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In Reply to: RE: New Idlers, But Only On The Cheap ... Our Designers Show Their Colors ... Again. /long posted by J.D. on August 14, 2007 at 13:23:01
I am familiar with the Lenco, Thorens and Garrard idler designs, not so much with the Russco and other idlers. I have seen pictures of the recent designs but have not heard them.
But, to go back to basics, let's consider WHY idlers designs were used in the first place. I think the reason is that, in the absence of electronic motor controls, they were designed to allow the possibility of changing platter speeds. The Thorens and Garrard allowed limited speed change by using magnetic braking, and the Lenco of course used a tapered spindle system for infinitely variable speed change. IIRC the first electronic speed change was the Thorens TD125 which used a DC motor and electronic speed control. Of course, direct drives also use electronic speed change.
However, back in the fifties and sixties, AC power basically meant one motor speed. Belt drive could do different platter speeds by manually or mechanically moving a belt from one pulley size to the next. Idler did it by mechanically moving a idler wheel from one pulley size to the next, or, on the Lenco, moving the wheel along a tapered spindle, with the pulley or spindle being directly attached to the motor. The idler itself provided a 1:1 drive, so there was no torque transformation.
The only other rationales I can see for having an intermediate idler are 1) possible noise isolation, although the "stiffer" the idler the less the noise isolation, and 2) to allow the idler to be disengaged from the platter when it was off to prevent flat spotting, which is a known problem with the Garrard 301/401, and to some extent with the plastic wheel Lenco - the metal wheel Lenco has a thin rubber coating and is reported to be largely immune to this problem.
Thus, if you can change speeds electronically, that removes one reason for needing an intermediate idler. If the motor is sufficiently quiet, that removes the second reason. If the pulley can be designed with sufficient friction to drive the platter directly, but stiff or resilient enough to prevent flat spotting that removes the third reason. Therefore, I see no obvious reason from a design standpoint why a rim drive with the motor driving the rim "directly" via a pulley/wheel would have to be a "cheapy" or "inferior" solution to using an intermediate idler. In fact, theoretically, either an idler or a belt introduces a potential source of "slop" in the system. The overall results would still depend on the implementation, as is usually the case.
Follow Ups:
The 301/401 and Thorens players were using motors that are called "shaded pole induction motors" These are not frequency dependent in the same was as a synchronous AC motor and will to some degree increase or decrease rpm based on the voltage amount supplied. Platter speed was controlled by stepped pulleys for different speeds, by voltage delivery and fine speed pitch by way of eddy brake. The eddy brake fine pitch control also compensated for wear over time to the idler wheel.
For Thorens it wasn't until the TD150 when they began using a 16 pole AC synchronous motor. This type of motor synchronizes itself with the frequency of the mains grid and is speed controlled in this manner. Therefore a TD150 or TD160 needs no other means to control platter speed other than to control the size of the pulley diameter for a given speed selection. Hence the stepped pulleys and belt derailleurs of the Td150 and TD16x models. The TD125 controlled platter speed via electronic feedback and used only one pulley diameter. Hence no belt derailleur on a TD125.
For those who have heard well setup idlers and "know" of the superior dynamic delivery of this breed of turntable, I would ask the following question: "How do you account for the inherent sonic character of such a machine if it isn't a product of its drive train mechanisms?"
-Steve
user510's system
All the legendary rim drive / Idler drives mentioned-- Emt, Garrard, Thorens, etc, have the intermediate wheel mechanism.And --even if you ignore the pitch control afforded by the eddy-current brake--- they all have a precise means, or several inter-acting means, of adjusting the coupling of same to the load.
