Kudos to speed controllers


I installed a Walker Precision Motor Controls in my front end. I adjusted on two internal pots by watching my KAB Strobe Kit hit right on rock-solid, steady, solid black bars that got mt TT to the correct speed. Damn, the music improvrment blow my away. Precise, PRAT, Tone, Texter, conherence. It was a big improvement over using VPI SDS speed controller to correct my Basis tt's spseed. VPI SDS was good, but was bettered in this test. Best improvement this year. The Basis error was just a monmentary very tiny shadow on the KAB lines. Almost too difficult to see, but apparrent when compared to the Walker. Kudos LLoyd- good job!
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I agree,I don't know how long I own the Walker controller for my Basis Debut now, maybe 4 years.
The Basis is one of those turntables which is a real top product from scratch. Real cleverness behind. The Walker Controller is a good addition.
I think, that's the reason why Basis offers an own Controller now, but don't know how good it is
Motor control units do substantially improve the sound of tables, though probably NOT because of more accurate long term speed control (what is measured with the strobe). The motor on the Basis table is an AC motor. It's speed is is determined by the 60hz alternating current frequency. Power companies must maintain that speed to a quite high degree of accuracy.

If the strobe shows that speed is slightly off, that is probably because of such factors as belt tension and slippage. But, even people with so-called perfect pitch would not hear the slight difference in steady state speed. What you probably are hearing is the great improvement in the smoothness of the motor turning (i.e., rapid changes in speed) because of the improved purity of the 60 hz sine wave that the motor controller is providing. Good controllers actually are amplifiers that regenerate the AC current as a more perfect sinewave (better shape, less noise).

If the Walker is a plug-in unit that does not require modification of the motor itself, then it is fundamentally different from the control unit supplied by Basis. The Basis controller requires modification of the motor itself. Turntable motors have mutliple poles to reduce cogging. That means that the different sets of poles have to be fed AC at different times. In the regular Basis motor, capacitors are used to delay part of the ac wave by 90 degrees to feed the other set of poles. With the Basis motor control, the capacitors are bypassed, and the controller itself generates a 90 degree out of phase wave that is purer than that which can be achieved with just a capacitor.

It would be interesting to see which controller actually does a better job.
Larryi, I think you're right on the AC purity part and this Walker must be doing its lob well.

To your second point, I'm willing to buy the $3500.00 Basis Motor Controller (not the correct name), but I wanted to try one first in my system. I tried my closest dealer in San Diego (500+ Mi.) for a loaner with the full intent of buy it if it worked well. After all, I'm modding the motor. No loan. I tried J. Conti several tries with no reply. So with no loaner, I'm not sure how much of an improvement it is. BTW, I already bought Basis recommended. precision belt for my system as is.
What Larryi says about why motor controllers make such a readily apparent difference is true, but the Walker may do the same thing as the Basis one, i.e., supply two sine waves in quadrature (90 degrees) apart in phase. I own a Walker and love it, but in truth I am not sure about whether it supplies two sine waves. I have been meaning to take mine apart to have a look. Regardless, it makes a huge difference. With a little web searching and elbow grease, one could build one's own two-phase motor controller for quite a bit less than $3500, however.
The Walker motor controller as supplied does not generate a “quadrature AC” source. The purpose of a “Quadrature AC” power supply in a synchronous AC motor application is to eliminate the phase delay capacitor. The walker motor controller is very good but it does not eliminate the capacitor used inside the AC motor. Apparently the reports I've heard from friends have stated that the Walker motor controller is able to drive the motor smoother than the VPI SDS with less vibration and noise transferred into the platter. I’ve listen to the VPI SDS drive a VPI table and it performed well. I've also worked with a few systems that have Walker motor controllers in them and they work very well. I’ve never directly compared the SDS against the Walker motor controller.

There is really no way to demo the Basis Syncro-Wave Power Supply with your current motor because it requires the motor to be sent to Basis to be modified. Therefore, one would need the entire drive system (controller and motor) to witness the results. Unfortunately, you are not going to find many, if any, dealers with Snycro-Wave drive systems available to send out for demo. It’s really unfortunate because the drive system really pushes the Basis tables even further forward in performance.

