Turntable speed accuracy

Hiho, FWIW, I use a 2nd generation PTP. As you know, it has provision for sliding the idler wheel without removing the platter; one is supposed to leave the two bolts under the platter slightly loose and tighten down only the one that is visible and accessible with the platter in place. That way, you can slide the idler by loosening only the one accessible bolt. However, I am not following that directive. I thought I was better off to get the speed as close to perfect as possible, with all bolts loose, and then to tighten down all 3 of them very firmly. From then on, I make fine adjustments to speed via the Walker Motor Controller. As you know also, the next mod was to remove the rubber bushing at the anchor point of the idler arm, so as to disallow even that small amount of play at its pivot. I have not done that, in the belief that there is some benefit to dissipating vibrational energy in the idler arm itself, by letting the arm "rattle" a little bit, so energy is not reflected back into the idler and thence into the platter. It's all a head game, because I have no data either way. I do like what I've got, however.

Dover, Cannot fairly answer any of those questions yet. I love them all in different ways, at this moment. With the Lenco, you want to root for it, because it is relatively inexpensive. If I thought I could live with only the Lenco, I could sell the others and put several thousand bucks in the bank (or elsewhere in my audio system). As Raul is fond of noting (and i agree), you cannot compare turntables when the tonearm(s) and cartridges are all different. But it would surprise me if the Lenco was the best of these three (or these four, if you include the DP80).

"A turntable needs the right speed, knowledge to make the area of the needle silent and a solution to remove the energy from the tracking." Amen. Very Zen.

What turntable?

I think you have it a bit backwards. Generally the motor chosen is related to the intended drive system. Plus there is a time-related effect. With regard to my first point, direct-drive motors pretty much must use some speed corrective mechanism, e.g., the well known quartz-linked servo. There are many ways of implementing this kind of circuit, and I am certainly no expert. The science of motors per se is amazingly arcane. However, just about all DD motors are either 3-phase AC synchronous types or DC types. Even within those two categories, there are many different ways to build each, which also will affect how the tt "sounds". Modern belt and direct drive turntables are still using the same technology, only with perhaps faster electronics. As regards my second point, 1960s and earlier turntables tended to use cruder single-phase or two-phase motors, e.g., Thorens, Garrard, and Lenco. But these were idler-drive and the motor is suited to that application. I just mean to say that you have broached a very complex subject and that in general it is not accurate to generalize on what type of motor per se is "best". You would not use a Pabst motor in a direct-drive turntable, for one example. There is more that I don't know about motors than what I do know. That much I am sure of. There are websites like this one where eggheads chat about motors 24/7, for example. Their jargon is at least as obscure as the one I work with all day long as a molecular biologist.

There are also crappy bearings in turntables both old and new.
As a lover of vintage turntables for perhaps irrational reasons, I want to agree with you, Thuchan, but a modern machinist would probably tell us that with the digitally controlled cutting equipment (CAD) and laser technologies available now, it is possible to create bearings that are at least the equal to anything ever made in the mid-20th century and for much less cost (because less human labor is needed). But whether this leads to BETTER bearings in modern top of the line turntables, I do not know. Anyway, we are talking about the creme de la creme of modern turntables, not those middle of the road products that "only" cost $5000. Your Continuum is said to have a spectacular bearing; have you examined it closely?

I owned a Sota Star Sapphire III with vacuum for many years. It was eclipsed handily by my Nottingham Hyperspace, which revealed to me that piano music does not have to have the wavering pitch that I always heard with the Sota. In fairness, the later Sota products are said to be much better in this regard. But then in turn the Notts was eclipsed by the Lenco and direct-drive, IMO and in my system. Actually the contrast between the SSS III and the Hyperspace may have been greater sound quality-wise than was the contrast between the Hyperspace and Lenco. I think the pitch instability of the SSS was caused by belt stretching as the platter bounced on the spring suspension whilst the motor stayed still because not suspended.

Lespier, Thanks for the information. When I wrote what I wrote, I was thinking of the seminal Papst motor, as used in the Empire tt's. I actually thought that the term "Papst" (Pabst?) refers to a particular motor configuration, patented or invented by someone named Papst, not to a company that makes a wide variety of different kinds of motor. But maybe you are inferring that the Papst type motor can indeed be adapted to direct-drive. Good idea with the Dual motor.

