Active versus Passive Isolation Platforms for turntables

[PeterA]

Ked, I believe I heard the GP on the Speirs well before the Illusonic came on board
In those days, his room was a veritable swamp of nasty nodes, but the tt held firm
I believe he told me that w'out the Spiers passive he could not get the tt to behave
That's as good an advert for the Spiers passive as I need short of demoing it here
He had commented on springy suspended flrs in his Victorian house, as well as (un)sympathetic vibns from traffic outside, and the Speirs/GP was plonked on a non inert, non audiophile chest
Again, all excellent adverts for the Speirs

I return to the point, and now I think about it I seem to recall, that the Speirs designer touted passive over active in all cases for tts because despite active isolating lower down than passive, sub 2Hz and somewhat sub 1Hz, passive is more reactive ie more instantly start/stop, primarily because it doesn't react to tt-borne vibns and noise ie moving platters and arms etc
So, passive not so impressive at low frequencies but a better "fit" to the device ie tt being isolated
The GP Monaco on the Speirs passive at Purite Keith's really did sail thru his Cessaro Liszt/brutal room nodes torture test

The other cogent point the Speirs designer made was that if his passive was 97% good down to 2Hz, and 50% below 1Hz, and the active 99% good down to 2 and 97% below 1Hz (I've made these figures up just to make my point), he really feels this should have no real world bearing on our enjoyment of Lp listening
1Hz equates to a subway train several miles below the surface, travelling away from your listening room several miles away
Really, is that noise going to impinge on our listening pleasure? He certainly didn't think so
In fact these specs have been driven not by the isolation gear designers, but by the lab people who really require isolation to go to limits maybe not really needed
I have concluded that I'm not going to get obsessive about worrying if "95% below 1Hz is practically better than 50% below 1Hz", go w the Speirs advice that passive suited better to tts, pocket the extra cash, and base my decision to buy on whether a trial of Speirs passive in my room replicates the clear benefits I heard at Keiths or go for passive "plus" w the Stacore Advanced and its touted extra benefits of greater broadband isolation, and constrained layer construction that may replicate PeterA's long discussed benefits on his SME 30/12

Marc, I think we need to dial back some of the claims. Ron is correct: I have not heard an active isolation platform under my turntable. Thus, I have no basis for such a comparison. I am confident that both active and passive solutions are effective, just based on my reading of reports from users. I simply started this thread to better understand the differences between the two approaches and to learn if one might be more effective than the other at isolating audio equipment in general, and turntables in particular, from environmental vibrations.

Also, I do not think that my particular isolation solution of a pre-loaded Vibraplane with a steel ballast plate constitutes a "constrained layer construction" the way that perhaps you are describing the Stacore device. Kinetic Systems, which designs and manufactures Vibraplanes, custom made my steel ballast plates out of the same materials that they make the top plate for the Vibraplane. The idea was simply to add mass to the system and make it more efficient and effective at attenuating lower frequencies. At one time, I did have a layer of thick roofing rubber between the two steel plates. This would have constituted a simply constrained layer, but I thought later that vibrations draining down from the turntable would be better absorbed by the mass if the two plates were in direct contact. For this same reason, the SME suspension towers rest on footers which terminate in a steel ball. There are rubber inserts to protect furniture, but those can be removed for better performance.

Finally, I made reference to what I call "analog jitter" as my layman's term to describe the potential fast speed feedback loop that may occur when an active platform and suspended turntable system go into oscillation. I have no idea if this is in any way an accurate phrase or way of describing what may or may not in fact occur. I simply think of the constant hunting and correcting of such a system as similar to the way some direct drive motors search for the correct speed. It is also a vague reference to timing errors that I may be mistakenly thinking of with some digital equipment. I do not want to imply that I understand much of this nor is it my intention to confuse others with a phrase that may not be accurate.

 

[spiritofmusic]

Sure Peter, no wish to misrepresent you
I'm certainly stating for the record the Speirs designer asserting passive isoln more suited to tts than active, for the reasons I gave earlier
And recollecting the stellar job the passive Spiers did w the GP in a maelstrom of brutal bass nodes on a non inert piece of furniture on a Victorian suspended flr, that demo of its abilities was as slam dunk as it gets
That's why despite the momentum of discussions here on WBF aimed twds active Herzan, I for one am happy to choose passive
That leaves me two choices, passive Speirs already heard, and further trial no issue, or the new boys Stacore

 

[BruceD]

Interesting and informative thread--I agree with Ron and commend all the participants for the candour and forthright opinions/views/etc

Hearteningly refreshing for what could have been confrontational

Kudos to all and keep up the banter

My only horse in this race is i use the Minus K-so passive was my choice

Couple of points--

Library of Congress use Passive under their TT's

Ah yes the "Mechanical Diode"--we can blame Goldmund for that!

Carry on chaps!

BruceD

 

[Ron Resnick]

Does the Library of Congress use the Simon Yorke turntable?

 

[microstrip]

Does the Library of Congress ise the Simon Yorke turntable?

As far as I remember they owned custom professional models made by Simon York. One of the professional features was the programmable constant linear velocity feature - the angular speed was permanently accelerating!

I loved the turntable (an S7), but hated the tonearm - there were no references or marks in the arm tube and adjusting the cartridge was a real nightmare. But it sounded very nice and looked great.

 

[Reid.Whitney]

Happy to answer any questions as a member of the Herzan team. If I am delayed in my response, it is likely because I am out of the office or traveling for business, so I ask for your patience and I will gladly attend to your question as soon as I am able.

Quick Primer on Our View of Active Versus Passive Systems
There are a lot of great resources out there discussing the merits of active versus passive vibration isolation systems, with many of them centering on three primary points: cost-benefit analysis, relative need for low-frequency vibration isolation, and the impact of the ambient environment.

Some applications can benefit from an active system and show demonstrable improvement, but the cost can be prohibitive and not able to justify the greater expense. Other applications cannot function without the level of precision offered by an active system, which then becomes a necessary "insurance" to the performance of the equipment. There are also times when the nature of the environment is such that low-frequency vibrations are greatly minimized, allowing equipment often supported by active systems, to operate fine on a standard passive system. The opposite can also be true as well: low-frequency vibrations within an environment can be significant enough to require an active system for equipment typically supported by passive systems. I am happy to give examples of each scenario if desired, but didn't want to have this post go on too long.

More often than not, equipment manufacturers know beforehand which isolation technology is the correct one to recommend, assuming they have done the necessary homework.


Our frame of reference when discussing these terms is rooted in the scientific research community, but there is a lot of crossover to applications outside of our primary industry. Please feel free to share your questions and I will work with our team to answer them in full.

- Reid

 

[Ron Resnick]

I talked at length today with Ann Scanlan, the Technical Director, President and Founder of Herzan LLC.

I hope I am correctly reporting Ann's advice and conclusions:

1) In general, stacking isolation systems is good: passive plus passive or active plus passive.

2) I explained the motion and vibration occurring on a turntable: the motor spinning, the platter spinning, the arm moving, the cartridge undulating in the vinyl groove. I explained twice the concern about the spring suspension of a suspended turntable "fighting" with the correction mechanism of an active isolation platform. I elaborated what we are concerned about -- that the turntable suspension is set in motion, the Herzan corrects that perceived motion, and then the turntable suspension is perturbed by the Herzan's correction.

Ann said A) the response time of the Herzan is very fast and, likely, a lot faster than the response time of a spring turntable suspension, and B) she does not see the feedback loop concern at all. She says the Herzan will absorb some vibration generated on the top of the Herzan by the turntable, but will not get into some sort of feedback loop from the movement of the suspension of the turntable.

3) Ann said that in almost all cases Herzan continues to advocate connecting the active isolation platform to the floor as rigidly as possible. I asked about the Herzan option to have a layer of visco-elastic material below the top shelf of a rack. Ann said that the damping layer -- usually Sorbothane -- might go underneath a shelf but would not go underneath a top plate. If for some reason a customer wants a visco-elastic layer underneath the top plate (I.e., underneath the active isolation platform) Herzan will oblige, but with only a very thin layer of visco-elastic material, Ann said.

Other than simply stacking an independent passive isolation system on top of an independent active isolation system, there is no sense in which Herzan is developing new products which integrate different vibration isolation techniques.

4) Ann said that, in general, combining isolation techniques will result in improved isolation (not necessarily twice as good, but better than either isolation system alone).

5) Ann said it makes sense to stack some passive isolation technique targeting vibrations greater than 1,000 Hz on top of an active isolation platform handling vibrations below 1,000 Hz.

6) I asked Ann if the still or vibration-generating nature of a component being isolated drives the answer as to the most appropriate form of isolation -- active or passive. I suggested that perhaps active isolation might be the best vibration solution for a still microscope, but that passive isolation might be the best solution for something like a motor.

Ann said she does not think of it like this, that the still or vibration-generating nature of the component being isolated does not necessarily drive the best isolation solution.

7) Ann said that filling up hollow rack legs with sand is beneficial to the overall vibration-reducing effort.

. . .

Ann was very friendly, very receptive to my questions, obviously extremely knowledgeable and truly happy to be of help!

 

[Ron Resnick]

Thank you very much, Reid!

 

[BruceD]

Yes-- L of C have/had Yorke S10s highly modified with 16 " arms etc on Minus K BM9/10s custom produced-- Micro-- Simon has retired to his Wine making in South of Spain if you ever across the border!

He is a friend--I've owned his Table and --Minus K at Simons behest--I gather from last correspondence I had with him--his sojourn into the Hi End was not as fulfilling as he'd hoped--now finding solace in the Climate and lifestyle Espana

Re the Herzan--I enquired of them when they were making out of Switzerland--before the US enterprise--good to see the established setup now in the US--:b

BruceD

 

[rockitman]

Re the Herzan--I enquired of them when they were making out of Switzerland--before the US enterprise--good to see the established setup now in the US--:b

BruceD

To Be clear, Herzan is the distributor name...not the actual maker of the product. The active isolation TS series is manufactured by Table Stable out of Switzerland.

 

[Stacore]

1) In general, stacking isolation systems is good: passive plus passive or active plus passive.

I would correct this statement : stacking is good IF you know what you are doing.
Stacking suspensions working in the same direction and having close resonant points can lead to beat oscillations.
Having said that, there is no other way to obtain a broadband isolation/damping as stacking (I explained that earlier)
as one suspension will not cover a considerable (for audio) range of frequencies. Generally the idea is to
stack each consecutive isolation technique where the previous stops working to overtake the job.
Whole our concept relies on that with mixing mass, bearings, damped pneumatics, CLD.

Filling hollow legs: this will take the metal skin modes (kHz region) out and add mass for mass damping. Use dry silca sand, but not to fine!
Otherwise it will solidify (like a sand on a beach). Fill to some 3/4 to leave it room for work. If mass is a problem
perlite works great. Not so efficient as sand but almost-almost and much lighter. You find it in every garden store.
You can make a simple experiment: move your ear
very close to the empty leg. Knock it and hear the metal ringing (if it rings). Then repeat after the sand filling

 

[Stacore]

Ah yes the "Mechanical Diode"--we can blame Goldmund for that!

Bruce, if you find a way how to make vibrations go in one direction but not in the opposite, I think you will be a strong
candidate for a Nobel prize

 

[spiritofmusic]

Well, we have opposing views on passive v active for tts in particular
No consensus
As it ever was in audio

 

[Stacore]

If I may suggest something that would be to experiment and listen to different solutions
in your setup. I'm sure there is a chance to have a platform for a week or so for auditioning and then return it
(we offer two weeks, no questions asked).
This will save a lot of time and energy and brings you directly to the goal:
the sound of your system, instead of the transmission curves, resonant points, isolation efficiency and other things critical in a lab
but not so obvious here. My 2c

 

[spiritofmusic]

Jarek, your offer is v kind
I've pretty much ruled out active, on the basis of cost (I really cannot stretch to the £8k pricetag on the Herzan), the POV from Speirs that passive is more suited to tts, good reports from passive users like PeterA, DCTOM Dave, the stellar demo in Purite's room w passive Speirs, and the fact that excellent passives like the Speirs and your Stacore Advanced are available much further down the pricescale.
At this point, my audio room fit out has flushed my bank account totally dry, and I'm just starting to put together any sort of budget for upgrades. a passive isoln solution for my tt is the first thing on my "to buy" list, and once I have sufficient funds for yr Stacore Advanced and a single-tier inert rack (poss Rogoz Audio or Northwest Analogue slate stand), I'll take you up on that trial
Jarek, the situation is that I'm very much impressed w what I've heard about yr product from you, but you are up against the worst kind of competition, lab grade stuff w data and specs that in many cases beat what the Stacore Advanced offers (the Speirs AMB air rolling diaphram passive damps down to a resonant frequency of 2Hz, not 4Hz like yours, and offers up to 97% broadband attenuation up to 200Hz, and has a partially constrained layer construction), and is effectively half the cost of yr unit. Remember any free trial would come at the consumer's need to cover carriage both ways, esp if it needs to be returned, and this is no mean feat w an item weighing 95kg

 

[Stacore]

Quite paradoxically, we are getting from time to time inquiries from lab staffs.
I immediately send them to lab equipment manufacturers, explaining that they need
hertz and percentages not sound. Go figure

Edit: The 2nd stage in Advanced has a lateral fres at 1.6Hz if that matters.

 

[spiritofmusic]

Jarek, please don't take any of my comments as a criticism of yr products
There is nothing but admiration from me for what you have brought to the market
However the fact remains the lab grade stuff is yr natural competition more than standard audio rack manufacturers, and the comparison in specs and data is what it is
FWIW, I very much like yr ideas on combining passive pneumatics and springs, constrained layer tech w slate, and lateral isolation, and so yr product is in Pole position (pun intended!) to end up in a trial at my place
But that trial will only happen when I have the £4500 needed to afford yr platform and an inert rack just for tt purposes (not sure it's practical or common sense to put the Stacore straight on the flr)

 

[Stacore]

Thank you for kind words, but I'm actually quite open to a healthy criticism

One clarification: we do not use normal springs! I'm afraid of them like hell. We use air springs = pneumatics.

Let me make some analogy. In labs they use a lot of DAC's (I worked in one of the leading EU photonics labs for yrs)
and there are a lot of lab grade DAC manufacturers. They champion linearity, S/N, speed, etc etc. Then, there is our friend
Lukasz Fikus making absolutely stunningly sounding, in my personal view of course, DAC's under the LampizatOr name.
Nobody goes checking if his linearity compares with the best lab grade, what is THD of his analog output (high of course),
what is the conversion speed and how close it is to the speed of light, and if his S/N is the lowest
possible on the planet. You know why? Because his DAC's simply sound great!

Let me finish with an obvious but often forgotten: Audio is an empirical activity!

 

[spiritofmusic]

Jarek, this is an interesting line
That the Stacore Advanced can't match the absolute specs of the best active isoln, but this in effect isn't as critical as the holistic effect of unique combination of pneumatic springs, lateral isoln, mass loaded slate/constrained layer construction
You're in effect saying even if a Herzan beats yr Stacore Adv on paper, there's no guarantee it'll do a better job in practice, and unlike Herzan, yr product should purely be judged on how it enables the tt to sound, and that COULD be better than the Herzan because the latter doesn't combine as many isolating techs and materials as yr Stacore?

 

[PeterA]

Jarek, I have a few more questions: In the photo in your avatar, I see three ball bearings. Do they correspond with the positions of your pneumatic springs? If so, is that to reduce stresses in the top plate of the structure? Do your devices have auto leveling and filling from a compressor similar to the Vibraplanes? What is the range of weight for the component that can be supported by your device?

Thank you for your participation in this thread. I realize it helps your marketing efforts, but it also makes us more aware of your brand, and that is a good thing for the audiophile community. I wish you success in your business.