Turntable Speed

Hello,
I think the speed of the turntable is a product of correct setup, and maybe manufactures have no choice but to claim that their tables operate correctly at 33 1/3 rpm under proper operating conditions when properly set up.
To explain further, I own a VPI Super Scoutmaster. My equipment rack is in a separate room (a 3-season room, if any of you know that term) from my listening room. The 3-season room is so called because it's small and has windows on 3 of the 4 sides. It also has french doors to close it off from the next room.
What does all this mean? In winter (the 4th season) in Chicago, this room gets VERY cold. If the french doors are kept closed, when I get home tonight the temperature in that room will be about 40. (It's about 20 outside right now).
If I go home and immediately turn on my turntable, my speed will probably be 28 rpm. I can use the SDS to get the speed back to 33 1/3, but as the room and the motor warms up, the speed will work its way back up. So I really have to let the room warm up first, or I'll be re-adjusting the speed after every album side.
Is this VPI's fault? Of course not. When the equipment temperature stabilizes the speed is dead solid 33 1/3.
Also, ignoring the temperature factor, the distance from the motor assembly to the plinth determines the belt tension. You can adjust the speed by moving the motor closer to or farther away from the plinth. Belt wear becomes yet another factor. The power supply to the TT motor is yet another variable.
So, I think I can summarize by saying that you SHOULD be able to get 33 1/3 rpm on a table if set up properly, paying attention to all these variables. A speed controller, in my opinion, should not be necessary just to ACHIEVE 33 1/3. It should provide a much more STABLE 33 1/3 compared to the wall power. It is also a very handy item to compensate for all those variables and irregularites, and my VPI SDS was worth every penny. If you cannot get 33 1/3 from a table without a speed controller, something is wrong. The speed controller just makes it a lot easier.

Cheers.

Tom

Addendum: With the VPI rim drive, the SDS frequency needs to be lowered considerably below 60hz. I once remarked to VPI that they should make it clear in their documentation or on their website that the SDS is NOT optional for rim drive users.

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.

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