My TT only has 1g tracking force. I also do not think this is an issue.
Go back to the title of the thread ultimate turntable design. It's unlikely any of these very small details will in isolation be audible, but the cumulative effect obviously is as is evident with TT's like the Caliburn and Helix, where attention to detail has been taken to extremes.
Precession however will cause flex in the bearing housing with a heavy platter. If I can flex the housing 10 microns with finger pressure how much will it flex under a 3kg rotating platter with a 160mm lever that will never be perfectly balanced and then the pivot point is 60-70mm below the COG of the rotating assembly.
Keep in mind groove modulation can be as small as 0.1micron so 10 microns flex is 100 times this micro detail.
The total indicated vertical runout in the SP10mk2 platter is 0.2-0.3mm at the outer edge, the platter on the surface plate is flat to less than 5 microns over it's outer surface.
Bearing clearance makes up 0.1mm as can be measured by lightly pushing on the outer edge of the platter, the indicator does not return to zero. Precession can also be estimated as a pulsing in the vertical indicator.
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When i see all these desastrous tolerances mentioned here i realize that hundreds of millions of cheap plastiky turntables couldn't replay one single tune without a DSP around, yet in my childhood i remember a dirt cheap turntable barely having 10 transistor count and plastic on metal loose sleeve bearings playing all these microwarps with grace and even giving out some music i could enjoy although at the time i had 3 times better hearing than now.It blooks like the Well tempered turntable teflon bearings can't play a single tune...Maybe i'm guilty for deviating the subject to vinyl cutters, i think that removing the tonearm from this discusion , although useful for simplification , also ignores some fundamental parameters of the discussions.There's an issue unresolved with how bikes can roll straight in line on pavement with so many loose factors around that may apply here when adding a loose tonearm to a loose platter because the platter spins at a speed that makes the cartridge stylus skate in the grooves as a train on rails and straighten the tonearm.If the stylus can affect platter speed , it can definitely affect tonearm position when the platter spins even though everything seem loose.
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I'm just not convinced that dragging a diamond down a plastic trough requires such ne plus ultra mechanical engineering.
All it really needs.
1. Geometric relational stability of motor bearing arm.
2. A quiet drive system who's action can't be heard through the stylus arm interface.
3. Speed stability better than a lathe.
4. Snr in the mid 70db
None of which requires sub micron tolerances. Just ask Bill Firebaugh
Perhaps before we go jumping off the deep end we should come up with a specification, rumble, snr, speed accuracy and precision that can be worked towards rather than wasting money of pointless design excess?
Unless of course this is just a thought exercise of excess?
All it really needs.
1. Geometric relational stability of motor bearing arm.
2. A quiet drive system who's action can't be heard through the stylus arm interface.
3. Speed stability better than a lathe.
4. Snr in the mid 70db
None of which requires sub micron tolerances. Just ask Bill Firebaugh
Perhaps before we go jumping off the deep end we should come up with a specification, rumble, snr, speed accuracy and precision that can be worked towards rather than wasting money of pointless design excess?
Unless of course this is just a thought exercise of excess?
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Beogram 2202 has 45 db snr unweighted and you still don't hear anything wrong with an almost weightless setup.With the best and most exotic ingredients you can still make some food that nobody will eat...while making extremely long poems on how gooooood your dish is..
LP playback benefits more from countermeasures against drift or modulation rather than absolute precision, IME.
We were Bill Firebaugh's Japanese distributor for over a decade, and made several special versions using WT parts or based on his ideas.
The bearings still benefitted from harder contact surfaces and less flexure in the spindle housing, the plinths still benefitted from higher mass and greater damping, the drive system still benefitted from smoother-turning motors, the tonearm still benefitted from a stiffer and deader armtube, the tonearm still benefitted from an additional filament to stop the paddle from gradually being dragged forward as the cartridge traversed the LP side, the silicon oil bath still benefitted from a stiffer and less resonant construction, the counterweight still benefitted from the addition of CLD, etc.
