Lewm: I agree with you that Win's Saskia is the closest approach to the ideal turntable. Resonant signature reduced to the max.Tight coupling bearing/tonearm. Deadened heavy platter. Slate plinth/tonearmboard. Idler drive. |
Ralph: brilliant description of the reduced resonance signature of the turntable parts. BRILLIANT.
My experiments with plinths and platters show that you are right on spot ! |
Thanks for the help, Mark. I actually found a plain old push-push switch that will likely do the job, but the relay is my next option. This is just to switch a Lenco motor on and off, so sophistication is not a priority. |
Lewm
The easiest solution I can see to your problem is to have the switch control a relay. If you have lowish DC voltages available (preferably either 5V or 12V) this is easy to do.
You'll need some logic to convert the momentary action to a latching action but it's not hard to do. Since I have B+ delay on all my valve gear I use mains switching by relay as a matter of course anyway and I like the safety aspects.
Mark Kelly
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Ralph, I agree completely with what you say re the effect of plinth-ing. I was surprised that the slate plinth had such a profound effect on the "sound" of my Denon DP80. I would have thought that a direct-drive system would be rather a closed one in which colorations introduced by the drive were directly "injected" (for want of a better term) into the audio signal via the coupling of motor to spindle. Thus, except for better controlling the inertia of the motor itself, I thought that the positive effect of the slate would be limited. I was quite wrong.
"bass will have more impact, overall greater dynamic impact (more lively, without added brightness), blacker backgrounds..." That's what I hear too. Win's turntable (the Saskia) must be quite awesome. |
Lew, 5/8" is a pretty big hole. The stomp switches are usually set up for 1/2".
We found that the plinth had a lot of effect too- again, it is a resonant signature, and one unique to each 'table. The more you can reduce this issue (along with tighter coupling between the platter bearing and the tonearm) the less signature the individual machine will display: bass will have more impact, overall greater dynamic impact (more lively, without added brightness), blacker backgrounds... again a lot of the same effects that deadening the platter has. |
Axel, You mean the "momentary" switch like the one I tried to use can also be used with a relay? That's an interesting point. There's no place to hide the relay in a solid slate plinth, but perhaps a small one mounted underneath would be unobtrusive enough to get by.
Ralph, those guitar switches are pretty big, are they not? Has to fit a 5/8'-diameter hole, but I will look at your referenced site.
Dave, I think I looked at the Allied catalog at about 2 AM last night. In my groggy state, I may have missed something. I did find a near-to-correct size switch made by APEM, sold by Digikey. I think I can fudge it with some washers.
Sorry, this is so-o-o-o off-topic. But it is my very preliminary observation that a massive plinth (layered wood or slate) makes good direct-drive and idler-drive turntables sound not only better but more alike than different from each other. I am pursuing this comparison further. It keeps me off the street, most of the time. |
Lew, I would look into the switches used on guitar stomp pedals, see: http://tubesandmore.com/
click on 'Switches & Footswitchboxes', then P-H493 |
Lewm,
I know it's more PT to wire it up, but most of these switches work with a relay. Press once it comes in (switches on), press again it trips (switches off) :-)
Have fun, |
Lew, See Allied Electronics p1069-1099 for many types with illustrations. |
Lewm,
How entertaining... a turntable with a deadman switch...
:^) |
Thanks, guys, for putting me on the right track as to the theory of the Verdier and the harsh reality of pushbutton switches. Sadly, I now see that pushbutton switches of the "push-on/push-off" variety are rare indeed, and I need to find one to fit the 5/8" hole that I already drilled to accommodate it. As Win and I discussed, the switch I did buy will work fine, IF I want to stand by the turntable with my finger on it whilst I listen to music. It does, however, fit the hole I drilled. Live and learn. |
Mark,
I believe Lew figured out (on). Now, he has the only Lenco that truly works only on demand. ;)
Thanks for saying what I meant regarding hydrodynamic drag. What I was eluding to is the constant war of trendy vs. innovative. It is easy to write copy that promotes a design, but it isn't so easy to create a design that stands on its own. That is what audiophiles should really look for in products, but it is hard sometimes when ad copy clouds the issue.
