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Turntable speed accuracy
There is another thread (about the NVS table) which has a subordinate discussion about turntable speed accuracy and different methods of checking. Some suggest using the Timeline laser, others use a strobe disk.
I assume everyone agrees that speed accuracy is of utmost importance. What is the best way to verify results? What is the most speed-accurate drive method? And is speed accuracy really the most important consideration for proper turntable design or are there some compromises with certain drive types that make others still viable?
I assume everyone agrees that speed accuracy is of utmost importance. What is the best way to verify results? What is the most speed-accurate drive method? And is speed accuracy really the most important consideration for proper turntable design or are there some compromises with certain drive types that make others still viable?
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Very well put, Learsfool. The importance of coherent rhythm can't be stressed enough. On a related note (and the subject of another thread), it is ironic that in spite of it's technically "superior" speed stability, digital recording technology can suffer from rhythmic blandness. It is not only rhythmic accuracy from one point in time to another that matters, but what happens in between; the motion moving away from one point in time and leading up to another. That is what gives music it's thrust and swagger. |
this is almost humorous, you folks are arguing about problems the older among us had to deal with in Dual and Phillips TT's of the 70's and 80's. If speed of a TT is constantly off the musical pitches will be off. Since all speeds are off proportionately, harmonic structure will still be intact. If its badly off the spoken/sung word will sound distorted because we are sensitive to the cadence of speech. Trying to play an instrument along with this becomes silly because you have to mistune your instrument. If the speed is variably off that becomes wow/flutter... thats musically unacceptable. What makes the finest turn tables is damping/filtering vibration at the micro level to prevent vibration reaching the arm and platter that would superimpose on the stylus tracked vibration, distorting the electrical signal created in the cartridge and played back as sound in your system. As an example put a vibrator on your cheek and try to sing... thats what a badly isolated TT does even with perfect speed. You can consider direct drive the equivalent of attaching a vibrator directly to the platter... Denon tried to sell a lot of these. Next best is belt drive... the motor still vibrates but the belt provides isolation in power transfer. But a platter mounted on same sub chassis as motor still sees vibration transfer through the chassis. Rega follows this model. Optimal is belt drive, suspension TT where platter and arm are on an independent subchassis... both are isolated. Linn Sondek,the AR and Sota follow this model And there are the exotic designs ( I believe I once saw something that floated the platter suspension in the equivalent of jello) |
Davide256: "What makes the finest turn tables is damping/filtering vibration at the micro level to prevent vibration reaching the arm and platter..."Isn't this "vibration at the micro level" a form of movement and doesn't movement consist of timing? So a turntable that takes care of damping/filtering vibration automatically make it the finest disregarding strict attention to speed issues? Now I know where those toy motors are coming from... Davide256: "You can consider direct drive the equivalent of attaching a vibrator directly to the platter... Next best is belt drive... the motor still vibrates but the belt provides isolation in power transfer."You're repeating the flawed notion that Lewm already objected to in one of the above posts. I just cannot fathom someone discussing about "the finest turntables" without thinking about speed accuracy or the importance of speed accuracy as if that's a dated issue. I don't know what else to say. It reminds me of a Chinese saying about a cowhide lantern...... _______ |
Davide256, With all due respect, you are wrong. Linn is OK right after the suspension is tuned and for the next week thereafter. AR and SOTA, up to and perhaps not including their very latest TOTL models, are seriously flawed as regards speed stability. My SOTA Star Sapphire III was a distortion generator on piano music. Have you ever heard a real piano? Do you really like stretch-y belts and belt creep that much? And AR? A classic, yes. A bargain in its day, yes. But an example of how to build a speed-stable tt? Puh-leeeeeze. Also and parenthetically, you don't understand the mechanism of a direct-drive turntable. I think I mentioned this to you somewhere above this last post. Do some reading on this subject. The issue in direct-drive is not noise but designing a motor that is free of cogging at slow speed. (The DD motor has to turn at 33 rpm, whereas belt drive and idler drive motors turn much faster. This tends to make them noisier than DD, not quieter, but a little easier to mask the cogging effect.} But the syntax of your post actually suggests you like direct-drive better than belt drive. (You start with your criticism of direct drive and then begin your discussion of belt drive with the phrase "next best", implying dd is better, which it actually is when done right, IMO.) |