To fastforward thru the thread, here's my understanding of why ::
Advantage of the motor-integral idler designs
*** Smoothing function of the Intermediate Wheel (idler) Mechanism on cogging, stylus drag
*** Ability to Mechanically ensure precise speed, (generally conceded to be more stable than, say, beldrive)--
*** Rendering a turntable that has speed integrity on it's own without the $K electronics box
*** No need to rely on precision or security of user placement, or physical drift in motor site & coupling characteristic
*** No expectation of Speed Deterioration due to wear on compliant drive surfaces. Metal-rubber-metal intermediate wheel contacts anticipate and obviate concerns
*** No independent, and possibly conflicting oscillation --uncontrolled micro-wobble-- afflicting the two (table, motor) independent structures, due to motor-integral design
But I haven't even mentioned the biggest one.
Controlled, adjustable, micro-tension-able COUPLING of the drive-capstan to the platter. Complete control.Leaving the tensioning of the drive-idler-platter interface to chance, good luck, or precise user understanding and setup, to me.... is a recipe for problems. Or at best, intermittent-ly correct performance, in the speed domain.
J.D.
Edit ...
I'll concede that a more perfected motor (perhaps the multiphase synchro) presents a challenge to my vive-le-precise-mechanics argument, but, even still. There are those who'd prefer a mechanical Patek-Phillipe wristwatch to event the most precise Seiko Digital you can buy...
But that's another thread, I think.
I was cured, alright.
JD, Interesting points.
*** Smoothing function of the Intermediate Wheel (idler) Mechanism on cogging, stylus drag
Yes, an intermediate wheel will increase the amount of isolation between the motor and platter. That is good if you have a motor the has a lot of cogging, as do most vintage designs. A belt drive provides a lot more isolation. Isolation also has a detrimental effect in that it delays delivery of torque limiting the motors ability to counter stylus drag. The Verus motor has several orders of magnitude less cogging than a typical idler motor so much, much less isolation is needed. In this case adding additional isolation via an intermediate wheel would almost certainly make things worse.
"*** Ability to Mechanically ensure precise speed, (generally conceded to be more stable than, say, beldrive)--"
With the Verus direct coupling there is only one friction surface rather than two, but otherwise the concept is the same. Is there any reason to think that adding an additional friction surface would deliver better speed accuracy? It seems logical that the reverse should be true.
"*** Rendering a turntable that has speed integrity on it's own without the $K electronics box"
Most idlers do not have a speed control box and that is certainly good from a cost perspective, but how is that a technical advantage? This has nothing to do with the superiority of idler drive. I have no doubt that a vintage idler would sound considerably better if the noisy AC motor were replaced with a low cogging DC motor or better yet, a multi phase sync motor... Hmm, that has me thinking...
"*** No need to rely on precision or security of user placement, or physical drift in motor site & coupling characteristic"
Well, this is only an advantage if precision placement is needed. The Verus motor does not require precision placement. You do have a point however about speed drift with wear. But as has been stated elsewhere the drift from wear is so small that it is really a non issue.
"*** No expectation of Speed Deterioration due to wear on compliant drive surfaces. Metal-rubber-metal intermediate wheel contacts anticipate and obviate concerns"
You lost me on this one. Wear and deterioration of the drive surfaces is an issue with any idler or rim drive implementation. If the rubber wheel hardens, gets flat spots or cracks it will always be a problem. I sure don't see how an idler wheel can fix this one.
"*** No independent, and possibly conflicting oscillation --uncontrolled micro-wobble-- afflicting the two (table, motor) independent structures, due to motor-integral design"
Another good point but this is a general issue that applies to any rim drive methodology. So are you trying to imply that a spring loaded idler wheel coupled to a spring mounted motor would be less prone to this type of problem?
"Controlled, adjustable, micro-tension-able COUPLING of the drive-capstan to the platter."
So how exactly does one control the coupling of the drive-capstan with an idler drive? Maybe it could be done by bending or stretching springs. With the Verus motor precise and repeatable control of the drive wheel pressure is obtained by placement of the rubber feet under the motor.
Don't get me wrong. It is not my intent to criticize vintage idler designs. But our goal was not to reinvent what has been done but rather to come up with something better.
