DIY Turntable Advice Needed!

patslice

patslice

Patrick
Hello everyone!

I'm willing to start a pretty ambitious project: building my own turntable!
I want to stay pretty simple with a classic look: a 33/45 belt-driven platter with solid wooden plinth and wooden faceplate. And I'm really loving this project so far!

I do have a few technical questions though, especially about the motor and platter choices.
I want to stay simple: a 12V one-speed motor with manual speed changing. Only one switch on the face plate, like the new essentials Pro-Ject or the old Thorens TD-160 etc. : On and Off.

To achieve that I have two options: (numbers for the 33.3 speed)
  • a 250 RPM motor with a 20mm pulley and a 150mm sub-platter (like an old Thorens);
  • a 500 RPM motor with a 40mm pulley and the belt goes directly around the 300mm main platter (like a Pro-Ject).
(PS: To calculate this proportions I found a very useful tool: a pulley calculator! )

Now, I'm in doubt between a motor intentionally designed to fit a turntable (eBay has a few), or a brand new and cheap gear motor. I've heard that the gear motors might be a little to noisy and inaccurate for the HiFi application, so I guess I'm going to buy an old rescued motor.
I have a few concerns about the platter too: it's pretty hard to find a platter with spindle and bearing, so do you have any advice for a DIY complete platter? (I don't have any machine or tool to ironwork though...).

So here are my questions:
  • What is the best motor option for my needs? (AC, DC, With brushes, brushless, ...)?
  • 250 RPM with sub-platter (prettier) or 500 RPM without sub-platter (easier to build and switch)?
  • Do you know any good producer of brand new turntable motors?
  • Do you have any favorite 2nd hand motor? Thorens? Linn? Lenco?
  • Do you know any good producer of brand new platters?
  • Do you have any favorite 2nd hand platter bearing and spindle?
  • Any other suggestions and advice for my project?
Thank you so much for your time! And have a great week y'all!
Greetings from Switzerland.

Patrick
 
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Have you looked at synchronous AC motors. Their speed is controlled by the AC lines frequency as long as the load is within the motors specified tolerance. That gets the incoming line frequency doing the speed control for you.
 
I'm going to follow this. I have an old Perpetuum-Ebner re-badged as a Fisher 402. The watch-works underneath are not useful to me and don't operate correctly. I want to make it an on and off total manual table. (I started in radio when we played all our music on vinyl.) Wish I still had all those tables that went through my hands now, and cars, and baseball cards and...
 
shelly_d said:
Have you looked at synchronous AC motors. Their speed is controlled by the AC lines frequency as long as the load is within the motors specified tolerance. That gets the incoming line frequency doing the speed control for you.
Click to expand...
Hey! Thank you for your answer!
I read about synchronous AC motors and similar stepper motors. It is apparently a good solution, especially because you can really set a precise speed; but I don't really know how I would generate the needed frequency. On this great DIY turntable project the author talks about the signal generation but it looks pretty complicated. I was really hoping for a "plug and play" motor, and then to work on the pulley's sizes to achieve the perfect speed.
Do you know something more about the frequency subject? If I power the motor with a simple 220VAC to 12VDC-50Hz transformer, would it work to generate an accurate (but not adjustable) frequency? Are there other ways to manage the speed?
Thanks again for your time!
 
turnitdown said:
I'm going to follow this. I have an old Perpetuum-Ebner re-badged as a Fisher 402. The watch-works underneath are not useful to me and don't operate correctly. I want to make it an on and off total manual table. (I started in radio when we played all our music on vinyl.) Wish I still had all those tables that went through my hands now, and cars, and baseball cards and...
Click to expand...
Hello!
Yes, this are really great and fun projects: it's pretty minimal and you really can get a great result!
Hope you'll find some useful information on this thread! (Check out this link for a great DIY project)
Thank you for your time!
 
patslice said:
Hey! Thank you for your answer!
I read about synchronous AC motors and similar stepper motors. It is apparently a good solution, especially because you can really set a precise speed; but I don't really know how I would generate the needed frequency. On this great DIY turntable project the author talks about the signal generation but it looks pretty complicated. I was really hoping for a "plug and play" motor, and then to work on the pulley's sizes to achieve the perfect speed.
Do you know something more about the frequency subject? If I power the motor with a simple 220VAC to 12VDC-50Hz transformer, would it work to generate an accurate (but not adjustable) frequency? Are there other ways to manage the speed?
Thanks again for your time!
Click to expand...