Win
Saskia Turntables |
Lewm
Win correctly described the influence of the Verdier's deliberate use of a trapped layer of lubricant to contribute hydrodynamic drag which lowers the Q of the platter / belt system.
That he did not use exactly those terms is neither here nor there - I have chosen my words to highlight the difference between two types of resistance which are usually lumped together as "friction".
Mark Kelly
BTW (on) usually means momentary.
|
As one who has just wasted the better part of a beautiful hot Sunday afternoon trying to assemble my Lenco in its slate plinth, only to fatally smudge the professional paint job on the PTP3 (it will need to be redone) and find that I had ordered the wrong very fancy push-button switch, I am in no position to take issue with anyone else's feaux pas. Who knew that "off-(on)" in the Mouser catalogue is not the same as "off-on"? I now know. This is not really OT because I am talking about assembling an idler drive tt. |
Lew,
Maybe I spoke out of school because I believe I am the one who may have confused the issue. Unlike either Clearaudio or Verdier, my turntable uses an eddy current motor. At least, I believe neither of them uses one. Anyway, I also am a believer in the use of hydrodynamic drag, as Mark calls it, so any reference to friction drag was maybe the source of confusion.
Win
Saskia Turntables |
Mark, Thank you for putting us back on the right track, as you always do. I had read somewhere else that the Verdier develops an eddy current effect by virtue of its apposed magnets, so I assumed that the same might be true of the Clearaudio. Are your remarks re the effect of bearing friction in agreement with Win's description of the virtues of the Verdier? |
Lewm
what Quiddity is relating, as I seem to understand it, is that eddy current 'friction' is very much on the minimal side with the magnetic repulsion, almost levitation, ring magnet concepts. Also recall those magnets are only about 1/4" wide rings. To support this, it is told, that if these platter are (disconnected from the drive) pushed by hand seem to run 'forever' and thereby VERY MUCH differently behaving the 'Platine Verdier' mentioned by example.
Now go figure yet some more ... :-)
Axel
PS: a difference in VFT of .75g, now I'm running at 0.75g with an Empire S1000ZE/X (0.25g! - 1.25g spec) as compared to 1.5g spec. for a 'M20FL super' give the my controller a lot more 'pain in the a...' - it take just longer to settle. This is for me a clear indication about what friction (needle and/or bearing) does in terms of motor/controller loop-feedback/response... |
Lewm
There is effectively no damping effect available from the two opposed magnets. Eddy currents are proportional to field strength times relative velocity divided by electrical resistivity. The configuration used results in low relative velocity. The electrical conductivity of available magnetic materials is quite high - NdFeB magnets have about 100 times the resistivity of copper.
For all: A distinction needs to be made between velocity dependent drag, which will tend to stabilise the system against speed variation and classical friction (velocity independent) which will not. Hydrodynamic drag and eddy current effects are in the former camp, standard bearing friction and stylus drag are in the latter.
Mark Kelly
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"This is in COMPETE contradiction to the 'Platine Verdier' tt which on purpose applies a constant bearing friction-load to stabilise their high-mass platter."
By my way of thinking, the Verdier approach is far more elegant. The bearing friction load, if that is what to call it, combined with compulsive obsessive tight tolerances can act in a way similar to a grease bearing by also creating a dynamic brake of sorts. The beauty here is that it doesn't have obstacles, like misaligned magnets to deal with, or any influences that might be caused by them. It's a case of less is more in that less complexity is involved to achieve a result that may in fact be superior. It also indicates to me that the manufacturer has taken more care in a traditional approach, if his result is an extremely good one.
A manufacturer can use tricks like magnets as a workaround for the unwillingness to spend extra for precision machining or better materials. I'm not saying that any particular company is doing that, but I do see the possibility.
Summary: I don't buy into magnetic levitation for platters.
