At the risk of disagreeing with those who know more,
- agree with the late legend Tom Fletcher, who thought that powerful motors generated powerful vibration hence audible distortion;
- agree with the air bearing crowd who think that all conventional bearings cause vibration in the platter, which is audible;
- agree with the massive platter crowd who think that moment of inertia is the best defence against vibration whatever the source.
My own DIY all-air bearing TT is capable of demonstrating that inaudible noise emanating from the plastic sleeve bearings of its precision 2W motor, has audible effects on the music. Those effects are similar in character to digital, although obviously much reduced. I note that during the launch of the SP-10R, I was allowed to inspect their motor - and I could HEAR bearing noise when turning the spindle by hand. Obviously that matters.
My DIY TT mounts a modified Trans-Fi linear tracker and a higher end Koetsu. Air bearing is the larger New Way thrust bushing running at 63psi. |
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@tzh21y
"Wow, you have sensitive ears. LOL"
The motor was naked for display purposes, and I held it next to my ear. The 2W precision motor was silent in the same test. |
@chakster
"Motor vibration or bearing noise ... it is all myth and fear coming from belt drive users."
No, it is demonstrable.
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Air bearing stabilizes the platter in 3 dimensions - there is no intrinsic bearing noise.
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@chakster
To demonstrate bearing noise, I listen to a revealing passage as per normal. Then I turn off the power. No change (other than the obvious slowing of the platter).
Then I remove the drive belt. Change for the better - trace of high frequency tizz disappears. That change is a fraction of the difference between good SACD and vinyl.
Equipment: DIY air bearing table with 45kg platter, linear tracker, Koetsu. |
New Way air bearings have amorphous carbon faces, resulting in literally millions of ’apertures’. I saw a U-Tube presentation of a shaft rotating in an air bearing (maybe New Way), spinning freely, when the high pressure air supply to the spindle was cut. The shaft came to an abrupt stop with a bang - it was immovable. Now that’s low tolerance! |
@atmasphere
Thanks for your thoughts, Ralph. About air bearings, I think that a very heavy platter on an amorphous carbon thrust bushing is virtually immovable - at least, mine is. You need a lot of force to raise it - and more to lower it - 87N per micron, plus the inertia. Compare that to a fragile cantilever. For radial stiffness, see above. The New Way figure is 34N/u.
What you get is a noiseless bearing, and you really can hear bearing noise. I've compared a first class turntable oil bearing with New Way air in a test rig, and it really is no contest. I've demonstrated sleeve bearing noise from a Premotec 1.8W motor through a belt - subtle, but it's there.
Could you please define 'isomeric isolation/mounting'? Is this a journal bearing in an elastic mount? Thanks! |
@chakster , have you considered graphite? The good people at the Graphite Store were very helpful. I use 1", which they thought was a bit over the top. |
@chakster , graphitestore.com helped me with expert advice and a good product at a very fair price. I was told that they have provided platter mats before, but never as thick as an inch.
My big iron platter rings at 500Hz, the graphite top rings at 2000Kz, and the combination is dead as a tomb.
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@tomwh , Suspended the pieces with string or rope and tapped with a small piece of softwood. It was easier to match the frequency to piano keys than to set up a microphone, Revox, and frequency counter; and my spectrum analyzer is old and too heavy to move around, and not necessary for this. On the piano, the fundamentals were one and three octaves above middle C.
When the two were stacked on the spindle, the combination was dead, dead, dead. So when I play music, no colouration of any kind. |
@lewm
That's right. So did their other top tables. It actually looks like a composite of some description, but performs very much like the graphite slab on my DIY. |
Perhaps you should try a heavy platter NA. I have one, and it does not suffer from the ills which you list. |
Alexberger" "After Lenco I use EMT 948.
It is a number of levels over Lenco and Nottingham Specced."
You surprise me, Alex. A legendary TT, costing 10x as much (used), beats entry level from Nottingham. Who would have thought it possible? |
@atmasphere
With Mijo, I wonder about that too. If you were running a really low output MC like some of the AudioNotes, you would think that the electro-magnetic noise from the motor might have an effect. It is not clear just how that noise would manifest, and if it were a subtle veiling of the music, one might ascribe it to something else, or even not hear it consciously at all.
That would depend on distance and magnetic isolation, I suppose - and on the plinth and platter material; so I suppose that aluminum (paramagnetic), or even better, copper (diamagnetic), might be a solution. Might that be why a copper mat works well on some turntables?
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It seems that 10x was an exaggeration. I stand corrected. |
@thuchan , the need for an all air design became obvious when I attended a manufacturer’s rollout for the big new Technics. They had a naked motor available for admiration, and so I picked it up, put it next to my ear, and I could hear the sleeve bearings when I twisted the spindle. Not loud, obviously, but the noise was there if you listened carefully. My New Way amorphous carbon thrust bushing is dead silent! |
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Larry, that's part number C303202 .
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@larryi , I installed that New Way thrust bushing on a platter board which is isolated from the motor. Technology is belt drive - as others have noted, anyone can build a belt drive in his workshop. |
Alas, I could not find a low power, ultra-low-noise motor with air bearings, and I have not got around to replacing the sleeve bearings with air. It’s pretty fiddly!
But those sleeves are a problem. This is demonstrable by removing the belt and manually bringing the platter to speed. The latter sounds more refined, less high frequency hash. When the belt is restored, hash returns. When the motor is turned on, nothing changes. Hence it is the motor’s sleeve bearings to blame, not cogging or other electro-mechanical effects.
This is a little surprising, given the platter's mass, about 45 kg. |
What New Way calls a thrust bushing provides an air cushion in 3 dimensions, i.e. the thrust bushing provides levitation as well.
I use an Italian compressor from Silentaire, oil technology, and heroic filtration. I'm thinking of upgrading to Juno, but so many calls on less money these days. |
@atmasphere
Once the motor is prepped for operation it might not do that. I pulled the motor out of my Technics as I am taking it to a machinist so I can run a longer spindle. Its really quiet!
That had not occurred to me. Thank you! Good to hear, so to speak.
But I can't hear the sleeve bearings on my little Premotec either - not until it is connected to the platter by a belt, and then only through the playback amplification. So I think that sleeve bearings are a problem anywhere in the chain, and the closer to the platter the worse it is. What do you think? |
@mijostyn , comparing my big Nottingham Analogue Mentor with improved plinth, motor, and motor controller (all to Dais standard), to my DIY air bearing, is indeed no contest. The air bearing is dramatically better. Same model tonearm (TransFi Terminator), same identical cartridge (Koetsu). |
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