Eminent Technology ET-2 Tonearm Owners

Could someone explain how to set up that magnetic damping mechanism to replace the trough?

John
I discussed magnetic damping with Bruce when it came up in discussions here in 201* - I can't recall the year. Bruce was very intrigued, so much so that he tested it out himself. His findings, as far as the interaction between actual spindle and using the strongest magnets; there is just not enough movement in the spindle to produce any effect. So that is what he found. Next time you are talking to him remind him of our conversation. I did sense that he really wanted it to work as the oil is - messy.

With that the experimentation involves placing magnets - same poles facing each other - on either side of where the spindle exits so it is passing through the magnets. The idea of course being that repulsion controls the movement of the spindle.

My Verdier La Platine platter system works in a similar way, but on a much larger scale. Now the system with La Platine works because the actual platter which has the (top magnet) attached to the bottom of it, is moving at 33.3 rpm so you have braking action happening with the bottom magnet due to the movement. This braking action also helps to deal with the records behavior with its constantly changing grooves.  I was fortunate to learn this from Mr. Verdier, before his passing.

Chris

Hi Chris! The magnet damping doesnt't work the way you describe it. What you describe is the magnet "levitating" of the Verdier (and others) by opposing magnets of same polarity.
The proposed damping works by eddy current, the same as eddy current brakes. Basically you put a magnetic circuit very close to a electrically conducting surface. The magnetic flux crossing the surface induces a current in the conductor / surface, which creates a counteracting magnetic field.
I placed a neodymium kitchen magnet (or two) on a blob of BluTak underneath and very close to the spindle. (I like my setups to be a bit messy - but reversible :-).
My wires exit the arm relatively "straight" at the end of the tonearm proper, the magnet is on the opposite side of the bearing.
The small round kitchen magnet has a magnetically conductive (steel?) "guiding" sleeve around the magnet that guides the back side pole to the front, so you have opposite poles in the center of the magnet vs. a circular opposite pole around.
In my case it works "enough", so that the arm has no high Q lateral resonance. It's probably still slightly underdamped though. Which is IMO desirable as a trade-off.
I don't have an alternative anymore, as my oil trough is leaking.

Hi Pegasus
Good to hear from you. :^)
The Verdier provides for Levitation AND Braking Action - and that is why I included the analogy. Everybody thinks about the Levitation but NO ONE discusses the braking action. 8^0

All I did was report Bruce’ findings. Not sure how he set it up.
IMO - John should also try it for himself.

I still have the trough attached but the paddle is not connected because I do not need it.

Pegasus
My wires exit the arm relatively "straight" at the end of the tonearm proper, the magnet is on the opposite side of the bearing.

Show us a picture of the wiring/magnet Pegasus.

John I would also like to see a picture of your modded Ibeam.

Cheers Chris

The magnet thing is pretty confusing. I don't know how to post pictures directly to the discussion, and I don't do the social media thing. So, I'll work on adding pics to my Audiogon identity? I'll have to work on that. Sorry. I'm not well versed in these things, but I'll geterdone tomorrow.
John

Hi Chris,
I'm about to take the plunge for Bruce's mag arm but thought I'd touch base with you first.  Over the last month + I have increased air pressure, moved weights out and added springs on the beam.  After each of these upgrades I heard a significant improvement in almost all parameters.  While I realize everything is system dependent and subjective, can you share with me what I might expect to hear going from the aluminum arm to the mag arm.  By the way I now have my system up on virtual systems.
Thanks,
Harry