I found a website where the owner installed a Papst motor in his Thorens TD124 and compared its performance to that of the turntable with its original motor. He liked the musical "drive" with the Papst but preferred the Thorens motor for its lower noise floor. However, he did also comment that with a true 3-phase AC synchronous motor controller (so you can throw away the phase-splitting capacitor), the Papst would have been MUCH quieter and therefore might outperform the Thorens motor in all other respects. So, Ralph, have you ever used such a motor controller with your Atmasphere 208 turntable?

I hope this is only slightly OT. :<)

Dev, Just read what Dertonearm is asking that bearing to do. (Did you take note of the 110-lb platter?) Then imagine the special tooling and labor required to make the bearing in very small numbers. Then you will understand the cost. Based on typical ratio of parts cost to retail price in the audio business, DT's turntable will have to cost around $70K, just to justify his use of that bearing.

Hiho, I am actually glad I did not know all those details about Papst. I have enough useless information cluttering up my mind already. Sherlock Holmes told Watson that the reason he did not know about Copernicus (or some other well known related body of knowledge) was that he had otherwise to keep in mind the appearance of the ashes and the distinct odors associated with 170 different kinds of pipe tobacco, in order to do his sleuthing. I have never owned a tt with a Papst motor, and I don't aspire to, so no need for me to know anything more than what I have learned by casual reading.

I and several others have been waiting for nearly 2 years for Mark Kelly's motor controller for Garrard and Lenco. I am not holding my breath. This is not to say that Mark is not a completely honorable and brilliant guy; he just has a lot on his plate to distract him. It will be worth the wait, I am sure, once it is done.

Ralph, By all accounts, a really accurate subdivision of the phases plus really accurate control of voltage and frequency can render a major noise and vibration reduction in 3-phase AC synchronous motors, but my disclaimer is I don't know nuthin'. I am mostly quoting the teachings of Mark Kelly.

FWIW, the KAB device uses (1) a much larger than usual diameter of strobe disc, which should enhance its accuracy, and (2) a battery-powered strobe which cannot be affected by variations in AC line frequency.

Ack, I think your approach is a good one. Find independent ways to measure tt speed and compare them. But I think it is "dangerous" in the logic sense to assume that your particular alternative method is the gold standard. It's more data of a different sort, but we don't know whether it's superior to other methods. Timeline is $400, not $900, BTW. The price is high at $400 but would be truly ridiculous at $900.

Hiho, Super Bowl is over, stuffed myself on chili and beer and corn bread. The lowly Redskins (my local team) beat the new SB Champs twice this year. Strange, indeed.

If the laser light stays in exactly the same place on the wall as the platter rotates but the "line" created by the laser beam gets longer, then it is at least possible that the tt is momentarily gaining speed above 33 rpm (assuming the flash of the laser is of constant duration, which is a fair assumption). But the fact that the light does not move left or right indicates that "average" speed is maintained. This is one explanation that comes to my mind; I have no idea what you are thinking, Albert and Henry. I would be interested to know.

It seems to me if the tt slows down momentarily, the laser spot would shrink, not lengthen.

Albert, I take all your points in support of the NVS, but the bottom line is what do you think of it in action? Does it blow away your SP10 Mk3?

If it were not for the fact that my neighbor, for whom I have done a lot of audio favors, owns a Timeline, I never would have been able to test my turntables with it. No way I would pay $400 to buy one. I was quite satisfied with the KAB strobe. That's just an honest statement of my position, right or wrong. It was mostly a morbid curiosity that drew me to it, like a moth to a flame. Now I'm done with it, since I am unlikely to purchase another turntable in my lifetime. (Well, maybe one more that I have in the back of my mind.) It won't sit down on the Lenco spindle, which is one of the large diameter types. Any ideas how to use it on a Lenco? Interestingly, the owner of the Timeline is in no rush to have it back, so it's just sitting here.

I guess I could have rationalized buying one on the premise that it would pretty much hold its value when I would have been ready to dump it.

Dear Dover, I think it was posts like your last one that got the NVS thread deleted. You have a perfect right to express your opinion, but I think we need to temper our remarks about specific products and manufacturers lest someone pull the plug on this thread, too. I hate that this is the case, and, believe me, I am on the side of free speech.

Sorry, I meant to address my remark in my last post to "Dev", not "Dover".

Dear Albert,
I guess I misunderstood your riddle. I thought you wanted to have an explanation for a theoretical condition where the laser beam appears to lengthen whilst remaining fixed in its location on the wall. My explanation would fit that condition, I think.