Win
Saskia Turntables |
Axel, This is like the eddy current brake on a Garrard. Mark Kelly has written much on this subject. I now get what you and Nilthepill are talking about; the repelling magnets not only provide a force in the vertical plane but also they resist rotation in the horizontal plane due to the eddy current effect. Cool. I neglected that factor in my earlier post. |
Lewm,
that 'Clear Audio' magnet repulsion is comprised of two ring-magnets ~ 2 1/2" outer diameter and ~ 1/4" in of magnet width. They then replaced the centre bearing pin with a ceramic pin (as you noted, I think). All it now does is not sit on a tungsten ball down the bearing well, but ALMOST float - presto.
This system is pretty much the same thing also use with the 'Pro-Ject 10' and some others like Transrotor that sells it as an upgrade purchase for e.g. the Fat Bob and Z3 etc.
This is in COMPETE contradiction to the 'Platine Verdier' tt which on purpose applies a constant bearing friction-load to stabilise their high-mass platter.
From experience I can tell, that the SME motor/controller is loop-locked much quicker when a small degree of friction is present. In fact if the controller is still trying to lock (can see on the controller's light indicator) and you only put the stylus in the start groove - voila, it's locked!
The looser the bearing the longer it takes the controller to lock (SME main-bearings are conical and can be adjusted for more or less friction)
Go figure...
Axel |
Nilthepill, I guess I don't understand the concept of the CMB. I made certain assumptions that must be off base. I've actually never seen any Clearaudio turntable, except perhaps their low end ones, in the flesh. But then, I lead a sheltered life here in the Washington DC area, where the hi-end audio emporium is as rare as a dinosaur. |
Hiho
When I said "about the lowest creep of any system outside DD" I was thinking that the drive I designed for Thom Mackris was probably slightly lower. I was wrong.
I've run the numbers, assuming you are running a 1/2" x 3mil Mylar belt around two 300mm platters placed 400mm apart, and you win. We have slightly lower compliance (0.063 mm/N vs 0.117 mm/N) but you have a longer effective pulley length (236 mm vs 68 mm) so your creep is lower: 0.003 vs our 0.005, referred to a radius of 150mm.
As a reference, a typical belt drive system might have a creep number around 5 - 10 and a good idler system (like Win's) will have a number around 0.05, over 100 times better than the belt drive.
Mark Kelly
|
Lewm, I did not mean to imply DD to be better, but equal in sound Performance characteristics w/ CMB, the latter having less-er friction. To tell you the truth I have both mechanical and CMB version and prefer the original mechanical bearing the best. It is not, i think, the magnetic bearing feature (which is horizontal BTW, the ceramic being the main spindle) but the ceramic spindle that hurts the overall performance. They have not optimized the stiffness spindle, me thinks and hence less stiff than the mechanical bearing metal ( steel)spindle. |
Hiho
The creep is proportional to the strain in the belt divided by the parallel sum of the wrap lengths of the pulley and platter.
The compliance of the mylar belt is quite low, so there's not much strain present. The wrap length of your "pulley" is about 500mm rather than the 10 - 50 mm of conventional drives.
Your system will give about the lowest creep available (this side of direct drive of course).
Mark Kelly
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"If the belt were equally stretched on both sides there would be no tension difference and thus no torque transmitted."
Thanks for the explanation. On my system, the active pulley is the same size as the passive platter so I would have to assume there would no or little belt creep, right? I use two identical turntables to drive each other via a VHS tape. So far this is the best sound I got from a belt-drive system and the only thing that can match it is a quality direct-drive turntable with a coreless motor. Since I am lazy, I like the convenience of direct-drive table with some automatic features. :-)
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Hiho
Consider the speed of three things: firstly the belt on the drive side of the motor pulley, this being the section which is pulling on the platter; secondly the belt on the non-drive side of the pulley, this being the section where the belt is feeding off the pulley onto the platter; and thirdly the surface speed of the pulley itself.
Belt slip is where the speed of both parts of the belt is slower than the surface speed of the pulley.
Belt creep is where the belt speed on the non-drive side of the pulley is slower than the drive side, so the belt creeps over the pulley to make up the speed difference. This is because the belt is stretched by the torque it is transmitting and that amount of stretch must relax over the pulley. If the belt were equally stretched on both sides there would be no tension difference and thus no torque transmitted.