Davide256: "the belt provides isolation in power transfer. But a platter mounted on same sub chassis as motor still sees vibration transfer through the chassis. Rega follows this model." The Sota Cosmos (couple models higher than your Sapphire, which I owned and used before) does the same thing and you know why? Because Sota wants to solve the speed issue from previous models! As mentioned by Michael Fremer in Stereophile, on many suspended turntables the motors are "hard-mounted to their bases; when the subchassis was horizontally deflected, the platter-to-motor pulley distance would vary, causing speed irregularities." I no longer own the old Sota Sapphire for a reason. _______ |
Dear Unoear, (why not Duoear ?) you are fully correct. It is not a big problem finding me if you are not restricted to the US as some people seem to be, like Audiofeil for instance. Nevertheless this guy knows all kind of ice cream tastes and National League players (of the US of course) - hmmm maybe interesting. But back to the topic. Has anyone really opened the Timeline and do you know what this means? Did you count the screws Halcro? Unoear is a nice acronym. Is Duoear still available :-) best @ fun only |
Dear Hiho, I am trying to understand your post on SOTA. Do you mean to say that the Cosmos is subject to M Fremer's critique (motor mounted to base/platter on spring suspension, which is also my criticism), or not? Most users seem to like the Cosmos and the Millennium, so I was not sure whether the current owners of SOTA had cured that problem (by re-design) or not. Surely it was a major issue with the Star Sapphire and that design flaw goes all the way back to the AR. (I have owned both for years at a time.) We forgave the AR for it, because the tt was so cheap and otherwise a good performer. I don't know how the Linn Sondek LP12 is built (never owned one), but the same issue is posed for any belt-drive/spring suspension. |
That is one thing about the original Empire table that they got right- the platter and the motor mounts are not floating with respect to each other. Wow and flutter on even the first models had excellent specs. The motor on those machines are also quite powerful and have a lot of torque. A powerful drive is really helpful to speed stability and is why the best vintage machines are still respected today. |
Hi Unoear - so the Sirius is yours :^) I have never seen one let alone heard one. If I owned one I would never sell it - even if it meant my two 17 years olds had to pay for their own university. FWIW - My earlier comment came from reading past posts here by members who have heard it and actually complained about some part of its sonics. Sounds unbelievable to me. I can only assume the setup (most likely the arm?) must not have been optimal. Cheers |
Dear all, I'm sorry I've stop watching the forum for a few days and so, I've admit I've felt somewhat pitty for no one of you could not indentify all of my bitter posts regarding the TT which been pictured by Hiho at 11-14-11. It is my (28000 EURO) Symphonic Line RG6 and I have it from 1996. I'm trying to sell it locally for about a year with no luck here in Greece. I don't know how to post a picture with my Pluto on it (please Chris if you have the kindness do it for me). It is not possible to convert it for other than the euro std of 230V/50Hz and it is a great challenge for me to pack it safetly so, no interest to sell it other than local pick up. I'm not satisfied by this TT and I've allready replaced it by Thorens TD124 II/Saec WE308SX. I would not comment furthermore about it as I've allready said more than enough. You can search my posts in Agon. |
Dear Nicola, this is the very first product by Rolf Gemein long before the appearing of Symphonic Line amplifiers. I know that Brinkmann was one of his employees. The RG6 was reviewed by TAS back at 1991 and praised as the best TT in the world. After living with it from '96 till today, I can say that it is not to my liking. |
Dear Geoch A pleasure to do so. Again thank you so much for the recommendation on the Lenco 75. :^) Please let me know if I ever have the permission to post a pic for the inspiration behind my symposium experiment. I will call it INSPIRATION. The people here at Agon would love to see it. Nikola I am sorry for making you look at this tonearm. I understand you are not allowed to buy it based on your principals. I respect u for that. Geochs TT |
