Turnable database with TimeLine

Lew
The Beat appears to uses electromagnetic drag to "pre load" the motor. Moving the rotor back in phase relative to the rotating field. I am not sure about the other TTs mentioned. The theory being that this artificial torque demand is significantly higher than any seen due to stylus drag. It seems like an elegant solution. The question is of course how does it sound? I do know that we are very sensitive to micro pitch changes and that stylus drag is large. The choice of open loop or closed loop speed control in ones TT is a personal one and we all make that choice with open ears and hopefully open minds.

Very interesting thread Peter. Thanks for getting it going. I'll volunteer my Grand Prix Monaco to be a test subject, as soon as I can barrow Albert's timeline...

The Grand Prix claims highly accurate speed control (from their web site):

"DSP Signal Processing / Active Feedback Loop Technology:
Our speed control features a CPU utilizing a Digital Signal Processor that interrogates and maintains the speed of the platter thousands of times each revolution and thereby ensures frequency accuracy and distortion free playback that is simply not possible with conventional types of drive systems. A highly accurate test procedure has demonstrated the speed error to be an extremely low .002%! Speed accuracy equals frequency accuracy, which means there is virtually no distortion on playback."

Peter, one thought on your SME, have you ever cleaned the motor pulley (and sub platter) and then flipped the belt over? I used to do this with my SME 20/2 every 9-12 months and it did seem to sound better...(that is unless you used a new belt for the test)...then I'd replace the belt every 18-24 months...

Thanks Jfrech. I used to clean the belt on my SME Model 10 about once a year. I've just ordered two new belts for my 30/12 which was new in March 2012. I'll clean the belt I have in the next day or two and see if I notice a difference. I sent the TimeLine back to Albert. I just can't see spending $400 on a new one.

Your Grand Prix will be a good addition to the database. Thanks.

Addendum to above post :
The big Micro's use DC motors with frequency generated servos built into the motor. So their response to speed issues has the same issues as the direct drive, the main advantage of the micro's is the large inertia. This would explain why some users prefer the Micros set up with a controlled slip by chalking the thread.
The Final Audio has a high torque ( the 22kg platter can achieve full speed in less than 1 turn ) AC synchronous motor with precision oscillators and 80 wpc power amplifier to lock the speed.
As Lewm alluded in his post the AC synchronous motor responds to phase lag by self correction. This is why AC synchronous motors can run accurately without servos. A DC synchronous motor will self correct to some degree, but the self correction is less sinusoidal and less smooth than an AC synchronous motor.
It is wrong to imply that the Technics SP10 relies on self correction of phase lag - its servos are active all the time, as is the case with the Victor/JVC and Goldmund.

Excellent Post from Dover.
Unfortunately no Audiophile will understand it :-)