Mark Kelly Synchrotron AC-1 turntable drive controller

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BobM

Well I finally finished this little project and I can say that I learned a lot, it was worthwhile (for me) and the music has improved.

Here's a link to some postings over at Audio Asylum and other people's implementations as well:
http://www.audioasylum.com/audio/vinyl/messages/71/718147.html

I would say that it is not a kit for a beginner, and some knowledge of what you are doing besides being ablt to handle a soldering iron would be beneficial. In my implementation I am not using a 12V DC battery, but rather an AC to DV 12V laptop power supply. My costs came in at about $400, about half of a used SDS, but the time it took to build was not insignificant.

I agree with Dave's assessment of the level of improvement (see Audio Asylum thread). Fundamentally I noticed that the image and soundstage are very stable now (they were pretty good before, but this is rock solid now). The 10W VPI motor that I have, in its housing, didn't seem to vibrate very much. However, when removed from the housing and held in the hand you can feel the vibrations clearly. This is due to phase problems with the AC coming in.

Mark's controller, aside from maintaining a stable frequency for speed control, does a wonderful job of synchronizing and stabilizing the 2 phases of AC power to the motor thereby making it very quiet. There is a truly noticeable improvement of how quiet the motor rund when in the hand, and a quiet motor will not transmit vibrations through the belt to the platter.

Enjoy,
Bob




TheChairGuy

Re: Mark Kelly Synchrotron AC-1 turntable drive controller
« Reply #1 on: 10 Jan 2008, 07:50 pm »
Brilliant Bob  :thumb:

I had no idea this existed...$550 for one fully pre-built (just add charger and battery I suspect)....a whole heck of a lot of enchiladas cheaper than VPI, Walker or Clearaudio versions.

I have a 'step' isolation transformer coming today to see how an isolation transformer and reduced voltages impact my VPI (and, eventually DUAL 1229 that HurdyGurdyDave 'sold' me)...but it toes nothing to correct the clipped 60hz sine waves apparently crucial to optimal AC synchronous performance. I'm also gonna' see if isolation transformer can positively impact DC Servo performance as standard with the Technics and JVC DD decks I have.

http://java.audioasylum.com/ca/ca.jtp?ca=12872

Thanks for letting us know, John

BobM

Re: Mark Kelly Synchrotron AC-1 turntable drive controller
« Reply #2 on: 10 Jan 2008, 08:16 pm »
Yes, the fully built kit is a bargain and a half. Knowing what I know now, after building it myself, I probably would strongly consider going that route. It was a LOT of work to put together and troubleshoot, but I had fun doing it (which is why I went with the half kit).

It is still not a plug and play option. You will need to get a new cable from the unit to the motor, and have that cable integrated with the motor properly. It is not a simple AC cord.

Enjoy,
Bob

TheChairGuy

Re: Mark Kelly Synchrotron AC-1 turntable drive controller
« Reply #3 on: 10 Jan 2008, 09:43 pm »
It is still not a plug and play option. You will need to get a new cable from the unit to the motor, and have that cable integrated with the motor properly. It is not a simple AC cord.

Enjoy,
Bob

Yeah Bob - I noticed that after posting..why is it NOT a plug n' play for one's specific type of AC motor?

That seems to add a whole level of complexity to the situation for non-DIY'ers  :scratch:

BobM

Re: Mark Kelly Synchrotron AC-1 turntable drive controller
« Reply #4 on: 11 Jan 2008, 12:51 pm »
There are actually 4 wires on the motor - 2 for one phase and 2 for the other phase of an AC "wave". In most turntables they simply split the phase with a simple capacitor network. This is a sub-optimal way of splitting the phase since they are supposed to be exactly 90 degrees opposite each other and this method is an approximation. So if they are not perfectly aligned you will get motor vibrations.

Mark's unit is separately adjustable for each phase, allowing you to minimize the vibration in the motor due to this. In order to hook it up you have to be willing and able to remove the caps on the motor presently (easy to do), identify which wires pair with the others (fairly easy to do), hook it all up to a 2 pair mains rated shielded cable (easy to do), and adjust the phase within Mark's AC-1 unit (not terrible hard, but you will need instructions). You don't need an oscilloscope, it can be done simply by holding the motor in your hand and feeling for the vibrations, although a digital multi meter would be highly recommended to check the resulting voltages on each phase.

