Off the top of my head, I can't se the difference between th common or traditional center spindle, or a secondary platter driven by some off center points....
Maglev or air bearing will take the load off a pivot point, but will a secondary platter isolated with e.g sorbothane introduce new problems? Some centering of the two will still have to be maintained.....
Maglev or air bearing will take the load off a pivot point, but will a secondary platter isolated with e.g sorbothane introduce new problems? Some centering of the two will still have to be maintained.....
You're missing the point. Nothing against thick platter but all they did was extending the bearing shaft and still have the same piece for spindle when they could just mount or bolt the spindle separately to the platter top and naturally decouples from the bearing noise. In fact a tall platter makes separating spindle from bearing shaft easier!
There's no need for a "secondary platter", just doesn't need the bearing shaft to protrude up so long to be a spindle. Have the spindle as a separate piece sitting on top of the platter. It can even be a piece of plastic. Think of the platter is completely flat with no spindle, and add a mat with a spindle above it. And the mat is the "secondary platter." There are turntables with platters made of multiple layers of material but that damn spindle is still attached to the bearing shaft as one single piece of metal! The point is that if possible why not make the bearing shaft separate from the spindle.
That's what I was eluding to when I said a thicker platter gives you more options.
jeff
The best way to decouple a record would be a screw down insert in the platter ( for centering and air seal) and a vacuum suck down of the record so when you unsnscrew the centering device all you have is the record touching the surface material of choice and platter under vacuum.
I would have to agree that the common shaft with all its transmitting potential is a drawback despite all the other advances around it.
An air platter that have a self centering design would fit the bill
Don't know if Tech Das 1 and 2 TT,s do this.
I,ll ask as our Newport show is coming this week end.
They were there last year and expect them here again.
Regards
David
I would have to agree that the common shaft with all its transmitting potential is a drawback despite all the other advances around it.
An air platter that have a self centering design would fit the bill
Don't know if Tech Das 1 and 2 TT,s do this.
I,ll ask as our Newport show is coming this week end.
They were there last year and expect them here again.
Regards
David
Not sure but may be if one makes a high quality bearing it would generate less noise and if heavy platter is used it would significantly dissipate the noise with added advantage of perfectly center platter. For example EMT uses heavy platter with strongly coupled spindle in the platter itself. So I guess isolated spindle and platter would be just another design approach if we think of the whole turntable as a whole system.
Your claim may well be true, but I'd like to see some testing done to give some indication one way or the other. It seems even in cases where the bearing and spindle are separate, they are both firmly attached to the platter, and any noise will be transmitted anyway.
My belief is that noise reduction is a very probable result out of this separation.
The general consensus is that inverted bearings are inherently more noisy because they place a noise generator near the record...so it's easy to assume that by doing one more stage of separation will be beneficial.
Having two separate platter layers with a middle layer of absorbing material (i have tested sorbothane with superb results) and centering the top platter not by the spindle but with three securing bolts placed equidistantly away from the center, creates a longer path for vibrations that is also heavily damped by sorbothane.
My next platter will be like this.
The general consensus is that inverted bearings are inherently more noisy because they place a noise generator near the record...so it's easy to assume that by doing one more stage of separation will be beneficial.
Having two separate platter layers with a middle layer of absorbing material (i have tested sorbothane with superb results) and centering the top platter not by the spindle but with three securing bolts placed equidistantly away from the center, creates a longer path for vibrations that is also heavily damped by sorbothane.
My next platter will be like this.
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I would like to see some testing too. I started the post with a question of "why bearing and spindle are machined as one piece?" so I would like to get some answers too.
I understand in some budget tables, the obvious reason is cost. But in the case of high end audio, I see way too many expensive turntables that just add mass to the platter without exploring more design options and still claim to be perfectionist. I suspect with the right amount of decoupling, noise can be reduced. Consider most records are not perfectly centered that the tolerance of the eccentric punched hole would be higher than the tolerance of spindle to bearing alignment if they are machined separately. So the machining shouldn't be that technically difficult.
