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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
johnbrown
195 posts
 
Dan-ed-

You're right of course-I should have emphasized the theoretical nature of that thought process (-:

Still, with the correct circuitry designed for a specific motor and application, you'd think they could get it right.

To take it a little further, those same DC- motored decks should, if anything, rotate *slower* with the effects of age, wear, dirt, belt slippage, etc., not, as is the case with the OP, faster. Which perhaps gives even more credence to the 'faster by design' theory, especially if the OP's deck is maintaining an always and constant (too high) speed. All theoretical, of course.

Maybe someone who knows a lot more than I about designing run circuitry for DC motors will join in-where's Mark Kelly or Chris Brady when you need 'em? I'm guessing, though, that a manufacturer could pretty easily add speed adjustment to their basic DC circuitry for Very Little Money-that is, if they didn't have an optional Motor Control ready to sell you.
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isanchez
276 posts
 
Frepec,

I totally agree with you. It seems that we, as audio equipment consumers, have grown complacent with the idea that it is not so relevant for analogue playback to have speed control with a turntable. The fact that there are so many turntables in the market without any sort of speed control is really puzzling to me. This is one of the main reasons why I sold my previous turntable and got the Acoustic Signature Mambo. I think most of the AS turntables come with the same power supply/motor controller.

There seems to be a new generation of turntables that take the notion of speed control a step further. There is the new Clearaudio Innovation turntable that reads the speed of the platter via a sensor and corrects it accordingly. Another turntable with its own speed correction technology is the Grand Prix Audio Monaco. To the best of my knowledge, both of these turntables are in the 20K neighborhood. It think it is a matter of time before these technologies drip down to more affordable turntables.

I think in some cases a turntable may not come with a motor controller in order to trim down the cost, but the manufacturer should warn the consumer that the motor controller is a necessity for the serious listener, which is the target consumer for the high-end turntables.

Best,

iSanchez
johnbrown
195 posts
 
To VPI's credit, they do give you the ability to (slightly) adjust speed even without a motor controller-the motor pulley on their decks is 'stepped' from a larger to smaller diameter, thus allowing you to move the belt to the pulley diameter that corresponds to attaining the correct platter speed. Credit where due, etc.
johnnyb53
3,510 posts
 
I can't help weighing in here that speed consistency was solved economically over 30 years ago with the quartz-regulated direct drive turntables. A $500 Technics SL1200 mkII will keep speed as accurately as a belt drive turntable costing thousands of dollars. There are currently armboards that enable you to upgrade the Technics to a tonearm from SME or any Rega-compatible tonearm, including the entire line from Origin Live.

The one remaining problem is isolating the plinth from the room, and draining in-base vibrations out. I wish the audiophile industry had spent more time and research lowering the noise level of direct drive instead of starting over with garden-variety AC motors and a rubber band. The best of them have wound up with a Rube Goldbergian complexity of mechanisms to keep the bearing on-center (since a belt pulls it sideways) and on-speed, or a bearing-grindingly high mass-loaded platter.

I'm not dissing any turntables or anyone's gear; I just think that if the British cottage turntable industry of the '70s had embraced the Japanese quartz-regulated direct drive mechanism, they could have turned their attention to NHV control and tonearms, because speed accuracy with them is not a problem.
frepec OP
17 posts
 
Yesterday, I borrowed a Clearaudio Synchro and installed it in my system. Using the Clearaudio readout in hertz mode, to get my 'table to run at 33 1/3 rpm, the hertz indicated on the screen is 57.2. Setting the Clearaudio to 60 Hz makes my 'table run too fast, about 34 rpms which is the speed I was getting before I had the speed controller in the system (see original post). All along everyone I talk to about my speed problem has been telling me that my electrical power is the cause. I have one question: To me, these results do not appear the substantiate that claim. Am I all wrong here?
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