DIY Turntable project!

[Hdale85]

Being as these forums are my home and I like to contribute with what I can I have decided to post all the info pertaining to the turntable I'm planning out and going to build.

All my friends have been getting turntables... So I decided to start planning out my DIY turntable. This is what I have so far of the base.

Image not available

The holes that are in a circle will have a .5" wide .125" deep rare earth magnet in each. The blue line represents where the edge of the platter will be. The bottom of the platter will have the same magnets in it so the platter will levitate. There will be a pole in the center that goes up through the middle of the platter and creates the pole piece that the LP sits on. So the pole will hold the platter in place and the magnets will be the bearing. I'm still working on what I'm going to do with the electronics portion of everything as far as motor and how to control speed. I might just do a 1 speed only which would be 33 as I'm not sure I would actually get a 45... but I guess its possible. The base is 2" thick the platter will be either some hardwoods laminated together or a bamboo butcher block and would like to be 3-4" thick. The tone arm I'm probably going to build my self but still working out how I want to do that as well.

So let me know what you guys think and I'm very open to hearing idea's about how to control the rpm of the platter as well as tone arm ideas.

[Raptor550]

Dude, I love this, keep going and be sure to give it a good finish! I will definately be keeping my eyes on this

[Gir]

I believe the one I have at home uses optics. There's a ring of black lines on the outer edge with a laser pointing at them. Every time the optics sensor sees the laser reflecting off the platter (wherever there isn't a black line), it can create one count. If it's not counting fast enough it speeds up, and if it's counting too fast is slows down. Printers do a similar thing with their paper feed, so you might be able to scrap an old printer for it. I actually have 4 from two old printers. As for the motor, I guess you would just use a DC motor with a variable voltage to control the speed.

What do you plan for the electronics to actually play it?

[servicetech]

Fortunately there aren't any electronics in phono players. You can hook the output from the needle cartridge straight to the phono input on an older amp (when was the last time somebody saw a phono input on an amp?) or into a "phono preamp adapter".

For the motor you can put coils under where the magnets are. For a control circuit you could get one out of a scrap VCR capstan motor. Or you could kick it totally "old school" and just use a cheap A/C motor and a belt.

Seriously though, I'd hit the local thrift stores/garage sales, people are giving turntables away all the time. Typical thrift store employees/shoppers have no idea what a quality turntable looks like, you can almost get it for free.

[JoshK]

Looks like a fun project. Dig through the old archives on the Teres project before Teres made all their products > 4G's. Also look at the diyaudio forum for threads about a motor project. This will give you a lot of ideas and also give you a realistic expectation about the amount of work required.

I have a DIY Teres TT that isn't set up right now. I made the base basically and bought the platter, motor & bearing. The bearing is probably the most crucial part and unless you have access to a precision milling machine, I'd probably try to buy one or salvage from another table. I might also look at salvaging an old DD motor out of a Thorens, Lenco, Technics or Garrard. The economies of scale at the time can't be easily beat under a few grand nowadays.

Note that Teres went to DD/rim drive for their big offerings. Other major TT manufacturers are capitulating on the belt drive. I find the film tape pulley on my Teres a PITA to deal with.

[JoshK]

P.S. you sure you only want 45rpm, i.e. singles? 33rpm is the standard speed for most LPs. Half the fun of having a TT is collecting LPs from dime stores, garage sales and dumpster dives. Most of what you'll find are 33rpm and maybe 1/4 of which are 45rpm.

[Johnloudb]

Very cool project. I love the magnetic levitation idea. One suggestion - use more magnets on the base so they're closer together providing a continuous magnetic field. Otherwise it could vibrate as the platter spins. The platter won't need so many.

You can get custom belts and other turntable parts, cartridges, etc. here:

http://www.kabusa.com/frameset.htm?/process.htm

Their website is a mess but they have some goodies.

[Gir]

Fortunately there aren't any electronics in phono players. You can hook the output from the needle cartridge straight to the phono input on an older amp (when was the last time somebody saw a phono input on an amp?) or into a "phono preamp adapter".

