Magnetic turntable bearing - Page 23 - diyAudio
Go Back   Home > Forums > Source & Line > Analogue Source

Analogue Source Turntables, Tonearms, Cartridges, Phono Stages, Tuners, Tape Recorders, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 16th December 2008, 06:07 PM   #221
Aengus is offline Aengus  Canada
diyAudio Member
 
Aengus's Avatar
 
Join Date: Apr 2004
Location: Victoria, BC
Quote:
... a lot of work.
That's why we're all waiting for you to do it.

Regards.

Aengus
  Reply With Quote
Old 15th February 2010, 06:06 AM   #222
diyAudio Member
 
Join Date: Aug 2004
Location: Queens, New York
Hi All,

I've only read the first ten pages of this thread so far, but I'd like to add a note that I own an older (circa: 1970-1975) belt drive, aluminum platter turntable on a plastic base (Not a really expensive or high end BDTT) from a maker who has been in the business for thirty or forty years now.

This 1970's BDTT has a dual ring magnet bearing under the fairly light weight aluminum platter. The ring magnets OD are approximately the size of an LP's record label and ID about 1 inch smaller. While I've never measured it, I guess the platter is suspended some 2 - 4 mm to unload the center bearing when a rubber mat and LP are in place.


-Steven L. Bender, Designer of Vintage Audio Equipment

Quote:
Originally Posted by YNWOAN View Post
YNWOAN Said in 2007 -

I notice in this months Hi-Fi+ that Clearaudio have produced a turntable using a similiar (in concept, but different in detail) bearing. I was not at all aware that any 'reasonably' priced turntable had employed this principal. The bearing experiments are only a small element of a much larger project to engineer a whole turntable. I have already done this a couple of times but am intending to approach this new design from first principles. Like Clearaudio I intend to use a low mass acrylic platter (lower than Clearaudio though), although every other aspect will be quite different. I notice that Clearaudio have used a ceramic bearing shaft to stop it from conducting the magnetic field. The bearing in my current design (Linn main bearing) does indeed conduct the magnetic field generated by my magnetic bearing, but I believe this to be irelevant to performance - leakage from the spindle is very low and has no measurable effect on the cartridge that I am aware of. I am pleased however, that Hi-Fi+ seem to hear very much the same improvements I reported.
__________________
--
Steven L. Bender, Designer of Vintage Audio Equipment
  Reply With Quote
Old 15th February 2010, 08:30 AM   #223
YNWOAN is offline YNWOAN  United Kingdom
diyAudio Member
 
YNWOAN's Avatar
 
Join Date: Jan 2007
Hmm...interesting; I'm not aware of the design you mention (though no doubt you are correct). What is the make and model of the turntable please? Presumably it uses ferrite magnets?
  Reply With Quote
Old 2nd June 2010, 07:06 AM   #224
diyAudio Member
 
Join Date: Jul 2007
Default Successful Mag Lev on a Linn Sondek LP12...Wolf in sheep's clothing...

Magnets....Sheffield...Magnets...Sheffield...

I read all the posts on this thread with great interest last night for a couple of hours....after I had looked up 'magnetic turntable bearing' on google...
Three things amaze me.

Firstly, I am very impressed with everybody's interest in the subject....I had thought I was alone!

Secondly, yesterday, after a few weeks of experimenting, I had managed to use mag lev on a Linn Sondek LP12, which, although it is alternately cast as an angel or a villain in the world of hifi, certainly has, in its natural form, a really musical toe tapping ability. For a few months now, a) because I am on a budget, and b) because I have engineering skills and can't ever leave well alone, I have been rebuilding my LP12 with:
1. a CAD designed water-cut single piece titanium subchassis & arm mount,
2. a CAD redesigned thicker water-cut stainless steel top plate,
3. new 7pm motor position,
4. new external & internal electronics,
5. thicker & more rigid higher tensile steel bolt & locknut components,
6. machined corian armboard,
7. machined corian baseplate,
8. lathe turned dural thickened bearing housing,
9. silicon or rubber rings on crucial parts to damp resonances,
10. molybdenum sulphide greased ruby motor bearing in phosphor bronze bearing housing,
11. laser cut and hand finished acetyl arm pillar mounted cradle for the armrest,
12. thick water-cut stainless steel motor mounting,
13. two-part mag lev ring bearing on main bearing, relieving thrust plate pressure and consequent reduction of friction & noise,
14. solid silver wiring throughout,
15. renovation of rosewood plinth,
16. rebuilding of internal hidden elements of plinth (eg internal mahogany top-plate supports)
17. other minor aspects....polishing of bearing shaft tip, etc...
and it is sounding SO good.....

Thirdly, when reading the thread, I notice that a few of you had talked about living in the UK, in Sheffield, in S11 or S7.
When I was a young guy, I remember Sheffield was world-famous for its steel works and I remember drinking Magnet ale...in fact the famous Sheffield United football team fans' song refers to 'Magnet' ale produced locally by John Smith's Brewery, a packet of Woodbines cigarettes, a pinch of snuff(tobacco), a night out in Sheffield and a greasy chip butty.

The full lyrics to Sheffield United's Greasy Chip Butty song are:

You fill up my senses Like a gallon of Magnet
Like packet of Woodbines
Like a good pinch of snuff
Like night out in Sheffield
Like a greasy chip butty
Like Sheffield United Come thrill me again....
Na Na Naa Naa Naaaaa, Oooooooh!"

Recognise it?

Well the thing is...
I was born in Sheffield S11 too...and lived there until I was 17....
There MUST have been something in the water....
:-)
  Reply With Quote
Old 4th June 2010, 01:25 AM   #225
diyAudio Member
 
Join Date: Jun 2004
Location: sheffield
Send a message via MSN to sq225917
could be....