Just because the fundamental concepts of a design are brilliant, doesn't mean that it has managed to tie down all of the issues that can affect performance.
We were Bill Firebaugh's Japanese distributor for over a decade, and made several special versions using WT parts or based on his ideas.
The bearings still benefitted from harder contact surfaces and less flexure in the spindle housing, the plinths still benefitted from higher mass and greater damping, the drive system still benefitted from smoother-turning motors, the tonearm still benefitted from a stiffer and deader armtube, the tonearm still benefitted from an additional filament to stop the paddle from gradually being dragged forward as the cartridge traversed the LP side, the silicon oil bath still benefitted from a stiffer and less resonant construction, the counterweight still benefitted from the addition of CLD, etc.
Just because the fundamental concepts of a design are brilliant, doesn't mean that it has managed to tie down all of the issues that can affect performance.
Jonathan,
I'm interest in your thoughts on bearings. One of my SP10mk2 motors has a bad sleeve so I need to make a new one. I was planning on using Vesconite for the sleeve. What you said about harder contact surfaces was this referencing the sleeve or thrust pad?
cheers Warren
I'm interest in your thoughts on bearings. One of my SP10mk2 motors has a bad sleeve so I need to make a new one. I was planning on using Vesconite for the sleeve. What you said about harder contact surfaces was this referencing the sleeve or thrust pad?
cheers Warren
Hi Warren: Please keep in mind the unique nature of the 5-point Well-Tempered spindle bearing, which is open on one side and held against 4 contact points (arranged in a vertically-oriented rectangle) on the opposite side by pressure from the drive belt, and supported from the bottom with a 5th contact point (which corresponds most closely to the thrust plate of a conventional design), with the spindle and contact points encased within a silicone oil bath that provides lubrication.
The contact points changed in material and construction a few times over the years, at first they were rubber-tipped screws, then one-piece teflon screws, then a somewhat harder plastic (that was still compliant).
On the premise that the teflon contact points could compress under the varying pressure from the drive belt, which would allow the spindle position and angle to change slightly during playback, we chose the highest-rigidity graphite-and-teflon loaded silicone-compatible plastic that we could obtain, which at the time probably would have been PEEK. The bearing housing was machined out of (probably) standard, non-bearing-grade PEEK.
A key feature of the WT bearing is that the bottom contact point is offset from the spindle center. Therefore spindle pressure can never squeeze out all of the oil from the contact surfaces; the wiping action of the spindle continuously transports fresh oil to the contact surfaces. The wiping action of the spindle also keeps the side contacts lubricated at all times, but here the pressures are lower and less likely to squeeze the oil out.
Today, while bearing-grade Torlon or Vespel are options, bearing-grade PEEK continues to be a decent, and not too insanely priced thrust-plate material.
I'm aware of Vesconite but have not used it, sorry.
kind regards, jonathan
The contact points changed in material and construction a few times over the years, at first they were rubber-tipped screws, then one-piece teflon screws, then a somewhat harder plastic (that was still compliant).
On the premise that the teflon contact points could compress under the varying pressure from the drive belt, which would allow the spindle position and angle to change slightly during playback, we chose the highest-rigidity graphite-and-teflon loaded silicone-compatible plastic that we could obtain, which at the time probably would have been PEEK. The bearing housing was machined out of (probably) standard, non-bearing-grade PEEK.
A key feature of the WT bearing is that the bottom contact point is offset from the spindle center. Therefore spindle pressure can never squeeze out all of the oil from the contact surfaces; the wiping action of the spindle continuously transports fresh oil to the contact surfaces. The wiping action of the spindle also keeps the side contacts lubricated at all times, but here the pressures are lower and less likely to squeeze the oil out.
Today, while bearing-grade Torlon or Vespel are options, bearing-grade PEEK continues to be a decent, and not too insanely priced thrust-plate material.
I'm aware of Vesconite but have not used it, sorry.
kind regards, jonathan
I already mentioned the wing aerodanamics operating in one motor driving the spindle from one side like in a belt or idle drive , but i feel a drawing was necessary.