My personal turntable is using a version of the Synchrotron AC-1 that I built which is similar to the Basis Syncro-Wave Power Supply. Both of these units require the removal of the phase delay capacitor in AC motors that run off the wall power. The result is a quieter motor with significantly reduced vibration. This is extremely apparent with the 45RPM setting because that particular speed is much more difficult for the SDS or Walker controllers to keep vibration down. Anyone with a Walker or SDS can test my observation in real time by feeling the motor in 33RPM vs. 45RPM mode. The synchronous AC power supplies are so smooth that it's difficult to tell (feel) that the motor is on without seeing the platter rotating in both speed settings.

All that being said, the use of a motor controller (Walker or SDS) on an ac motor is great for adjusting precise speed. If I had to choose between the SDS and the Walker, I’d pick the Walker even though it’s not as nice looking. I lean significantly more toward substance, operation, and function than aesthetics…

For those with Basis turntables (Except the Debut) without speed controllers, you can still get the speed set precisely by adjusting the distance of the motor pod from the platter. My estimate would be that you could have as much as a .2% range of adjustment using extreme distance changes. For the most part, the basis tables using the proper belt are very close, if not on speed, to being correct to begin with so the extreme adjustments are most unlikely.

Hope this helps,
Dre
The Walker motor controller as supplied does not generate a “quadrature AC” source. The purpose of a “Quadrature AC” power supply in a synchronous AC motor application is to eliminate the phase delay capacitor. The walker motor controller is very good but it does not eliminate the capacitor used inside the AC motor. Apparently the reports I've heard from friends have stated that the Walker motor controller is able to drive the motor smoother than the VPI SDS with less vibration and noise transferred into the platter. I’ve listen to the VPI SDS drive a VPI table and it performed well. I've also worked with a few systems that have Walker motor controllers in them and they work very well. I’ve never directly compared the SDS against the Walker motor controller.

There is really no way to demo the Basis Syncro-Wave Power Supply with your current motor because it requires the motor to be sent to Basis to be modified. Therefore, one would need the entire drive system (controller and motor) to witness the results. Unfortunately, you are not going to find many, if any, dealers with Snycro-Wave drive systems available to send out for demo. It’s really unfortunate because the drive system really pushes the Basis tables even further forward in performance.

My personal turntable is using a version of the Synchrotron AC-1 that I built which is similar to the Basis Syncro-Wave Power Supply. Both of these units require the removal of the phase delay capacitor in AC motors that run off the wall power. The result is a quieter motor with significantly reduced vibration. This is extremely apparent with the 45RPM setting because that particular speed is much more difficult for the SDS or Walker controllers to keep vibration down. Anyone with a Walker or SDS can test my observation in real time by feeling the motor in 33RPM vs. 45RPM mode. The synchronous AC power supplies are so smooth that it's difficult to tell (feel) that the motor is on without seeing the platter rotating in both speed settings.

All that being said, the use of a motor controller (Walker or SDS) on an ac motor is great for adjusting precise speed. If I had to choose between the SDS and the Walker, I’d pick the Walker even though it’s not as nice looking. I lean significantly more toward substance, operation, and function than aesthetics…

For those with Basis turntables (Except the Debut) without speed controllers, you can still get the speed set precisely by adjusting the distance of the motor pod from the platter. My estimate would be that you could have as much as a .2% range of adjustment using extreme distance changes. For the most part, the basis tables using the proper belt are very close, if not on speed, to being correct to begin with so the extreme adjustments are most unlikely.

Hope this helps,
Dre
I'd like to take exception to the statement that the Synchrotron AC-1 is similar to the Basis unit. Perhaps I should say "was", the AC-1 kit has been withdrawn permanently.

The AC-1 was an original design which used a different circuit topology to achieve different results. It offered a couple of features which are not offerred by any available controller (adjustable phase angle, adjustable harmonic tuning).