In addition, your Verus motor has the advantage of simplicity & adaptability to a wide range of modern TTs that may surpass vintage idlers by virtue of modern platter bearings and superior resonance control associated with high-mass platters. Given the number of expensive models in current use, the compatibility of your motor with existing platforms is probably more of a contribution to the marketplace than would have been any "clean-sheet" design for a new TT.
If when used with a modern TT, your rim-drive approaches the speed-stability of a classic idler but is quieter due to the quieter motor in combination with a modern platter & platter bearing & plinth, then the Verus should help the average TT guy separate & understand the relative contributions of speed control and resonance control in his analog system. Unfortunately for some forum posters, a mixed bag of plinths, platters, and motors will make it more challenging to propagate sectarian views.
It's amusing that given the attention to detail that's necessary for vintage restoration & for any analog set-up, JD doesn't accept the small burden of siting a separate motor. With an unsuspended TT on a proper platform, there’s no reason why a rim drive motor should be unstable relative to the platter.
Here are some contrary thoughts."In addition, your Verus motor has the advantage of simplicity & adaptability to a wide range of modern TTs that may surpass vintage idlers by virtue of modern platter bearings and superior resonance control associated with high-mass platters. Given the number of expensive models in current use, the compatibility of your motor with existing platforms is probably more of a contribution to the marketplace than would have been any "clean-sheet" design for a new TT."
... bizarre argument. A retrofitted aftermarket Add-On is better than a 'clean-sheet' design ?
Kinda like the way you can change your pickup truck into a camper if you buy one of those camper-top add-ons ?
Consider that an existing Beltdrive table may not be the ultimate platform-- it isn't--- to reconstruct into a 'rimdrive' re-think product.If when used with a modern TT, your rim-drive approaches the speed-stability of a classic idler but is quieter due to the quieter motor in combination with a modern platter & platter bearing & plinth, then the Verus should help the average TT guy separate & understand the relative contributions of speed control and resonance control in his analog system.
If we may presume that by "modern" tables you mean something like the current Teres beltdrive, then you've got problems with this claim.
Two of them right off the top concern the High Mass Platter.
The sound and intact pacing of a classic idler has to do with a medium mass platter. Control and stability issues begin to get outsized as the platter gets outsized.
What was necessary to flywheel-stabilize a beltdrive design isn't necessary for the closely coupled idler style of design.
And those huge, dense, acrylic platters rob immediacy and punch from the sound, in my view.Unfortunately for some forum posters, a mixed bag of plinths, platters, and motors will make it more challenging to propagate sectarian views.
Not sure at all what this means. Maybe I'm just not one of these 'unfortunate' posters.
It's amusing that given the attention to detail that's necessary for vintage restoration & for any analog set-up, JD doesn't accept the small burden of siting a separate motor. With an unsuspended TT on a proper platform, there’s no reason why a rim drive motor should be unstable relative to the platter.
I know what you mean here. This isn't a pursuit for those who can't reliably manage to get both shoes tied each morning.
But it's worth doing to say to those who would call themselves designers ... 'hey, that's not really a Design. And more importantly, that's no Camper.
That's a pickup truck with a camper-top thing screwed into the cargo bed. And that sucks.'Your opinion may differ.
J.D.
.... I was cured, alright.
turntables-- particularly the better ones-- are not RVs, pickup trucks, or Carvel ice cream. If they were then every obese, pick-up driving burgher in America would still have a TT.
From what I've read, Teres has tested rim-drive with both heavy and light platters. Most listeners seem to prefer rim drive to belt drive irrespective of platter weight. However the greatest improvement over belt drive was with lighter platters. That the greatest improvement was with a lighter platter may mean (1) that as you say, there is inherent synergy between direct-coupled drive and a light platter, or (2) that with belt drive, a heavy Teres platter had already achieved close to optimal speed stability, or (3) that the superior resonance control of a heavy platter was "weighing in" as a variable in overall performance.
BTW, the composition of the platter (e.g. acrylic vs. wood vs. laminate) is a variable independent of platter mass and should be considered elsewhere.
But it's to be noted that incombination with platters of high & low mass, the sound of Teres's belt-driven tables was improved by switching to a direct-coupled motor.
Has anyone actually refitted a vintage Lenco or Garrard or any other idler with a heroically heavy platter in order to make a determination as to which is best? Perhaps the original choice of medium-weight platters reflected build-to-cost business models or merely prevailing design practices?
As has been remarked elsewhere, there are too many linked variables in the composition of a vintage TT to be certain how much of its performance is due exclusively to idler drive. Put another way, the noise associated with older motors & bearings & transmission systems in these vintage idlers, may add problems that do not afflict modern belt-driven TTs refitted to rim-drive.
Your bias toward "clean-sheet" designs flies in the face of the evolutionary nature of TT design. As HW has said, it's a mature business and designers can make a turntable sound pretty much anyway they want. Why not then the hobbiest himself? I have converted my VPI TNT to thread drive and a rigid suspension and noted changes that I prefer to the VPI "house" sound. I will have been well served if this TT can be further improved with Teres rim-drive while preserving my investment. I will also have fun determining whether or not the VPI TNT flywheel has synergy with a direct-coupled motor. Isn't tweaking of this sort much of what vinyl is all about?
THESE AREN'T TOO GOOD AS PICKUP TRUCKS, AND THEY DON'T MAKE GREAT CAMPERS, EITHER !! In order to avoid mincing detail ad infinitum, I'd say that, regarding your "belt-driven TTs refitted to rim-drive" (as you put it)..........
1... No, and no thanks, I'll stick with my assertions, and re "afterthought" retrofits of turntables designed with something else, something very different, in mind.
(dd motors leaning on beltdrive tables to produce a 'rimdrive' pastiche )2... It's really kind of touching (& scary)--- the brand loyalty thing that people have with their enablers.
(Probably me too. No exception.)
But to stick to the convoluted logic of the retro-future-aftermarket-product-introduction-product-reversal that this represents for both Teres and Vpi..... on the coat-tails of a perceived market trend... strikes me as really amazing.Teres & Vpi both have championed the excellence of Beltddrive, for way too many years, and relieved consumers everywhere of a sizeable chunk of their soundsystem finances ----
ON WHAT MR BRADY NOW CALLS THIRD BEST and, well, placing last in the race ?
Astounding that they'd like us to try on the next trend, a complete shift in intent, with such a casual shrug, doncha think ?Sorry, it is, in fact, a camper-add-on-for-pickup-truck. And the brand-loyalty is touching, all-too-human, and.... daft.
J.D.
.... I was cured, alright.
it is not physically or theoretically possible to improve on something that was expensive to begin with.
It is so obvious, don't know why it took me 3 days to figure out. But then again, I have never been the sharpest knife in the drawer.
WHEW! I can finally get some sleep...
Purposefully misconstruing my very clear argument does you no favors.
Actually makes it look like you don't get anything in the thread , to be honest.
Thanks, and-- we'll certainly all be looking for your future thoughts down the road.
I was cured, alright.
FOR COMPARISON, THE DRIVETRAIN OF THE EMT 930st Lotsa topics, but here :
""control of the drive wheel pressure is obtained by placement of the rubber feet under the motor."
.... is the dealbreaker.We could go thru my list again, and I could make comments on each aspect of your comments.
But what's definitely not going to happen at any point is that the Manufacturer here, that would be you---
...is going to say, 'wow, we really do have a lot more work to do on this idea and we'll just pull it while we change some things'.You don't care to offer the classic precision of a mechanical idler-drive.
Okay.You'd like your motor + electronics to take up the slack. Fine.
And, most important .... You'd like to offer your existing customer base a way to pretend they've got the trendy and au courant Idler/Rim sound.
By aftermarket-retrofitting a clumsy device that leans against the platter of the table they alread bought from you. So be it.Stick with it.
No matter what I may think, you're still light years ahead of HW's "idea". Light years.A motor from a Directdrive product that skips the precise coupling of an Idlerdrive, calls itself Rimdrive, and leans against the platter of an older Beltdrive product.
Underwhelming ...is only my opinion.
J.D.
.... I was cured, alright.
EMT sometimes considered the best idler drives on the planet, and yet even EMT put belt drive way third, idler second and after serious r&d direct drive at the top.
Teres have arrived at the same conclusion, and it should be interesting to watch the faithful convert belts to Verus over the next few months. Time will tell if the Verus rim-drive is good, bad or indifferent.
Others are working on ways to improve the performance of decks like the 301, using modern ideas and technology to create better motors, bearings etc, and the Verus will be another player in that mix. It won't work so well with the strobe platter though! :)
Verus may become the most important analog development for many years, cheap clones from China will be powering flea-market PL12Ds and allowing any vinyl fan to witness the sound that made records worth listening to in the first place.
The blue touch paper has been lit ................. :)
Or not, well in that case just leave the PL12D and take the Lenco. :)
"You don't care to offer the classic precision of a mechanical idler-drive."
So once more, what lack of precision are you referring to? We get it that you don't like the idea, but still don't see why.
Uhm, you're making it painful. See photo, previous post.
.... I was cured, alright.
Is that a technical term?It would appear that the manner in which the drive wheel pressure is applied to the rim of the plater may indeed be the weak link.
It is subject to quantum fluctuations in the force of gravity, while a simple spring, which forces the "Idler" against the motor capstan and the platter, is not subject to these small quantum fluctuations.
Clearly the a spring is superior. ;-)
Nobody here but us chickens.
Well, springs as components in a precise and minutely adjustable mechanical system that ensures just the right coupling ----
... as opposed to a gravity-assisted 'just-sit-it-down-where-you-can-see-it-rubbing-the-platter' situation .... ?
Well, yeah. Give me the Precise And Minutely Adjustable Mechanism.
Every time.
.... I was cured, alright.
Classic idler and Verus drive in theory both allow for as precise and minutely adjustable coupling as you would care to implement.
I do not know of any idler that however has capability for adjusting this parameter (other than blindly tweeking springs).
Repositioning of the rubber feet under the Verus motor allows for fine tuning of the drive pressure.
So in what way is there an idler advantage for this capability?
But once again we are beating a dead horse. I have spend a lot of time experimenting with drive wheel pressure. Easy to do with Verus by the way. Well guess what, the pressure really does not matter much at all.
BTW: placement of the motor is also quite unimportant. The motor just needs to be placed so that the housing is largely vertical. If the placement is off the motor will tilt slightly but the change in drive wheel pressure will extremely small which in turn is not at all critical.
JD, I can see that this offends your sensibilities, but I don't see that there is a technical issue.
Chris
Chris,This has got to be the last go-round on this.
The beauty of idler drive is that it gets you away from the hoplessly feeble "two islands" approach of separated engine and load...
that you have with the standard tiny-motor-and-rubber-band beltdrive situation.Various idler models I've mentioned do in fact have very precise mechanisms to adjust the coupling characteristic. Internal adjustments, not front-panel-dial kinda things.
This integral precision-mechanics approach, again, is the beauty of these models.
They represent the opposite side of the world from the Slush-Instead-Of-Pace effect you get with beltdrive.You may forgive me if I'm incredulous that
"Repositioning of the rubber feet under the Verus motor allows for fine tuning of the drive pressure." or
"If the placement is off the motor will tilt slightly ..."
represents anyone's idea of an improvement on simple rim drive.
Let alone an assault on the qualities of vintage idler-drive.
Especially, as mentioned, with the examples out there being so mechanically impressive (Emts, etc).
I am underwhelmed.And Harry's, (with the scout-ac-synch) --is laughable.
J.D.
.... I was cured, alright.
;0)!
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