Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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

Magnetic Suspension Platter
Magnetic Suspension Platter
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 30th September 2017, 07:21 AM   #1
gigigirl is offline gigigirl
diyAudio Member
 
Join Date: Oct 2016
Question Magnetic Suspension Platter

Hi guys, I have toyed with this idea for a while, but have little experience with magnets so I though I would seek opinions, augments and hopefully helpful suggestions on this idea of a magnetic floating platter. It is well known that one of the major drawbacks of the Lenco T/T is the amount of motor and to a lesser degree Idler wheel noise that is transmitted through to the platter via it's direct contact to the platter and plinth and from there to the music chain via the stylus. So obviously, (well I hope it is) if the LP is sitting on a floating platter then virtually all of this noise will be eliminated from the reproduction loop. There will be still the problem of motor noise getting into the arm via the plinth, but this is easily illuminated by using an off-board arm stand, which I have done in my system to great effect already with my 12" Temmad Titanium arm. The magnetic cones are not that hard to get hold of and depending on the strength required cost between $4 to $6 each. The bottom magnets are less of a problem but again strength is still to be determined. The recessed lead filled holes in the to platter are there to force the top platter cone magnets into the ring magnets as I believe that the weight of the top platter alone will not be enough to force the cones into the ring magnets. Also it may have the added advantage of adding inertia to the platter rotation, (without adding to much stress on the bearing) therefore increasing speed stability











So Gentlemen, (and maybe Ladies) I am looking forward to your feedback on this a idea. Regards
Attached Images
File Type: jpg 002.jpg (105.7 KB, 173 views)
  Reply With Quote
Old 30th September 2017, 09:35 AM   #2
JonSnell Electronic is offline JonSnell Electronic  United Kingdom
diyAudio Member
 
JonSnell Electronic's Avatar
 
Join Date: Dec 2012
Location: The Jurassic Coast, England. GB
A floating platter as you have described will theoretically have no friction, so no error can be detected meaning a constant speed cannot be maintained.
I would play with a linear motor and a heavy aluminium platter.
With a linear motor, a constant height and speed can be easily maintained.
__________________
Support for Fender, Marshall and all Valve Equipment; Audio Innovations, Audiorama FU29, Quad and Leak. www.jonsnell.co.uk
  Reply With Quote
Old 30th September 2017, 09:54 AM   #3
gigigirl is offline gigigirl
diyAudio Member
 
Join Date: Oct 2016
Jon, Thanks for the reply, Yes it will have normal friction. The configuration is made up from 3 platters,
- Bottom platter is original one from Lenco 75, that the idler wheel drives.
- 2nd platter is the one containing the ring magnets.
- 3rd platter (top) the one containing the cone magnets.


Sorry, perhaps my sketch is not very clear. Cheers
  Reply With Quote
Old 30th September 2017, 11:56 AM   #4
alighiszem is offline alighiszem  Hungary
diyAudio Member
 
Join Date: Nov 2007
There is no way permanent magnets could levitate an object. Earnshaw's theorem does not allow it.
"One of the most common questions about permanent magnets is whether there exist a stable and static configuration of permanent magnets that will cause an object to be levitated indefinitely. Obviously the levitation itself is not a problem, because many magnets have fields strong enough to lift their own weight. Equilibrium is also not a problem, because there is obviously a configuration at the boundary between falling and rising. The problem is stability. In order to have stability, there must be a restorative force counter-acting any displacement away from the equilibrium point."
  Reply With Quote
Old 30th September 2017, 01:27 PM   #5
Pyramid is offline Pyramid  United States
diyAudio Member
 
Pyramid's Avatar
 
Join Date: May 2006
Location: Behind the Cheddar Curtain
It's been done:


YouTube
  Reply With Quote
Old 30th September 2017, 01:37 PM   #6
alighiszem is offline alighiszem  Hungary
diyAudio Member
 
Join Date: Nov 2007
No, it's not done. Mag Lev Audio functions with a set of solenoids and servos, not with permanent magnets.
  Reply With Quote
Old 1st October 2017, 03:55 AM   #7
gigigirl is offline gigigirl
diyAudio Member
 
Join Date: Oct 2016
Hi, Thanks for the replies guys. alighiszem from your reply from what I understand is that the concern is "stability, there must be a restorative force counter-acting any displacement away from the equilibrium point."
This is what the lead filler will do in the top platter, it will provide a downward force on the cone magnets. Cheers
  Reply With Quote
Old 1st October 2017, 04:47 AM   #8
jcx is offline jcx  United States
diyAudio Member
 
Join Date: Feb 2003
Location: ..
Default "It's just as hard with the weight of lead..."

err, no

clearly don't understand Ernshaw'a Theroem, the attendant conditions, the time it hasn't been overturned (pun intended)

the 'cheat' is to use diamagnetic materials - but you only find 'toy' demos of stable permanent magetic suspension/levitation
  Reply With Quote
Old 1st October 2017, 04:48 AM   #9
Shhh its me is offline Shhh its me
diyAudio Member
 
Join Date: Mar 2017
Location: Melbourne, Vic, Australia
What about the affects of that much magnetic flux in close proximity to the magnetic pickup ?
  Reply With Quote
Old 1st October 2017, 05:08 AM   #10
gigigirl is offline gigigirl
diyAudio Member
 
Join Date: Oct 2016
Hi, back again. Yes jcx, you are right I do not understand Ernshaw's Theroem. I said in my opening passage that I had little experience with magnets. I do know that magnets plinths are commercially available and work and as I said before I have previously built a working magnetic platter that repels the platter away from the plinth so there is no friction on the centre bearing ball. (Unfortunately this method cannot work with a Lenco as it is idler wheel driven)
Shhh, No I do not know how much the magnetic flux will affect the cartridge, but as stated earlier I believe I can partially shield any effect.
  Reply With Quote

Reply


Magnetic Suspension PlatterHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
stiff suspension or loose suspension for the home subwoofers? rhythmsandy Subwoofers 67 21st October 2013 06:27 PM
Self-centering Magnetic Suspension? Stocker Everything Else 19 14th January 2013 07:17 AM
Looking for non-magnetic platter Jorgitox Analogue Source 3 7th January 2010 02:14 AM
Magnetic suspension for Cd player peranders Digital Source 16 14th February 2004 07:32 PM
Magnetic suspension linear-tracking tonearm? Shaun Analogue Source 5 4th June 2003 11:21 PM


New To Site? Need Help?

All times are GMT. The time now is 03:24 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio
Wiki