Magnetically suspended flywheel !!!

[skaloumbakas]

Hello and congratulations for this excellent forum.

Although I haven't made my turntable myself (I own the Swiss made 'a.a.s Gabriel' magnetically suspended t/t, same principals as the Verdier but heavier), I regard myself some sort of DIYer since I have made many modifications regarding the arm (Clearaudio Souther linear tracking TQi) and the t/t itself.

You can see some of these mods below:

http://aca.gr/paper02.htm
http://aca.gr/paper12.htm
http://aca.gr/paper14.htm

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Lately, I have an extreme dream to add to the 20 Kg platter, a very heavy flywheel of 32Kg rotating weight, doubling or tripling the rotational inertia this t/t platter already has!

Adding this, I am thinking to apply the same suspension philosophy, by inserting 2 large repelling ring magnets, (as the 'Gabriel' and the 'Verdier' platters have), below the main flywheel body, which by the way I want to rotate with a 140 RPM more or less rotational speed.

Making a search about magnets, I want to give you first some info, asking you if it would be better using Neodymium or rare earths magnets which seem to be stronger. Here is the info and please put your comments about possible pros and cons:


A. HERE IS THE INFO I GOT from a t/t manufacturer:
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Magnets used in big woofers are nearly always made of plain ferrite, and their strength relative to size is very poor, but they are relatively cheap. The dimensions you suggest they may be as little as £40 or so. They can also demagnetise when used in this configuration, so beware.

In the case of my turntable we used a very high power rare earth magnets, which are ultra, stable but cost me a whopping £2000/pair. to lift the 40 kgs they are smaller than your spec and only 8mm thick. It is also important to have them magnetized in the correct pattern, otherwise they can "cog" as they rotate.

It is cheapest if you can use a "stock size " magnet, which may be made in small production. I would expect to be able to supply you one of the better quality magnets close to your dimensions for around £500/pair if you want to do the job right first time.

I will also say that you should machine magnet back plates, and they will affect the repelling force significantly. Fitted them is a special job and can be VERY DANGEROUS. I think that if the two magnets in my turntable were to come into contact when in their back plates their would take around 300 kg, yes 300 Kg !!! If you got you fingers in the way, you would lose them!! BE VERY VERY VERY careful. You have been warned!

To have them made, I would need to know the required lift, air gap, and limitations on size, and also your budget. Sorry but that's the way it is. Or just experiment with the woofer magnets you suggest. Be careful though as they will be very brittle.


B HERE IS THE INFO I GOT from "EA Magnetics INC."
***************************************

Neo-35, Nickel Plated Ring
5.90"OD x 2.36"ID x 0.984"Thk.
Magnetized through the thickness
2 pieces @ $ 192.75 each


Here are some answers to questions I have asked them (about materials, dimensions etc.), after they gave me the above price quotation:

1. If we go thinner, the straight will go down. We are already working with the best material available. The thinnest we could go is 25 mm. to meet the lift requirement of 32Kg.

2. All of the Neo material is an-isotropic. This simply means that it is oriented during the manufacturing process, and must be magnetized in the same direction. All of the strongest materials are an-isotropic. As far as the magnetization goes, we were planning on magnetizing them straight through the thickness with one pole on the top, and one pole on the bottom. The magnets will repel each other and rotate smoothly. However, with type of magnetization, one magnet will not drive, or rote the other magnet with magnetic force.

3. The magnetization will last for very long time. There is no date on this, but some have been tested for over 10 years so far.


So, to conclude:

1. Please tell me Pros and Cons regarding this idea of adding a 32 Kg. Flywheel to a 20 Kg platter?

2. What kind of ring magnets (top and bottom) should I use for this huge 32 Kg repelling action I will need?

3. Where can I get them from?

4. Any other 'secret' you would wish to share.


Thanks in advance - Best Regards

[livemusic]

Hi Chistos,
Your Gabriel looks very impressive, both from engineering and aestetical point of view. Seems like you managed to keep this level during tweeking/upgrading...
The first question regarding your flywheel: why so heavy? Such a mass rotating at 140 RPM must be perfectly balanced both statically and dynamically - next to impossible without special balancing machine. You have to make a flywheel rather high/thick to keep a desired mass, so dynamic balancing and lateral forces equilibrum became an issue. Not a simple task, and if you fail, additional layer of vibrations will be added to the main platter. Will the expected sonic improvement worth a mess? I remember one guy reported better results after he get rid of the flywheel on his TNT turntable...
Regards,
Michael

[fdegrove]

Hi,

Michael,

I remember one guy reported better results after he get rid of the flywheel on his TNT turntable...