I had the same result as you report with Timeline vs Mk3. (As you know, my Mk3 was purchased NOS and then completely serviced by Bill Thalmann.) Could not make it show any error whatsoever. I realized after I wrote the post that I may have put you on the spot in asking so directly for your opinion about Mk3 vs NVS, because of your potential commercial interests. I apologize for that. In any case, you were kind enough to respond.

Peter's post harkens me back to a question I asked JTinn on the other thread: How does the NVS maintain correct speed? What I mean is, does it use servo feedback mechanism or some other strategy? I never got a response to that question, and the information is not clearly given on the NVS website. No problem if JTinn wants to keep a trade secret. Same question goes for The Beat DD turntable; Steve Dobbins writes that he did not use a servo because of the "hunting" issue with servos. (This paradigm says that the platter is constantly being jerked around by the servo, at a micro level, because the servo constantly is reacting after the fact to minute variations in speed. Those who don't prefer DD turntables often allude to this phenomenon and say they can "hear" it happening.) I think The Beat uses some sort of viscous drag on the bearing and a 3-phase AC synchronous motor that works against the constant drag force to maintain speed without benefit of a servo. (But my Denon DP80 uses a 3-phase AC synchronous motor too yet takes feedback from the read-out of platter speed effected at the rim of the platter by a sensor and somehow incorporates a quartz-linked servo in the process.) The options are many and complex and somewhat interesting as they bear on what we ultimately hear. Bill Thalmann, a guy I respect who actually can figure out these circuits tells me the Denon one is quite advanced, even for today.

Dear Henry, I guess I have been too lazy to check the Kenwood L07D with Timeline so far. However, my neighbor's Timeline is still sitting around my listening room, and I will do it today, sans LP and sans stylus drag. If there is a consistent error up or down, that would not concern me, because speed is adjustable within the outboard PS. (The L07D does not provide user accessible fine tuning, as does the Technics Mk3 and the Denon DP80,) I had two L07D's until recently and was using one heavily whilst the other was being "refreshed" by Howard Stearn (the L07D guru who is also an orthopedic surgeon, not the shock jock on radio). Howard did a fabulous job on my first one, so I trust him to have done similar work on my second. (I bought the second so as to get the original Kenwood accessory record weight and platter ring that go with the L07D and because it was in mint condition.) Anyway, I sold the first one and have not yet got the arm mounted on the second one, because I want to re-wire it. This is why I am in between L07Ds. With the Lenco and the Mk3 in full service, I hardly feel the screaming need for a 3rd table. The L07D was far and away my favorite table before I had the Mk3 up and running.

Albert, EMI picked up by the cartridge from the L07D motor was rumored to be an issue. It seemed improbable to me, because the platter and mat constitute two solid slabs of stainless steel which ought to afford some decent shielding. Nevertheless, I made an LP-size shield out of "TI Shield" (Texas Instruments), the best shield around for a combo of EMI and RFI, and I inserted it over the spindle and in between the platter and platter mat. This actually did result in a noticeable but small increase in transparency even though I heard no "noise" per se prior to installing it. The Mk3 ought not to have any issues in this area, because its thick brass and SS platter is an even better natural shield than is that of the L07D.

Hiho, Well said. The L07D is among those that use the servo feedback sparingly or gently, whichever term fits best. But since I cannot understand any of the feedback circuits without a tutor, it is hearsay evidence coming from me. I am reporting what is implied in the owners manual for lay persons to read.

Halcro, I tried to test the L07D with the Timeline today. It's the first time I had this unit up and running. But sadly the test could not be done, because the Timeline will not fit over the L07D spindle. Apparently, L07D has a "fat" spindle like my Lenco. The L07D ran spot on with the KAB strobe, however and for whatever that is worth. Sutherland should make some sort of adapter to accommodate each of the 3 possible spindle diameters. it would not be difficult.

Guys, Yes, I thought of offsetting the Timeline so it rests essentially above the spindle or so that the spindle can enter it just enough to center it. However, my fear then is that if the Timeline is even very slightly off center, it will make the TT appear to be off speed. This is because the Timeline seems SOOO sensitive to slight speed variations. It seems to me that it would not be difficult to provide 3 different adapters with the Timeline so as to fit each of the 3 possible standard spindle diameters snugly. Errors due to off-center positioning of the Timeline could be quite misleading. (Or maybe not; I have to think about that.)

