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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
 
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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isanchez
276 posts
 
In many instances, the power that comes from the electrical outlet is unstable. This instability tends to affect the speed of many turntable motors. So it is quite possible that electrical power is one of the main causes for your turntable to run faster.

As mentioned in previous posts, there are other variables that also affect the speed of a turntable. The leveling of the bearing will affect the speed of a turntable in many cases. In this scenario, the weight of the platter plays a more active role. In my particular case, I set a calibrated PRO 3600 digital protractor on top of an Avid 45 adapter to level the platter bearing. The PRO 3600 has accuracy of 1/100 degrees. When my platter is perfectly leveled, speed accuracy of 33 1/3 is dead on. The platter will play at this speed for as long as the turntable is absolutely leveled.

If a turntable uses a bearing well with oil, as the oil dries out, one should expect the speed to slow down with it. Also, Many oils will change viscosity as their temperature changes. Since the bearing friction will increase the temperature to some extent, one can expect the turntable to go through some speed changes.

The Synchro is a power re-generator, so it will output whatever frequency you set it up to, regardless of the input frequency from the electrical outlet. What you're experiencing with the Synchro is normal.

Best,

iSanchez
mosin
410 posts
 
"A $500 Technics SL1200 mkII will keep speed as accurately as a belt drive turntable costing thousands of dollars."

Maybe it will be more accurate than many turntables out there, but it isn't the end all answer to proper speed control. The reason is because it creates a sort of analog jitter in the process of maintaining the desired speed. So, if you think about it, it isn't accurate at all because both detail and dynamics suffer. A better solution is to generate perfectly tailored power to a superior motor. That can be done a variety of ways with any drive system, but you don't really fix power after the fact. A correct fix is made before it is created.
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