Trust me, I'm no expert. I was hoping to isolate the platter from noise/vibrations coming through the floor and I also figure that the floating platter would have the double benefit of a quiet bearing (by not having a conventional one) and very low friction allowing for leas stress on the motor. I figured this would permit things like higher mass on the platter. Plus as an engineering challenge its hard to resist.
Sent from my TARDIS at the restaurant at the end of the universe while eating Phil.
A floating platter would couple at specific frequencies just like any other coupled system, it's effectively just another frequency dependant spring.
A pressurized bearing might be a simpler engineering challenge with similar potential results and a lot less headache.
But have at it, I'm more than keen to see what you can come up with.
A pressurized bearing might be a simpler engineering challenge with similar potential results and a lot less headache.
But have at it, I'm more than keen to see what you can come up with.
FYI.
Some data from my air bearing TT16" about "Friction" & "higher mass":
1) friction: Free run from 33,3 rpm to 0 rpm: total time 11minutes 45 seconds
2) mass: Dynamic mass: 12kg
One musical note: flore noise (TT) ... near "zero".
Karel
and what about the noise generated by your cartride?
I guess that a lot of folks forget about a lot of things.
I guess that a lot of folks forget about a lot of things.
Wow! Very cool.
Sent from my TARDIS at the restaurant at the end of the universe while eating Phil.
Hi,
That plus the fact that laws of physics seem to be rewritten every other day.
Cheers,
That plus the fact that laws of physics seem to be rewritten every other day.
Cheers,
HI guys, my 2¢ worth
So we have to look at a couple of things before we all go crazy (again for me ).
What are the effects of coupling vs. isolation and why bother?
Isolation is just that. A means of isolating a system (or portion thereof) from the rest of the environment. Thus minimizing the effect of external disturbances. How is this accomplished? Usually through the use of "lossy" materials or suspensions. Think of a semi tractor/trailer (preferably loaded) rolling down your street while you play a record. An isolating device would minimize the effects of the low frequency (and quite large amplitude) of the seismic event on the stylus and arm (and of course the relationship between them and the vinyl being played). So ideally nothing is added to the sound .
Coupling is maximizing the contact pressures so that a group of components act as a single system, requiring more energy to perturb it. It also increases rigidity. So lets say that we want to couple a cartridge to a tonearm? How best could this be done? The use of good mounting screws/bolts/nuts that allow us to maximally tighten them This can be assisted by using hard points on the headshell to stand the cartridge off of the headshell.
Here the question seems to be one where the reasons of possible mag-lev use on a platter would occur and to what end? Personally I believe that this is the wrong question to ask if concerned about isolation. If the platter is isolated but the cartridge and arm are not, there will be some errors of addition occurring. To my way of thinking this is not desirable.
If the idea of a mag-lev bearing is to help reduce noise, the assumption is that reducing the thrust on a bearing will reduce noise. I suggest to you all to look at a typical or traditional bearing and see where that leaves you. Anybody want to guess? The lateral friction of the spindle and bearing walls are dominant and the resulting redux in vertical loading of the bearing will be minimal. so a very minor redux in friction may occur. In the case where an undersized spindle is kept centred in a tubular well and being kept away from the walls of the bearing housing, while having no reduction in vertical thrust, then the potential exists for greatly reduced bearing noise.
Or do as Roksan has done with the Xerxes turntable and use a long thin spindle with a very good bearing well. Bearing friction is reduced (for obvious reasons), while still being able to maintain control over the platter.
If mag-lev is to be used as a means of isolation, consider using it to act on the platter/bearing/sub-chassis/armboard/arm/cartridge system as a whole. Within that system couple the parts together as rigidly as possible. That's where the mileage using mag-lev in an audio system can be had.
At least to my way of thinking (and of curse I could be completely wrong, but tests using pneumatic isolation seems to suggest exactly the same thing.
So we have to look at a couple of things before we all go crazy (again for me
).What are the effects of coupling vs. isolation and why bother?
Isolation is just that. A means of isolating a system (or portion thereof) from the rest of the environment. Thus minimizing the effect of external disturbances. How is this accomplished? Usually through the use of "lossy" materials or suspensions. Think of a semi tractor/trailer (preferably loaded) rolling down your street while you play a record. An isolating device would minimize the effects of the low frequency (and quite large amplitude) of the seismic event on the stylus and arm (and of course the relationship between them and the vinyl being played). So ideally nothing is added to the sound .
Coupling is maximizing the contact pressures so that a group of components act as a single system, requiring more energy to perturb it. It also increases rigidity. So lets say that we want to couple a cartridge to a tonearm? How best could this be done? The use of good mounting screws/bolts/nuts that allow us to maximally tighten them This can be assisted by using hard points on the headshell to stand the cartridge off of the headshell.
Here the question seems to be one where the reasons of possible mag-lev use on a platter would occur and to what end? Personally I believe that this is the wrong question to ask if concerned about isolation. If the platter is isolated but the cartridge and arm are not, there will be some errors of addition occurring. To my way of thinking this is not desirable.
