your local car mechanic just cobbled together.
See msnpassion. All this is meaningless mental gymnastics.Any minor irregularities are filtered out by the mass of the platter. They never make it to the record.
Millercarbon since I know you are a smart guy I have to believe that you have never had a chance to live with a properly designed suspended turntable. The Linn is far from properly designed. It is designed to give you heartburn it is so unstable. Once you live with an SME or suspended SOTA for a while you would not live with anything else. They are amazingly stable and nothing gets to them. I can not speak for Basis as I have never lived with one. Get or borrow a medical stethoscope and listen to the surface your turntable is on. Even if it is granite on a concrete floor you will be amazed at the stuff you will hear like the washing machine and your air conditioning compressor not to mention all your subwoofers. Listen to your platter. Hopefully you hear nothing. Don't forget to take the mat off. If you listen to a Linn platter you will be able to pick up radio stations. If you listen to an SME or SOTA platter you will hear nothing. Now if your setup is on a wood floor there is absolutely no comparison. If you jump up and down in front of a Linn you will send your cartridge to the moon. If you do that in front of any mass controlled table you will get the same effect. If you do that in front of a SOTA or SME you will see their suspensions do two or three slow cycles and the tonearm and cartridge continue to track perfectly as the whole mess is moving perfectly at 2-3 cps well below the cartridge/tonearm resonance frequency. 
Millercarbon since I know you are a smart guy I have to believe that you have never had a chance to live with a properly designed suspended turntable.

My first turntable was a Technics SL-1700. Still have it. Next was a Basis 2005, another suspended table. Had that one around 10 years. Not sure about the Technics, but Michael Fremer himself recommended the Basis (along with a similar VPI) when he called to help me out. So pretty sure that yes, I have lived with a properly designed suspended table.

Living with the Basis taught me a lot about turntables. Taking it all apart, seeing how its all made, modifying and hearing how each mod affects the sound. Its all been described before but every part- motor, belt, power, platter, bearing, suspension- was over the years changed. Not merely swapping out one whole table for another like most guys do. How can anyone possibly gain any understanding of what each part is doing if all - the whole thing- is changed at once? Impossible. Changing just one part at a time- the belt for example, or the motor, or the bearing- that's how you learn what's going on.

Any minor irregularities are filtered out by the mass of the platter. They never make it to the record.

Good example. First thing I ever did, swap the power cord on that Basis turntable. Same platter, same mass, same bearing. Same motor. How could the power cord make a difference? It did. 

I have changed motor, pod, motor pod feet, motor pod support location, and material, motor controller, motor controller umbilical cable (!) and more- all with the same bearing, plinth, and massive platter. Easily heard differences each time- not all of them a lot or good but always a difference. If platter mass filtered it all out then how is that possible?

Oh and yes some of it is damping. Also have changed damping under the motor, turntable, plinth, and base. Individually. So I know exactly what each change sounds like. There is definitely a difference between the lowering of the noise floor and revealing of inner detail that damping achieves and the reduction in grain and glare and improved air and depth and imaging that comes with more precise speed control.

Every single one of these is a trade off of some kind or other. Damped and isolated lowers noise- and dynamics. Massive and stiff is more dynamic- and noisier. There's a million different stories but its trade offs right down the line. Would love the chance to hear a SOTA. Never even heard of anyone who has one, least not around Seattle. 