Huh, I had no idea. I guess it's just a bit before my time

[Dryseals]

Since the needle is mounted to a metal arm and moves either the coil or the magnet, won't the magnets in the turn table cause the arm to move each time they pass by?

[littlesaint]

Possible non-starters:

1. Magnets and phono cartridges may not play well together.

2. Using multiple small magnets may make the platter unstable since the magnets may have different strengths and may degrade at different rates, not to mention the changes in magnetic field as the magnets move across one another. Using two large opposing magnetic plates would work better.

3. Magnets will not decouple the platter. Assuming the magnetic fields are constant (they better be if you plan on playing records ), any disturbance of one side disturbs the magnetic field and subsequently the magnet on the other side. It should reduce friction which could be beneficial, but the patter will still be subject to vibrations, possibly even more so than if it was attached to the base.

[Hdale85]

Wow lots of posts. Ok as for the platter being unstable I plan on using some magnets that are hugely powerful and making the platter somewhat heavy maybe even weighting it if I need to. This way the platter is only hovering like 1/4"-1/2" with it riding on the pole piece I think this should be ok. Also the platter will be something like 4" thick I really doubt the magnets being that far away are going to have little to no effect on the needle or tone arm. The tone arm will be made of aluminum so magnets won't effect that either. As for the motor most TT's use motors that change speed based on frequency's fed into them. I've thought about getting an old TT or even a new DJ belt drive TT thats around 100 bucks and using the motor and what not out of that. As for electronics more then likely I'll build my own phono stage. Thought about a tube phonostage possibly.

[Hdale85]

As for variances in the magnetic field this is why I used so many magnets. It shouldn't change enough to really make the table unstable. It's cheap enough that its worth a try at least. I think it should work great. The magnets I'm going to use are here http://www.rare-earth-magnets.com/detail.aspx?ID=71 .

As for a finish. I'm thinking the base will be painted black and the platter will be hardwood and dyed with a blue aniline dye.

As for speed I got them mixed up when I posted early this morning. If I did a single speed would be 33 rpm. Chances of me buying a 45 are slim to none.

[Dennis H]

The cartridge itself uses a tiny magnetic field to generate the (very low voltage) signal so, as others have said, it may not like being placed near powerful magnets. Maybe it's not a problem but I'd do some experimenting before committing to the build.

[kevmurray]

...So let me know what you guys think and I'm very open to hearing idea's about how to control the rpm of the platter as well as tone arm ideas.

Very cool project!
Potential problems I can forsee:

1. Fabricating a DIY platter that is fully ballanced. Machining your bamboo block is a must I think. Hopefully the material is fairly consistant in density throughout to make balancing unnecessary.
2. Platter not running true on the post axle without a hub bearing. Tight tollerances and a viscous lube may solve this one, though it would negate some of the advantages of levitation. I think I'd go with a ball bearing fixed to the platter and sliding on the post.
3. Platter bobbing up and down slightly as upper magnets pass through space between lower ones. Might have to come up with some sort of quadrature pattern to maintain equal support through 360*. Otherwise at rest it would seem to be "in a rut".

Speed control can be accomplished with an opamp integrator scheme if you want simple analog. Either an optical sensor or a hall effect sensor since you already have magnets in the platter. Otherwise a microcontroller could be used... then the whole thing could be designed for SPDIF digital output. :T OK I'm getting a bit crazy but you gotta admit it would be cool to have a digital turn table.

[pedroskova]

J.C. Verdier has been doing this for years. You might want to search for his name over at diyAudio/analog. People have tried magnetic bearings in both platters and tonearms.

[Hdale85]

Well my plan is to have the magnets close enough together that there aren't any dips or ruts between magnets. As for a digital TT isn't that sort of defying the point of having a TT? It's supposed to be purely analog. No digital to analog conversion. If I made it digital then I would be back to needing an amazing DAC which can get very expensive. I've thought about using a bearing in the middle of the platter as well to keep it nice and smooth. I still haven't decided how I'm going to make the platter exactly. I'm thinking with the magnets all around the outside it might not matter as much that its COMPLETELY balanced but as long as its mostly balanced and flat should turn out pretty good. I would love to throw a block of wood on a lathe and carve it out. Unfortunately I don't have a lathe or access to one. And definitely not one large enough to do a 13"x13"x4" block of wood.