With that kind of motor, it will lock to the the frequency of the line. Since you are in europe, the mains frequency is 50 Hz. The power company is generating that. The motor will spin at a set speed basied on that. It would be up to you then to size the motor pully and platter or sub platter to get the right speed for the record. You would need different sized pullys for each speed, one for 33 1/3 and one for 45. The pullies would need to be sized very precisly and then tested in service as belt tension sometimes affects the speed and performance of a belt drive turntable. Once tested, they might need adjustment to correct the speed.

Such a motor would not have any speed control.

Shelly_D
 
shelly_d said:
With that kind of motor, it will lock to the the frequency of the line. Since you are in europe, the mains frequency is 50 Hz. The power company is generating that. The motor will spin at a set speed basied on that. It would be up to you then to size the motor pully and platter or sub platter to get the right speed for the record. You would need different sized pullys for each speed, one for 33 1/3 and one for 45. The pullies would need to be sized very precisly and then tested in service as belt tension sometimes affects the speed and performance of a belt drive turntable. Once tested, they might need adjustment to correct the speed.

Such a motor would not have any speed control.

Shelly_D
Click to expand...
All right, sounds good then! That's exactly what I'm searching. Thank you for your answer!
What about the wiring though? I saw that some motors have 2 or 3 or 4 wires; shouldn't I just connect it to the power transformer?
(Sorry I'm pretty new in the motors field).
Thanks again!
 
patslice said:
All right, sounds good then! That's exactly what I'm searching. Thank you for your answer!
What about the wiring though? I saw that some motors have 2 or 3 or 4 wires; shouldn't I just connect it to the power transformer?
(Sorry I'm pretty new in the motors field).
Thanks again!
Click to expand...

Typically, they will need a capacitor hooked up to them to provide a phase shift to a seperate winding inside the motor called the start coil. It is there to insure that the motor has enough starting torque in the correct direction to turn in the correct direction at the correct speed even under load. The size and wireing of that capacitor will vary from one motor to the next.

Shelly_D
 
Unfortunately, since the AK site upgrade, I am having difficulty finding the thread I started on this build, but if you go to this page,

http://s95.photobucket.com/user/nicholasfowles/library/Dads TT?sort=3&page=1

you will find pics of the TT I built about 6months ago. For the motor, I used an infinitely variable speed motor from e-Bay. In order to set the speed I used both a strobe disk downloaded and printed from the web as well as a 60 hz tone record and a platter speed app from the apple app store. Both worked equally well. Not shown in the pics are the marks I put on the motor to indicate the correct position for both 33.3 and 45 rpm. As for the spindle and platter, both were also sourced from e-Bay. With a bit of patience, you will find all that you need.

Good luck and please post pics
 
Scuba,
I love your TT; plinth is just phenomenal with that unfinished face. Very clever.
Thank you.
 
scuba said:
Unfortunately, since the AK site upgrade, I am having difficulty finding the thread I started on this build, but if you go to this page,

http://s95.photobucket.com/user/nicholasfowles/library/Dads TT?sort=3&page=1

you will find pics of the TT I built about 6months ago. For the motor, I used an infinitely variable speed motor from e-Bay. In order to set the speed I used both a strobe disk downloaded and printed from the web as well as a 60 hz tone record and a platter speed app from the apple app store. Both worked equally well. Not shown in the pics are the marks I put on the motor to indicate the correct position for both 33.3 and 45 rpm. As for the spindle and platter, both were also sourced from e-Bay. With a bit of patience, you will find all that you need.

