Another DIY turntable project

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Hey all,

Some here may recall my recent DIY turntable and even more recent addition of a DIY tone arm. Link to images attached for reference.

Link


Well I am going to embark on another DIY turnable for winter. I recently picked up for $5.00 Cdn. a 1980's Akai Direct Drive APD2 turntable. I figured why not try a DIY direct drive project. This table is in proper working oder and has a pretty decent factory low mass tone arm. The stylus for the supplied cartridge is broken but who cares?

My concept will be to build a high mass plinth for the motor to be rigidly mounted to and its switch gear routed through. The tone arm will be mounted to a separate high mass base. The idea is to keep noise and vibration of the DD motor to a min. I figure mounting the motor rigidly to a high mass plinth will help "soak" up some vibrations. The tone arm being separate and also high mass mounting will do more of this.

The plan for the platter will be one of two. I may go with the stock aluminum platter as typical of many Japanese tables of that vintage. If I do this I will add damping to the underside of the platter to help filter out noise and vibration. Or I may use the stock spindle as a mount for a DIY high mass platter either made from Corian or MDF. The platter will be lightly press fit on top the existing spindle. I will make a separate spindle to poke out top for the LP's to mount over top. This will be a higher mass and thusly more able to "soak" up noise and vibration from the DD motor. It will be more work but hey th ar is what DIY's are for.

I think my concept is a good one. Will it work as hoped? I don't know. I am trying to keep the DD motor noise and vibration from getting too much into the playback of the records. Rigid mount in a high mass plinth should help this I figure. I will stick with the stock arm as I said it's really not too bad. I wonder how well it may work out.

Anyways feedback and ideas to this concept will be appreciated.

Thanks.
 
cubastreet said:
What's the motor control like? I imagine this will be an important part of the TT and something which could probably be improved upon in an old DDTT

The motor looks to be a typical Japanese D.C servo controlled direct drive unit from the early to mid 80's. It's stamped model number is DDM-6F Mfc. Japan Servo.

It has a servo lock for speed and does not offer any user adjustable via any pots anyways speed control. I guess it has some sort of feedback servo to control rotation. It looks beefy has a large power supply.

I took the botom of the turntable off to see its guts. Lots of crap is going to have to be gutted such as the cutoff and auto-return stuff. Though it would be easier to just plunk this stuff into a newer chassis all these things are noise makers and resonators. It will require some careful surgury but I took a few dozen close up photos of things so that I can study and devise a game plan for project construction.

I had a closer look at the platter and it's more beefy than I thought easily 3+ lbs of solid aluminum. If I keep it I will probably Dyna-mat the underside to help cancel ringing and deaden sounds from the motor and stuff.

I can se a few things in dong thts beinag Pee off but It wil jus ad to ther challegnvde
 
Will be interested in how it sounds when all is done.
I've got a marantz 6300 that i've given to my old man on permanent loan. I quite like the shutoff mech - it has a little card connected to the bottom of the tonearm which breaks a beam of light when the tonearm swings in. The TT then disconnects the signal and raises the arm. No autoreturn but I like the fact that it doesn't keep playing all night if you fall asleep on the couch.
I'm currently modding a big old philips belt-drive - a 31d or something, but one day I might give the marantz a look over as it looks great and is real nice to use.
 
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