DC, AC,, battery, asynchronous?

Hi all,

Planning on getting a new turntable at some not-too-distant point in the future, and so am obsessing and researching. One issue over which there is much chatter is the sort of power supply. Is someone out there willing to give me primer on this issue? What are the costs and benefits, in principle and audibly, of A/C (as in Rega -- a P25?), D/C with a transformer (as Michell offers -- thinging about a Technodek or used Gyro), D/C from battery (probably out of my price range, at least at first)? And what is the deal with synchronous/asynchonous power (if that's even a coherent way top put the question)? I know at least one frequent poster here thinks this is a central distinction. Enlighten me. If it matters, amp is a Naim Nait 3 with flat cap. Current deck: Planar 2, RB-250, Dynavector 10x5.
I am not sure what exactly you are trying to achieve. Though judging by your questions, you are a good candidate for really good table. You did not specify your target price range, but if I understand it from your examples, I would suggest you considering rebuilt Technics from KAB.
In my opinion it would be way better that anything you mentioned.
Good luck with your search.
Um, just so the thread doesn't get derailed before it even pulls out of the station, I'm not looking for advice on what to buy, but for info and a discussion on costs/benefits of various sorts of power supplies for t'tables.

The main problem with AC motors is that they run in a constant series of shove-coast cycles. They don't run at a steady speed, they're shoved around and then coast, like those hand-powered merry-go-rounds we rode on as young kids in the playground. This is called the "cogging effect" and all AC motors have it, no exceptions. The effects can be minimized by choosing a motor with more poles. More poles per revolution = smaller shoves and shorter coasts between shoves. Another approach utilizes very low torque motors, thus reducing the effect of each shove. A third approach uses very high RPM motors, often in conjunction with a flywheel. Rubber or neoprene belts are usually specified, the idea being that the stretch in the belt will shield the platter from from unavoidable speed irregularities from the AC motor. AC motors are also sensitive to input frequency, so a speed controller circuit that stabilizes power frequency is helpful.

DC motors accelerate at a steady rate. No cogging effects. Their downsides include sensitivity to input voltage and a tendency to drift away from a preset speed. Input voltage can be controlled with a good power conditioner. Speed drift is only controlled, as far as I know, by the unique motor controller of the Teres tables, which reads a strobe on the platter and adjusts input voltage to the motor accordingly.

Hope that's helpful in a general way, but if choosing a table is what you're trying to do, specifying a budget and musical tastes and goals would get some more real-world responses. You certainly shouldn't choose a TT simply on the basis of motor type. There are other factors of equal or greater importance.
Thanks Dougdeacon,

I certainly wouldn't choose on motor type alone, or on anything technical aspect alone, or even set of them. Sound's what matters -- and build quality, so that sound and value last. But at the research stage, I like to understand what I'm reading, and have some ability to assess the degree and kind of difference a given feature might make to the overall mix. For what it's worth, budget: under 2k -- probably quite a bit under, depending on how a few things work out. Musical taste? Varied: the whole range of classical (except opera, for the most part), Zappa, blues/rock, bluegrass, and acoustic jazz from big band to bop to Bill Evans; as far as system demands, that doesn't leave much out. Table must have excellent PRAT, but I'm not too concerned about recording artifacts (precise plament, depth of soundtage, etc: never could hear that when well placed in the concert hall. Bit of a flat-earther, I guess. It also must not be too picky about support and must stay set up once set up.