2. analog
  3. 1233265575

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
frepec OP
17 posts
 
Tom:

Thanks for responding. My 'table is in my house so temperature is not an issue, but since the bearing is oil lubricated, I do let it "warm up" by letting it run for a few minutes before I play anything. All speed measurements were taken under warmed up conditions. Also, I am aware that changing the distance between the motor and the plinth will effect platter speed. I have played with this on several occasions. In order to get the platter speed close to 33 1/3, my motor has to be so close to the plinth that the belt sags and speed consistency suffers. I even bought two new belts and that made no difference.

When you say "If you cannot get 33 1/3 from a table without a speed controller, something is wrong," I agree totally. But from what I am hearing and from over a year of on and off investigating, that doesn't appear to be the reality. I seems that most turntable owners are using some kind of speed controller just to get correct platter speed. This exercise on Audiogon,is just the latest in a series of investigations I have made into this subject. I could be totally off base here, but I am becoming more and more convinced that accurate platter speed is not a given when one buys a turntable, unless it comes equipped with a speed controller, as is the case with more expensive 'tables. A review of the replies in this thread seems to substantiate this conclusion.
tfkaudio
591 posts
 
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
lewm
13,473 posts
 
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.
palasr
529 posts
 
The Origin Live controller is designed for DC motors and is, AFAIK, the only commercial aftermarket controller solely for DC motors.

-Richard
sonofjim
557 posts
 
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.
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