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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
hdm
1,062 posts
 
How does it sound running at the lower voltage? If it sounds good, personally I would leave it. In theory (and in practice in my case), the lower you can get the voltage without compromising speed stability the greater the reduction in motor noise and improvement in sound quality.

I don't own an SDS or a VPI product but did start to use a variac with my table (a Gyrodec) a few years ago after Harry posted about the benefits of doing so at Audio Asylum. I believe he has used variacs with Empires that he has and ramped the voltage down as low as 55V with them.

The Linn Lingo also drops voltage down to around 72V I think. Ultimately, it will be motor dependent. I find that with my Gyro speed stability might suffer once I drop in to the mid to high 50's. 62V seems to be the sweet spot for me with my table.

If it works well and sounds good at 72V I would probably not be increasing it.
stringreen's avatar
stringreen
6,460 posts
 
Adjust it to the VPI spec as explained and don't second guess.
actusreus OP
733 posts
 
Stringreen,

As explained where? The manual is completely silent on the voltage selection as the unit is supposed to be calibrated before shipping. C'mon man.
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.
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