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New SDS settings

I got a new SDS unit and the voltage drops to 72 V on both 33 and 45 RPM settings upon start-up. In my old unit, voltage would drop to 72 V for 33 and 102V for 45. I called VPI and Steve, who calibrates the SDS before it's shipped, told me that it should be 96 V for 33 and 102 for 45; he also said that the motor would not have enough torque at 72 V for best sound. Are we talking the platter speed being affected more by more difficult passages at a lower voltage? His recommendation was to recalibrate the unit.

I find it interesting as I thought the idea was to get the lowest voltage that would be enough to get the platter spinning. So if the platter spins at 72 V, it would be better than 96 V. I'm also very surprised the 'table works at the 45 RPM setting at such a low voltage.

Does anyone have any insight into this matter, or perhaps experimented with different voltage settings on the SDS? What is the interaction between voltage and sound? I guess the bottom line question is: what voltage is optimal for best sound?
actusreus
don_c55
1,025 posts
 
The 72 and 102V settings were originally for the TNT series motors for which the SDS was mainly intended. Maybe 72v was not enough for the more modern VPI turntable motors.

Lowering the voltage after startup reduces motor noise only, and does not affect speed unless it is too low and the motor does not turn.

I agree 72v for 45RPM is wrong.
kgturner's avatar
kgturner
663 posts
 
I run my SDS at 72V for 33 RPM and 90V for 45 RPM with my Aries 3. Everything sounds fine and dandy to me. On my motor startup, the voltage jumps to 115, but comes back down after a few seconds.
brf
1,715 posts
 
Go to the VPI website and download the SDS calibration manual which will give you instructions on how to change the voltages settings. This way you can experiment with different settings and decide for yourself.
ct0517's avatar
ct0517
2,041 posts
 
Actusreus here are the instructions.

SDS Calibration Instructions

If I remember back I believe my SDS needed in the 90v range to work properly with my thread drive TNT otherwise 72 as the others have indicated with belts.

Cheers
actusreus OP
733 posts
 
Thanks everyone. I listened at the run voltage of 72 with both 33.3 and 45 records, but didn't get a chance to experiment with different voltage settings. Will do perhaps this coming weekend, but both worked ok as far as the speed stability. However, at 45 it did seem that the usual pace and dynamics were somewhat diminished, but I need to listen to more records to be sure.

Does anyone have any input or opinion on the torque issue with different voltages?
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