If the idea of a mag-lev bearing is to help reduce noise, the assumption is that reducing the thrust on a bearing will reduce noise. I suggest to you all to look at a typical or traditional bearing and see where that leaves you. Anybody want to guess? The lateral friction of the spindle and bearing walls are dominant and the resulting redux in vertical loading of the bearing will be minimal. so a very minor redux in friction may occur. In the case where an undersized spindle is kept centred in a tubular well and being kept away from the walls of the bearing housing, while having no reduction in vertical thrust, then the potential exists for greatly reduced bearing noise.
Or do as Roksan has done with the Xerxes turntable and use a long thin spindle with a very good bearing well. Bearing friction is reduced (for obvious reasons), while still being able to maintain control over the platter.
If mag-lev is to be used as a means of isolation, consider using it to act on the platter/bearing/sub-chassis/armboard/arm/cartridge system as a whole. Within that system couple the parts together as rigidly as possible. That's where the mileage using mag-lev in an audio system can be had.
At least to my way of thinking (and of curse I could be completely wrong, but tests using pneumatic isolation seems to suggest exactly the same thing.
What little noise there is (lets call it unwanted energy) from my cartridge travels up the arm into the silicon bath at the other end and some of it out down the arm mount into the turntable chassis.
Some of it is dissipated in the vinyl itself. Most of it in my case as I use a central record mat that lifts the record clear of the platter by 2mm or so, and in doing so removing those theoretical reflections one would get from the impedance mismatch of vibrations bouncing between stylus, record, platter and back.
Frankly I'm far more concerned about the noise from my fridge and the central heating boiler that I can feel through my floor getting to the cart than I am any uncollected energy from the transcription process adding back self noise.
Please explain what you think the cartridge noise is, what form it takes and where it comes from and how it might be 'directed' to ground via the magic of diodic isolation
I'm not trying to be a wise *** but can any of you guys actually "hear" problems with a properly designed spindle on a pad bearing design? When I rebuilt my old Pioneer PL41D TT, I spun the platter up without the belt on and it took a full 3 minutes for it to stop. No vibration, noise or anything. Just a well crafted design. I used a teflon pad in the bottom of the spindle well for a bearing and a good grade of light hydraulic oil. (Hydraulic oil is mostly refined oil unlike motor oils that contain a very high percentage of additives that have no use in a TT spindle).
Building something different and unique is fun but I really don't think your likely to see much in the way of performance gains for the effort involved.
BillWojo
Building something different and unique is fun but I really don't think your likely to see much in the way of performance gains for the effort involved.
BillWojo
That"s a fair observation and congrats on that turntable, its a nice one.
But you"re not giving enough weight to your own statement of building something different and unique. Its more than just fun. Its extremely gratifying and there IS a chance that it will sound much better than my current MMF-5. Slight though it may be.
DIY is like amateur astronomy. Every once in a while its the guy in his backyard that finds the new planet.
Sent from my TARDIS at the restaurant at the end of the universe while eating Phil.
I can't speak to any other deck but you can remove 3-4 db of noise from an lp12 by floating the main bearing magnetically to eliminate the point contact. A Teflon pad yielded only a modest 1.5db reduction by comparison.
So there's ground to be won.
Fdgrove, I'm not entirely sure what you mean with your 'writing on a pillow ' comment, could you elucidate?
So there's ground to be won.
Fdgrove, I'm not entirely sure what you mean with your 'writing on a pillow ' comment, could you elucidate?
Hi,
Quite simply that the stylus/groove interface is a mechanical one.
It therefore needs a form platform, not one that can move, flex or reinjects energy back inti the stylus in any way. Etc., etc.
Someone mentioned "mechanical diode" IIRC and that's what you want the system to do.
There are of course several ways to skin that proverbial cat.
Cheers,
Quite simply that the stylus/groove interface is a mechanical one.
It therefore needs a form platform, not one that can move, flex or reinjects energy back inti the stylus in any way. Etc., etc.
Someone mentioned "mechanical diode" IIRC and that's what you want the system to do.
There are of course several ways to skin that proverbial cat.
Cheers,
I agree with sq225917 about the "noise reduction" by floating the main disk support & without (eliminate) the (bottom) central point/bal contact.
It's my experience with my concept air bearing ... a significant (spectacular) noise reduction ...
It's music ....
Agreed, my friend Mark has his platter magnetically floated, it was a huge improvement. Similarly air bearing decks always sound sublime when well implemented, both use a compliant vertical support. As long as the vertical stiffness of the combination of platter and record surface as experienced by the stylus is sufficient to allows the stylus to accurately transcribe, without creating some feedback loop its all good.
I'd rather block any noise from reaching the stylus than stress about extrabeous noise generated by the stylus.
I'd rather block any noise from reaching the stylus than stress about extrabeous noise generated by the stylus.
Hi,
Just speaking in general. I haven't followed the thread in all its detail.
If I find the time I'll look into it further.
Cheers,
Just speaking in general. I haven't followed the thread in all its detail.
If I find the time I'll look into it further.
Cheers,
Hi,
Someone mentioned "mechanical diode" IIRC and that's what you want the system to do.
Cheers,
You need a better word, a "mechanical diode" is thermo-dynamically impossible.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.