Like I said, it is not plug and play, but it is a better solution for a little bit of effort. I don't believe any of the other competing units take this approach, probably because you have to go into the motor and change things, and that is not consumer friendly. But then, most consumers aren't as looney as most audiophiles. :icon_lol:

Enjoy,
Bob

Rocket

Re: Mark Kelly Synchrotron AC-1 turntable drive controller
« Reply #5 on: 12 Jan 2008, 12:56 am »
Hi Guys,

How do these turntable driver controllers work? 

How are they connected to your turntable?

Could it be retroffited to my bluenote piccolo turntable?

http://www.eminentaudio.co.uk/Instruments/Turntables/Piccolo/Piccolo.htm


Thanks

Rod

andyr

Re: Mark Kelly Synchrotron AC-1 turntable drive controller
« Reply #6 on: 12 Jan 2008, 11:49 am »
Hi Guys,

How do these turntable driver controllers work? 

How are they connected to your turntable?

Could it be retroffited to my bluenote piccolo turntable?

http://www.eminentaudio.co.uk/Instruments/Turntables/Piccolo/Piccolo.htm

Thanks

Rod

Rod,

Get thee to "Vinyl Asylum" and search for posts by Mark Kelly ... and ask the man himself!

He lives in Bendigo, BTW!  :D

Regards,

Andy

Plink

  • Jr. Member
  • Posts: 133
Re: Mark Kelly Synchrotron AC-1 turntable drive controller
« Reply #7 on: 12 Jan 2008, 04:21 pm »
BobM, any chance you can provide a pic of the cable and where it meets the motor?  if too big a PIA, don't worry about it.   :thumb:

BobM

Re: Mark Kelly Synchrotron AC-1 turntable drive controller
« Reply #8 on: 12 Jan 2008, 10:57 pm »
There's 4 wires on the motor, 2 (+ and -) for one pase and 2 (+ and -) for the other phase. There are 4 wires out of the controller, 2 for one phase and 2 for the other phase. They just connect up, very easy to do.

2 of the wires on the motor are probably the same color and are most likely connected together right now. One of them will show some conductivity with one of the other primaries. You'll need a meter to find out which one. The other one will show some conductivity with the other primary. Now you've identified your 2 phases on the motor. Get rid of all the caps in there now and wire up to the cable to the speed controller.

Enjoy,
Bob

lazydays

  • Full Member
  • Posts: 1256
Re: Mark Kelly Synchrotron AC-1 turntable drive controller
« Reply #9 on: 13 Jan 2008, 12:37 am »
Brilliant Bob  :thumb:

I had no idea this existed...$550 for one fully pre-built (just add charger and battery I suspect)....a whole heck of a lot of enchiladas cheaper than VPI, Walker or Clearaudio versions.

I have a 'step' isolation transformer coming today to see how an isolation transformer and reduced voltages impact my VPI (and, eventually DUAL 1229 that HurdyGurdyDave 'sold' me)...but it toes nothing to correct the clipped 60hz sine waves apparently crucial to optimal AC synchronous performance. I'm also gonna' see if isolation transformer can positively impact DC Servo performance as standard with the Technics and JVC DD decks I have.

http://java.audioasylum.com/ca/ca.jtp?ca=12872

Thanks for letting us know, John

My Final Tool uses an electronic drive to control the stepping motor. It takes AC current and converts it to DC and send it thru several other changes before going to the motor itself. If I remember right it finishes out at 24 VT. DC. I checked it once with an electronic strobe and an optical one as well. At first I thought the strobe was dead, but it was really as steady as a rock. My Opera isn't quite as steady, but still is very good (I'd say about + or- a half RPM). Some of the variation may be in the monofilment string drive; where the silk thread on the Final Tool just dosn't seem to stretch at all. If you can add a good motor control to your table then by all means do it!
gary