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Old 27th May 2002, 03:44 PM   #1
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Default DIY Turntable

I am looking into designing and making my own turntable, was just wondering if anyone had any advice or useful links so i can do some research.
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Old 27th May 2002, 04:58 PM   #2
arnach is offline arnach  United States
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Default Teres

http://www.teresaudio.com/
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Old 27th May 2002, 05:49 PM   #3
BrianL is offline BrianL  United States
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Default teres

I'll second that, though the current pricing is not the "steal" it was at first. Still an excellent design and if properly built will
be right up there with the high-bucks stuff
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Old 28th May 2002, 09:08 AM   #4
AuroraB is offline AuroraB  Norway
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If one has the necesseary mechanical skills, or knows someone who is willing to make the parts for a reasonable price, the Teres is an outstanding project.

Commisioning the parts from a regular mechanical workshop willl probably bring a price roughly equal to the Redpoint part prices....

Still- an excellent project,- I am working one for myself.....
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Old 28th May 2002, 07:07 PM   #5
dice45 is offline dice45  Germany
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Digger,

i see from your tag you are UK-located.
Maybe the German Scheu kit is cheaper to import to the UK. I would estimate it as equivalewnt to the TERES-kit.
Sorry, have no web adress, best use www.google.com for search.
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Old 28th May 2002, 10:33 PM   #6
lohk is offline lohk  Europe
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It is

http://www.scheu-analog.de/
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Old 5th June 2002, 08:23 AM   #7
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I am just in the planning stages of building one too. This is my suggestion. For the rotating platter, consider using a flywheel from a manual transmission car. Several reasons.

Cheap
Readily available
Heavy e.g. 11kg for 6 cyl one
Already balanced
Has gear teeth on perimeter for speed sensing or strobe (137 on mine)
Usually has flat area next to gear for drive belt to go
Holes already drilled around centre with great accuracy

For a drive motor I am thinking of using either a dc servo motor out of an old HP Deskjet. This has virtually zero cogging effect (lumpy torque), and has an inbuilt 400 pulse per rev rotary encoder disk, or perhaps an old IDE hard disk with a flywheel glued to the disk and a spindle out the centre. The motor in these is a 3-phase synchronous type so no speed feedback necessary.
Have a look also at a vcr capstan drive motor. They sometimes have an integral flywheel and speed sensor.

Let us know how you go.

GP.
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Old 5th June 2002, 08:33 AM   #8
Apogee is offline Apogee  United States
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I would also recommend checking out Redpoint Audio Design. They are the later iteration of the Teres project...

I've spoken to Thom a couple of times and he is absolutely great! I am basing my table on their bearing and platter... Thom can give you a run-down of what has proven to work and what hasn't... I also like the idea of a vinyl platter for a better impedance coupling to the vinyl record...

Also take a look at their bearing... About the nicest that I've seen...

They can be found here:

http://www.redpoint-audio-design.com/index.html

Good luck,

Steve
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Old 5th June 2002, 11:54 AM   #9
dice45 is offline dice45  Germany
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GP,

Quote:
Cheap Readily available Heavy e.g. 11kg for 6 cyl one Already balanced Has gear teeth on perimeter for speed sensing or strobe (137 on mine) Usually has flat area next to gear for drive belt to go Holes already drilled around centre with great accuracy
great idea! nothing beats rotatioanl inertia. Except more of it. Any further idea how to combine that flywheel on top with a thick layer of PVC/Vinyl?

Quote:
For a drive motor I am thinking of using either a dc servo motor out of an old HP Deskjet. This has virtually zero cogging effect (lumpy torque), and has an inbuilt 400 pulse per rev rotary encoder disk, or perhaps an old IDE hard disk with a flywheel glued to the disk and a spindle out the centre. The motor in these is a 3-phase synchronous type so no speed feedback necessary. Have a look also at a vcr capstan drive motor. They sometimes have an integral flywheel and speed sensor.
if the servo motor you mention is a mechanically commutated DC motor (similar to the maxon), go with it! Low-to-zero torque ripple make live life easy here! Moreover, this sort of motor is an asynchronous one. Means: no "rotational spring constant" like with synchonous motors. TTs with synchronous motor belt drive are 2nd order system in best cases (if the belt is non-elastic, stiff against extending) whereas DC-motor belt drive is a 1st order system hence incapable of rotational oscillations.

If you should need such a motor, i have some left, you could buy one or two from me.

Hint: keep the rotational inertia of motor low, the one of the platter high. The motor is not meant to store rotational energy but the platter is.

Another hint: steer clear of ball bearings for the platter spindle, no matter how high the temptation is (i.e. you get the spindle of an old monster harddisk for free). Stick with plain bearings. With friction bearings. By any means!!

And yet another hint: stick with non-elastic belts. Use magnetic tape, does a fine job here. And you have to compensate for the belt's lack of elasticity, the motor has to sit on a sled or a lever pulling moderately outwards.

Have fun!
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Old 5th June 2002, 03:49 PM   #10
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Not sure what to put on top of the platter yet. Yep, the motor is a commutator type made by Buhler or Buehler, can't remember how you spell it. I nevere thought about oscillations in a synchronous motor in this application. Thanks! Actually I have read that in sizes of >1000 hp this oscillation thing can become quite an issue.

Bearings, yeah. At first I was trying to use a big stepper motor and go the direct drive route (did I hear someone fainting there ? ) but even after lots of fiddling with the drive waveform harmonics I still couldn't get a satisfactory result so I have ditched that idea.

Belts stretchiness is also someting I had never imagined would cause a problem but if the drive motor had lots of iertia as well, then I can see a disaster just waiting to happen.

Here is the text I posted to a newsgroup recently of my adventure a long time ago with a turntable belt : "Twenty-one years ago, having a good hifi was *the* most important thing as far as I was concerned. So I went out and bought myself my first ever belt-drive turntable. (they were for records, son). Anyway, it ran just fine, and here I was one day just feasting my ears and eyes listening to, and watching it play. It had written on the front "FG servo" which I assumed meant that it had some kind of oscillator driven motor and an incremental encoder of sorts on the platter for feedback. There was also a neon stroboscope next to the rim of the platter for messing around with speed adjustment if you wanted. I discovered this day that if you slowed down the rotation of the platter with your finger, the speed would dip a little then pull back up to what it was. Conversely, when you lifted your finger the speed would rise momentarily and then drift back to the set point. I would dab my finger on and off while watching in childlike wonder the transient response of this feedback loop while contemplating the complexities of the proportional, integral and derivative factors of this beautiful servomechanism. Oh joy! Then one fateful day I decided I just had to see what was inside this awe inspiring machine, so I opened it up to see and what a letdown! Gasp! There was no incremental encoder driven from the platter. It turned out that what I imagined was the undershoot and overshoot of some fancy feedback loop was merely the stretching and contracting of the drive belt under a changing load. D'oh! If only I had left it unopened...

GP.
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