OK guys, now what about those overpriced dinosaurs full of glamour & macho BS ? As you see their imposing sight can bring many faulse hopes and great expectations. For me this particular is a cheater but for some others may be the end and all of an analog source. Is it only about the money maker mind behind them ? I asure you NO! Mr Gemein is the kindest of souls among us. So, it is my estimation that we audiophiles, we just don't accept the same values or priorities in music reproduction. I regret that I had to pay such a high price and lost 15 years only to find my own priorities. |
"After living with it from '96 till today, I can say that it is not to my liking." Dear Geoch, After reading the line I have pasted above this one, I would have to say that 15 years of suffering gives you the right to criticize. Now you can get rid of the damn thing. You've given it a fair chance to impress you. |
I would be glad to trade it for a Goldfinger, a SAEC WE800SX, a Centroid or even good DAC. Especially if for the SAEC WE800SX, I would be happy to also give my own WE308SX with the RG6. I don't expect for anyone to reply in this forum, (it is not possible for me to accept the challenge of safetly packing it) but I want to give you an idea of my desparation as I even can't stand to see this TT anymore in my house. I'm sure that someone could bring up the apparent modifications (in motor, PSU, symmetrical flywheel & thread) and perhaps makes it sing to his satisfaction. Others are allready love it's way of performing, but for me it was a very bitter & dissapointing experience and I have to stop here. Impress me yes. This of course is the danger of hearing it without understanding what is going on. The huge wall of sound of it's personality is endlessly throwing dust to your eyes so you can't clearly recognize it's faults. |
Hi Geoch, May I suggest the German sites : www.ebay.de and www.audio-markt.de. Your TT and the tonearm are familiar in Germany and the Germans are the only reach people in Europe at present. You should sell both apart and , considering the postage cost for items above 20 kgr., restrict the delivery of your TT to E.Union. If you need help with German you are welcome. Regards, |
Hey Geoch, Nandric is right. You will definitely get a good price in the German market for your TT. I have seen one in an exclusive High End shop recently. They sell it as a Brinkmann Project. I would rather go on ebay, maybe ebay.com than on Audio Markt. At Audio Markt you will be confronted with lots of stupid questions. No need for this experience. Best @ Good Luck |
Dear Thuchan, thank you for your interest. A price of 5000 EURO is enough for me, but I'm not really prepeared to mess with packaging this monster. The company's original package was a joke : 3 big boxes full of urethane chips and nothing else. Anyway I'm glad that you guys want to help me with your advice. It's good to know that I have international friends. |
Dear Thuchan, With all your gear (past and present) you of course have much more experience with selling than I. But I have much more time to watch the 'markets' mentioned. Ebay.de is different than audio-markt.de . The latest one is more suitable for the items with an 'fixed price' in mind ,the former if one has a vaque idea about the price. The listing time is also different: 10 days versus 1 month min. Ebay.com is more problematic for his TT because of the postage cost and transport outside of Europe. But like you I also prefer ebay.de. In casu however it is about Geoch and the question what may be the best solution for his problem. Geoch, Since Brinkmann was employee by Symphonic line it may be the case that he designed this TT? To me your TT looks like an Brinkmann TT. Regards, |
Certainly looks like a Brinkmann but the bearing is quite different and unique. I find it quite unlikely if Brinkmann designed this bearing 20 years back and now abandoned this in favour of the very small & plain bearing inside the new TTs with Brinkmann logo. Honestly I don't really care (as I would'nt trade it for a Brinkmann TT). The only thing that I would miss is the helpfull armboard. |
Lewm: "Do you mean to say that the Cosmos is subject to M Fremer's critique (motor mounted to base/platter on spring suspension, which is also my criticism), or not?" The Cosmos had the motor and platter mounted on the same subchassis, according to a review in the old AUDIO magazine and Stereophile, therefore it is an improvement over the earlier Sapphire and Star in terms of speed stability. Cosmos's design was largely responsible by the talented Allen Perkins of now Spiral Groove and he is one designer who does care about speed issues. Atmasphere is right that Empire had the foresight to do the same thing in the 208 decades ago and is one of the greatest vintage turntables. Respect! P.S. Linn has a fixed motor and suspended platter. _______ |