Although some might say it does not apply to audio turntables because of the slow speed of spindle spinning , it's not true because of the micron size clearance between the spindle and bearing .
The pictures are exagerated of course , but here's why one motor traction is actually making that system much more stable than a 3 motor system.I've put the link to Neumann Lyrec motor, but nobody said anything about the hidrokinetic transmission that also contributes to stabilizing the platter center spining, not just to lowering the noise coupling. In Neumann system is the bearing that rotates driven by the motor and the fluid between the bearing and the subplatter spindle( a bigger one, of course).
Just curious :when SP-02 motor came , was the hidrokinetic system discarded too?
Although some might say it does not apply to audio turntables because of the slow speed of spindle spinning , it's not true because of the micron size clearance between the spindle and bearing .
The pictures are exagerated of course , but here's why one motor traction is actually making that system much more stable than a 3 motor system.I've put the link to Neumann Lyrec motor, but nobody said anything about the hidrokinetic transmission that also contributes to stabilizing the platter center spining, not just to lowering the noise coupling. In Neumann system is the bearing that rotates driven by the motor and the fluid between the bearing and the subplatter spindle( a bigger one, of course).
Just curious :when SP-02 motor came , was the hidrokinetic system discarded too?
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Yea when the Lyrec is upgraded to a Sp-02 the oil cup arrangement is removed.
in a Lyrec install the motor goes in the bottom of the lathe cabinet and connects to the bottom of the oil coupler via a drive shaft with a couple of spring joints to take out any misalignment, speed stability is basically ensured by platter mass.
There are limit stops in the oil coupler and a pair of springs to centre the thing when running, but it can still move by a 1/4 turn or so before it hits the limit stops. The oil provides damping but is not (steady state) involved in the power transmission.
In an Sp-02 install the motor, drive shaft, oil coupler and all are removed and the lower platter directly connected to the motor (which mounts where the oil coupler used to be).
The VMS 80 (And 85, which was the DMM variant) used altogether more modern doings basically everywhere.
Do not take too much from the design of a good lathe over to a playback turntable, they are DIFFERENT machines built for different purposes.
in a Lyrec install the motor goes in the bottom of the lathe cabinet and connects to the bottom of the oil coupler via a drive shaft with a couple of spring joints to take out any misalignment, speed stability is basically ensured by platter mass.
There are limit stops in the oil coupler and a pair of springs to centre the thing when running, but it can still move by a 1/4 turn or so before it hits the limit stops. The oil provides damping but is not (steady state) involved in the power transmission.
In an Sp-02 install the motor, drive shaft, oil coupler and all are removed and the lower platter directly connected to the motor (which mounts where the oil coupler used to be).
The VMS 80 (And 85, which was the DMM variant) used altogether more modern doings basically everywhere.
Do not take too much from the design of a good lathe over to a playback turntable, they are DIFFERENT machines built for different purposes.
I don't actually...i advised on that too, but i'm really curious to see some pictures with the oil coupling system and platter bearings in older VMS sytems cause i couldn't find any.
Thanks Jonathon, I remember seeing the WT bearing and thinking what good design, I guess it just needed some engineering tweaking.
I bought some Vesconite to experiment with.
I love bill's stuff, they are masterpieces in low cost engineering reductionism. I'm not so sure they'll win awards for best possible measured performance though. At anything near the price though, they're unbeatable.
My absolute favorit is based on the Lenco L75 idler drive with proper bearing build in a low mass extreme stiff plinth and coupled to a very high mass slate base. We compared this to all giant turntables in a shootout.All high mass designs have timing problems in my opinion.
Good morning, great to see that response, might you post some details of the L75 project here please, or a link, i am just starting on that route, many thanks, Mike
The plinth is made of 4mm maple tonewood inside is a honeycombe structure made of 2 mm spruce tonewood. The cutouts for motor an bearing are supported by 10mm multiplex wood
Do you mind sharing which high mass designs you compared? The usual suspects like Transrotor are ridiculous of course, combining a homungous platter with a weak motor and coupling the two with a flexible belt.