Holy Earthquake, Batman!
The Minus K BM-8 Isolation Platform
By Jeff Dorgay
Aside from friends that have had too much to drink vibration is your turntable's biggest enemy. The more you can isolate your table from your environment the more musical detail your analog rig will be able to resolve.
If you've been in the audio game for sometime now, you know how many different solutions there are available. I've tried a few of them myself, with mixed results. I seem to recall analog maven Michael Fremer reviewing a cool active vibration base that they use for sensitive laboratory instruments and was really excited about it until I saw the price tag-about $8500 bucks (if memory serves me correctly!)
Ouch! At that point in time I was listening to a Rega P25, so I filed that into the more-expensive- tweak-than-the-gear file and forgot about it, until I stumbled on to the Minus-K website. At $2795, this is still not a pocket change item, but for those of you looking to wring the last bit of performance out of your analog rig, this may be just what you are after. At about the price of a pair of mega interconnect cables the BM-8's price tag is palatable.
The cool thing about the Minus K platform is that it is a passive device, so that means no vacuum pump and none of the extra noise that goes with a pump or the complexity that it brings to the table. After all, the quieter and more resolving your system gets, the last thing you want is a pump in the background chugging away!!
Most of Minus K's customers are scientists. These typically get used in a laboratory underneath scanning microscopes and other precision instruments. The resonant frequency of the platform is .5hz.
Unpack and Adjust
The BM-8 is 18" wide by 20" deep and 4.6" high so make sure that you have enough room on your shelf or rack, as well as the ability to support the 35 pounds of the platform in addition to your turntable. There are three models, to accommodate equipment from 10-105 pounds. I would suggest to get maximum performance, if you can match the model you need so that your table is in the middle to high end of the weight range.
Setup is a breeze, unpack the BM-8, put your turntable on the platform and unscrew the four red anodized collars. Next, make sure the vertical position indicator is as close to the middle of the range as you can get it. You can adjust this with the crank adjustment that is immediately to the left of the indicator. I found you can be a little off with this, but the closer you can get to the middle, the more effective the BM-8 will be.
Once you have completed this part, nailing the sweet spot for the vertical softness adjustment will take a bit more time, but is somewhat of an adjust to taste setting. This affects the bounciness of the springs in the platform and again after a lot of listening noticed that by going from loose to tight will affect the overall sound. As you might expect going a bit tighter consequently tightens up the sound, and going a bit more springy gives the overall presentation a bit warmer feel.
Even if you are a bit off the mark, you should notice a good degree of improvement and I felt that the more you listen and make fine adjustments, you will notice a sweet spot where you are getting the maximum isolation without the presentation getting too warm or bouncy. Almost like setting VTA, there is that perfect spot lurking out there!
To be really fair to the BM-8, I used it with six different turntables: The SME 10, the AVID Volvere, Oracle Delphi V, Rega P9, VPI Scoutmaster and my favorite budget table, the SOTA Comet. I wanted to make sure what I heard initially was happening in a repeatable fashion as well as to see where the threshold for increased resolution would fall off.
The good news is that the BM-8 worked very well on every table I put it under. The bad news is that it's 2800 bucks. However, to put things in perspective, I would spend this amount of money on one of these before I bought an equally expensive pair of interconnects or power cord.
Let's start at the bottom and work our way up.
I noticed two major areas of improvement to the analog presentation with the BM-8 in my system: Tighter, more tuneful bass and better resolution of low-level detail. Just to make sure I wasn't going mad, I picked out a wide range of albums to listen to right in a row and then put the base in and listened again. I used a lot of standards that perhaps are not the audiophile standards, but records that I am infinitely familiar with.
The first record I put on was Donald Fagen's Morph the Cat, because the title track has fairly loose, whumpy bass. Another favorite in that department is Thomas Dolby's Aliens Ate My Buick. Immediately, I noticed the bass tighten up a bit and it seemed to have a bit more texture. As I spent some time with some records with acoustic bass, I was definitely experiencing more texture.
I also noticed a substantial decrease in woofer movement on my REL subwoofer, I could even leave the dust cover up on my P9, where in the past that was begging that devil rumble to sneak in at moderate levels.
Though this was great, the biggest improvement was the in the area of low-level detail retrieval. I kind of freaked out from the minute I started listening and the more time I spent with the BM-8, the more I found myself pulled into the music. Listening to all of my Doors albums (the DCC versions) I really enjoyed how much more air was in the presentation; there was so much detail lurking in these already great LP's! Again, this was not that subtle of an improvement. I could really hear my system take a big jump in low level resolution. This was one of those improvements to your system that makes you go right to a lot of your favorite records just to get a quick read on the sound!
Variation on the theme
While vibration is the enemy of all things electronic, I did try the BM-8 with some electronics as well just to conduct a thorough investigation.
I got the most improvement with tube electronics first, CD players second and power amplifiers last. However, I did not feel that this platform made enough of a difference on any of my electronics to justify a few more of these for my components too. Unless you have a really disproportionate amount of disposable income, I'd just think turntable on this one.
A significant improvement
The BM-8 is not a budget audiophile tweek. But in the world of 1200 dollar coat racks and little blocks of wood with metal cups that cost 800 bucks a throw, this is at least a solid product with some science behind it, that will truly increase the resolution of your system.
I highly recommend the BM-8 with only one reservation; I would make this device the icing on the cake of a very good system. If you have everything else in your system the way you want it (including room treatments) and are just aching for a little more performance, I think you will be pleased with this upgrade. It's not going to turn a budget table into a mega analog rig, but it will allow you to see further in to the presentation on a first rate system. I'm kind of thinking I need one...
The Minus K BM-8 isolation platform
Minus K Technology
460 S. Hindry Ave. Unit C
Inglewood, CA 90301