Does any Audiogon member have a Holbo air-bearing turntable?

@frazeur1 

Hi Tim

There is not much information on Holbo’s website except for a long list of excellent reviews!  These can be a bit confusing:  some reviewers have the platter at 5-kg, some at 5-lb.  Others have the stainless steel mount at 5-kg and some at 5-lb.

Given that stainless steel is about 3 times denser than aluminium, I lean towards a 5-lb platter and 5-kg mount.  Have you ever pulled yours apart?

If I were trying to reverse-engineer the platter bearing, I’d make the mount as a solid, rather flat cylinder with a central hole for the air feed, venting at its top.  The platter would have a rim which descends around the mount with that legendary 10-micron clearance to let the air out.  The total area of the gap would be the circumference times the gap - say pi x 300 x 0.010 or approximately 9 sq mm or the size of an 1/8" hole.

The air pump itself reportedly produces quite a low pressure at about 1/3 of an atmosphere.  One atmosphere is about 15-lb per square inch, so say 5-lb per square inch.  Without leakage, 1 square inch would be enough to lift a 5-lb platter but the total area is just a bit under a square foot, so the platter could easily be 5-kg!

The total power consumed by the air-pump / power supply is just 10-Watts, with 2-Watts seeming to power the motor.

Sorry about mixing imperial and metric measures!

What have I got wrong?

@richardbrand Yes often I see review specs that are questionable, almost like one review got it wrong and others are just copy/paste from wrong info. I try to just use manufactures spec as much as possible, not that they can’t be occasionally wrong as well! 
 

When I first got my table, I recall the air pressure supply weep hole being on the top of the stainless sub platter, not too far from spindle location. It has been awhile though. As to supply pressure, it is low, not sure of figure though. I was going to bring home a calibrated low pressure standard to measure it initially, as a base line, but never did. 
 

Anyway, so far no complaints with my Holbo. I do like the Mk2 having all the bits in a single box, and operationally being much simpler. My unit I have to remember to always switch on air pump prior to starting platter, really no big deal, just new model is a bit easier. Maybe I will update mine at some stage, who knows. Tim

@frazeur1 

often I see review specs that are questionable

Thanks Tim

My Reavon universal disk player is a classic example of this,

Reviewers rave about how good the sound quality is, but in analogue mode, SACD is actually down-converted to CD quality and that was obvious to me within a minute of listening.  Its dacs do not natively handle Direct Stream Digital, but nevertheless Reavon could have done much better than CD quality with the dacs they use.  This I confirmed in emails with Reavon.

Apparently the Mk2 Holbo keeps its air pump running for a few minutes after switching off.  One reviewer reported that with the drive belt removed, the platter took about 3 minutes to stop from 33-rpm.

My personal curse is that I like to try to understand the physics behind products I use.  Does the Holbo's spindle do any more than position the record and puck on the platter?  In other words, does it play any role in centering the platter itself on its mount?

I guess I will have to buy one to satisfy my curiousity!

I found out about the Holbo when I went to a demonstration evening featuring B&W loudspeakers.  One listening room was playing vinyl and I could just make out that the deck had a tangential arm.  Later I grabbed some favourite LPs and had a private demonstration, through McIntosh and Musical Fidelity electronics.  There was a fair amount of quiescent noise but it turned out to be the McIntosh.

The importer made me a good offer on the demonstration unit, but it was way beyond my means at that time.  Holbo's direct sales model has dramatically reduced the price of a new unit in Australia

@whart 

I've been using a Kuzma Airline since around 2006-7. I really like what it brings to the proceedings, and it seems to like a stiff cantilever

Thanks - I have just checked the Australian price for the Kuzma tonearm, and it is almost three times the price of the entire Holbo system!

Unfortunately, I have a budget to keep to!

Yeah, it's big bucks now. It wasn't cheap when I bought it, but it uses an air bearing like the Holbo.