As for the bobbing I think if I weight the platter down so that it's only hovering 1/4" or so and so that its in a more stable field of the magnets it shouldn't bob at all and as I said before I'm hoping the magnets will be close enough together so that there aren't any ruts between fields. Building isn't really what I'm worried about as it is enjoyable by me. I figure I can get the wood and magnets and try out a simple platter and build the base and work from there. If it doesn't work I can scrap the magnets and should easily be able to add some sort of bearing.

[Hdale85]

J.C. Verdier has been doing this for years. You might want to search for his name over at diyAudio/analog. People have tried magnetic bearings in both platters and tonearms.

I knew I had heard of peopel at least trying magnets but didn't know any MFG's actually used them. At least not for the platter I've heard of some using it for the legs as decouplers.

[Cataclysm]

J.C. Verdier has been doing this for years. You might want to search for his name over at diyAudio/analog. People have tried magnetic bearings in both platters and tonearms.

I really enjoyed reading the information on that page, especially the bits about how long and scrutinizing his review of the turntable was. Subsequently, I began to notice glaring spelling errors every other sentence and began to question all of it. :lol:

"i.e. are able to accurately transcribe the received signal and produce a facsimile of the original. The Verdier does just chat. This review has taken an inordinate amount of time and at times confounded my patience with the innumerable permutations available in the process of nailing down the sonic signature of the turntable. In fact I don't think that f have yet got to the bottom of the character of this deck. There can be no question chat a large part of what it does is due to the suspension and the engineering principles employed in its design."

[Hdale85]

I did a little render of the platter.

Image not available

As you can see there is a linear slide (I believe that what this would be called) bearing in the center to help reduce friction. This would be the bottom side of the platter.

[Hdale85]

I had an idea to put a second row of magnets closer to the center of the platter and base that would fit between the first set so there would pretty much be no gap between magnets at all. Would add a lot more holes and magnets but could work better and smoother.

[Gir]

I think what would be better is to get something like this. Put this in the center and you avoid all magnetic vibrations from uneven fields, which I imagine there will be plenty. Not to mentions it's not all that expensive and it has a 36 lb pull. You may want to go even lower than that, but it depends how heavy your turn table is.

[Hdale85]

I'm not to sure the field will be all that uneven the way I'm planning. But that is an idea but 36lb pull is way to much. You have to remember that there will be 2 magnets pushing against each other. Also the magnetic field of a 36lb pull is going to be quite large and could very possibly cause issues with the cartridge. I was looking for ways to keep the field small and still get nice performance as well as really smooth platter movement. But those magnets look interesting. I just made a thread at another forum where there have been many that have built TT's going to see what they say.

[tyler]

Looks like a fun project. Dig through the old archives on the Teres project before Teres made all their products > 4G's. Also look at the diyaudio forum for threads about a motor project. This will give you a lot of ideas and also give you a realistic expectation about the amount of work required.

I have a DIY Teres TT that isn't set up right now. I made the base basically and bought the platter, motor & bearing. The bearing is probably the most crucial part and unless you have access to a precision milling machine, I'd probably try to buy one or salvage from another table. I might also look at salvaging an old DD motor out of a Thorens, Lenco, Technics or Garrard. The economies of scale at the time can't be easily beat under a few grand nowadays.

I agree with Josh. Consider Teres for DIY and the bearing is the most important factor.

J.C. Verdier has been doing this for years. You might want to search for his name over at diyAudio/analog. People have tried magnetic bearings in both platters and tonearms.

JC Verdier is using the magnets for the platter bearing and Schroeder is using magnets for there tonearm bearings.

[Hdale85]

Teres is a bit far out of my price range by a long shot :B

[Johnloudb]

I think what would be better is to get something like this. Put this in the center and you avoid all magnetic vibrations from uneven fields, which I imagine there will be plenty. Not to mentions it's not all that expensive and it has a 36 lb pull. You may want to go even lower than that, but it depends how heavy your turn table is.

