AC motor controller

[Jim R.]

Grainger,

I was just doing a bunch of research on power plants and conditioners andthe kind of control unit doc is talking about is far more accurate than the voltage regulation tolerances of even the best power plants.

Actually it's a different animal altogether as this kind of motor control regulates and allows for very fine adjustment of frequency whereas power plants are mostly designed for voltage stability -- and the PS Audio units seemed to have the largest voltage swing/lowest regulation tolerances -- 5% vs 3% for companies like PurePower.

I actually settled on a completely differentapproach -- an Equitech balanced power center -- no voltage regulation to speak of, but real, honest-to-goodness professional studio quality balanced power.

But if you are not jhaving any issues with speed control, the ps300 is probably good enough.

Another use for the kind of thing Doc is talking about is for 33 to 45, or maybe even 78 rpm switching without belt and pulley changes -- just turn up the frequency to get higher speeds.  BPI used to make the PLC (which I used to own) which did sort of the same thing, and they also make the SDS -- synchronous Drive System, which is what it sounds like Doc is talking about here.

HTH,

Jim

[Grainger49]

Jim,

You have a PM.

[keto]

I would be very interested in an AC motor controller kit!

[xcortes]

I use a variac before my Garrard 301 to adjust speed instead of using the garrard magnetic break. Would this control substitute the variac?

[Mikey]

Subscribed... 

[Jim R.]

Giving this a bump to see if there is any decision or progress on this?

-- Jim

[Doc B.]

No progress, we are still flogging the active step up idea, which is turning out to be quite a challenge.

[rockpassion]

Doc, I have a VPI MK IV TT and have a real hard time justifying $1100 - $1300 for the VPI controller.  So IMHO this is a GREAT idea.  As long as it is reasonable in price sign me up.

Hopefully it is something that could be done soon.

Thanks,

Richard

[Kmmm]

YES

[Paully]

I would like to echo that I have a VPI and I would love to be able to unplug it from my PS Audio power conditioner into a designated controller and be able to more accurately control the speed.  It has to be tube rectified though   But also, as others have stated price concerns, if it is a $1,000 or more I probably won't buy it.  For me, it needs to be in the $500 range and then I am very interested.  I would wonder if it is even possible at that price point, but beyond that I would rather be honest and state upfront that I probably wouldn't spring for it.  I would rather buy the Bee Pre!

[Brillo]

No progress, we are still flogging the active step up idea, which is turning out to be quite a challenge.

Just curious - is the motor controller topic dead?

Chris

[Doc B.]

We are up to our necks in getting the DAC and a couple of other things out, which will keep us busy for the rest of this year. But I have already suggested that the motor controller should be put back on the table for consideration in 2015.

[Pfenning]

I'm interested for sure. Forgive my ignorance, but could this design your considering be adaptable to rim drive? We have a pile of 3" thick 6061 Aluminum material at my shop, and I've been dreaming about a new DIY turntable with a 3" thick platter. I was considering trying to build a rim drive for the heck of it. Maybe a plywood prototype base, with the aluminum platter and a bearing (built in my shop). I figure if I'm building the platter and the drive pully, I can adjust the diameters to get the speed close, and dial it in from there. If it works good, then pull the platter and bearing ahead into a nice finished base. If the rim drive idea crashes and burns, it would be easy to use with a belt and pully. There's lot's of ground to cover here, and I'm at the dreaming stage. My current DIY table uses a Terres motor kit that measures a strobe disk on the bottom of the platter to maintain speed. It features a super simple homemade bearing, acrylic platter, and Rega RB250 with Incognito upgrades. I think it works and sounds pretty darn good, but i don't have much to compare it too. 

Pfenning 

[Paul Joppa]

I helped a friend set up something to drive a rim-drive table, really made much more difference than I expected. I don't mind making some electronic designs, but the big question is, what are the requirements - voltage and current? Sine-wave distortion? What tables might need the most power?

Pretty much anything will drive an old AR, but how about a Rek-O-Kut? I can easily see a low-power source that overloads on startup but eventually gets the platter going, and then keeps it going well.

Probably we should build something and try it out ...

[Chris65]

Something like this maybe: