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Minus k Technology BM-8 Isolation Platform

Just wondering if anyone out there is using one of these to isolate their turntable. It is a passive design using what the company calls negative stiffness isolators.  Very clever design. You really have to see a picture of the isolator    https://www.minusk.com/products/bm8-vibration-isolation-platforms-bench-tops-isolators.html
It looks to me given the specification that you could isolate any turntable with one of these as well if not better than SME, Basis and SOTA  do with their designs. It is not much to look at and at $3000 it is not exactly cheap but it would be a miracle for someone with foot fall and feed back problems. I personally think equipment racks are unattractive and will not have one in my living room. My equipment is hidden in an antique armoire. I'm thinking about replacing my old suspended turntable with a new one and this platform would give me a lot more flexibility and choice.  Just wondering if they really work👩‍🦳
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looscannon
wrm57
1,092 posts
 
I've used them with 3 different turntables, soon to be 4, and I've always been able to achieve proper balance. The key is to use an oversized shelf of some sort on the top plate, which is rather small itself, to give room to reposition the turntable.
wrm57
1,092 posts
 
Hi whart, what an awesome looking deck. Is that an HRS platform under it?
whart's avatar
whart
3,225 posts
 
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 !
indranilsen
113 posts
 
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?



bdp24's avatar
bdp24
10,306 posts
 

For a table with asymmetrical mass distribution, one can use the Townshend Audio Seismic Pods of different weight capabilities. The Pod is offered in ascending weight load ratings: 1-2kg, 2-4, 4-8, 8-16, 16-32, 32-64. I've tried them in sets of three and four, and unlike cones and spikes---which should be used in trios, I've found Pods (or springs) to be more stable when used in quartets.

The exception to that rule is when the component has no moving parts: my bigger tube power amp has most of it's mass on it's power and output transformers side, and two Pods under that side/one under the other side works very well. I could have used Pods of different loads ratings---two higher-rated ones under the transformer side, two lower-rated ones under the other---but three Pods are cheaper than four. ;-)

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