active vibration management

Has anyone tried active vibration management systems like a vibraplane or something like a kinetic systems electron miscroscope isolation system for their turntables? They go on ebay for very reasonable amounts of money...

I am interested in hearing about experiences with these systems if anyone has tried it.

Regards,

Nick.

 

Be aware that some use noisey compressors.

The ones we have here (work place) dont stop movement, rather they make it a slow controlled wobble as opposed to sharp uneven movement (hope that makes sense).

They certainly help us in relation to the equipment used on them, no idea how that would operate in a hifi situation tho.

 

Well I would be interested to know isolation from 1 hz to 100 khz say. I guess slow and controlled is fine so long as it is below a few hz.

Yes I knew about the compressors - same as the airtangent arm, but apparently some very quiet ones are available or you can stick them in another room.

Are there are variety of different types of active solution?

Going from mana to townshend I noticed a big improvement with the deck, which is non-suspended, (note: under no circumstances is this an invitation to discuss mana on this thread!) and the manufacturer recommends active solutions as best alongside the HRS supports.

Do you do electron microscope work with them or something else?

 

A friend in the US used to have a Vibraplane under his TT, but ended up convinced that the system sounded better when the pump was disconnected entirely from the mains. This was despite running the support through an Equitech.

He ended up with a suspended subchassis deck and has been delighted ever since. The lesson appears to be that if you must use a solid deck, mass load it on a solid platform if at all possible. The BCD racks can be revelatory under such turntables.

 

BBV, i'm not sure what frequency they operate at, i could possibly enquire but it probably wouldnt help as they may be different to the ones you are considering.
I would hazard a guess that it is under a few hertz, as the movement is visibly slow. You can push on one corner and the return is a controled rise above and then back down to the original position.

Screw type compressors are fairly quiet, although IME run quite hot.

I'm not sure on other types, we use the air type and that is my only experience of them.

We have one under an SEM yes, and a few others for various measuring and alignment equipment.

 

Thanks - which TT was it?

The Brinkmann Lagrange I use is already pretty heavy. It seemed to benefit from the townshend. Deflated it sounds awful. I havent heard a suspended chassis deck that comes close yet.

BCD racks?

 

Penance - I would be interested if you can get an idea of the dsegree of isolation and over which frequency range. I think any standard SEM active support solution will do. I used to work in a silicon processing group and they used them in the lab. From what you have said the controlled movement is sub-hz.

 

I will try and find out, or get a manufacturer and model so it should be available from them, will probably be next week now - best to remind me then.

I think the unit under the SEM is specific to the scope, but others we have are more generic.
We also have some stands/tables made of heavy mass damped legs and large granite tops, used for less sensitive equipment.
I would change the granite for another material tho, maybe slate.

 

Thanks!

Yes I saw these other types on ebay as well.

Marble resonates at undesirable frequncies - slate should be more inert due to its laminated structure. What about granite?

 

I've tried granite under speakers, it completely killed the sound dead!
Lesson learnt there.
I think it was Paul Ranson who warned me (hope i got the right guy), i should of listened.
So if you want 2 x granite surface blocks im yer man!

 

mmm might not be the same with speakers - will bear your offer in mind! I am using townshend with the pmcs currently.

 

How do you find the air plats under speakers?

 

The trouble is you'll then need a support underneath the compressor, to stop it's noise and vibrations. Ideally that would be another vibraplane, and so on. When will the complexity end? It's like a dog chasing his tail.

 

Nah the air goes through a thin pipe - no transmission I hope ;-)

I found the platforms made a difference especially in the bass and mid and made the sound cleaner but the damn things keep deflating and need pumping once a month. Fiddly to get level too.

 

Ive been considering them to help with a suspended floor, should get round to it really.

 

I bought on ebay - overpriced otherwise but worthwhile for £300. I have a concrete floor though so it mayhelp more on a suspended floor.

 

He had a Nottingham Analogue Dias. Compared many of the alternatives although not your TT (I recall he tried another Brinkmann but found it lacking on more modern music). He ended up with a SME 30 and is delighted.

BCD racks are very stable - I use one myself. They offer a mass loaded structure with adjustable damping and work superbly under all turntables.

 

Resonate ferquencies have more to do with material mass and rigidity [springyness].
We can look a density as a good measure of mass.

So often the denser the material the more energy it will require to resonate

Slate will not be less resonante due to the laminations,

Granites are have a specific gravety of about 2.75 and are relatively light.......

that is why you granitic intrusions in more mafic country rock. Think of the tors on dartmoor, these have risen from an area of subduction in the devonian period [if my memory serves] As a subducting plate decends it melts and the lighter fraction rise to the surface.....hence the granite plutons

denser rocks should sound better.....dolerite [fine grained gabro] should have a sg of about 3

slate on the other hand has an sg slightly less than granite .

further details can be found
http://www.edumine.com/Xtoolkit/tables/sgtables.htm

 

Not with active damping, it is controlled by oposite movement.

 

What is needed under a TT is something which resonates very easily, so that vibrational energy passes into it.

Slate is good.