air bearing turntables

Theoretical advanatages and disadvantages versus conventional bearing? Any ideas or info on air bearings?

Thanks!

Nick.

 

If you have $US73,750 to spend, none whatsoever:

http://stereophile.com/analogsourcereviews/258/

(except for the extra cost of reinforcing the floor).

 

Hi Nick,

The main advantage of air bearings are lack of surface contact. This leads to zero friction. There will be less noise as there is no contact plus no wear and tear or need for lubrication.

They work on pressurised air flow which need to be supplied by pumps.

Here is a brief run down

http://bearings.globalspec.com/LearnMore/Mechanical_Components/Bearings_Bushings/Air_Bearings

Also some people who have used air bearings

http://www.6moons.com/audioreviews/walker4/sota_4.html

http://www.walkeraudio.com/proscenium_turntable.htm

http://www.vyger.com/inglese/home.htm

http://www.enjoythemusic.com/magazine/equipment/0801/vygerindian.htm

SCIDB

 

Thanks - and what is the downside if any?

 

Cost/hassle of maintenance and noise, mostly. The air needs to be filtered and de-moisturized before it can be pressurized. That means filters, which need to be changed on a regular basis. Some air bearing arms have also had pretty severe rust problems IIRC, but a tt with air bearing will be made of non-oxidizing parts, hopefully.

The pump will make a good bit of noise and will ideally be seated a long way away from the listening position (cellars and attics are popular, I think). Then you need to route the air pipe from the pump to the tt.

 

any resonance or movement based effects?

 

Resonance - not if correctly designed.

Movement - how?

 

Just curious - I dont know anything about how the arrangement works - I dont suppose you have any links online to a fuller explanantion?

 

Dean's links should be a good start.

 

Checking them out now...

 

I don't know if the London Live DIY group is still around - the web pages (http://www.earthcurrents.com/london-live/index.html) are a bit static. But in their early days there was a prototype air bearing turntable - not sure whether it ever played records. It might be worth seeing if there's still life over there - the people involved did some quite basic (as in fundamental, not superficial) research. There was an arm projected as well, but that may not have happened.