None of the power supplies mentioned here, including any of the Linn options or the VPI PSs, incorporate a feedback mechanism whereby instantaneous changes in platter speed can be sensed and corrected. What you do is to set the PS such that your platter is turning at 33.333 rpm using one or another technology (recommend KAB strobe device)  to monitor the speed while you set the power supply. After that, the platter is on its own; the PS cannot account for belt slip, belt creep, stylus drag, etc. Phoenix Engineering made an aftermarket power supply with a separate tachometer that connects to the PS and feeds back speed errors that could be due to any of the above, which are then corrected.  PE no longer markets these devices, but SOTA has worked out a deal with the PE engineer, Bill Carlin, and essentially PE equipment can now be purchased through SOTA. Some think this sort of mechanism introduces new problems due to the act of correcting the aberrant speed, which, such persons think, has the potential to be as audible as is any momentary degradation of speed control.  I don't agree based on my personal experiences.
The mentioned method of running the turntable motor on reduced voltage to reduce noise does not always work well with all types of motor, and carries with it the penalty of a loss of torque. In fact, I think at least one of the VPI devices works by lowering voltage and/or current. I don't know whether Linn uses an AC or DC motor, but if you can adapt an AC synchronous motor to your Linn, then in my opinion the very best option is to buy such a motor and the SOTA/Phoenix Engineering products to run your Linn.  In my experience, ANY competent motor power supply makes a huge upgrade for a belt-drive motor, but the PE stuff is the absolute best.
I am not a big fan of suspended turntables with lightweight platters, but if I had to optimize one, I'd go that route.  I do use the original PE gear to run my Lenco, and I am very happy with the results.
None of the power supplies mentioned here, including any of the Linn options or the VPI PSs, incorporate a feedback mechanism whereby instantaneous changes in platter speed can be sensed and corrected.
You’re incorrect, both the Linn Lingo 4 and Radikal use sensors in a closed loop with a speed control which monitors platter position once per revolution. The Lingo 4 accomplishes this with an AC motor and the Radikal a DC motor. I have direct experience with both and they are at the very least equal to the Phoenix Roadrunner/Eagle (I owned and used both Phoenix products on VPI and Basis turntables.).
@saburo   +1

There is, as usual, a ton of misinformation and pure 'BS' being foisted by those who really have absolutely no clue about the sound of a well set up Linn LP12. 
I love this from mijostyn...'listen to a Linn platter, you will be able to pick up radio stations'..ridiculous!
Millercarbon, the power cord made a difference only because you wanted it to. In reality it did not make any difference. Don't feel like I am picking on you. I sometimes have trouble separating psyche from reality. I have never used either turntable you have mentioned and can not speak to their performance. If you had problems with them then I would have to believe they were either not set up correctly or were not good examples of suspended turntables. Neither the SOTA or the SME are sexy turntables. The industry knows that if you make something look sexy enough many people will think they sound better. The reason most turntables are not suspended is because it is not an easy thing to do.
You either have to make it massive so that any additional mass (the tonearm) is trivial (SME) or create a system were in you can compensate for the mass of the tonearm (SOTA). Both turntables are far more accurate than the resolution of your brain to detect any speed variation flutter, wow or otherwise. All you are going to get out of a more massive platter is higher shipping cost and faster bearing wear. 
Very few upgrades result in "huge" improvements.  I think you minimize your opinion by describing variations this way. Whenever I hear "huge," "dramatic," "incredible," I automatically turn the comment off. 
I heard a demonstration comparing a Clearaudio Statement/Goldfinger combination with an SME 30/12/V12/Goldfinger combination and if there was a difference I certainly could not hear it neither could anyone else I talked to. None of us knew what was playing at any specific time until the end of the demonstration. 
Davey, I lived with LP12s for 10 years. The only thing I have nice to say about it is that it had a dust cover. The only reason I stuck with them is because until the SOTA Sapphire came along everything else was worse. You want to know how crappy the LP12 is? Get your self a SOTA Sapphire. 
"There is, as usual, a ton of misinformation and pure ’BS’ being foisted by those who really have absolutely no clue about the sound of a well set up Linn LP12.
I love this from mijostyn...’listen to a Linn platter, you will be able to pick up radio stations’..ridiculous!"
The problem here is that some posters insist that what they hear and experience should be exactly the same as what you hear and experience. If it’s not, they insist the problem is with you, and not them or attributable to some other variable. There’s no way to reason with such folks. Beware the audio guru.

The LP12 is an extraordinary turntable - truly first class. It’s not my preference at all, but I surely wouldn’t criticize anyone who has chosen one for their system, especially if it’s one of the later versions. Linn has updated this turntable substantially over the years.
Saburo, thank you for the correction. I admit I was not familiar with the very latest Linn add-ons. Perhaps they’ve been inspired by Phoenix. My general point about the capacity for speed correction is still my recommendation, while I also recognize it can be a negative if not done well.
Mijo, perhaps the modern or updated versions of the Star Sapphire are speed stable, but my late 90s Series III was anything but.  At the time, it was all I had to judge by, and it had me thinking that it is the nature of vinyl not to be able to deal with sustained piano notes. Then I found out, after owning a succession  of other turntables, that the star sapphire was the absolute worst in that regard. Every belt drive, idler drive, and direct drive turntable that I have owned since about 2000 is superior to the Star Sapphire in speed stability, and its shortcomings are quite easily heard. I do respect SOTA as a company, and rumor has it they fixed their problem, whatever it is or was. Surely they’ve now fixed it with the adoption of the Phoenix Eng control system. But please don’t suggest that speed instability can’t be heard.
@lewm wrote....Mijo, perhaps the modern or updated versions of the Star Sapphire are speed stable, but my late 90s Series III was anything but.

That was my experience with SOTA as well. The Phoenix inspired 3 phase SOTA Eclipse motor is an add-on option for the Sapphire and Nova series of tables and standard on the Cosmos. I am not sure how the new SOTA stock motors fair when compared to the older generations. I always admired SOTA's build quality
@mijostyn  You say you lived with an LP12 for 10 years...when was that?...thirty years ago!! 
Funny thing, I used to own a SOTA Sapphire, liked it for the time, but sold it and replaced it with a VPI 19, which killed it...then i sold the VPI when i heard what a well set up LP12 could do. This was many years ago, since then I have basically taken that LP12 and updated it to current Klimax status. Only thing left of the original LP12 is the top plate. To say that my old SOTA Sapphire could even come close to competing with my current Linn is a total joke. I will say to you...IF you want to hear how crappy your old SOTA Sapphire sounds, listen to a new LP12 Klimax. LMAO. 

@cleeds   +1
Hi Dave,
Could u tell us about the Klimax upgrade?
I have to say I never feel the LP12 sound stable, my direct drive t/t sounds better and less complicated to setup.
I felt the construction of the LP12 is flimsy and not exactly well made.

There are so many new entries t/t to the market in the last 10  years.
I am not sure how well the Lp12 lived up to the modern design.

@msnpassion. The LP12 Klimax...in its full guise consists of the Radikal Klimax motor controller, a Urika 2 phono stage...which is mounted on the Trampolin 2 base, the Keel sub-chassis and the latest corner reenforced plinth, the Cirkus bearing,the Linn Ekos Se tonearm and lastly the Kandid cartridge.
i personally don’t use a Urika phono stage, or the Ekos Se, Kandid or Klimax cased Radikal. Nonetheless, I think that all of the updates from the stock LP12 from years back transform the table into a far more accurate and resolving platform.
The Radikal and the more rigid subchassis, DC motor, and the more precise Cirkus bearing brought very very significant changes to what was an already good table....but not one that in the past could really compete with the best today. Personally, I believe that these later mods have brought the table competitive again.
Now, let’s hear it from the naysayers who heard a poorly set up LP12 decades ago...or owned one of the basic models and never got it set up right.
You say it feels flimsy??— not sure what you are talking about, or your frame of reference. Flimsy certainly isn’t one of the things that I would describe the LP12 as....robust yes,..flimsy, nah.
daveyf, not even close. You have to have experience with multiple other turntables to know exactly how hopeless the LP 12 is. It is just not easy to make a silk purse out of a sow's ear. It does not feel flimsy, it is flimsy, Don't waste your money trying to make an LP 12 better save up for an SME or SOTA and get a real turntable.
Lewm, I have never had any speed issues with my SOTAs, not near as bad as tonearms bouncing off into space with the LP 12. But in case you are skeptical the new SOTAs have DC motors with microprocessor control. 
Daveyf, anybody who prefers a fixed table over a properly suspended one does not spend much time listening to vinyl. Unipivot tone arms are made by manufacturers who want to increase their profit margin. The newer Graham arms might be an exception. But even Graham had to resort to all kinds of magnetic wizardry to make it work. No anti skating? That should tell you something in and of itself. The last LP 12 I had was sold in 1980 for an Oracle another table that had much to be desired. I have not played with a recent one
Oh and Daveyf I have SOTA Cosmos with a Kuzma 4 point 9 on it as well as an SME 30/12 with a 4 point 11 along with a multitude of cartridges. 
If I can save someone the misery of buying an LP 12, even a used one I am a happy guy. You are better off buying a Rega or Project. At least you don't have to worry about your tonearm bouncing off into the ozone. There is no way to set up an LP 12 correctly. It is hopeless from the start which is why so many people have to invent up grades to it hoping that somehow they will be able to make it work right?? Give up. It is not worth the heart burn. Get yourself a Victrola. Play some old 78s. 
@mijostyn,    Since you just posted that the last time you owned an LP12 was in 1980...I think that tells us all we need to know. 
“There is no way to set up a LP12 correctly”...i’m sure back in 1980 that was your experience. LMAO.

