liquid suspension tonearm

[gain-wire]

Hello all!
From time to time I wonder about this: Has there ever benn a linear-tracking turntable that used a liquid as the medium to "slide" the tonearm across the record? If so who made it? Is there one on the market today? I have searched the internet a bit, including DIYAudio, and found nothing. Maybe I'm not searching enough?

-me like Vinyl-

I'll never tire of rooting for analog!

[owen]

The problem is maintaining a reference for the bearing that is sufficiently rigid. It could be done using magnetic repulsion on both sides of the 'carriage', but that doesnt stop rotation...

So there are technical problems, that could be technically fixed, but after the efforts to do so, the result is worth listening to is anybodies guess.


Owen

[tvi]

Yes

JP56080801
GB1025844 1966-04-14

Regards
James

[tvi]

Teragaki do make turntable and Tonearms, but I haven't seen one anything like the one in the patent.


Teragaki Labs

Regards
James

[gain-wire]

Hey you all, thank you for your help! But I would also like to know if anyone has actually put a product on the market that uses these ideas. All quite interesting (and old) ideas! I really don<t know why they haven't been implemented more.

[moray james]

BMW built an big engine that had no rings on the pistons. The tollerance between the piston wall and the cylinder wall was so close that a film of oil was enougn to seal the compression chamber and they were able to reduce the friction of the rings. I think that if this could be done then an arm could be built so the arm carrige could slide with very low friction however the tollerance would be very tight and so expensive to make. Regards Moray James.

[jeff spall]

"...the tolerance between the piston wall and the cylinder wall was so close..."

Hi, surely once you reduce the clearance so much that you are just running a liquid film don't you simply have a plain bearing and drag defined by hysterisis x surface area?

I do seem to recall both tonearms and other instruments running on mercury bearings, but I can't remember where.

Looking at the patent, which I think would have expired, I notice no-one's taken it up in 40 years, which is maybe a pointer to how practical it is.

I think the patent design is a real non-starter. Moving the float through a narrow trough is going to create quite a lot of hydraulic drag compared to an air-bearing solution and if you've read the discussions in the forum on magnetic control you'll realise how hard magnets are to implement. Those wierdo liquid contacts look like another bad idea. Also, the arm has no damping or positive stability. I have a suspicion that as soon as the arm plays a note whose frequency corresponds to a multiple of the dimensions of the trough, you'll get ripples in the liquid and the thing will oscillate between those magnets for ever.

Linear-tracking fans tend to forget that records aren't perfectly concentric and the patent design has massive inertia that the poor that little cartridge would have to overcome twice a revolution as it waggles in and out following an off-centre record.

Sorry to be so negative, but I think this is kinda like getting the car industry to change over to swash-plate engines.

regrads, Jeff

[gain-wire]

So wouldn't that make the REVOX style motor-driven linear arms the best type? It must be because as I understand it, such electronically-assisted arms guide the cartridge, leaving it no chance to oscillate on excentric records (as opposed to this free-running system which lets the cartridge do the "driving").

[moray james]

all have a window in which they controll the position of the cartridge. Too far ahead they slow down, too far behind they speed up. If you think about it they spend more time correcting the error than they actually do being spot on correct. I would go with a mechanical system rather than a servo controlled motor drive. Regards Moray James.

[jeff spall]

Hi, yes I feel that even though a linear arm might have very low friction, the inertial mass of the bearing tube/plate or whatever is being moved with no mechanical advantage, a huge drawback. The cartridge has to overcome the mass at a 1:1 ratio rather than the 10-20:1 it would normally get on pivots or unipivots. If an arm just mechanically tracks records, you could easily have a cartridge offset of 1mm or more.
regards, Jeff