Wasn't that refering to the TNTs' "Electronic Fywheel"?
I assume you're talking about that particular VPI TT.

Christos,

I will gladly look into the detail of that beautifull TT, in the meantime let me tell you that I'm no big fan of having magnetically suspended platter systems.

I'll comment further soon.

Cheers and congratulations on your lovely audio website,

[skaloumbakas]

Originally posted by livemusic ... Such a mass rotating at 140 RPM must be perfectly balanced both statically and dynamically - next to impossible without special balancing machine ...

Agreed,

In fact, having to turn the platter at 45 sometimes, the 140 will become 200 rpm, so this may be a problem. This is why I am thinking it over and over again and just yesterday I have discovered this interesting forum to get some ideas.

The rotating part should be machined 'in one pass' and the axis should be about 20mm. in diameter - thick enough and not very long to avoid lateral forces, but still I think I will need a very accurate and calibrated lathe to do the job...

Anyway, let's wait for some other ideas...

Thanks

[EC8010]

This is the second DIY turntable from Greece that has appeared recently on this forum. Is there a reason for this? Are LPs particularly cheap in Greece?

[skaloumbakas]

Originally posted by EC8010 This is the second DIY turntable from Greece that has appeared recently on this forum. Is there a reason for this? Are LPs particularly cheap in Greece?

Mine is not a DIY, I just made some tweaks on it...

Yes, you can find cheap vinyl records here in Greece as well as expensive but this has nothing to do with DIY or not.

By the way...

Another question occured to me:

Where would it be better to put the flywheel ?

close to the platter,
close to the motor or...
away from both ?

Cheers

[skaloumbakas]

Hello again, after 6 months I opened this topic...

I wish to report that my heavy weight-high rotation magnetically suspended flywheel for my Swiss hand-made aas gabriel t/t and its magnetically suspended 20Kg platter is ready and spinning...

In this Audio... Paper, there are about 35 pictures to enlarge and most of the technicalities of the flywheel design are described. I am also taking the chance to review my whole analogue set-up. So, I am covering the following subjects:

• The current state of the analogue set-up
  The description of the t/t elements
  The flywheel project
  The finished analogue system set-up - Accessories

Listening comments and concluding notes will follow in a couple of weeks, after the break-in period, I hope they are ready before Christmas...




I simply just want to say that I wouldn't go back for anything in the world!!!

I get a big smile in my face when I still hear people talking about 'dynamic impact', 'stereo separation' and 'silence between notes', digital is supposed to beat analogue...


Enjoy the music
PS: I will try to get a drums set in my room and compare! (Better be a good one...)

[livemusic]

Hi Christos,
Thank you for sharing you unique experience! May be the most challenging tweak ever implemented! Very interesting and well documented report indeed.
Seems "the more mass the better" is unquestionable statement in TT world. Added rotation moment may have a major sonic effect, as you proved. And additional flywheel is definitely the way to "lift-up" existing TT, though hard to implement and rather expensive one. But considering a new design, I'd rather go for one piece super heavy platter with hybrid bearing: conventional ball bearing with reduced by magnets axial load. Verdier already did something similar, to best of my knowlege.
Regards,
Michael

[innernerd]

Has anyone considered, or tried, electro-magnets rather than permanent magnets. Wouldn't they have the advantage of allowing the amount of float to be adjusted?

[fdegrove]

Hi,

Has anyone considered, or tried, electro-magnets rather than permanent magnets. Wouldn't they have the advantage of allowing the amount of float to be adjusted?

Actually, from an engineering POV this would be much better as permanent magnets don't mimmick a "permanent field" at all, they are a "permanent field" when power is applied.

Just make sure you maintain contact with the central bearing or you have yourself a flying saucer.

Make that at least 10 lbs of contact pressure for energy release.

Cheers,