Vibraplane vs. Minus k for Turntables

I'm not sure what's meant by "100% effective." Whether f0 = 2 Hz is enough depends on specifics. In my case, I live in an 80-year-old house with suspended wood floors and there are plenty of ambient noise sources near 5 Hz, e.g., washing machine, outside traffic, etc. As for not hearing the difference, one can experiment with the BM-8's resonant frequency by manually adjusting the suspension's stiffness with an Allen wrench. I could hear a significant change in the sonic character of LP reproduction - mostly tighter bass and improved image stability at lower f0s. I haven't yet brought home an accelerometer/vibration analyzer to correlate the isolator's performance with acoustic power spectra, but probably will do this eventually.

100% effective means that it prevents any footfalls, subwoofer feedback from effecting the sound. In the past my subwoofer - which is close to the turntable (6 feet) would cause the turntable to skip. This is on concrete floor. Also if I jumped or touched the rack below the turntable you could hear it. Once I added the Promethean jumping, hitting my rack, playing the same tracks which caused feedback etc were all eliminated. Is it perfect? I don't know. Just worth the little it costs. I am sure the Minus K is more ergonomic and probably even better. Is it worth more money (in my case about 5K for my table due to the weight etc.) is a difficult call. I have eliminated tonearm resonances and improved over definition with the addition of the Promethean. Everyone who has come over hears the upgrade instantly. It is as if I can hear all that my cartridge can do for the 1st time. I wanted the Minus K originally but the price increase to accomodate my turntable was just too high for me.

About 10 years ago Stereophile had a good article on vibration control. It is well worth reading. It mentioned Newport Corp, which has a lot vibration control products, and I ended up using their air pods which have active isolation in both horizontal and vertical planes. I forget the f but it is on their website. By using their pods I was able to custom make my own rack where each shelf has active air isolation.

I did not like the Vibraplane because of the inconveniece its weight and that is uses rubber-like pucks for the horizontal plane.

Steve Klein of Sounds of Silence, who adapted the Vibraplane for audio, said he tried the next level Vibraplane which had a lower f (I think 1Hz) and said he could not hear a difference. But as stated above this would depend on your environmental factors.

No experience with the MinusK. Other than its size limitation it looks impressive. I'm sure all three companies have graphs showing the resonant frequencies and attenuation so one can compare performance.

I considered the Minus K unit as well as the Halcyonics. The Minus K is basically a well designed spring system. At it root the Vibraplane is also a spring system, in this case a bladder with a resonant frequency like any spring support. The Halcyonics in contrast is active with sensors and voice coils to counter the movements in the vertical and horizontal plains that its sensors sense.

I had what I thought was the best economical platform, the Neuance. I had six of them. I then tried the Acapella Silencio base which was much more authoritative in the bass in particular. I had a Vibraplane once but found the Mana Reference stand to be clearly superior. When I put the Neuance on the Mana that was clearly better. Then when I put the Acapella on that was a further improvement.

When I tried the Halcyonics under my cd player, I frankly thought I could not be hearing such an improvement. Although it was a pain to take it entirely out from under the cd player, a brief listening without it showed it was indeed making a greater difference than I had ever heard. Nothing in my experience even comes close.

What is the problem with the Halcyonics? It is too expensive! I don't know if the Minus K gets 50%, 70%, or even 90% of the Halcyonic. If I ever have a chance to compare the two I would welcome the opportunity. I suspect, however, that being a spring system, the Minus K would be nowhere near as effective.

The BM-8 gives vertical transmissibility values that are comparable to Halcyonics' benchtop product (the Micro) in the range >=5 Hz. However, the BM-8's horizontal isolation is significantly less effective than the Halcyonics product. As Tbg points out, there are significant differences between the Minus-k technology, which involves a resonant system, and an active electro-mechanical vibration-suppression system, such as that used by Halcyonics, Herzan, etc.

In most cases, laboratories opt for passive isolation over active. There are two main reasons for this: cost and complexity. Active systems have the edge in applications where settling time is critical - basically these systems behave like overdamped oscillators over a wide frequency band. A downside of active systems is that the cost is proportional to the number of degrees of freedom because of the number of transducers required. Also, feedback loops in such systems become complex; for example, small angular displacements of a payload can generate significant horizontal accelerations. Settling time shouldn't be much of an issue in analog playback as long as the resonant frequency of an isolator is well below that of the tonearm/cartridge combination. Also, for most audio applications, vertical isolation is likely to be much more important than horizontal.