Turntables currently considered top of the range. Do you know what they are ?

If you guys want to see something wild - check out these 2 video clips I made a couple years ago, with a VPI Aries 3, stylus in groove (at rest), and system on with volume set to "loud" listening level. This was my "energetic" problem room (small office).

https://imgur.com/a/HMASPUi

The 1st video shows extreme excitation at ~ 100-ish Hz from lightly tapping the shelf surface the TT sits on. It’s literally like a drum. Laptop speakers won’t reproduce this frequency; you need headphones or desktop speakers. And turn the video volume up. I could absolutely hear this frequency creep during playback, from feedback. It sounds remarkably like a ground hum, except that it rises as you increase volume. At a certain point, it can runaway (very bad, had to keep a finger on mute).

2nd video shows a greatly reduced effect, even as I slap the platform much harder! And it’s at the same system volume level. This is thanks to the metal 10.5i arm and HW-40 feet (squishy foam - with hockey pucks for spacers), versus the 3D arm and Classic Signature feet (hard - with Herbie’s giant fat dots for spacers). I should have made a video with the same feet, to show that much of the blame actually goes to the 3D arm. Fatboy arms were a similar story.

That’s a not-cheap CMS Sotto Voce rack and $2K Platinum shelf. Completely useless at this frequency! In the end, I think the rack’s architecture, table plinth design, and 3D tonearm are all to blame. And the Avenger Reference did nothing to help here. I thought its tripod plinth design might help, but it didn’t. Might have a video of that floating around somewhere.

Anyways, the Clearaudio Innovation compact had NO problems at 100Hz, but you had to watch subsonic feedback for woofer flapping (dangerous) - that’s from the float bearing IMO (again, the Master adds enough mass it’s less problematic). You can put this on a Townshend spring platform and it helps a lot! The problem with the VPIs, is their size makes it hard to fit onto a Townshend if you’re space constrained. I guess I should’ve tried the pods.

And the SOTA Cosmos, of course that does fine no problems :)
If I could re-do the rack choice I’d get an Adona with the cross-bracing. I think rigidity - in all directions - is a rack’s #1 job.

Best turntables I've ever heard, bar none:

https://www.idler-wheel-drive.com

Have a Clearaudio and an upgraded Oracle to the MK VI.  My Nantias modified idler arm is the best thing I've ever heard other than a fully restored Ampex professional reel to reel like this: https://reverb.com/item/36230409-ampex-300-3-tube-reel-to-reel-tape-machine.  And those two are close.  Makes the reel to reel not worth the trouble.

Any thoughts on the Holbo deck from Slovenia? It combines an air bearing turntable with a linear tracking tonearm, which also runs on air. 

@richardbrand Generally speaking, you want zero slop (play, endfloat, whatever you want to call it) between the surface of the platter and the mount of the cartridge. The engineering problem is very much like that of the steering of car or motorbike, where a little bit of slop can make the vehicle dangerous and unsettling to drive.

Air bearings can work but they have to be done properly to get around this issue of zero slop. Its not a trivial problem!

BTW this is the same reason the plinth of the turntable (which is the thing to which the platter and its bearing are bolted) should be exactly the same thing to which the tonearm is mounted. For example if the arm is mounted to something that is damped better than the mount of the platter bearing, any vibration that the platter bearing might be subjected to can by picked up by the tonearm. To prevent this (to lower noise) the mount of the platter bearing and the mount of the tonearm are the same part. 

@atmasphere

That was pretty much Ivor Tiefenbrun's thesis at Linn and it makes perfect sense!