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-   -   Motor for turntable. (http://www.diyaudio.com/forums/analogue-source/20725-motor-turntable.html)

Tomek 25th September 2003 02:30 AM

Motor for turntable.
 
Hello, I think about building my own turntable. The first met obstacle is to find good motor. New ones are beyond my financial reach. Used ones, like from entry level turntables, are not powerfull enough for heavy platter. Is it possible to adopt electric motor not ment to be used for this purpose,, but with proper control circuit converted into precise turntable driver? Or.......any suggestion?
Thanks!!!

jam 25th September 2003 02:33 AM

Check here.

http://www.originlive.com/

Regards,
Jam

PGW 25th September 2003 05:30 AM

I think most of the AC motors used in the synchronous-motor turntables (e.g. LP12) come from Airpax, try this link:

http://www.turntable-kits.com/1-kit-turntable-hfw.htm

As well as origin-live, you can get good quality DC motors from maxon:

www.mpm.maxonmotor.com/


-- John

Brett 25th September 2003 12:50 PM

Low power motors will be enough. Just do like Nottingham and start the platter with a bit of a hand shove. Once moving at the correct speed it takes sweet F.A. to keep it moving.

Tomek 26th September 2003 01:43 AM

Thank you all. I will try to contac Maxon, it looks they have a nice selection.
I did try to search the forum for any schematic of motor control circuit, but with no success. Can anyone point me to not extremely complicated one?

krishu 26th September 2003 10:00 AM

Hi,

i tried several motors on my diy tt and can tell you a few things:

a dc-controlled maxon needs a quite difficult control circuit (shown somewhere at www.teresaudio.com), i buil one just using a LM317 voltage regulator and this did not work well. When the needle tip dives into the groove of the record, speed decreases dramatically. Which means, the speed not only depends on the voltage, it also depends on the mechanical load. This varies across the radius of a record an from music to music.

Then I tried a PLL-regulated DC motor like the one Thomas scheu sells (www.scheu-analogue.com). It was only 10$ and works fine so far, you can adjust speed without having to lathe an new pulley. The only thing is that you should use a string belt (no rubber) an the motor is not the quitest I've heart yet.

Please read my experience at www.krishu.de > hifi stuff > turntable stuff > tt motor.

There are some people who sucessfully use stronger maxon motors than the one i had without the difficult control sold by teres. This uses a Linear Technology Chip (i forgot the number), but unfortunately i did not get a circuit until now.

Maxon motors are not too cheap, but the quality is really good.

Cheers
Christian.

Werner 26th September 2003 10:57 AM

Quote:

Originally posted by krishu
i buil one just using a LM317 voltage regulator and this did not work well.
But you did not use the 101189 Maxon that the Teres people use, right?

Speaking from experience with the Michell motors, something of the torque and power of that Maxon runs constant enough for turntable use.

Of course, if you use a (much) smaller motor ...

krishu 26th September 2003 11:53 AM

Quote:

But you did not use the 101189 Maxon that the Teres people use, right?
You are right. Did i mention that my maxon motor is way smaller? And as said above, i know that some people use a Maxon without such a difficult control (as teres sells) with great results.

Cheers
Christian.

Hamish 26th September 2003 12:21 PM

2 Attachment(s)
I'm actually building a controller using the same motor krishu originally used with this rather simple circuit. It seems that you either need a ridiculously heavy platter or some kind of feedback to get an accurate speed. I could be wrong, but this is just my observation so far.

i haven't been able to test it properly as i haven't yet machined up my bearing, but i have done some rather rough and shoddy tests hooking it up to my Technics DD platter (don't ask......), and it seems to be better than just a voltage reg. It will however need some tuning to fit your application. As the pdf says, not the be-all-and-end-all, but better than a poke in the eye (so to speak).

jackinnj 26th September 2003 12:28 PM

Quote:

Originally posted by krishu
a dc-controlled maxon needs a quite difficult control circuit (shown somewhere at www.teresaudio.com), i buil one just using a LM317 voltage regulator and this did not work well. When the needle tip dives into the groove of the record, speed decreases dramatically. Which means, the speed not only depends on the voltage, it also depends on the mechanical load. This varies across the radius of a record an from music to music.
Before I upgraded from my Thorens to Linn LP12 about 15 years ago I read a lot of the material relating to motor control -- and just as you mention, the electronic means of control with an unsatisfactory feedback system -- i.e. an LM317 -- weren't sufficient for the Golden Ears of Linn-Land. If I can find some of the stuff I will post it.

Perhaps the most satisfactory means of control is just "mass" and the moment of the wheel.


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