”I have not played with a recent one”....but that doesn’t stop you from bringing us your two cents worth...right!
Quit being a troll and go to another thread.
Mijo, With due respect, I think the old problem with the SOTA Sapphire was that the motor was mounted on a stationary platform while the platter, of course, was suspended.  When the suspension was activated, that caused the belt to stretch and contract in time with the bounce.  This resulted inevitably in speed instability that was quite noticeable.  In fairness to SOTA, I heard or read they solved that problem a while back.  DC motor would not be as good as their latest Eclipse option, the one that incorporates the PE technology, which works on AC synchronous.

@lewm, lots of other tables have had their motors mounted on a stationary platform and their platters suspended: the Acoustic Research, Thorens 125/150/etc, Oracle, VPI HW-19, and of course the Linn Sondek itself. Did the old Sapphire have the slow-acting servo-control speed-correction that was clearly audible?

The new SOTA/Phoenix Engineering combination motor/power supply/tachometer is a dedicated, 3-phase DC motor design. Honest! SOTA is offering a version for use in VPI tables, the DC motor replacing the stock Hurst AC motor. PE’s Bill Carlin is adamant that a properly designed DC motor is far better than an AC: less noise and vibration, more torque and "drive".

There is, as usual, a ton of misinformation and pure ’BS’ being foisted by those who really have absolutely no clue about the sound of a well set up Linn LP12.
I love this from mijostyn...’listen to a Linn platter, you will be able to pick up radio stations’..ridiculous!

The Dunning Kruger effect is alive and well on this thread and A’gon in general. I pity the OP that was looking for info on the LP12 and then watch his thread devolve into a discourse on why Linn’s are a POS. unbelievable.

I have two LP12s, one with Basik arm and the other with Ittok ii. Also have a nice SOTA Sapphire with Well Tempered arm, and previously had a Star Sapphire. All fine tables, just simply a matter of personal preference, and mine is for either Linn.

The better power supplies do improve the sound of the LP12, making the table sound more grounded and locked in, so to me they are viable, though hardly a bargain.
Dear Bdp, I’d like to hear from Bill Carlin himself, if he really said what you say he said. If Bill did say that, of course I would yield to his far superior level of knowledge, compared to mine. But to take your point, first of all, DC is Direct Current, meaning it has no frequency; therefore it has no phase differential. So there can be no such thing as "3-phase DC". In a DC motor that operates off the wall socket, there is a conversion of AC to DC. (Teres had a DC motor that incorporated a battery option, I think.) I am guessing that AC to DC conversion may be happening in the new SOTA Eclipse motor AFTER the power supply works on the AC side to regulate speed. I really don’t know what’s going on there, but I also saw what maybe you saw on the SOTA website. It does mention the term "3-phase DC", which is an oxymoron. They’ve probably dumbed it down for us audiophiles. But most of all, if you read my earlier post, I too recommended the Eclipse upgrade, so we have no argument there. I don’t think a DC motor has inherently more torque than an AC motor. One DC motor may have more torque than another AC motor, etc. But there is no general rule. And anyway, where did I say that AC motors were superior to DC motors? (Your comment suggests that I did say that.)

I do know that the original AR X turntable was built as you say, with the motor on firm support and the platter suspended. Probably that was also the case for the Thorens TD125. (At one time or another, I owned both.) In my opinion, that’s a problem of design for suspended belt-drive turntables that has to be dealt with in one way or another in order for platter speed to remain stable when the suspension is disturbed. My AR X and my TD125 were no great shakes for speed stability. Finally, I have not been bashing the Linn LP12 or even the SOTA; I am just pointing out some issues. Nothing is perfect.
Ivor T used to believe that AC motors were the only way to go, that changed with the introduction of the Radikal...and its DC motor. ( Linn was never supposed to be interested in digital either...that also seems to have changed over the years.) 
Nonetheless, owning both the Radikal D with its DC motor and prior, the Lingo and Valhalla platforms with their AC motors, I can say that the Radikal D is a MAJOR step up in SQ over those speed controllers/motors. 

lewm, it was on the VPI Forum (as well as others) that Carlin voiced his opinion of the superiority of DC motors over AC ones in turntable applications, and he was also brutally honest in his critique of the Hurst AC motor VPI installs in their tables. He and Harry and Mat Weiseld really "got into it" on one thread, and Harry locked it. It's still viewable, however. I would provide a link to it, if only I knew how!

