Power Supply Units For Turntables

I've noticed that a number of more expensive turntables, such as the Rega Planar 6, come with power supply units. What are the benefits, other than not having to lift up the platter, when changing speeds?

 

Power supply stability for the motor - which can, depending on a host of other variables, reduce wow 'n' flutter.

For example, VPI has their SDS speed controller. On my old VPI HW19 Mark III, it made an audible difference in background noise and image stability. Also piano sounded cleaner. The SDS quieted down the tired motor too.

With my departed Aries 1 turntable, with it's much heavier platter and better motor, I didn't hear as much as a change with the SDS. Maybe inaudible.

 

This is a complicated question and the answer is -- it depends: depends on what the power supply design is, depends on the nature of the motor, depends on the design of the turntable, etc.

A turntable's motor is one of the major sources of spurious vibration in vinyl playback so the more you can limit the transmission of vibration (and speed irregularities) from cogging torque and physical vibration etc., the better (you'll have better tracking, playback will sound less congested on tutti peaks, you have significantly greater revelation of low level detail, you'll have the impression of hearing deeper into a more continuous soundstage, etc).

But there are AC motors and DC motors, there are direct drive tables and belt drive tables (and idler wheel tables), there are different kinds of AC and DC motor...there are tables with heavier platters and lighter platters, tables which physically decouple the arm mounting from the motor mounting and tables that have both mounted to the same surface. So difference abound.

Rega tables use AC synchronous motor and belt drive and they mount the motor and arm to the same surface, so reducing motor vibration ought to make a considerable improvement -- using motors with more poles, and driving the motor with separate power line for each phase, or providing some means for trimming the phase, would all be good. Most motor supplies for AC synchronous motors don't do those things (some do -- Basis had one like that for its tables I think, and Merrill has one like that for his tables). With most, the motor is what it is, and the power supply typically just has a cap to split phase, but maybe they reduce voltage after start up, which will reduce torque and cogging. I think the Rega supplies might also have separate phase caps for 45 and 33, which is good if you listen to 45s.

There could also be improvements to speed/pitch stability, but again it depends on the nature of the power supply (you might also be able to fine tune rotational speed), and the nature of the platter and any flywheel effect of the platter.

That's part of the long answer. Like I said, the short answer is, what benefits you achieve really depends on the table, the motor, the nature of the outboard motor controller, etc.

 

Improved speed accuracy and stability is the selling point.

 

The Basis power supply does split the phase, and if you get it for a Basis turntable, you have to send the motor back to them for conversion (two power feed, no cap to split the phase). That really is the proper way to do a power supply that changes motor speed.

 

In my experience better power supplies can really improve the sound of higher end turntables, when I switched from the standard supply on my old Michell Gyro SE to the better outboard HR supply the most obvious improvement was a tighter, better bass, as a bonus it also allowed easy speed adjustment, on my Roksan Xerxes 10 the top of the range Xerxes power supply improves the sound across the board compared with Roksan's much cheaper basic supply, so at least in those cases you get what you pay for, even if the costs are quite high. At the moment I'm very happy with the sound of my Garrard 301, but if funds allow then I might give an external power supply a try although in the case of the Garrard it allows you to drop the voltage and take the brake out of the equation so somewhat different to what power supplies do on non idler decks.

 

You seem a little vague about what the Rega power supply does.

To quote Rega..."Using the same DSP (digital signal processing) generator found in the RP10 the Neo is built upon a high stability crystal. The Neo features an advanced anti vibration circuit, fine motor speed adjustment and the convenience of electronic speed change. The DSP generator will divide the accurate signal from the crystal to the exact frequency required to turn the platter at the selected speed whilst will producing a near perfect sinusoidal waveform to drive the 24v motor."

The old TTPSU likewise used a sine wave generator.

 

I have all my components into a Monster Power Conditioner. Would that not serve much of the same purpose of a power supply? BTW my Rega turntable runs at pretty much perfect speed, so that isn't a consideration for me.

 

I have a P6 with the new Neo supply. I traded in a 2016 P3 on the P6. There is a solidity to the image with the P6 that escaped the P3. I am sure the aluminum subplatter helps, but the Neo is a big part of it. I actually was quite happy with my P3 and only traded because my dealer made me a great offer. 4 months later, you would have to kill me to take away my P6.

The new Neo PSU is a simplified RP10 power supply. It is worth every petty if you can afford it. If your P3 has the 24v motor, I think it would work. Of course, if it an original P3, it would need the new motor.

 

No. Depending on a turntable's motor type and design, a turntable power supply will have an impact on the motor's vibration and as a result reduce the motor-induced noise that masks detail and harms tracking, as well as improve the turntable's speed stability and accuracy.

Typically in a turntable with an AC synchronous motor these effects are achieved through one or more of the following circuit elements -- some kind of digital or crystal based frequency reference, maybe even some kind of tach or servo to adjust speed continually on the fly; maybe separate motor supply legs for the different phases of the motor drive but if not that maybe a reduction in motor voltage after start up to reduce cogging torque; as well as perhaps the convenience of push-button speed selection. Your Monster power conditioners don't do any of those things. Completely different devices for different purposes.

 

A good power supply generates a low distortion sine wave to replace the one coming from the wall, which can have significant distortion components. It can have tighter short term frequency control too, and (usually) provides adjustable frequency control. The down side is that it is another amplifier in the chain, and most of them use digital synthesis now so it is also a source of noise, and some of the cheap ones have a lot of distortion under load, so it isn't a guaranteed improvement over connecting directly to the wall, or to a good power conditioner, but in your case for best results, you may want your turntable motor connected to a separate conditioner, or isolation transformer with good quality input and output filtering.