The similarlity with the Basis is simply that both are two phase controllers, but that's a bare minimum for any modern controller in my opinion.


Mark Kelly

Mark,

"The similarlity with the Basis is simply that both are two phase controllers"
This is exactly what my post was about.

I'm fully aware of the unique features of the AC-1 but that was not the purpose of my post. It was simply to point out the fundamental difference between two-phase units and those like VPI and Walker that are not two phase units.

I also have no idea how the Basis unit is adjusted to the motor when it is sent in to be modified and I simply won't comment on an aspect of the design that I'm not familiar with.

As you had stated, you pulled the kit permanently. It didn't make any sense to tout the unique aspects of the AC-1 when the readers of the post couldn't have access to it. It's kind of like a "look at what I have but you can't have it" comment. Personally, for me to say something along those lines would have been in very poor taste.

Although we haven't conversed via e-mail since I sent you comments of the results of the build, I hope you are working on something to offer in the future for those that didn't get the chance to enjoy your work.

Dre
I don't know really, but I have the strange impression that all those motor controlers are "band aids" for weak designed motors. why should a very good motor design and passive speed control need an electronic motor controler?
I seems like a very expensive solution.
Dre

I sorry if I came across too strong, it's not your understanding of the situation to which I am taking exception. I guess I overstepped the mark but I'm not keen on my designs being called "similar" to others.

By the way, the reason that the single phase controllers have trouble with different speeds is an inherent feature of the phase shift capacitor. The capacitor value is equal to the square of the drive frequency (in radians per second) divided by the winding inductance. Since the winding inductance is fixed, if the capacitor is correct for one frequency (say 60 Hz for 33) then it must be wrong at any other frequency (say 81Hz for 45).

To answer your question, yes I am working on a new design. For a long time the development of the harmonic tuning concept was stuck because my analysis indicated that the effect should occur at the second harmonic but my measurements showed that third harmonic worked. It finally hit me as I drove home last weekend why this is so; I now have a clear path ahead.

To Jloveys: Your challenge, should you choose to accept it, is to find me a motor whose performance is not improved by a dedicated controller. I will gladly pay you $1000 each for them.

Mark Kelly

Agree! I recently added a motor controller by way of a PS Audio P300 unit which has the Multiwave II oscillator board. I am able to precisely control the motor speed in 1/8th Hz steps. Indeed, like you, I can see the stroboscope lines lock i.e. stop inching forward or backward when the speed is correct.

Another thing is that leveling the TT is an absolute must. I re-levelled my TT yesterday after what seemed a long time & boy, did I reap a reward.
Dear Mark: no challenge here. The answer is simple: the TD 124 motor.
Cheers,
Jean.
JLoveys

I disagree profoundly.

The 124 uses either a shaded pole single phase motor or the Papst three phase (one replaced the other).

Both of these are distinctly improved by a dedicated controller. Of course the controller involved is different in each case.
Mark, I stand ready and waiting for your new controller. I am just about healed up from kicking myself for not buying the last of your kits.
Mark, do you think this new controller of yours would work for a Garrard 301 and possibly be on par with the PSU 301 AR?
Mark: what speed controler would you recommend for the E50 motor of the TD 124 that could be used with Lenco L75 and Garrard 301 motors ? Or should I have a dedicated motor speed controler for each turntable ? Are your models DIY or can we find finished products ?
Thanks,
Jean.

Let's not turn this into a discussion of vapourware.

I'd prefer to be judged on results.

Mark Kelly


Arrgh! Stupid software! The above was in response to Perrew.

To JLoveys, again I don't wish to discuss vapourware but in general optimal results require that a controller be tuned to the motor it is to run. As long as the parameters required are reasonably close this should be achievable with the same basic architecture.

To this end I expect that the upcoming drive which has been designed for the 301 / 401 would be able to be tuned to the other two tables. The question of whether it would be worth disturbing the tuning for the primary table to accommodate the other two is opne that only you can answer for your situation.
Im not familiar with the previous product but if this new one would be an alternative to the PSU 301 AR I would be very interested, since the loricraft is quite costly. Are there any more info available?