Just to help spread the word, this particular isolation platform gets some mention but there's not much information from product owners. During
last week's NY Audio Rave, a few guys also asked about it, but I didn't go much further than saying it's made by
MinusK.
Last year, I was happily using a
wall shelf for my turntable when I decided to organize all analog gear into a
single rack. This brought on a problem-- playing through the Dynavector arm at increasingly loud volumes would cause distortion to creep into the sound, and the louder I played, the louder it got. Because this problem didn't affect the other arm (perhaps due to that arm's unipivot design), I temporarily taped the Dynavector's tonearm cable to the wall and looked for a solution.
Although the Yorke is usualy paired with the Vibraplane, I couldn't use that platform because it's too heavy for the rack. Halcyonics was another option but the MOD-1M platform was smaller than the Yorke's overall footprint. Enter MinusK who, this year, released more audiophile-friendly, smaller form-factor products. After a friendly chat with their president, David Platus, I decided to go with the BM-8.
Viewed from its underbelly, this passive isolation system looks, feels, and is built like industrial instrumentation, no audiophile eye-candy here.
The general idea is to make the isolation platform
float, keeping the vertical position indicator (which is attached to the platform) zero'd on the center line between High and Low (see picture below). Depending on the weight of the table, this adjustment is made by turning the crank clockwise or counter-clockwise. After turning the crank a few times and not seeing the indicator move, I also had to adjust the stiffness screw using an allen wrench that's supplied with the package.
Minor issue-- as the platform is adjusted with the full weight of the turntable, removing a record weight/clamp, for example, changes overall weight that the platform would rise. Nothing to it, except the vertical position indicator would make a sound when it hits the upper edge of its hole.
Then we get to
leveling. In my case I use a set of Finite Elemente Cerabases under the granite shelf where the BM-8 sits and positioned a couple Walker Audio discs (see lower right, below) for "ballast".
Less than an hour after receiving the package, I was checking speed and ready to go.
The MinusK BM-8 (click picture below to visit manufacturer website) is an isolation platform that can achieve a horizontal frequency of 1.5 Hz and a vertical frequency of 0.5 Hz. The gist of the
transmissibility curves is that a resonance of 2Hz can be 93% isolated, 5 Hz - 99% isolated, 10 Hz - 99.7% isolated.
In other words, if you shake the table two times a second, either up/down (vertically) or left/right (horizontally), in theory, only 7% of that shaking energy will be transferred to the table, whereas 93% will be "drained". As frequencies go higher, the platform behaves even better, claiming to outperform air-based isolation systems.
MinusK isn't secretive about how this is achieved, explaining "how it works"--
Problem solved, thanks MinusK!
