Vibraplane: Should it be loaded close to limit?


I just bought a Vibraplane 2210. It has a maximum load of 275 lbs. I plan to put my unsuspended SME Model 10 turntable on it, replacing my Townshend Seismic Sink. My question is this: Because my turntable only weights about 30 lbs, should I preload the Vibraplane to get the total load with my turntable closer to the maximum load? Will this improve the isolation? If so, what do you recommend I use to preload it? I was thinking a sheet of steel, aluminum or granite. Any advice would be greatly appreciated.
peterayer
I too recently picked up this unit (active version with compressor - 2212-01), and would also like to know the answer to this question. The instruction manual states 275 lbs as the maximum load.
I did hear back from Kinetic Systems and from Sounds of Silence. Tony at KS suggested I contact Steve Klein at SOS as he has more experience with the VP in audio applications. The maximum net design load of my passive 24" X 20" Vibraplane 2210 is indeed 275 lbs. Steve wrote me that there will be audible improvements when pre-loading the unit in the 125-150 lb. range and then diminishing improvements from that point on.

Neither gentleman recommended one type of slab over another but Steve did mention that a critical decision would be what material to use between the slab and the top of the VP. He recommended researching materials from EAR.

My VP arrived today and I think I will start by just setting it up as is and comparing it to my Townshend Seismic Sink. I may end up moving my TSS under my phono amp as I have another one under my pre amp and it did improve the sound. After I live with the VP under my TT for a while, I will experiment with pre-loading it. The unit weights about 150 lbs, so if I add another 150 lbs plus my 30 lb TT, that will be a lot of weight on the top of my rack.

Thanks for all the feedback and if anyone has anything else to add, I would appreciate it.
I've been poking around the web trying to come up with a BOM list for building something like this. As it turns out, even though I already have a compressor it would cost me at least $1200 just in parts to get the features of the 2210.

Here is a spec sheet for an air spring similar to what is used in the Vibraplanes. The graph at the bottom shows the information Peter was looking for, just not specific to that exact product. Still, we can see how adding mass moves the frequency at which damping is the least farther down the graph. Neat stuff.

Air Spring