They do work. The Minus K has to be carefully balanced for leveling. I use a Vibraplane which is similar, but uses air suspension instead of springs.
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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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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In my opinion, minus K or the Vibraplane are superior to any of the built in suspensions in the turntables that you named. But realize that you should not use an independently suspended turntable with an outboard suspension system like the minus K or the Vibraplane. If you do that, antagonistic effects can be had. You need to use an unsuspended turntable with a minus K or Vibraplane. |
the big issues with a Minus K for a turntable are; (1) the turntable design needs to have it’s weight evenly distributed on the footers.....so it can be centered. some turntables have more weight to the back for instance. it needs balance to ’float’ and decouple. (2) the floor needs to be solid below the rack. if it’s moving around then you cannot stabilize the Minus K and it will be ’nervous’....reducing the performance. a vibra-plane, or even better a Stacore, can work with a floor not solid. they are passive air bladder type devices and while not as effective as a Minus K, are not as needy for stability. |
Mike, you're right in your observations. My rim drive tt is asymmetrically loaded, and in my short, frustrating trial with it, I absolutely struggled to sort this. Additionally I needed to mass load the MK to get close to it's limit, and of the three slabs I used, I could "hear" them clearly. No go for me. |
I have the BM-1, which was spec’d for a 250 lb load. I am in an old restored Victorian with springy wooden floors and the Minus K does work to effectively isolate the table- a Kuzma XL with an Airline am- from footfalls. Where I ran into problems was trying to add a second arm, with arm tower. I could not get it to center and fully isolate in all planes -- part of it was due to the fact that there were multiple heavy pieces to the turntable assembly at different distances from the center, but I suspect height of the mass factored in. Here’s where I was with it a year ago: [url]https://thevinylpress.com/app/uploads/2019/04/Kuzma2arms-sized.jpg[/url] |
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? |
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. ;-) |
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 |