(currently S11)
__________________
hoping to pick up some things.
  Reply With Quote
Old 7th June 2010, 05:06 AM   #226
andyr is offline andyr  Australia
diyAudio Member
 
Join Date: Nov 2003
Location: Melbourne (Oz, not Florida!)
Quote:
Originally Posted by ictmanager View Post

Secondly, yesterday, after a few weeks of experimenting, I had managed to use mag lev on a Linn Sondek LP12, which, although it is alternately cast as an angel or a villain in the world of hifi, certainly has, in its natural form, a really musical toe tapping ability. For a few months now, a) because I am on a budget, and b) because I have engineering skills and can't ever leave well alone, I have been rebuilding my LP12 with:
1. a CAD designed water-cut single piece titanium subchassis & arm mount,
2. a CAD redesigned thicker water-cut stainless steel top plate,
3. new 7pm motor position,
4. new external & internal electronics,
5. thicker & more rigid higher tensile steel bolt & locknut components,
6. machined corian armboard,
7. machined corian baseplate,
8. lathe turned dural thickened bearing housing,
9. silicon or rubber rings on crucial parts to damp resonances,
10. molybdenum sulphide greased ruby motor bearing in phosphor bronze bearing housing,
11. laser cut and hand finished acetyl arm pillar mounted cradle for the armrest,
12. thick water-cut stainless steel motor mounting,
13. two-part mag lev ring bearing on main bearing, relieving thrust plate pressure and consequent reduction of friction & noise,
14. solid silver wiring throughout,
15. renovation of rosewood plinth,
16. rebuilding of internal hidden elements of plinth (eg internal mahogany top-plate supports)
17. other minor aspects....polishing of bearing shaft tip, etc...

and it is sounding SO good.....
Impressive, mate. Can you tell me more about your mag-lev ring-bearing ... it's something I've been thinking about doing ever since I saw YNWOAN's post on (I think) PFM, a couple of years ago.

I'd also be interested to know what made you decide on #2 - in comparison, say, to a CF top-plate? Does your new top-plate use the same fixing bolts/ screws as the stock one? And what does the extra thickness deliver?

And I have #18 for you - but you need access to a sophisticated (CNC?) lathe. That is, to get both the inner & outer platters dynamically balanced!

An Aussie on Stereo Net Australia (SNA) had this done and, on the basis of his review, I decided to get mine done. Haven't got them back from the guy, yet, though (so I'm vinyl-less ATM).

Regards,

Andy
  Reply With Quote
Old 7th June 2010, 07:53 AM   #227
diyAudio Member
 
Join Date: Jun 2004
Location: sheffield
Send a message via MSN to sq225917
ictmanager, your post is nothing without pics... ;-)
__________________
hoping to pick up some things.
  Reply With Quote
Old 12th June 2010, 01:05 PM   #228
bappe is offline bappe  Sweden
diyAudio Member
 
bappe's Avatar
 
Join Date: Sep 2002
Location: Furulund, SWEDEN
Default Bearing thoughts

Hi Guys,

I have read parts of this thread with great interest!
Me and a few friends made an experiment with a DIY Platine Verdier about 20 years ago and came to the conclusion that it sounded better with the platter resting on the ball than not. Better dynamics in the lower registers and an overall more stable presentation was the result from the second the ball was in place. I do not know how much weight that was put on the ball but it was not much at all, we are talking about a lot less than 100g here .
Reading through a few posts in this thread got me thinking, if mechanical grounding is so important maybe a zero play bearing like the one used in the Well Tempered Record Player (without the bottom ball though) can be used to good effect here. A non inverted bearing with the sleeve replaced by two V-shaped pieces of POM would be a good start. If the force from the belt is not enough to bias the bearing this could be done by small modifications to the magnet circuit. One could either tilt the lower magnet plate down slightly on the side towards the motor or simply remove a few magnets on that side.


BR,
Anders
Attached Images
File Type: gif tech_diagram1.gif (3.3 KB, 666 views)
File Type: gif tech_diagram2.gif (2.9 KB, 652 views)
  Reply With Quote
Old 15th June 2010, 06:42 PM   #229
kach22i is offline kach22i  United States
diyAudio Member
 
kach22i's Avatar
 
Join Date: Oct 2009
Location: Michigan
Nice thread, I have not read all of it, mostly looked at the pictures.

Keep up the good work.

.....................back to reading what I skimmed over.
__________________
Tubes and Martin Logan's
  Reply With Quote
Old 3rd December 2010, 01:23 PM   #230
diyAudio Member
 
Join Date: Sep 2010
Location: Leuven
interesting thread, also because I am planning to make my own TT.

I had drawn a lot of plans with a normal bearing like we all now them with the ceramic bal at the button.

Than I saw this thread and began thinking about it, this must be the way to go I thought.

So after some searching I saw that the Da Vinci Audio Gabriel AAS MK2 also used a magnetic bearing.

Here is a photo of that one :

Click the image to open in full size.

Could some one help with calculating how much magnets you would need for a 20 kilo platter ?

Thanks
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Air Bearing Spindle DD Turntable monsieurphot Analogue Source 18 12th April 2008 08:05 AM
Other bearing for turntable use? Zero One Analogue Source 4 27th May 2006 02:13 PM
DIY turntable bearing bigbulb Analogue Source 9 11th July 2005 03:16 PM
Turntable bearing Tee-Rex Analogue Source 3 5th May 2005 07:55 PM
turntable bearing design sc351cobra Analogue Source 1 24th March 2005 11:30 AM


New To Site? Need Help?

All times are GMT. The time now is 01:43 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2