Turntable Speed


I own a Transrotor "Atlante" turntable. I purchased it about 2 years ago with all the available upgrades (platter and tonearm). This unit was $4500.00 without cartridge. It is a belt driven product with an outboard power supply which lowers the incoming voltage to the 18 volts the motor requires. My problem is turntable speed. My 'table speed is about 34 rpms. I could be more accurate if I had better measuring equipment. Anyway, that's about 2% over the correct speed and you can definitely tell the difference in sound quality between 34 and 33 1/3 rpm!. I was a little upset with this revelation and called my dealer about it. I also talked with the dealer's supplier. I received several reasons from these people as to why the speed was not accurate among which was that my power was "out of tolerance." But when all was said and done, none of the given reasons held water and I am now being advised that really there is nothing that can be done. That there is no defect in the equipment and if the speed problem continues to bother me, I should invest $1700.00 in a Transrotor speed controller. As I think over this, I wonder why platter speed is never mentioned or measured and reported on in the reviews for turntables in the major audio mags. (This could be because there isn't any problem, except for my 'table, or there is and no one is admitting it). To my way of thinking, platter speed has to be one of the primary functions of a turntable and that manufacturers would be making sure that their products' platter speeds were within strict specifications. At least better than 2% margin of error as is the case with my turntable.

My question is: Is platter speed error a given in this industry or is my 'table actually in need of repair? And, if platter speed is an industry problem, why are we as consumers paying thousands for equipment which actually doesn't work up to expectations?

frepec

I keep track of the frequency and voltage coming from the wall outlet, and very few times I get to see 120v @ 60Hz. This varies from different utility companies though.

Best,

iSanchez
With all these aspects effecting turntable's speed and no practical universal way to correct it, I say every hi-end turntable SHOULD have a speed controler so the user can at least have their table run at the correct speed for a few hours listening duration.

Experienced all this, I would never buy another hi-end table if it does not offer a way to fine tune speed. Save me a lot of headache.
The 20 years old classical book The Art of Electronics by Paul Horowitz and Winfield Hill fully described a high quality variable sinusoidal power supply that could be easily built with a full cost of less than 50 usd in parts. I can not understand how any one can think of connecting a synchronous turntable motor to a dirty mains plug!
All DC motors for TTs will have by necessity some form of feedback to control their speed. If a TT has a DC motor it will come with a dedicated speed controller. AC motors "synchronise" with the frequency as has been dicussed. That is not the only reason for a controller. In an ideal world all loads would be purely resistive and the AC waveform would not be distorted. With compact flouresce lights and AC motors and other reactive loads adding distortion, throw on top of that the typical PSs that draw most of their current at the AC peaks which tends to flatten the peaks, the AC waveform coming from the wall is hardly a pure sine wave. This will effect the sound of a AC driven TT. Even if your TT ran dead accurate, there is still a case for an outboard controller.