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 think you are correct and I would agree that a speed controller is an indispensable part of a high performance analog setup.
But I still think that 33 1/3, if not perfectly stable, should be achievable without a speed controller. If I couldn't get 33 1/3, even briefly, without my speed controller, I would take the table back to the dealer and let them prove to me that the table lives up to it's high-end reputation. Because, to me, this is job #1 for a turntable.

Cheers.

Tom
If the Transrotor motor is indeed a DC type, as you suggest above, I don't think that a typical after-market motor controller (e.g., the Walker Audio PMC or the VPI SDS) will help your problem. The ones I know about are made to control AC synchonous motors, where the frequency of the AC input voltage will affect motor speed. You should check this out with a Transrotor representative. However, I do believe Transrotor make an optional outboard DC supply which might solve your problem. By all means, don't spend your money until you are sure you are buying a cure for your problem.
The Origin Live controller is designed for DC motors and is, AFAIK, the only commercial aftermarket controller solely for DC motors.

-Richard
I also don't see how any turntable could be accurate without a speed controller. I check my speed every day and often have to make minor adjustments with the SDS to get right on 33 1/3. I'm sure a multitude of factors work together to change speed slightly from day to day. Keeping it accurate is an ongoing process.
"Keeping it accurate is an ongoing process. "

There are, however, several steps that can be taken to ameliorate having to tinker continuously. Make sure the belt and belt path are scrupulously clean; be certain the table's bearing is clean and properly lubricated; be certain the table is level (this is a must); try to maintain a constant ambient temperature in your listening space - believe it or not, the viscosity of both the bearing and motor lubrication change considerably over a relatively small temperature range. I'm sure there are others I am neglecting.... Good listening,

-Richard