|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
203.206.77.18
In Reply to: DIY wood posted by Kiwi Brian on May 14, 2007 at 01:59:11:
What does the magnet do? It looks as though the arm is suspended and balanced on a thread. Does the magnet just keep it centred?
Follow Ups:
Very strong Neodynium magnets in tone arm and base attract each other and create an arm "bearing". The space between the magnets has a significant effect on the "tightness" of the bearing, the damping of the arm, and therefore the sound. Like all utterly brilliant ideas, it's a "Why didn't I think of that" moment.The trick is getting the force between the magnets (and therefore VTF) constant across the LP from outer groove to inner. My first one varied by about 0.1g - close enough for a DL-103 maybe. The second one is much better - more like 0.02-0.03g. The magnets don't set the VTF, but the damping they cause effects it a lot, so it has to be very stable.
that suspends the arm. I put together a mule using 0.010 wire but it seemed too stiff.
Fishing line actually - the modern filament lines are remarkably thin and strong. I used 'Berkley Fireline" 0.3mm diameter 20lb line. I am sure that there are a hundred equivalent brands out there. IIRC, Frank S has hinted on various online forums that this is not a million miles from what he uses.
Would the magnets used in computer hard disk drive's head positioning systems be useful for a design like this? If so, I can try experiment with something like this for very little cost (not that magnets would cost much anyway I suppose).Playing around with things like this appeals to me. Might be my next project :-)
-----------------
Don't know about HD guts. 1 x R834DIA and a couple of R822-CS from hereset me back about $6. The secret for me was finding and using the diametrically magnetised ummm magnets...
This makes it much easier to get the magnets aligned properly - otherwise two disc magnets would need to be perfectly parallel with each other to get even VTF and azimuth across the record.
Send me an email if you want to discuss further
This post is made possible by the generous support of people like you and our sponsors: