2020 update : JC Verdier La Platine

@ledoux1238  No, I have not try putting the motor on a separate platform, partly because it is not that practical in my setup, but mainly because I simply do not believe in it. I doubt that he remember this, but many years ago I had some email exchange with Thom of Galibier, where we talked about having the motor and plinth on separate platforms. I learned a lot about the drawback of such arrangement from him, and it all made sense to me. Even today, if you look at some of the top turntables with separate motors, such as the Kuzma XL and even the Walker, they all have their motors relatively close to the plinths. I think that is not a coincident.

About pneumatic platform, I have been using the floor standing model from TMC since nearly 20 years ago. I was thinking if it was good enough for Rockport, it probably was good enough for me. I have always been very satisfy with them!

While you can certainly test it yourself, I would strongly recommend against putting the motor on separate platform if you are using a pneumatic platform, and especially the MinusK. I have seen the MinusK working in my friend's system. It has very soft springs, so I am pretty sure the pull of the belt (if the motor is on separate platform) will affect its leveling. And yes, the MinusK doesn't like asymmetric load, so you may need to experiment with placing weight on different positions on the platform to achieve leveling. Also, it is so sensitive to the weight that if you use a record weight during setup, you will always need to use the record weight, or you may throw the platform out of level. It is because of all these inconvenient that kept me from using the MinusK, although, at least on paper, it performs even better than my TMC.

I would never recommend mounting motor and TT on two separate platforms especially if either one of the two is sprung or otherwise designed to move in response to external stimuli. In that case both devices must be on the same platform of course. (Minus K doesn’t use springs.)

The MinusK does use springs, but probably not in the conventional manner.

According to their website: "Vertical-motion isolation is provided by a stiff spring that supports a weight load, combined with a negative-stiffness mechanism (NSM)."

Thanks for the correction.  I wonder what is an NSM.  If you push on a Minus K, it does not behave as if primarily spring loaded, which is to say that a spring will exert a force directly proportional to its degree of compression or extension from rest, among other factors of course. So, if you push on a spring loaded shelf, the shelf will get more and more difficult to compress, and the reverse happens when you release the shelf allowing it to restore its steady state position. The Minus K seems to exert a constant force restoring it to its steady state location, up or down. For this reason, I intuitively think or thought of it as using something other than springs, at least primarily.

Hi Lewm,

You can read about how the NSM works here, but can’t say I understand it completely:

Yes, the feeling push down on the MinusK is so different from normal springs, so smooth and well damped, almost feels like hydraulic!