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Using the VPI SDS with non-VPI turntables

The SDS makes a profound improvement in the sound of my early-model VPI TNT and is also great for changing the speed from 33 to 45 rpm. Now I'd like to try the SDS with another of my turntables, a modified Lenco L78, but want a little reassurance beforehand.

According to the SDS manual: "Remember, you can use the SDS for better sound on any turntable, but you can adjust the speed ONLY on turntables which have AC synchronous or induction motors and which have no electronic circuitry of their own." I have no idea what kind of motor is in the Lenco, but there's no electronic circuitry. One issue is that with the TNT at least, the SDS automatically reduces its operating voltage to 72 vac when set for 33 1/3 rpm.

Is anyone using the SDS with other (non-VPI) turntables? I'm mighty curious about whether the SDS would improve the Lenco, but I sure don't want to damage either one. Any thoughts? TIA, Dave
dopogue

Showing 1 response by jameswei

jameswei
883 posts
 
The SDS regenerates the power sine wave, so the power is cleaner and the sine wave frequency is what you set it to be.

The capability of varying the frequency of the sine wave is important to determining the speed of "hysteresis-synchronous motors," like those used in most turntables today. "Induction motors" are relatively insensitive to frequency variation and will tolerate a fairly wide range of frequency variance from their nominal rating at 60 cycles. A better way to vary the speed of an induction motor would be to change the voltage, which the SDS also does.

Naturally, the turntable could sound better just from the improvement in how much cleaner the power sine wave could be.
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