My hunch is that the single-piece method became a convention by most turntable designers because it is just how it's been done for so long that they never bother with alternatives. And judging by the confusion over my initial question only reenforced my hunch.
You're correct that more testing would be welcome in order to draw a better informed conclusion.
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I agree. This table's innards is an example. As you can see the spindle cap is the thrust plate itself and it's only about one CM below the record surface.
Subplatter attached to spindle cap with three screws.
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Inverted male bearing shaft.
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Spindle and thrust plate as one piece.
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Another aspect that is massively over looked is the damping of the metal supporting stucture of the shaft .
I would like to see someone doing something about it.
At least some tight pressing o-rings around it or sinking it in a tube made of a different metal with damping or not...
And there is really no need for the thrust plate to be absolutely firm pressed against a metal back.
One could easily apply some form of micro-vibration damping by placing a sheet of absorbing material behind it.
I would like to see someone doing something about it.
At least some tight pressing o-rings around it or sinking it in a tube made of a different metal with damping or not...
And there is really no need for the thrust plate to be absolutely firm pressed against a metal back.
One could easily apply some form of micro-vibration damping by placing a sheet of absorbing material behind it.
All,
the concern is structurally justified: the bearing shaft will transmit trust bearing noise to the spindle and into the record, due to the high speed of sound and low damping in the metal. But significance of the effect can be another matter; it depends very much on how quiet the trust bearing is.
I have described my non-inverted bearing earlier in this thread; it uses a centered 3.5mm ruby ball resting on a piece of virginal PTFE. Despite the small contact face, i could not measure the bearing's spectral noise pattern or noise level because it is too far under the noise floor created by the record playback.
So ... for me ... significance is zero.
Nevertheless, on a future TT design, I definitely would keep the platter spindle independent from the bearing shaft to simply eliminate a possible structural flaw. But i would do it for yet another two reasons :
1.) i want to be able to make up my mind later how the platter spindle is shaped (threaded, smooth, barbed, acting as a 7.2mm reamer etc.) to suit eventual other needs or providing interface for different record clamps;
2.) experience tells me that the record clamp interface (an M4 tapped hole in my case) is prone to wear and has to be replaceable.
Hi Bernard.
I agree, the present generated noise floor is important ...
FYI.
My plan (schets) about my home made "air bearing TT".
Central spindel, fix (3 screws M2,5) in the first PTFE, three points centered in the second PTFE screws M4 (c.f.r Well Tempered T) ...
In fine:
Center ... "near" absolute center.
Noise floor .... "near" zero .
Easy maintenance ....
Air bearing TT ...... It's music, I like it ....
Caeles
All,
the Caeles TT got praise for its sonics by Thomas Schick. I know Thomas, he loves idler wheel drives and sells a very high-tech idler wheel drive TT himself. And he does not like high-mass belt-driven TTs at all. Because of sonics.
So when he gives such an oil-drilling platform a thumbs-up
, that means quite something.
I had a lengthy talk with Stefan Goetze, the mind behind the Caeles. What he does is making sense and i have tried out his decoupling techniques in my TT and under my speakers as well. It works. Stefan Goetze just took it to another level.
Stefan uses an air bearing for the platter, BTW.
All,
the Caeles TT got praise for its sonics by Thomas Schick. I know Thomas, he loves idler wheel drives and sells a very high-tech idler wheel drive TT himself. And he does not like high-mass belt-driven TTs at all. Because of sonics.
So when he gives such an oil-drilling platform a thumbs-up
, that means quite something.I had a lengthy talk with Stefan Goetze, the mind behind the Caeles. What he does is making sense and i have tried out his decoupling techniques in my TT and under my speakers as well. It works. Stefan Goetze just took it to another level.
Stefan uses an air bearing for the platter, BTW.
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