Dougie, I think something like Tyler suggested would be ideal. It's in the center of the platter where the magnetic field would have much less effect on the needle. I doubt it would too much force. When two magnets are oriented to oppose each other much of the external magnetic field is canceled out I think. If not, there are also ways to shield magnets. Magnets put farther out on the platter edge would be more prone to vibration. Although, I think that method could also work.

[Hdale85]

Just wanted to post an update. A lot of this info is from another forum so it's just copied and pasted. As for magnets I'll probably be using something like 2 of these http://www.magnet4less.com/product_i...roducts_id=321 they have to be quite powerful I guess because their push strength is a lot less the guy on another forum said devide the pull by 3. And then you have to factor in the weight of the platter.

Images not available


Post #27
I had an idea for a speed control. I figure I could hook up the motor and what not and then get a potentiometer and hook it up and use the strobes to find the correct speed for 45rpm and then measure what the resistance is on the pot and do the same for 33.3 rpm and then wire up a switch with something close to the 2 resistances probably a bit less then what was required. After that would be a small pot for fine adjustments on each. Possibly build this into a power supply box or something.

I guess there isn't to much more that I've added. I'm currently rethinking the design of the TT as in shape and what not. Going to try and come up with something a little neater. I've been thinking about getting a Grado Prestige Gold cartridge and a Jelco SA-250 tonearm. http://www.jelco-ichikawa.co.jp/e_tone_arm.htm the tonearm is here at the bottom. http://www.gradolabs.com/frameset_main.htm this is the cartridge.

I've also found some info on a linear sliding air bearing tonearm. I've thought about building it but I'm still unsure? It looks nice and all just not sure I can tackle it so well

Heres the info on the tonearm http://www.aiko.com/roscoe/arm2.html

Some pics and video of it in action http://www.transaxeguitars.com/nonguitar.htm

Let me know what you guys think? I've been considering ditching the magnet idea as well. Although I like to do things unique and differently so I'm not sure? Apparently things like the Grado cartridges which are supposed to be real good are real sensitive to magnets and electrical noise.

[Curt C]

I'm still working on what I'm going to do with the electronics portion of everything as far as motor and how to control speed.

Here's a link to use a floppy dirve motor as your turntable motor:

http://blog.makezine.com/archive/2005/07/diy_floppy_moto.html

Hopefully the link still works. It's blocked here at work...

C

[Hdale85]

Yeah I've seen that before. Just not sure how much torque a floppy drive motor has or how long it would last. I'm guessing my platter could weight something like 40lbs.

The link actually doesn't work... I'm trying to find the info I saw.

[Hdale85]

I've pretty much decided I'm going to take a stab at the linear tracking tonearm as it would be cheaper then buying one although more time consuming and should be better in the end.

[Hdale85]

I spent a little more time on the design of the TT it self today. I did some renderings in Solidworks. I think it looks nice. I didn't draw in the tonearm yet I have to figure out where and how I'm going to do that. Obviously there isn't a space between the platter and the base this was just kind of a quick rendering. The platter is 3" thick on this one.

[Hdale85]

After talking to some people at DIYaudio I did another redesign somewhat.





As you can see the motor is no longer housed on the same base. This should keep vibrations from the motor away from the TT and keep noise down. I also drew in part of the tonearm.

[kevmurray]

For every force there is an equal and oposite one. How will you keep the motor torque from spinning the motor base? Seems to me that no matter how you do it you are ultimately going to have to couple the motor to the platter. Might as well isolation mount the motor to the base you drew this morning. In my opinion the belt is isolation enough. Of course I'm assuming you plan to use a belt.

[Hdale85]

The base for the motor with the motor in it will be heavy enough that it won't. Lots of people do this with their DIY and even some commercial TT's.

[Saurav]

That's how my TT works - the motor pod is completely separate from the plinth, and the weight of the pod (plus some sticky feet) keep it from turning. I have the Bix, which is semi-DIY - it was sold as a kit.

For this kind of a design, I don't think you'd want a TT motor with much torque. I spin my platter by hand before I start the motor, otherwise it takes a long time to come up to speed. I think there are turntables where the motor isn't powerful enough to get the platter spinning from rest. You're relying on low friction bearings and the platter's inertia to make this work.

Using a high-torque motor would probably be a different approach to designing a turntable.