Hiho, I think the L07D servo was designed to be "underdamped" as well. Whoever the guy was who modified his own Technics, he either has developed a good understanding of how its servo works or... not. The very idea of playing around with the servo is a whole new can of worms.

While I agree with Albert on the importance of the mass and the material composition of the plinth as a determinant of dd performance, you should know that there is a whole "school" of thought on the other side of the question, that holds that "no plinth" sounds best. Those guys place the naked DD chassis on nothing but a set of isolating feet, like for example the old AT feet. Then they mount the tonearm on an outboard pod. To me, this is a violation of many different "rules". But I think it may indicate that a bad plinth can be worse than no plinth at all.

Dear Lespier, Good point. adding mass to the platter definitely has an effect on the servo, but I have to think whether that would reduce the damping effect or enhance it, i.e. under- vs overdamped. If I start with the idea of no platter, the servo mechanism is rapidly hunting for correct speed, so maybe that is the condition of underdamped. Ergo, adding mass to the platter, e.g., via a heavy platter mat as is done by many, would tend to overdamp the servo response, I think.

The L07D has a secondary switch on the PS chassis that one engages only when using the accessory peripheral ring weight. This switch alters the servo response so as to account for the added weight. I checked my L07D using the KAB strobe both with and without the ring. The speed was accurate both ways.

Hiho, The point is that if you don't know enough about the circuit to fiddle with the servo at the level of its electronics (which includes me), you can at least affect damping by changing the rotating mass of the platter, which is a parameter built into the servo system. Easiest way to do that is to alter the mass of the platter mat. Adding mass does not "overwhelm" the servo; it adds damping to the system as a whole, if you take the "no platter" condition as "undamped". I think in engineering terms this is the correct way to think of it, but I am more than willing to be corrected by an engineer.

But I agree with the sense of what you wrote, mostly. The L07D and perhaps the aforementioned TT101 may be examples of servos that don't attempt to control speed as tightly as does, for example, the Technics system. The engineers that worked for Denon, Kenwood, Victor, Technics, Pioneer, etc, each had a go at deciding upon the optimum way to achieve the same goal, and they came up with different answers.

Dear Dover, You wrote, "Correct me if I'm wrong, but isn't the need for servos because DC motors inherently do not respond in of themselves to changes in loads." OK. You are wrong. First you are wrong because your statement carries the assumption that all DD motors are DC motors. I am not sure you meant to say that or perhaps you meant to type "DD" and out came "DC". In fact, a major fraction of DD motors are 3-phase AC synchronous types. DC motors are also used in some pretty fancy and expensive belt-drive turntables. Second, you have failed to define what you mean by "load"; I assume you refer to variations in forces due to stylus drag, etc, that occur during the course of playing an LP. Third, you are wrong because your statement carries also an assumption that all DD turntables use servo feedback. Some of the new ones don't, e.g., The Beat. In any case, I think that the adoption of servo mechanisms has to do with the fact that a DD turntable motor has to turn constantly at the relatively slow speed of 33 rpm, and using servo feedback is one way to reach that goal. As we have been saying, there are many many different ways to apply servo feedback. Belt-drive motors run much faster and for some the belt itself is used to smooth over small changes in speed. Also, it's cheaper not to use any feedback. But major point is that in principle DD motors qua motors (thank you, Nandric) are no more and no less inherently speed constant than are belt-drive motors. I do not think it is possible to argue from generalities that one way is better than another.

Hiho, Lets keep in mind that what you quote from the Brinkmann website is a commercial, full of blather with a sprinkling of fact. Like many politicians, they set up a "straw man" controversy in order to show how their product "solves" the problem that may or may not be a problem in reality.

What I especially found questionable was the part about 32-pole motors causing increased cogging. More poles should mean less cogging, if done right. Anyway, I am sure the Bardo is a nice product in spite of their blarney. The design brief resembles that of the L07D in many ways, including the copying of the Dual coreless motor with the odd raster. What's a "raster"?

Dover, I think my response to you was too harsh. I apologize. Denon DP80 uses a 3-phase AC synchronous motor and also uses a quartz-referenced servo. Speed is monitored via a tapehead that "reads" the inner rim of the platter as it rotates. Knowing this, I was a bit confused when I read about The Beat turntable, which also uses a 3-phase AC synchronous motor that is claimed to self-correct by virtue of being so. (I think with The Beat there is a small amount of constant drag on the bearing, and the motor works against that.) Suffice to say that we need a motor expert here to straighten this out. I do think that the motor technology has not changed at all since the late 70s and that the designers of the tables you list used motors that they felt were best suited to the task. There are many high-dollar belt-drive turntables that use DC motors and no servo, as you know.

