New acrylic platter for the SL-1200/1210

[MCRU]

Hey marco the marvellous, can I borrow your MN platter whilst you give Arthur's new platter some serious listening time?

Go on, you know you want to.

[Marco]

Lol - how am supposed to compare the two platters against each other, if you've got one of them?

It'll be 3-4 weeks before I get the acrylic platter, anyway, dude. Once the comparisons are over and done with, yes, you can borrow my MN one, provided you get a bigger power supply to take it...

Remember, you need a Paul Hynes SR3, SR5, or Timestep SE, before you can use an MN platter, and TBH, a better bearing than the stock one (Vantage Audio or MN)

Marco.

[MCRU]

I have a better bearing thanks and a chunk of metal rotating at 45rpm for 15-20 mins. will not need a better PSU, I only need to listen to my favourite 12" singles to see if I want to buy one. The audition will be done within 1/2 an hour and findings reported upon.

Nice one.

Oh I forgot to mention besides my very own design of platter which I will be launching soon I will also be looking into building a PSU.

[Marco]

Half an hour's auditioning? Lol - you're a right thorough bastard, eh!!

Have you got an MN bearing? If so, I didn't know.

Your Techy will sound pish with the MN platter fitted, if you use it with a PSU which can't handle the extra mass. It affects the speed stability of the T/T (making it sound soft and woolly) whether it's for 15-20 mins or 0.5 secs!

Best plan is for me to bring the platter round, along my SR5 PSU, and fit both to your T/T, and let you hear it that way

Marco.

[MCRU]

By the time you send me the platter I will have a PSU built and in place so don't concern yourself with trivialities.

Don't forget to send my Bollinger for services rendered.

[Marco]

Let me know then when you've built your PSU, and we'll take it from there!

Marco.

[MCRU]

NO, NO, NO

The PSU is a 2 minute job so don't delay, 4 weeks from now is 09.06.11, it is in my diary already.

[Mike_New]

Hello Dave,

[QUOTE=Mains Cables R Us;214005]

"I have a better bearing thanks and a chunk of metal rotating at 45rpm for 15-20 mins. will not need a better PSU, I only need to listen to my favourite 12" singles to see if I want to buy one. The audition will be done within 1/2 an hour and findings reported upon."

With all due respects Old fellow I really do not think you know what you are bloody well talking about.
The increase in sonic quality does not operate on a time frame such that for the first "15-20mins" you can magically assess the quality of my "chunk of metal (nea my Quality solid alluminium and bonded copper platter)" whilst using an inferior bearing and power supply. And to boot you offer to publish your findings. God help us!!! but he probably can't save us from some people!!!!

Marco was absolute correct in his sage advice to you.

[Mike_New]

Hi Chris

Hello Mike

A couple of question's for you if that's ok .


How does the Technics magnet function then? and ...


What sort of flux pattern do you actually get using the Technics magnet (with or without the platter)?

The Technics magnet functions in the same way that all magnets do when interacting with another magnetic field (flux) generated by driving coils.
The secret is in the way Technics have designed what is known as a isotropic radially poled magnet, the many poles of which are designed to be synchronously acted upon by the twelve stationary coils. Which in turn, are synchronously switched by the position rotor. In fact the slightest incorrect positioning of this rotor on the platter can actually cause the platter to rotate in reverse, or worse still, not to perform correctly in the forward direction.

The flux pattern is a radial one as explained previously, In simple terms it’s strength, at any point in space, will be moderated by any material that may be placed in the path of the flux field. For instance the flux field from the OEM transformer of the SL1200, is shielded in a crude way, by what I believe may be Mu metal sheets place around the transformer.

It is very interesting, since posting my first observations on this subject I have carried out some simple tests on my Benz Ruby MC. This cartridge has a hugely powerful ‘rare earth’ type of permanent magnet; as indeed do all other quality MCs.

Now I will leave you to speculate on what the results could, be when the field of theses very powerful, but small MC magnets, come into reaction range of another magnetic flux field, especially a rotating one!!!!!

I will post a description of my thoughts on this, if people are still interested.

[chris@panteg]

Hi Chris


The Technics magnet functions in the same way that all magnets do when interacting with another magnetic field (flux) generated by driving coils.
The secret is in the way Technics have designed what is known as a isotropic radially poled magnet, the many poles of which are designed to be synchronously acted upon by the twelve stationary coils. Which in turn, are synchronously switched by the position rotor. In fact the slightest incorrect positioning of this rotor on the platter can actually cause the platter to rotate in reverse, or worse still, not to perform correctly in the forward direction.

The flux pattern is a radial one as explained previously, In simple terms it’s strength, at any point in space, will be moderated by any material that may be placed in the path of the flux field. For instance the flux field from the OEM transformer of the SL1200, is shielded in a crude way, by what I believe may be Mu metal sheets place around the transformer.

It is very interesting, since posting my first observations on this subject I have carried out some simple tests on my Benz Ruby MC. This cartridge has a hugely powerful ‘rare earth’ type of permanent magnet; as indeed do all other quality MCs.

Now I will leave you to speculate on what the results could, be when the field of theses very powerful, but small MC magnets, come into reaction range of another magnetic flux field, especially a rotating one!!!!!

I will post a description of my thoughts on this, if people are still interested.

Thanks Mike

The OEM transformer is indeed shielded by Mu metal , this along with Richard's explanation as to how the Technics magnet works and i can quote him .

The ring rotor used in the Technics was designed to focus all flux patterns to the inside circumferance of the ring. There is a very simple test you can do to see this in action. Take a metal screwdriver blade and present it to the outer surface of the rotor ring. Do the same from the top and lower edge. Now present the blade to the inner circumfernace of the rotor (be careful here as you do not want a sudden shock impact of the blade against the ring in case you "chip" the ring. Just use a wee bit of sense here and retain a firm grip on the blade). What result do you find?


Remember basic physics and flux patterns in ring magnets. Most times flux leakage is associated with "air gaps" and is put to good use in loudspeaker drive units. The idea of a ring magnet is just that - direct the flux pattern where you want it. Look at the flux patterns for a ring magnet and you will see the pattern concentrated on the horizontal axis and any vertical axis flux pattern will be introduced via an air gap on the open face.