Mark Kelly
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Nilthepill, To answer your question with my opinion, no. I don't see how a magnetic bearing, which acts in the vertical plane only, can possibly have such a dramatic effect on the drive system, which is mostly operating in the horizontal plane. But your question assumes that low mass/direct drive is inherently superior to belt drive/high mass, which probably is not categorically true. Success of either design philosophy will have a lot to do with execution. I am thinking that, while I personally have begun to favor the low mass platter/direct- or idler- drive turntables based on my listening, this approach is the most difficult and potentially expensive to perfect. Whereas I think it is easier to get "decent" results with a high mass platter/weak motor/low compliance belt. Maybe that explains the predominance of the latter type of turntable in the "high end". I'd love to hear a Grand Prix Monaco myself. I wonder whether the carbon fiber adds a coloration, for one thing. |
"without a VERY good motor controller your wish is not going to be much of an improvement over a high mass platter - maybe quite the opposite!" - Axelwahl
I should be clear when I said "good motor" I also infer good motor and its associated controller as a system. Good motor system, that is.
My motor for tape driving is the Technics SP-10mk2 which I think is good enough for me.
|
Hiho,
y.s:
>> I rather have a better stronger motor to get the dynamic I want than to get it from a high mass platter <<
As you have noted I am with you actually. BUT without (and I said it much earlier) a VERY! good motor controller your wish is not going to be much of an improvement over a high mass platter - maybe quite the opposite!
The same applies to DD tables if not even more so.
Hard drive-line + so, so, controller = incoherent sound.
There are hardly any VERY good motor controllers commercially offered for all I know. So be careful what you wish for.
To my knowledge there is nowhere near close a solution, even with 'upper-class budget' , to replace soft belt and mass platter -- also supported by my mentioning these Audio magazines.
But if you are fine blowing ~ 25k plus, then you might even get a decent controller with a lighter = more dynamic! platter.
Therefore my point = simply - a Reality-Check!
Greetings, |
Does efficient bearings like Clearaudio Magnetic Bearing bring belt drive/high mass platter design CLOSER to low mass/direct drive design?? |
A belt creep is someone who has a size 54 waist, but still uses a size 34 belt, hung WAY low over the grossly protruding beer belly :-)
Belt slip is when he reaches for something over his head and his pants fall down :-)) |
.
Mark,
Sorry, I should have quoted you completely instead of edited. Can you elaborate on the difference between belt slip and belt creep? I know you posted extensively on a different forum. Care to briefly illuminate the less technical one here? Thanks.
. |
.
Axelwhal,
Just because many so called "high end" - a relative and useless term to me - turntable manufacturers use soft rubber belt does not make it right or enough to overwhelm alternatives. These days turntable manufacturing is a cottage industry, compromise has to be made for ease of production. By the way, what exactly is your question or point, as you seem to reinforce what I said in my last post? I personally do not subscribe to heavy heavy weight approach as it will reach a point of diminishing return. I rather have a better stronger motor to get the dynamic I want than to get it from a high mass platter. To me direct-drive is the most elegant approach or belt-drive with non-compliant material or idler-drive with a quieter motor. Basically, all three drive systems can sound good with different approaches to compensate their inherent problems. That's why is called engineering, isn't it?
The Monaco turntable is the most desirable turntable for me if I can afford it as it suits me from a technical and aesthetic standpoint. It's elegant. I haven't heard the sound but I have a feeling I will like it.
. |
Sorry that last part was measnt to be for Hiho not Axelwahl. |
Clarkie
You appear to be making two statements:
1: High mass platters improve the speed stability of belt drives
2. The transmission in an idler is stiff, so the motor is tightly coupled to the platter.
and following them with a conclusion:
3. Therefore "the two systems are completely different".
The two statements are reasonably uncontroversial, but I cannot see how they are supposed to lead to your conclusion.
The obvious implication from your statements is that belt drives are necessarily less tightly coupled than idlers and that the platter in a belt drive is somehow free to rotate in an uncontrolled manner. This is supported by a statement in your previous post where you said that a belt drive has "a motor that only really pushes when the platter slows".