Excerpt from Stereophile review of the Sota Cosmos: "In the Star, the motor is mounted, for isolation purposes, on the fixed portion of the base assembly separate from the suspended subchassisthe usual practice in this type of turntable since AR started the breed in the '50s. In the Cosmos, the motor is mounted directly on the suspended subchassis, along with the bearing, platter, and arm. This provides an unvarying geometry between the motor and the turntable. The Cosmos relies on its damped subchassis and multi-layered platter to isolate the arm and record surface from motor vibrations."_______ |
Thanks, Hiho. I am heartened that SOTA fixed that problem. For years with the SOTA Star Sapphire, i thought pitch inaccuracy on piano was normal for LPs. (It replaced a TD125 way back in the early 80s, but I have no recollection of the sound of the TD125.) I have heard from a reliable source that the Spiral Groove tt's are superb as well, attesting to the design skills of Perkins. For an embarrassingly long period of time I was laboring in my spare time on a complete revision of my Atma-sphere amplifiers. Thus I was not really doing much listening except with a Parasound ss amplifier that did not compel me very much. Two or three days ago, I got my system back up and running with the Atma amps driving the Sound Labs (also with highly modified and very simplified input circuit). By the same token, it was my first extensive audition of my Technics SP10 Mk3 with Reed tonearm. All I can say is "My goodness". Talk about speed and pitch stability and rhythm; that thing is amazing. My wife, who takes only a passing interest in my audio system and in my jazz listening, sat with me for 2 hours, riveted as was I. I have been an audiophile for 35 years but only with DD and idler-drive for maybe two years. I have no plans to go back to bd. |
I have read this post with fascination and it has lead me to do some measurements and calculations. I am an engineer. This sort of thing is what I live for. I have an expensive belt drive tt and therefore I became very interested in determining if I need to invest $4k+ into a tt upgrade because I am missing out on some musical pleasure from my vinyl. My first measurement was to pull out my strobe disc and fluorescent light. (Ugh I can hear some of you saying, but just listen a moment) I fixated on one black mark and in 10+ revolutions, that mark did not drift as best my eyes could tell. Next, I dropped the needle on the record while remaining fixated on that black mark. Again, no drift at all as best my eyes could tell. I must comment that considering the cost of most of our turntables these days, they sure better be able to hold speed with or without stylus drag. It would be a pretty poor turntable that could not. After all, this is the primary function of the tt- spin the platter. So at this point, I'm pretty convinced that my tt holds rotational speed very accurately even considering the apparent disadvantage of being a belt drive. Next I put on my Stereo Test Record and played a 1000 Hz test tone. I can hear some Wow in the tone. The "A" tone, 440 Hz makes the Wow much more apparent. So where is the Wow coming from? The specs on my tt state a Wow and Flutter measurement below 0.03%. I believe it. That's part of what I paid for in this very expensive tt. I look at the record, and this is supposed to be a test record, and I see some serious runout. I can hear the Wow precisely when the tonearm is rocking outboard as the record is spinning. As with many records, the tonearm is swaying back and forth due to the runout- ie. the center hole is off position relative to the center point of the grooves. At this point, I would like to borrow a dial indicator from work to measure this runout. (I would also like to see just exactly how much runout is in my platter.) Since I cannot do that today, I measured the distance of the center hole of the record to the outer edge. I found the center hole of this record to be off center by 0.8mm or 0.0315 in. This would yield a runout measurement of 0.016 in. After searching the internet a while I found a specification for records that says the runout tolerance of the hole can be +/-0.015in. Allowing for some measurement error on my part, this test record has runout at the maximum industry tolerance. What does that mean from a sound standpoint? Well, I measured the radius from the center of the record to the grooves with the "A"/440 Hz. That measured 3.5 in. This puts the groove velocity at that point at about 12.22in/s. Now factor in the runout of 0.016 in and the speed change is 0.05497 in/s. That causes a frequency shift of 2Hz. It is actually +/-2 Hz. This is the theoretical calculation. Now to measure the actual shift. I happen to have a FFT analyzer handy. (Engineers, sheesh!) So I measured the frequency of the 440 Hz tone being played on my