Active Isolation Versus MinusK for Tube Amps?
- Thread starter Ron Resnick
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IMO you must state a particular amplifier to ask such question. I can't explain why but found, for example , that an ARC amplifier had a very different reaction with a Finite Elemente Pagode platform than a conrad johnson. The ARC sounded lean on the platform , the conrad johnson sounded great.
When addressing platforms we must think of two aspects - vibration isolation and vibration coupling. So we want isolate our amplifier or do we want to couple it to a large mass?
Very true!
As with lots of things in this hobby a priori assumptions are ill-advised. Ideally I would try it both ways and see what I hear.
If I have to guess I would seek vibration isolation -- a la MinusK or Herzan.
As I research the MinusK (used under my friend's Berning SETs to happy effect) I have learned that the center of mass of the device being isolated has to be in the middle of the top of the MinusK platform. This is a problem if an amplifier is heavily weighted to the rear with big transformers.
A plate would have to sit on top of the MinusK with such an amplifier moved forward to locate the center of mass of the amp over the center of the MinusK -- seems like an unsightly project.
A plate would have to sit on top of the MinusK with such an amplifier moved forward to locate the center of mass of the amp over the center of the MinusK -- seems like an unsightly project.
The challenge with any isolation platform in audio applications is the secondary vibration path set up by connected cabling. This is even more significant when those cables are relatively heavy. In my experience, the MinusK platform is particularly sensitive to cable drag.
I wonder if the best operating environment for sensitive electronics (those with highly microphonic components) and transduction sources (vinyl playback) might be in a room which is isolated from and separate to the primary listening room.
I wonder if the best operating environment for sensitive electronics (those with highly microphonic components) and transduction sources (vinyl playback) might be in a room which is isolated from and separate to the primary listening room.
Agreed … this is how my primary listening room is configured. Beyond isolation there is an added benefit of not creating a large mass of equipment in a primary reflection zone. On the downside there are UI/control issues and long cable runs to contend with.
I have read on this before but I find it a bit perplexing. Alone, I can understand the idea of either a) rigidly affixing a mass to a larger one to eliminate vibration, or b) isolating a mass from external excitation. But, when I read about various stands they claim to effectively do both. I suppose if the frequencies at hand under (a) and (b) are different it is possible. Do you have any sense of this?
every chassis design and internal circuit structure is different. and the level of distortion in the gear performance can be too off neutral one way or the other to work with certain racks, footers and floors.
all passive isolation that decouples floats and settles. basically they are all mechanical springs. being passive, they have no ability to stop and start. so they are soft. and will always have an influence on the sound in some way. some gear is voiced for particular footers or types of passive treatment. so you 'tune' gear by choosing the complimentary passive device (or combination of passive devices) that results in the most pleasing performance. sometimes decoupling is combined with coupling or mass loading in layers so changing the pathway of resonance. floors have considerable influence too.
OTOH active is stiff, hundreds of times stiffer than passive since it can start and stop. it does not settle. assuming the gear resting on the active device does not create it's own excess resonance and create a harmful feedback loop, active should not change tonality. it might bring too much focus by eliminating resonance, but mostly that is not a negative. while active has the highest performance, it is not a universal solution.
Thanks, Mike!
I have a gaggle of Grand Prix stands and a pile of Sorbothane pucks and a couple HRS stands. I suspect that some combination will work great. Now, if I just knew which combination!
A friend of mine who just got Devore O96s with a MastersounD integrated amplifier experimented with a MinusK platform underneath the amplifier. He is quite sure that he prefers the sound of the system with the amplifier on the MinusK.
I am tempted to try MinusKs under the Jadis amps or under other future tube amps.
I am tempted to try MinusKs under the Jadis amps or under other future tube amps.
Know that Minus K devices are calibrated for specific weight gear. They have to float in a particular way. And cable dressing (need to be unweighted to optimize the float effect) is important as the float is the deal.
So they are somewhat futtzy to get optimal. If you are constantly switching out gear it might drive you more battey.
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i owned Grand Prix Monaco stands for 5 years back in the day. those pucks really did work but changing them every 6 months to get the full benefit of the design was not fun. or finding the right combinations. lifting the platforms to change the pucks was hard for a wimpy guy like me. trying to position the pucks correctly in the rear bottom of the shelves a challenge.
like changing gear ratios for different tracks.
ended up selling the GPA and went to solid Adona racks and treated each piece of gear with footers and active 15 years ago. but the GPA was beautiful and very high performance.
Yes, I understand this, thank you. They have to be ordered with a particular weight load and size in mind.Know that Minus K devices are calibrated for specific weight gear. They have to float in a particular way. And cable dressing (need to be unweighted to optimize the float effect) is important as the float is the deal.
So they are somewhat futtzy to get optimal. If you are constantly switching out gear it might drive you more battey.
I agree they are not for somebody who is "constantly switching out gear."
Mike,
IMO your perspective on platforms is too superficial and can lead to the wrong conclusions - isolation properties can't be checked pushing the platforms. As I said before we have to consider the objective of the platform when analysing it. Considering isolation, the main objective is avoiding vibration coming from the floor to enter the device being supported. So stiffness must be checked between the platform and the main table disturbing the whole table with the mechanism, not disturbing the platform. If you disturb the table the you will find it is not stiff - on the contrary the active actuators will help you to move it keeping the table stable and immobilized. If it was stiff it will transmit the vibration. The price to pay for this benefit is having a system that involves active negative feedback - people who have fundamental dogmatic issues on "seek and error" will create negative bias against such devices ...
I am not criticizing or saying which is better, just saying things are much more complex than marketing literature. Unless we have a proper complete analysis it is better to rely just on our listening for evaluations.
Again saying that we are comparing listening with or without active platforms just switching it on and off can be extremely misleading - an active platform switched off can behave as a passive undamped resonator. BTW, passive tables are not just "mechanical springs", many have pneumatic devices and have complex damping systems.
of course if one goes to active there is a use case and proper support. floors and racks have to be complimentary. agree. it's ideal in limited particular uses.
air tables still float and settle. like springs. they have no feedback to resonance to react. some are yet very high performance. and they don't have some of the restrictions of active. i seriously considered the Stacore for my Saskia and CS Port tt's. it's very good. but i would have needed a custom size so just too expensive to buy (shipping was very spendy).
living with 5 active devices daily and having been involved with the development of the Taiko Tana system i do understand how this works and how compares on and off and in and out of my system; and compares of switched off active to alternative decoupling systems go. i have much active optimization practical experience and have done the work.
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One of the main reasons I do a lot of my critical music listening with my TOTL Headphones and Headphone Amplifier and not through my speakers for my HiFi system in the UK i.e. no worrying of any equipment vibrations, speaker placement, speaker isolation, room acoustics, my placement and seating position in relation to the speakers etc. etc. !
agree that headphones have advantages. however; earth noise is real, and still there even if you eliminate acoustical and mechanical feedback from speakers. turn active on and off using headphones and you will hear it; i did. headphones will help you hear the delta more.
there is a reason science uses active devices for the most sensitive lab gear when possible.
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Yes, I have seem them being used force atomic microscopes that image surfaces at the atomic level. But science uses them because our purpose is just maximum isolation from ground disturbances, particularly at very low frequencies.
Most times in high-end audio we must have a compromise between isolation and coupling (draining vibrational energy from equipment) - and in the field we can't rely just on specifications and charts.
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