This is completely wrong. If the two systems are designed to have the same drive compliance then they are by definition equally tightly coupled. There is nothing to prevent this being achieved in practice; that it has not been seen as a desireable goal by the designers is an historical artefact, not a matter of physical necessity.
Axelwahl
you have confused the terms slip and creep in my post. They are not the same thing.
Mark Kelly
|
Hiho,
well, well, well.
What you seem to overlook is the reality of it all. Just have a look at HOW MANY tt manufacturers use exactly that 'rubbished' approach and then ask yourself why.
I think a STABLE AC motor (not DC which is prone to drifting) is just cogging, some more, some less, even 3 phase, and so along comes the soft, long, or what ever, belt to 'fix' it. At the same time mass is added, has to be added to the platter, to counter act the soft belt drives lacking dynamic performance.
Practically ALL tt's that make the top grades (Hi-End rating > 100 points) in all known to me German Audio Magazines are designed that way.
Then a 'controller' may be added (in some cases more of the name then the real thing), at extra expense.
The question: how much does one actually hear the difference?
Point to add: it was one of these 're-worked' Garrarde's (by Loricaft) the wound up pretty much on top of the heap. It was superior DYNAMIC performance that did it to the testers... alas not the high price with some questionable suspension on squash-ball, and other sundry items.
Greetings, |
Mark: I am no expert but my experience is that the heavier the platter on the belt drive T/T the more likely we are to have less variations in speed. I owned a Michell Gyrodek for some years and always knew that its speed stability was marginal. It wasn't until I purcahsed my present Acoustic Signature Analogue One Mk 111 that I realized how bad the Gyro had been. I know that things are relative. I have to assume that both decks are well engineered within the requirements of each design. I am inclined to believe that the real reason that the AS is better is because the platter has higher mass. I am not aware of how heavy the platters are on idler T/T's but would make an educated guess that they are much less than the AS which I will use as my reference.
In the case of the idler T/T at no point is the platter allowed to rotate in a 'free' state. The idler drive is always in contact and driving, even if we admit that there IS some compliance in the rubber driving material.
I stand by my firtst statement that the two systems are completely different and both can work or fail. It's really only about engineering.
Clarkie |
"I understand the theory of it (belt creep) being used in an attempt to reduce cogging but I think it's the kind of half baked idea propounded by people who really don't understand the mechanics of TTs." - Mark Kelly
I cannot agree more. Well said!
Once again, if a turntable needs a soft rubber belt to reduce coggging or noise from the motor in order to sound competent. Get a different motor or change to a different drive system. It's just that simple to me. Some think platter or bearing is more important because motors don't get the blink blink like a thick shiny platter and they are always tuck away in the back or hidden and do not get the attention they deserve. |
Mark,
I have not mistaken you for someone else. I am aware of your issues with belt creep. In fact, because I was trying to dance the long way around a subject which I think may be of commercial importance to you, I ended up mis-communicating. Please ignore my comment.
Play on ladies and gents... |
T-Bone
Maybe you have me confused with someone else.
I have never advocated the use of any form of slip in a turntable transmission. I understand the theory of it being used in an attempt to reduce cogging but I think it's the kind of half baked idea propounded by people who really don't understand the mechanics of TTs. You will have noticed that there are a lot of them about.
I have pointed out many timnes that belt creep (and idler creep) is an inevitable consequence of using compliant coupling materials but that could not be construed as advocating its deliberate introduction.
Mark Kelly
|
Mark,
This aspect of inertia of the motor is something I did not really understand the last time it came up (because I assume you are not referring to motor inertia the way the Micro SZ-1 motor does it). If you were talking about that, then I can start to see where you see the similarities between an idler with a high inertia motor and a belt drive with high inertial motor where the belt slippage issue is addressed by bringing the slippage away from the belt-platter interface and to a kind of clutch mechanism which allowed the motor to more or less "apply" the belt to the platter with even force on both drive side and lee-side of the turn. |
Clarkie
I can't see where the distinction lies. In both cases you have a passive inertial element (the platter), an active source of energy (the motor, which also has inertia of its own) and a transmission (belt or idler) which links them.
