Active vibration isolation

[purite audio]

Next week Chris Brady is very kindly bringing one of these ,

http://www.accurion.com/active-vibra...ducts/silencer
He is going to conduct some accelerometer tests and we will look at the data,and
compare the sound of the turntable with and without the active isolation unit.
Anyone tried active isolation?
Keith.
Marco please move or remove if you feel it is inappropriate , I have never tried active isolation,
it might be interesting.
Keith.

[The Black Adder]

Page not found, Keith :)

[orbscure]

Try this one Joe ;)

http://www.accurion.com/active-vibration-isolation-products

[purite audio]

Ideal for those long house of card building evenings.
http://www.youtube.com/watch?v=S77LUwnjQ0o&feature=youtube_gdata_player

Keith.

[Stratmangler]

That's a decent demonstration of the platform's isolating abilities.
I do wonder what the platform would do under a turntable.

What does it cost?

[purite audio]

That particular one is around £6k but Vibraplane make a range which is lmore reasonably priced.
I will let you know how it fares.
KR Keith.

[Stratmangler]

Ouch!
That rules me out of the list of prospective purchasers, unless of course my lottery numbers come up.

Any idea how much I could get for a healthy 13 year old boy on the "for medical experimentation" market?
I have a specimen here :eyebrows:

[nat8808]

These ones from a company called Minus-k have much better isolation graphs (transmissability graphs): http://www.minusk.com/content/products/standard/bm8-vibration-isolation-platforms-benchtops-isolators.html

And it looks like they are imported or at least availabel to buy in the UK by these people: http://www.orlin.co.uk/vibration-isolation.htm

Here's a 6 Moons mini review: http://www.6moons.com/audioreviews/minusk/platform.html - seems to be not as user friendly simply because it's so sensitive to movement, such as lowering an arm, or putting on a heavier piece of vinyl.

Then there's the lab brand of the Vibraplanes - exactly the same but different paint work, not as neat looking: http://www.kineticsystems.com/page136.html - That's the OEM page but not sure where you get them from in the UK.

There have been a couple of the Kinetic Systems Benchmate 2212 (same as Vibraplane 2212) on ebay for ages unsold - about $1099 or offer but shipping is too high probably to consider it.. then you need the pneumatic thing to regulate pressure.

Good that these you mention don't use air lines and compressors but instead just plug in to the mains. Although the Minus-k ones are completely mechanical and supposed to be the absolute best ! A triumph for old-school mechanics.

[purite audio]

I think I have discounted Minus K, appears to be too much of a faff.
Keith.

[nat8808]

I think I have discounted Minus K, appears to be too much of a faff.
Keith.

That's how it read to me too - but perhaps if it were used with a heavier platform on top (or a more massive deck) then the movment of putting on the record etc should have less of an effect. I wonder if it moved so much because the deck itself is the only mass on top.

Probably a much better system via Minus-k would be whole rack isolation - that would be a nice over-kill project with a specially made low slung platform on which to place a wide rack, just like their ES Microscope platforms..

[walpurgis]

I'm going to have one under every piece of my system. £47,000 doesn't seem too bad really. :)

[nat8808]

Don't be daft....

It wouldn't be necessary unless your equipment is producing all the vibration?

No, you just need a set of 3 of these bases and a base frame which sits on top: http://www.minusk.com/img/products/cm1_negative-stiffness_cubic_vibration_isolator_minus_k.jpg

http://www.minusk.com/content/products/standard/cm1-low-frequency-cubic-vibration-isolation-isolators.html

Would cost only $10.5k plus the frame/stand. Add another special one for your tt for another $2.5k. So that's only about £8k - less than Marco's Tannoys and Technics combined.

[nat8808]

I'm going to have one under every piece of my system. £47,000 doesn't seem too bad really. :)

Sorry, just realised you were talking about the £6000 items at the beginning of the thread! Yes, daft price.

[guy]

Going by the links, am I correct that they are being considered as isolation from footfall and similar?

It seems to me that they would not address airborne vibrations from, say, speakers as the isolator operates at between 1 and 10 Hz - or am I wrong in my assumptions:scratch:

[purite audio]

You are correct, they can only isolate vibration from below , traffic,foot fall. room resonance.
Keith.

[nat8808]

Going by the links, am I correct that they are being considered as isolation from footfall and similar?

It seems to me that they would not address airborne vibrations from, say, speakers as the isolator operates at between 1 and 10 Hz - or am I wrong in my assumptions:scratch:

But how much does airbourne vibrations directly effect a record player?

Id say that a lot of airbourne vibration will only effect the player through the supports via bass vibrations, standing waves going through the stand or wall or whatever. OK, depends on your deck I suppose - probably a hollow plinth like a Linn will start to resonate like any other ported box at certain frequencies.

If you think of how much in a room there is to absorb airbourne vibration and resonate/move in sympathy (therefore using up the sound energy) the record player will only be affected by a small percentage of that total. I guess too, that anyone going to spend a fair amount on isolation then wont be placing their sources between the speakers either, probably a fair distance away.

[guy]

But how much does airbourne vibrations directly effect a record player?

Id say that a lot of airbourne vibration will only effect the player through the supports via bass vibrations, standing waves going through the stand or wall or whatever. OK, depends on your deck I suppose - probably a hollow plinth like a Linn will start to resonate like any other ported box at certain frequencies.

If you think of how much in a room there is to absorb airbourne vibration and resonate/move in sympathy (therefore using up the sound energy) the record player will only be affected by a small percentage of that total. I guess too, that anyone going to spend a fair amount on isolation then wont be placing their sources between the speakers either, probably a fair distance away.

I do use an LP12 (not between the speakers though!) and yes, vibrations can be felt when the volume is turned up, particularly lightly touching the lid (resonating box, is part of my thinking in playing with no base board or lid in place).

My interest in vibrations was sparked by watching a video clip of how airborne vibrations affect objects in a room (Not much use but I can't for the life of me remember the name or source - sorry - used to use it in Physics lessons many years ago). From memory, the energy of a vibration wasn't particularly easy to get rid of - even very massy/"solid" objects were vibrating, just at different frequencies to the original sound.

I don't think that a massive granite block used with a DD or idler drive would be immune. May be bollocks, but I believe that the trick is to channel vibrations somewhere else as quick as possible (a la Linn) or convert the kinetic energy to thermal.

The idea of having an active response to vibrations is very appealing, but I do have suspicions about the effectiveness of any servo systems - used to watch them "hunting" with great amusement many years ago when we used them for temperature control in reactors in the plastics industry.