Travis has a DP100. But where is Travis (aka T_bone)?

I sent him a private email about 10 days ago but have had no response. He recently moved from Tokyo to Hong Kong, but he was communicating with me even during the packing and moving phase. He should be stabilized by now in HK.

It may be overly simplistic to think of a particular servo mechanism as "tight-fisted" vs "gentle". From speaking to Bill Thalmann, I gather that these circuits are quite complex, and the real differences in how the different ones operate may be accordingly complex as well. One is nevertheless free to choose a favorite based on listening.

Albert, Will talk to Bill this week on that subject, I hope.

I guess there is not much juice left in this topic. Here's a tidbit. I noticed someone on Vinyl Asylum out up a URL for a new line of turntables, made by a company called "George Warren". It's really one belt-drive model that comes in several finishes. They use a Maxon motor, which is a high quality DC motor. Platter speed is monitored much like what Denon and Sony did 30 years ago, by a sensor at the platter. Then corrective information is fed back to the motor via the controller. No mention of quartz referencing, but the concept fits in with what we have been talking about, DD technology used to stabilize speed of a BD turntable. Like someone else pointed out, using a DC motor, which needs it.

No argument here. It does use fishing line for a drive belt, which would have little elasticity, at least.

"2 mm on the wall" is meaningless, unless you tell us the distance from spindle to wall surface, but in any case it sounds like the effect of stylus drag is very tiny, probably not audible and probably not worth worrying about. Unless I misremember some of the earlier posts, it sounds like the Final Audio, as you have equipped it, is among the best of the belt-drives in terms of resisting stylus drag.

Dear Dover, I don't. But I am surprised you were even able to perceive (visually) a 2-mm displacement, although I guess over time you could measure a larger distance and then extrapolate backwards to determine 2mm per revolution.

Dear Peter, I hate to be a pain in the arse, but you wrote, "I found that the Fieldpiece readings were not repeatable and by just moving the device closer to or further away from the platter, the reading changed, though I know the platter speed remained constant." How in fact do you know the platter speed remained constant? I think you are going to say that you know it by virtue of the KAB strobe, but I have been told ad nauseam by others who use both that the Timeline is more sensitive to very small aberrations (like the ones you report) than is the KAB. (I must admit that when I compared a borrowed Timeline to the KAB in my home, using four turntables, I got the same impression.) This says nothing up or down about the Fieldpiece, however. Does the Fieldpiece strobe plug into the wall socket? If so, there could be its Achilles heel. There is a slight variation in AC line frequency, which is why KAB use a battery-powered strobe.

I guess in the best of all possible worlds, your turntable's speed irregularity would combine with your LPs off-center spindle hole to give you perfect pitch.

Thanks, Peter, for your further description.

Banpuku, Have you looked at the TT Weights rim drive or the Trans-fi Salvation rim drive? Each has its strong advocates. Both seem to ascribe to the heavy platter/rim drive paradigm. I have not heard either, but I note that both seem to use a rather small diameter wheel to drive the huge platter(s). On the other hand, the VPI and Teres rim drive(s) use a rather larger diameter drive wheel. Where do you come down on this design choice? No doubt you've given that a lot of thought. Just off the top of my head, I would have thought that the larger the circumference of the drive wheel, the better, right up to where the diameter of the drive wheel would equal that of the platter.

Dear Skos, You are preaching to the converted. I am a confirmed DD junkie. I still do like my highly modified Lenco, however. I was unable to test it with the Timeline, because the spindle hole in the Timeline is too small to admit the spindle of a Lenco (or of my Kenwood L07D). This to me is a major oversight in the design of the Timeline, as I think it would have been easy to supply alternative spindle hole pieces for it, especially at the price. (I could imagine a removable rim-threaded bottom puck; three such pucks could accommodate all typical spindle diameters, with a snug fit.)

I think I remember your earlier posts on the TT Weights. It appears that their drive wheel and the rim of the platter have been re-engineered in their latest models or their revised older models. Perhaps those issues were resolved.

God never meant for audiophiles to have a warm and fuzzy moment. If an audiophile is not worried at any given moment, he is compelled to search for something to worry about. Enter, the Timeline.