Hi Larry,
I have a Minus-k BM-8 system that supports my TNT Mk.? (upgrades of various vintages). Performance is extremely impressive and I especially like the maintenance-free aspect of the isolator. Although I have no experience with the Vibraplane per se, I have professional experience with similar isolation systems for electro-optical instrumentation and atomic-force microscopy (I'm a biophysicist). You can expect significantly better performance from the Minus-k BM-8 than is available with passive air isolation due to the fact that the BM-8's resonant frequency of 0.5 Hz is at least a factor of 4 lower than that of the Vibraplane. What this translates to is 99% isolation at 5 Hz vertical frequency versus 50-75% for the Vibraplane (depending on load and air pressure). To get better performance than this using an air table requires some sort of active isolation, which is not worth the trouble or expense in my opinion.
I'd be happy to tell you more offline, so feel free to send email to me directly. |
I am using the Promethean Base. 100% effective. Brings the resonant frequency to below 2 HZ which is more than enough. You wont' easily hear a difference w more. Last of all, it is much less expensive than either.
Negatives, not a convenient to use as it wobbles (that is why it works) and it is DIY job.
All are a must I depends on you. Go after the Promethean 1st and use it elsewhere if you want to try something else. |
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. |
Ten months ago I looked into the Vibraplane, Minus K, and the Halcyonics platforms. The Minus K web site, namely the links to the audio applications, prompted me to lean toward Minus K. It is made in America, utilizes only passive components that won't hold you hostage to a foreign manufacturer to keep your device working.
I began my turntable project needing a 350 lb isolation device. It rose up to more than 600 lbs. My Minus 650 BM 1 will be here in about a week. I've never seen one but the help I received from the folks at Minus K prompted me to opt for their product.
The Library of congress uses them along with Simon York tables for archiving. They looked into the Halcyonics units but chose the Minus K. Keep in mind that they don't have acoustic feedback problems at the Library Of Congress, monitoring is probably done with headphones.
All that said, I don't anticipate problems with horizontal oscillations with a 650 lb table spiked to a concrete floor. The Minus K should have vertical isolation equal to the Halcyonics.
Vibraplane, I checked them out when I saw, "the table only," on Audiogon for $2200, that was a year or so ago.
I found the company that manufactures, and private labels the Vibraplane, and received a quote from the industrial distributor of the product, $1500 without the pump. If you feel that a Vibraplane is your ticket, Google it and save some money.
I'll post after I have it up and running and confess if I've spent my money unwisely.
Ken |
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Ken,
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Thanks for sharing your thought process in deciding to get the Minus k. I am leaning towards getting the Minus KWS-3M Vibration Isolation Workstation for my upcoming 220 lb Teres Table. The work station sits at 29 inches high and solves my problem of what stand to use with the Minus k.
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Did you ever consider get the work station or have any conversations with the Minus K people about using a workstation? What type of stand are you planning on using under the Minus k ?
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Do know if the Minus k products have any provision for leveling ?
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Regards,
Larry
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Larry,
All the Minus K vibration isolators have leveling feet. I don't know about the work stations as I never considered purchasing one. They are, however, very robust and will no doubt provide you with a stand second to none with regard to rigidity.
I'll be fabricating a welded tubular steel stand for my table. I want the platter chest high for ease of use. I also need the stand to accommodate the vacuum pump for the platter along with 3 Krell KPE Rerference head amps with the separate power supplies, one for each of the 3 arm-cartridge combos on the table. Since the KPE units only have single ended outputs, it would have been necessary for me to locate the table next to the processor - preamp, something I didn't want to do. The turntable will be across the room from the processor so I have a Krell KCT pre amp directly under the KPEs acting as a selector - preamp that will send the signal via balanced lines to the processor. Since the KCT also has CAST outputs I can use them sometime in the future when I upgrade my HTS 7.1 The remote controlled KCT will also enable me to make direct comparisons among the 3 cartridges as they all track the same groove. Lots of stuff on the stand, it's good the room is on a slab.
Good luck with your TERES project.
Ken
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Any updates on the Minus K or Halcyonics platforms?.
I have a similar problem to Dgad, except that nothing happens to my needle, just a low frequency feedback sound if I stamp down close to the turntables.
I might go Dgad's much cheaper route, as I would need to go BM-1 size with the Raven AC-3. |
I had never heard of Minus K, until this thread. So thanks for putting it up. I just went to the Minus K website to check out their prices and specs. Seems like the BM8, which costs less than $3K, would be a good choice for most tt's, which tend to weigh less than the 105-lb upper limit of this model. Plus, the level of isolation is only a hair's breath less good (f=1.5Hz vs 0.5Hz) than their top model. Has anyone tried the BM8? Thanks. |
Whoops! I see above that sdlevine is an owner of a BM8 and likes it. Moreover, I erred in reporting the performance of the BM8, which is f = 0.5Hz in the vertical plane, as sdlevine says. I will have to struggle with my conscience over purchasing one of these, maybe sell an extra turntable to pay for it. |
HI Downunder
I have been using a Minus K for over two years now. Mine is a custom BM-8, and it will support the Raven AC-3's weight and size.
The advantage to BM-8 over the BM-1 is the lower center of gravity, reduced height and looks.
Zero maintenance, once setup you can forget about it. You can jump up and down next to it and it will keep on playing cleanly.
Email me off line if you want more info.
Paul |
