VPI SDS use question

I recently made several upgrades to my Scoutmaster and now have an SDS. I've got everything set up and running, but just had a question about the operation of the SDS. When the SDS is on, but the table is off, the voltage is steady at 72. When I turned the table on and set it to 33 RPM, the voltage jumps to 84. Changing to 45 RPM makes the voltage increase to 102. I just wanted to make sure this was normal operation as I'm not familiar with the SDS and the manual (like most VPI manuals) isn't very clear.
The SDS adds extra power to start the platter moving, then cuts back when platter up to speed. I do not, nor ever have owned a VPI, but I read the blurbs in thier adverts, and have remembered it.
the voltage change is a normal VPI thing.
Mine does about the same thing.
I could be wrong, but something doesn't sound right to me with your unit.

As I understand it, the VPI SDS will ramp down to a selected Voltage, and this ramp down voltage is user selectable-adjustable, via the calibration mode. The calibration mode is on VPI's website, in PDF format.

My works the exact same way, but when my Table is then switched on, my Unit will output 115V initially, then after a couple seconds, after the Motor comes to speed, it will revert back down to the pre-selected ramp down voltage.

Your's seems to be only putting out 84V as you say, and I see no provision in the calibration mode for adjusting max output voltage?

Aren't all the USA Models supposed to put out 115V maximum upon initial fire up?

If no one else knows the answer to this, then I do suggest calling VPI, and tell them what you have told us here. There may be possibly another adjustment in calibration mode, that I/we are not aware of? Or the Unit is possibly faulty? VPI will know for sure. Mark
OK. Thanks.

I'll have to check when I get home, but I think I've seen the SDS display 115 on start up. Then it ramps down to 72 after the start up sequence is complete. If I turn the table on and set it to 33, it ramps up to 84. I only used the SDS briefly this weekend as I had family in from out of town. I'll try to give it a full work out this evening to see if it drops the voltage back down to 72 after getting the platter up to speed.

I believe it was once our wise fellow agon member Nsgarch, who gave good, valuable advice about the VPI SDS, in that the lowest ramp down voltage of 72V may not always be the best-optimum choice per a given application.

Although, I myself have never experienced a speed fluctuation issues running at 72V ramp down voltage, on a HW-19 Table, with 16lb MK-IV Platter, there may be possible applications-instances with ultra heavy Platters, or due to increased bearing drag, that critical speed stability "might" be better attained at a slightly higher ramp down voltage setting. Again, hope this helps.
I posted at audio asylum, directly to Harry Weisfield of VPI,, the possible issues about initial voltage at the SDS, which I believed should be exactly 115V.

Harry concurred, and said yes, that start up voltages should be 115V, and if not, to give him a call ASAP.

When I fire up my HW-19, I first turn on the SDS. It will read 115V, then drop to the selected ramp down voltage, which in my instace is 72V.

Then, when I hit the power button on the side of my HW-19, to get the Platter spinning, my SDS will automatically ramp up to 115V for a short period of time, then automatically ramp back down to 72V,

A pretty slick device, I'm real happy with mine.

In conjucntion with my KAB Strobe Disc, and with the record in play, (The strobe disc is slightly smaller than a 33-1/3 LP, and permits accounting for Stylus drag) I get dead stable speed on my rig at 33-1/3 at exactly 60.17hz.

I get the exact same results when switching to 45rpm, (up to 115V, then down to 72V) but forget my personal "hz" settings offhand.

That the strobe doesn't waver-budge 1/32" from dead on for countless minutes. That's multitudes better than what I got minus the SDS in my system. Mark


Thanks for your input. When I turn the SDS on, it does start at 115 and then drops to 72 after a few seconds. I printed out the calibration manual and when I got home, I looked at my settings and my SDS was set to 84 for 33.3 and 102 for 45. My software version looks to be 1.1 so I reset the corresponding speeds to their factory default of 72 and 90. I also have a KAB strobe. My 33.3 setting is 59.83 and my 45 setting is 80.80. I'm still gotta fine tune my settings, but things look pretty spot on.