Minus k Technology BM-8 Isolation Platform

Yep, had the HRS made shortly after I got the table- which is the original model, two AC motor job. The presence of the HRS does change how the Minus K sees the weight since it is distributed but man, I can't tell you how many hours I put into tearing down and setting that thing up. The folks at Minus K gave me a few suggestions for moving around the Sorbothane contact pads between the internal mechanism and the top plate, but it didn't really help. 
With just one arm tower, which itself weighs around 30 lbs, the whole thing works fine. So, I'm back to one arm for now on that table. 
I did buy the Minus K stand which is in some ways a bargain- welded steel, very sturdy, adjustable feet for leveling with a nicely finished phenolic top for under a grand. Good to see you @wrm57 !

Hello,
I have some experience in building, DIY, isolation platform using a pair of 1 inch thick maple plywood and springs. I selected the springs with lowest possible spring rate for a given load such that the natural/resonance frequency of the unit dips down to 5hz or below. I encountered three  issues with the platforms 
1. Levelling components having asymmetrical load distribution. In order to get the maximum isolation benefit I needed to equally distribute the load to each spring such that each carries a load very close to its max load bearing capacity. With asymmetrical load distribution this was very difficult and I can see this as a key issue with MK, Vibraplane, Townshend or any such isolation platform.
2. The combination of steel and wood platform was adding some colour to the sound output that I didn't like. I hope the platforms used in these commercially manufacturered products is very neutral.
3. Cables specially thick aftermarket cables attached to the components degrade performance by adding more than required damping and compromising the freedom of movement of the platform.
Did you guys face any of the above issues with your platforms?

My independent very low-profile 1” tall, small effective surface area tempered steel springs are inherently more stable (higher lateral stability) than air bladders and larger springs and have a much more ideal geometry. Since they’re independent the springs can be positioned so they support equal loads when the component’s mass is distributed non uniformly (as long as the bottom of the component is a smooth surface.) High-mounted heavy platters can create instability for some iso stands due to high center of gravity. Ditto speakers. This problem of high COG can be solved by employing a large dimension plate under the component so the independent springs can be positioned in a very wide pattern, thereby increasing lateral stability. 🤗

I eschew using relative soft materials (Wood, Brass, Aluminum, carbon fiber) in conjunction with mass-on-spring iso systems, and recommend extremely hard materials to support the iso stand as well as the component on the stand. E.g., NASA grade ceramic DH (Diamond Hardness) Cones for extremely rapid evacuation of energy from the isolation system.

Note that a mass on spring iso system works TWO ways - prevents the transmission low frequency vibration from the floor to the component AND reduces vibration induced on the top plate by the component itself or acoustic (mechanical) waves in the air. My small independent springs provide 2 Hz performance in the vertical direction 🔝 and most rotational directions. 🔄

For the advanced student there is the dual-layer heavy mass on spring platform, comprised of three heavy granite or bluestone slabs, the top two slabs separated by springs, thr bottom slab acts as bass. The number of springs for each layer pre-calculated based on total mass. With this design sub Hertz performance can be achieved for most front end components. Cost for such a device is surprisingly low. 🤗

Geoff Kait
machina dynamica
advanced audio conceits