The Black Hole......

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#4,861
hhoyt said:
The air bearing is ideally suited to ultra-high-speed shafts where shear in a liquid lubricant would be excessive. In these systems the viscosity of the air is sufficient to provide entrainment and a hydrodynamic cushion (see Streibeck curve). Studying this characteristic of hydrodynamic bearings shows the slower the tangential velocity of the shaft relative to the bearing and lower the viscosity of the lubricant, the thinner the lubricating film.

A 10 mm shaft diameter turning at 33.33 RPM only has a tangential velocity of 17 mm/s, extremely slow. Also, the lubricant is air which has a viscosity 3000 times lower than that of typical oils used as lubricants. This likely results in an air film of a tens or single digits of microns.

This is not such a good idea in TT bearings, either for the tonearm or platter. They must be linked together as tightly as possible to eliminate any differential movement. Radial differential movement in between the platter and stylus is a good description of the desired cartridge output signal. Due to the low viscosity of air, the radial tracking forces will likely be able to modulate the air film thickness, so the differential relationship between the platter and stylus will not be fixed as it needs to be. This would seem to apply to air-levitation platter systems as well.

Of course, I could be full of s#!t...
Cheers,
Howie
Click to expand...

I wouldn't say you are full of s#!t.... 🙂
However, air bearings are definitely a solution for the highest precision
applications which require very tight constrainment and they can handle
considerable loading.

Radial Air Bearings on a Precision Shaft - YouTube


TCD
 
#4,862
vacuphile said:
This is what I have never been able to figure out. Diana Krall's voice is heavily processed, as I noticed in all of her vocal excretions I have been confronted with.

Yet, many audiophiles use this super processed voice to determine how natural a stereo set up sounds.
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I saw a photo in Stereophile a few years ago of a guy at RMAF with a T shirt that said 'For the love of God, no more Diana Krall' Everyone seems to drag her stuff out at HiFi shows.

The gold standard for me is Ella Fitzgerald sings the Irving Berlin Songbook. Her George Gershwin Songbook Vol 1 is also good, but they overdid the reverb on a few tracks - pity. Imaging on both is absolutely stellar.
 
#4,864
Terry Demol said:
I wouldn't say you are full of s#!t.... 🙂
However, air bearings are definitely a solution for the highest precision
applications which require very tight constrainment and they can handle
considerable loading.
Radial Air Bearings on a Precision Shaft - YouTube
TCD
Click to expand...

Hi Terry,

That is a great demo video! I have used porous ceramic bearings in a few projects for both air-bearing and vacuum clamping and really appreciate their virtues as well.
This group is famous for thread drift, and when I composed the original post I was thinking about standard TT bearing geometries which are indeed ill-suited to air bearings. It would be pretty cool to see a super TT made with one of these other air bearings posted here, not that I could ever afford it!

Cheers!
Howie
 
#4,865
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#4,869
I used to have an across the street neighbor. When she got married her parents bought the couple the two story duplex. They lived on the second floor and rented out the first.
Her husband at that time drove a beat up pickup truck. The only truck in the neighborhood.

It was not uncommon in the nice evenings in the neighborhood for folks to sit on their porches, read or just nap.

After the twins were born, the police started making regular stops! After half a dozen such visits the pickup truck stopped being seen.

Shortly thereafter a folksinger replaced the pickup owner. This began their practice of sitting on the balcony porch and playing and singing. She was quite an acomplished musician.

For some reason I have never had a music reproduction system provide as much enjoyment.
 
#4,871
vacuphile said:
This is what I have never been able to figure out. Diana Krall's voice is heavily processed, as I noticed in all of her vocal excretions I have been confronted with.

Yet, many audiophiles use this super processed voice to determine how natural a stereo set up sounds.
Click to expand...


Reminds me of when SY posted up one of his recordings. One man and a guitar recorded with a single stereo mike. Someone said they couldn't comment on the quality as the production values were too poor 🙂
 
#4,872
hhoyt said:
Hi Terry,

That is a great demo video! I have used porous ceramic bearings in a few projects for both air-bearing and vacuum clamping and really appreciate their virtues as well.
This group is famous for thread drift, and when I composed the original post I was thinking about standard TT bearing geometries which are indeed ill-suited to air bearings. It would be pretty cool to see a super TT made with one of these other air bearings posted here, not that I could ever afford it!

Cheers!
Howie
Click to expand...

Howie,

Yes, amazing technology. These bearings are not Ceramic but porous Carbon.
Some info here:

Air Bearings | The Proof in Porous Media Technology

WRT thread drift, it often opens up the most interesting content, especially precision mechanically related stuff. My training and early career was
mechanical, being a Toolmaker by trade, progressing into Engineering, manufacturing, special purpose machine and product design etc etc.

WRT TT's, I've set up a few expensive TT's for friends & clients, that was enough for me. Vinyl can be a very deep rabbit hole. When I see these TT's
worth a few hundred thousand dollars, I can't help but think that the quality ceiling must be largely the original Neumann or Scully etc cutting lathe which
most certainly didn't have air bearings.

cheers

Terry
 
#4,873
simon7000 said:
I used to have an across the street neighbor. When she got married her parents bought the couple the two story duplex. They lived on the second floor and rented out the first.
Her husband at that time drove a beat up pickup truck. The only truck in the neighborhood.

It was not uncommon in the nice evenings in the neighborhood for folks to sit on their porches, read or just nap.

After the twins were born, the police started making regular stops! After half a dozen such visits the pickup truck stopped being seen.

Shortly thereafter a folksinger replaced the pickup owner. This began their practice of sitting on the balcony porch and playing and singing. She was quite an acomplished musician.

For some reason I have never had a music reproduction system provide as much enjoyment.
Click to expand...

Nice story, it reads like a well written novel.

Hans
 
#4,876
billshurv said:
Pandit Jasraj: A ‘huge pillar of Indian music has fallen’ - BBC News


Pandit Jasraj may not be a well known name to all here, but I think I can name a couple of people who will be aware of his work. He gets played most mornings in our house.
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Not familiar with him unfortunately. I’ve been watching quite a few very good Indian classical music videos on YouTube recently. I find it interesting that their tradition is built around improvisation, whereas in Western classical movement that is not the case - it’s an interpretation of the score with little latitude. My youngest was explaining the music structure to me while we watched one of the videos - fascinating and how the hell the musicians all come back in at exactly the right time after wondering off on their improv solos beats me. Fantastic stuff.
 
#4,879
john curl said:
I perceive that you guys are thinking of fixing problems that have been addressed over the last 40 years or more. What is important in phono reproduction is a turntable that effectively does its job, much like a car that will get you to work, the store, etc, and back.
Last night I listened to a Zoom conversation about audible turntable adjustment that would drive almost anyone here, crazy. It was a dozen careful adjustments too far. To appreciate a good vinyl recording mainly consists of a clean, not too worn, record, a decent phono cartridge, and turntable without too much rumble, or wow and flutter. To get the best performance, takes a lot more money, better cartridge, playback electronics, and turntable sensibly set up according to the rules, but it is not absolutely necessary to appreciate what a vinyl record can sometimes give, beyond a CD or equivalent playback.
The people that I was listening to last night went far beyond this to using special test equipment, test discs, hired expert, etc, etc. Even I don't bother to go to this level, and I doubt than many here will as well.
Click to expand...
The problem with the turntable is the correction. On the smudge, many companies applied their own correction in the process of cutting the master disc, not to mention the countries. In pre-amplifiers and correctors, only very few producers have the opportunity to choose the correct correction.
 
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