Good luck and please post pics
Click to expand...

That is a slick looking turntable. Congrats on how good it looks.

What tonearm is that please?

thanks

Shelly_D
 
Thanks Shelly_d. It's a Mayware formula IV. An oil dampened unipivot design.
 
I will be watching this thread..I would love to do this, great winter project, Im thinking laminated plinth..Im thinking laminated might have better anti resonance?
 
shelly_d said:
Typically, they will need a capacitor hooked up to them to provide a phase shift to a seperate winding inside the motor called the start coil. It is there to insure that the motor has enough starting torque in the correct direction to turn in the correct direction at the correct speed even under load. The size and wireing of that capacitor will vary from one motor to the next.

Shelly_D
Click to expand...
Thanks for the instructions! I'll work on it and keep you guys updated!
 
scuba said:
Unfortunately, since the AK site upgrade, I am having difficulty finding the thread I started on this build, but if you go to this page,

http://s95.photobucket.com/user/nicholasfowles/library/Dads TT?sort=3&page=1

you will find pics of the TT I built about 6months ago. For the motor, I used an infinitely variable speed motor from e-Bay. In order to set the speed I used both a strobe disk downloaded and printed from the web as well as a 60 hz tone record and a platter speed app from the apple app store. Both worked equally well. Not shown in the pics are the marks I put on the motor to indicate the correct position for both 33.3 and 45 rpm. As for the spindle and platter, both were also sourced from e-Bay. With a bit of patience, you will find all that you need.

Good luck and please post pics
Click to expand...
That's a great looking TT scuba, love the wooden plinth and tonearm! Thanks for your help! I will keep you guys updated as soon as I find a few more components!
 
vonclod said:
I will be watching this thread..I would love to do this, great winter project, Im thinking laminated plinth..Im thinking laminated might have better anti resonance?
Click to expand...
Yeah definitely a fun project for the colder days! I'm thinking laminated too, solid, light and pretty easy to work !
 
Update!

I bought a motor along with another few components, it's a AIRPAX AC synchronous motor, and it's really what I was hoping to find!
That's the product, and that's the complete data sheet.
Important specs:
  • 220VAC;
  • 250 RPM at 50Hz;
  • Working torque: 2.0 Ncm.
It's great because I can directly link it to my main power source (220VAC) and it has a stable speed. I'll just have to work on the pulleys to get the perfect platter speed. And for 50 bucks I think it's a good solution!
However I'm not sure about the wiring. There are some schemas on the data sheet, but I'm not an expert in electronics connections. Can someone help me or link me a good guide on the subject?
That's all I know for now: I have a 220VAC input through a filtered IEC power socket, I want to fit an on/off interruptor , and I (think) I know that I have to fit a 0.1 uF phasing capacitor on the circuit. Am I missing something?

Thanks for your help as always guys!
Greetings.
 
Not sure that will have enough torque for this application. If I have the spec correct (big if, I can't translate the product page), the motor can handle an intertial load of .02 KgCm^2. It turns at 250 RPM. To get 33 1/3 RPM you need a 7.5 : 1 gear ratio. Since the inertial load it can handle will increas by the square of the gear ratio, that means your max inertial load is .02 x (7.5^2) or 1.125 KgCm^2. The diamiter of an LP and therefore a plater is 30.5 cm and the formula for finding the inertia of a disk is 1/2 m r^2. Using the 1.125 Kg for maximum inertial load and a platter radius of 15.25 cm to find the mass of the platter, I come up with a mass of .009675 Kg. That is an awfully light platter. (this assums I've done this math correctly.) I would assume you would want something much heavier for a turntable. My Thorens belt drive turntable has a platter mass close to 3.25~3.5 Kg.

Hope this is a correct analisys for you.

Shelly_D
 
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