speed stability

Rodrigal and Benjie, thanks for the update.

The reason for using PSA, SDS or any other regenerator isn't voltage regulation but frequency control. Frequency control allows you to control the speed on tts without that capability, like your Classic. You're going to need a strobe and a disc to measure the speed of your Classic. I'm not familiar with the PSA units, don't know how flexible they are with frequency regulation.

Benjie, SDS & PSA are exactly the same thing, both are digital regenerators! The only difference might be that the SDS will allow finer tuning of frequency adjustment to control speed of synchronous motors. I'm not familiar with the current ones but earlier PS Audion units did have a certain amount of frequency control too.

"By reducing the voltage to the tt motor, the motor produces less vibration and makes a significant improvement in sound reproduction. Hey, we all know that less vibration to a turntable means better sound. The SDS is a truly amazing piece of electronics." This is completely false and is in the same moronic category of using expensive power cords on tt motors and claiming it improves sound quality. There's nothing amazing or revolutionary here, the SDS is just another AC regenerator and at the 2k price there are plenty of more featured industrial units around. Only the interface is audio specific.

Elizabeth, a steady 60hz cycle doesn't guarantee the correct speed of your tt. A frequency controller is a pitch/speed control for synchronous motors and allows one to set the correct frequency to achieve the right pitch for 33/45/78 rpm if your table is setup for it, not every table will give you all 3 speeds. Servo controlled motors, direct or belt driven aren't the most accurate and further servo control has negative impact on sound quality while continuously tweaking the speed.

Lewm, tweaking the frequency slightly above or below 60hz has no effect on electronics, just motors. In general you really shouldn't use a regenerator with your electronics because of the negative impact they have on sound quality. Some manufacturers do advise against using any regenerator with switching power supplies, irrespective of frequency control.

Wynnosu, I'm not sure where you live that you would need protection for your equipment. The PS Audio regenerators are sold for cleaning your ac and in theory making your system sounding better. In my experience with the PSA along with quite a few other regenerators the opposite was true. Hence my comment regarding the PSA. Also all regenerators dump a lot of noise back in the lines and you have your amp plugged in that line. Of course depending on the equipment and location your mileage might vary. Interestingly I am testing a new regenerator that is showing potential and might be the exception to the rule.

Hi Benjie, I never said that SDS or other speed controllers don't affect sound, of course they do. A stable speed with the correct pitch will have a positive effect on sound. And I agree that motor induced vibrations can have negative sonic effects. My comment was about reducing motor vibrations by dropping voltage. What are they dropping the voltage to? Does the SDS ramp up to over voltage and then drop down to the correct voltage or does it drop down to some nominal voltage like 40 volts?

Don't know about your TNT but none of my tt motors will work properly with significantly lowered voltage.