Active vibration isolation

[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/content/produc...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

[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

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.