motor types head to head for a TT

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Hi all,

I've tried to decide which kind of motor will I use with my turntable. The old one is an ac-motor and it's noisy. Which type of motor you prefer? (and why)

-AC
-DC
-Stepper motor

If you have built a controller for a stepper motor please share your thoughts.

The motor (+ controller) should have these functions: 33, 45, stop + fine tune speed control for a belt driven TT.

My TT is an old B&O 3000 modified with a 300mm diam x 20mm thick acrylic platter.

Thank you!
-Pete
 
Stepper motor is a valid option. Check this.

He uses a stepper motor with a dedicated wave generator (aka cdplayer) for both poles (or whaddahell should we call it since it's a unipolar stepper) and a special supply unit to provide the motor with enough throttle (aka stereo amp).

I have not tried but it is a rather tempting diy project.
 
torzsok said:
Stepper motor is a valid option. Check this.

He uses a stepper motor with a dedicated wave generator (aka cdplayer) for both poles (or whaddahell should we call it since it's a unipolar stepper) and a special supply unit to provide the motor with enough throttle (aka stereo amp).

I have not tried but it is a rather tempting diy project.

Hi,

Ok, but he is using it as a synchronous motor, :)/sreten.
 
actually, the altman's idea is one I've planned to try. That's the reason I have included the stepper motors in my list. I have plans to try it first with a mp3 player + amplifier and if it works the plan is to make a generator with sini wave + 90deg phase another one.

Anyone tried this yet?
 
Hi Ghianni,

I'm not sure. I got this for free from a friend. Here's a picture.

Br,
Pete
 

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Well, thats the type as I mentioned before (model type of 70s) , but the arm is not the original B&O and I believe that the pentulum suspension (floating chassis) has been modified also as well as the mechanism of the arm motion. This TT had a humming AC motor and a mechanical speed change control via a rubber wheel - pulley combination and a round belt. If you want to change the original AC motor, you can leave the mechanical speed change control and use a DC motor instead (may be a Maxon motor) as I have done.
 
Here are the pics:

1-The TT as is now,
2-1st platter removed,
3-2nd platter removed, you can see the original conical motor pulley and also the change speed mechanism, the motor runs at about 2800 rpm,
4-A close-up, the dc motor is screwed on the original motor plate, you can see a part of the motor control pcb (from an old japan dc motor),
5-The motor is higher than the original slim line one so I added some extra "feet" to each foot of the TT's base as you can see here from below, left side of the TT and near the fine speed adjustment wheel. So, the TT is now about 2 cm higher than it was before the mod.
 

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Some other member also tried that, if I am not mistaken. Another possibility is to use the AC motor from the old beogram 4002 series which is driven by an electronic circuit, very stable and slim line, which can be fitted in beogram 3k on the original motor plate and it has about the right weight for the suspension springs.
 
Well done. For your info: as you have seen the motor has two bearings and two felt washers. The bearing is porous and must be kept for some weeks into some kind of thin silicon oil before the use. The felt washers need some drops of the same oil. After the motor reassemble, it must run free for about 12 hours and get warm. The motor speed depends upon its temperature. After you put the motor assembly back to the TT be sure that the motor plate does not touch any part and hangs free. The motor induce some hum to the cart. when it is near the end of the record.
 
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