The motor's function is to replace the energy lost from the system. The transmission's function is to adapt the speed of the motor to that of the platter.
Most of the distinctions made betwen belt and idler can be viewed in terms of how lossy the transmission is, it historically having been the case that belt TTs were made with a much lossier form than were idlers.
I think the inertia of the motor is also important but misunderstood.
Mark Kelly
|
I would just like to add my five-penneth.
Aren't the idler wheel and belt drive systems completely differing technologies/sciences? On the one hand (Belt) you have a large mass in rotation, a motor that only really pushes when the platter slows, and a flexible drive system (belt). One the other (idler) you have a clamp sytem where the idler wheel (inside rim) pushes the platter away from the centre bearing or (outside) pushes the platter towards the bearing. The platter is trapped between the bearing and the idler. (Depending where you are standing both idler types are the same.)
I don't see how a comparison can be made. They are just different and both work well or badly depending how well they are engineered and built.
:-) |
All, I just caught on to this thread and need to find the time to digest it in its entirety before replying, but one thing jumped out at me as I was scanning through it - Axle's comment (quoted below). I'm not singling you out Axel. It's just that your clear writing called my attention to it. Axelwahl wrote:
The platter material / mats / pads / and other damping are ALL colouration items (excluding some really heavy lead-loaded mats adding more mass) I contend (as Ralph does) that a compromise in dynamics is a coloration, and if dynamics are unconstrained, then you are more faithful to the music. As far as mats and other materials are concerned, I subscribe to the following position. A part of the job of the various components in an analog rig is to transmit (as opposed to reflect) vibration down the chain at EACH and EVERY materials interface. A mat is just one more part of a turntable - whether supplied by the manufacturer or purchased in the aftermarket. It either "works" or it doesn't. It adds another interface to the equation. Examples of interfaces are: - cartridge to tonearm - tonearm to base - record to platter - platter to bearing - bearing to base - base to stand and so forth ... until we work to the Earth's core, the sun burns out, and life as we know it ceases to exist (grin). Material selection is critical here, with one consideration being to match the relative speeds of sound of the interfacing material pairs. Think of how a flat stone can be thrown so that it either skips across a lake or alternatively passes immediately into the water. There's much more to this, but I don't have the time to explore it at the moment. I'm deep in the throes of supporting Mark's controller design, but I'll try to find the time to read this thread from start to finish. Cheers, Thom @ Galibier |
I don't know about the benefits of achieving maximum "deadness". I've run some informal experiments using different damping materials on my TT's plinth. I definitely found thet there is a point where there is too much deadening which sucks the life out of the music. Yes, you have to address gross vibrations and such, that's not what I'm talking about. AFTER you have got is pretty right this is the fine tuning. Just don't over do it.
Bob |
Hiho, for the record, the Empire does not go off speed if properly serviced, and can be expected, once serviced, to run for years without further attention. I have seen the motor angle being so poorly set that the belt engages the wrong part of the motor spindle, and I have seen motor spindles so dirty that the diameter was increased. The actual spec of the stock machine is impressive- well within the specs set by the best of the DD machines.
Lew, I don't know all of what Warren put in his mat, but I understand it contains an aluminum disk, and there is a thin Sorbathane layer where the mat meets the platter, so the material is not amorphous.
Although it is by far the best mat that I have heard, it is obvious that it could be a lot better- otherwise damping the platter would not have the rather obvious improvement that it does! OTOH it might be that the best we can hope for is a platter pad that can do what I said- have the hardness of vinyl so maximum vibration transfer without reflection is achieved, and otherwise maximum deadness. |
Axelwahl
I don't have enough information to make an informed judgement about the SME's controller implementation.
Mark Kelly
|
Mark,
since you ARE in the know about PL(L), servo loops, 3 phase conversion, quartz reference, current supply ability, and on.
Have you any comment on the SME controller implementation, from what I posted earlier or any of your own more detailed insights?
Axel |
