Perimeter Ring Clamps: Yay?, Nay?, Sources??

I have a VPI Classic 4 that came with a periphery ring, which I promptly sold. It is big, heavy, and an accident waiting to happen. Maybe I'm a little clumsy. My first bad encounter happened with one more than 10 years ago when I bought one for my Classic. When I set my Benz Ruby 3 down, the ring promptly grabbed the cartridge and forcibly drew it over. Amazingly, the stylus was not bent. So, VPI sent me a higher quality SS ring with no ferrous content and that problem was solved, but I still didn't like the overall risk of dropping it on my arm or table.

The Benz Ruby, Gullwing, and LP / LPS models have vastly stronger magnets than any other cartridge (excessively large neodymium). They can do this because the ruby coil plates aren't magnetic at all. But their magnets are insane. You're gonna have a bad time if you happen to try using ferrous hardware to mount them, or if your ring clamp is ferrous at all. I did not encounter such issues with my Clearaudio ring. But I almost trashed my LPS not thinking and using a ferrous flathead screwdriver to start mounting it lol. Fortunately it didn't slap against any delicate bits. 

High quality stainless steel is not magnetic at all.  Cheap stainless steel usually is.

It is sooo good to benefit from your collective experiences. I always do,

thanks to everyone who responded,

Elliott

mulveling, I am surprised to learn that the Benz cartridges you named would have such strong magnets, because they also have high-ish internal resistance for an LOMC, which suggests that the coils have many windings, yet the output is "low". Thus you’d think the cartridges could get by with a weaker magnetic field. On the other hand, my Ortofon MC2000, with an internal R of only 2 ohms and a vanishingly low output is probably dangerous for anyone with a pacemaker; its magnets are scary. The MC2000 inadvertently revealed to me that the Kenwood L07D platter sheet (made of stainless steel) is mildly ferrous; the MC2000 nearly committed suicide by squashing against the sheet. Since then, I had a copper platter sheet made for the L07D; better shielding of the cartridge from the motor EMI and totally nonmagnetic.

@lewm those Benz models use a Ruby plate to wrap the coils around. Most cartridges use a ferrous material which increases the output level for any given amount of coil windings, but also (supposedly) causes the assembly to disrupt the magnetic flux when in motion. The downside of the Benz Ruby approach is that it requires much more coil windings to create the same output level (compare to their highest iron cross model Ebony L with 0.26 mV output from 5 ohm coils, or Zebrawood L at 0.4 mV from 12 ohms). But it can also use a much stronger magnet because the armature is not reactive to it. Look at the Gullwing (Ruby) magnet in pics, it’s twice the size of the Glider (iron cross) with the same open body design.

There is an interesting video with Mr Fremer and the Windfeld Ti designer where he briefly mentions the choice of armature material that balances between the two - only slightly ferrous. The Anna uses a completely non-ferrous armature, but not Ruby (polymer?).

Some time ago I too learned you have to be mindful of MC cartridges on some metal platter :)