I'm unable to discuss what constitutes a 3-phrase DC motor/power supply/etc., as that is over my head technically. I'm only repeating what, not SOTA, but Bill Carlin said on the subject.

lewn, I did not say, nor even suggest, you had stated AC motors are superior to DC motors. Where did you get that impression? The same is true regarding the bashing of the Linn LP12 or SOTA.

The "problem" of a base-mounted motor in a suspended sub-chassis design is of interest to me, as the VPI Aries 1 I recently acquired has it's motor (the Hurst AC, of course, though the SOTA DC is being made available for it) mounted in a 15 lb. pod separate from the plinth holding the platter and tonearm. That is in effect no different than an AR/Thorens/Oracle/Linn, except for the fact that the plinth sits on "isolation" cones, not springs. But I just replaced those cones with Townshend Audio Seismic Pods (springs in a bellows-type rubber sleeve), for true isolation (cones provide that down to only 10Hz or so, not nearly low enough). Ya just can't win! But then, the Seismic Pods absorb vibrations, so perhaps their presence does not break the motor/platter/arm/cartridge mechanical integrity. Again, over my head ;-) .

No problemo.
if the new SOTA Eclipse motor is DC, and unless Carlin has totally changed his original design, I would bet the control is done on the incoming AC before it’s converted to DC to drive the motor.
If you guys are interested in what Bill did you might was to look on the DIY site.  There are quite a few threads on 3 phase controllers there.  Bill helped a lot, to say the least.

If I am not mistaken,  he is using a 3 phase AC frequency generator with even more bell and whistles than what we built.  He is running a 3 phase DC motor on 3 phase AC.  What Lewn has is a single phase frequency falcon or eagle, which I use to have.  The only DC that is going on is in the name.

Bill is a sharp cookie. Glad to see Sota realize this.

Enjoy the ride
There are two types of DC motors: Brushed (DC) and Brushless (BLDC).  Even with a brushed DC motor, the current through the windings must be reversed as the motor rotates;  this is done automatically by the brushes and the commutator ring, so a steady DC current is all that is needed from the supply.  BLDC motors do not have mechanical commutators to change the current, they are electrically commutated (EC) by using Hall sensors to signal the controller when to switch the currents.  When operated this way, they still behave as DC motors where the drive voltage determines the speed.  The speed of DC and BLDC motors operated this way are dependent on the drive voltage, torque load and temp, making speed regulation more difficult, especially without feedback.

  BLDC motors can also be operated as a 3 phase synchronous AC motor where the speed is determined by the frequency of the drive signal, which is made up of 3 sinewaves 120° out of phase.  The electronics to accomplish this correctly is more sophisticated than EC control, but it produces smoother operation, less cogging and more precise speed control.  The SOTA Eclipse motors use a 3 phase AC controller.  The speed can be controlled very precisely without feedback.

You can find more information at these links:


@phoenixengr   I believe in the Linn Radikal upgrade the motor is a brushed DC design.
@daveyf- I believe that is correct. If I’m not mistaken, it also uses feedback from the platter for accurate speed control.

Mark Kelly had an innovative design for a brushed DC motor controller that did not require speed feedback from the platter, but as far as I know, he never pursued it.
@phoenixengr That is also correct. There is an optical reader that mounts under the platter and reads a mark on the platter every revolution.
@phoenixengr - Mark Kelly had two very unique designs for open loop controllers, the brushed DC controller being one of them. The other was the Synchrotron AC-1, which was an open loop controller for synchronous AC motors. That controller was the most accurate open loop motor controller I’ve ever used, and every conceivable motor parameter (frequency, amplitude, phase angle, harmonic distortion, etc) could be adjusted. This level of parametric adjustment allowed cogging to become nearly non-existent.

I still own both.
Do you mind if I ask how does Open Loop Controller work? 
If it is an open loop, it does not need a controller since there is no feedback and therefore no correction is required.