Disclaimer - I'm not a physics expert, so this is all just my understanding of how this works.

[Hdale85]

Yeah was going to be my second comment is that the motors aren't that high torqued. Also they aren't spinning all that fast. I've seen the Bix before its rather nice. Just not DIY enough for me

[Jed]

Dougie,

You can get some ideas about turntables from these guys:

http://www.youtube.com/watch?v=xs1aUws0Lrs

:rofl:

My wife has permission to shoot me if I ever get this addicted to audio (metaphorically speaking).

Jed

[Hdale85]

I was actually thinking about doing a platter like that with the weights hanging but I would have to get every weight exactly the same.


....230k euros on 2 channel.... HAH! Even if I was a millionair that would never happen... although I diy just about everything so be hard to spend that much...

[Saurav]

Just not DIY enough for me

Yeah, it was a pretty easy kit to assemble, you didn't really have to do anything. Some parts of my system are DIY, some parts I decided not to mess with

[Hdale85]

So far my speakers, and amp are DIY. Going to be adding a DIY DAC, and TT soon. And going from a DIY amp to an Emotiva XPA-5 at least for now. I may build a 2 channel amp for my mains later.

[Saurav]

Good luck with the DAC. I decided not to mess with high speed digital circuits, so I bought my DAC My TT, phono stage, linestage, amps, speakers are DIY. A Behringer active XO replaced a DIY effort, and I have a Behringer sub amp and BFD.

[Hdale85]

Well the DAC is actually relatively simple. It's going to be a DAC from Twistedpearaudio.com and its pretty much a series of modules depending on how you want to use the DAC and your just wiring them up more or less. It's based on the new ESS Sabre DAC though which is supposed to be the new best DAC out there.

[Saurav]

Thanks, I'll look into that.

[Hdale85]

The Sabre based one isn't out just yet. But their Opus DAC is based on the Wolfson WM8741.

[kevmurray]

You can get some ideas about turntables from these guys:
http://www.youtube.com/watch?v=xs1aUws0Lrs:rofl:

LOL! Thanks for the link Jed. Everyone is entitled to their opinion of course, but this is getting crazy. :roll: "...the electricity is 50% of the sound... the rack is 30% of my sound..." I wonder how the speakers and room factor in?

Jokes aside, can one buy vinyl recordings worthy of equipment this spendy? I mean what is the performance level of modern vinyl recordings, or am I committing heresy by asking?

[JoshK]

IMHO modern vinyl pressings are hit and miss. Some are done pretty well, but still not knock your socks off quality IME. Most are just vinyl pressings of the digital recording and you are better off with the CD. (I'm a heretic I know).

Older recordings recorded in the hey-day of the recording era done in all analog can honestly sound remarkable on vinyl. I have a Monty Alexander trio Live performance on vinyl that is mind blowing (to me at least) and I don't like jazz. The piano is so realistic sounding its like no other recording I've heard. I've heard a remaster of the same recording on CD and it was nothing special, just like the typical recordings I have.

So to me atleast, vinyl is really something if you are into music from an era that was recorded in analog, and/or have a massive LP collection or access to one, or can obtain tons of LPS cheap (which is part of the fun).

Lots of classical recordings were released on LP and never redone on CD, so it opens up a world to the classical music aficionado. Lots of cheaply available LPs out there. Not all of them are decent quality and/or good condition but there inlies part of the hobby which is the hunt. There are cults of LP hobbiest who come up with cleaning methods that can make a noisey LP sound halfway decent too.

To me you really have to ask yourself whether the music available on LP (not including modern stuff IMO) has a big overlap with your tastes and go from there. Don't get into LPs just because it is fashionable and you gain audiophile cred, it is just too much of a hassle and you aren't likely to get much return on your time/money. Its a deceptively expensive hobby, don't let the cheap LPs fool you. Cleaning equipment, needles, arms, this, that, etc all adds up.

My suggestion is to start with a cheap Technics DJ table, like a used 1200, and see if you enjoy it and whether it is worth it to you. Then consider upgrading the table via the KAB method or embark on something bigger. A DIY TT project, I don't mean to persuade you or discourage you, is a very big endeavor.