tt and coming out of the speakers. Guess what! I see the periodic Wow in the trace and I also see the frequency varying from 338 Hz to 442Hz! How about that? I conclude that my tt maintains speed at least an order of magnitude better than a record with production tolerances. If the runout is 0.016in, then the Wow will be 0.45%. That is over 10 times the spec for my tt. Okay, what does all this mean subjectively? I think that rhythm and pace is definitely a variable among turntables. I have heard it myself on different systems. I don't understand how it differs from one to another. Maybe no one does completely which explains the myriad of solutions in the marketplace for spinning a platter. Maybe someone could come up with a platter design that can true the record to the center of rotation. |
A point was stumbled upon here, but no one followed through with the observation. Halcro noted, "...you would have seen.......about half way through the video......where he drops the cartridge on the record and immediately.....the speed decreases? And this is only the beginning of the record. Not a heavily modulated passage? Can you imagine what happens with a really heavily modulated passage? And that turntable in the video has a very heavy platter." Of interest to me isn't that the speed controller, assuming there was one, is inaccurate. It may be perfectly designed; we don't know. So, what basic principle would cause the speed drop? It isn't electronics, so it must be mechanical. If that is the case, all the electronics in the world cannot fix a fault because of a faulty design in the parts that make the turntable. My point is that inertia has to be addressed at the outset of a turntable's design, and that electronic speed control merely augments it. I strongly believe that 100% success is not found unless the all the pieces work in unison. Sure, you can improve a turntable by adding an electronic speed control. The true nature of the recording is best exemplified when inertia is a major consideration to the basic design, in my honest opinion. |
Tonywinsc, interesting what you experienced during your test measurements. on all my TTs I experience a change in speed when the needle hits the record. Regarding the different carts and weights of the headshells I usually adjust speed by my speed controllers. Belt drive not necessarily needs to be a disadvantage (thread). I usually measure my wow & flutter with a test tone of 3150 Hz and on the EMT by 5000 Hz (J60s). You are so right on the Influence of the exact spindle position of the record. Most turntable designs don't refer to this issue. I know one design which does optimise the center of rotation - the Nakamichi TX 1000. Best @ Fun Only |
Dear Thuchan, The Victor TT-101 is quartz controlled direct drive and automatically runs at a true 33.3rpm or 45rpm. It has pitch adjustment in 6hz increments in both positive and negative direction.....but I never use this feature. The servo control is bi-lateral........it works to speed up AND slow down. Most other servos only are capable of speeding up and then rely on natural friction (or stylus drag) to be detected as 'too slow'.......for it to 'then 'speed up'. This natural time delay is too slow with too much speed variance to really be critically effective IMHO? Do you notice this slow-down when the stylus lands.........on your Nakamichi as well as your belt drives? |
My point is that inertia has to be addressed at the outset of a turntable's design, and that electronic speed control merely augments it.Mosin, as inertia is directly related to mass and friction.....are you saying that heavy platters have inherently greater inertia than light ones? If you are?.........how do you explain that the turntable in the Timeline video features the Fat Bob platter with a massive weight and slows down alarmingly when the the stylus hits the record? Yet my TT-101 has a puny 2.0 Kg cast aluminium platter which has zero deviation in speed with one, two or three cartridges lowered onto the same record? All speed control is via the direct drive with servo control. This instantaneous speed control I believe, is far more critical than inertia? |
I found an article online about the Nak. Very interesting tt. The author had an excerpt from an interview with the designer. He substantiates my point exactly. He says vinyl record runout is the elephant in the room that tt designers ignore. As for inertia: Torque= J*omega, which is the angular term for F=ma. The tt motor provides the torque and the platter bearing and stylus apply a counter torque. The inertia of the platter determines the rate of change in speed (deceleration). Say for example the motor is uncoupled from the platter. The platter is spinning at 33.33 rpm. (ignore bearing friction for a moment) Now drop the stylus onto the record. A 20 kg platter is going to decelerate at a lower rate, for example, than a 2 kg platter. Now let's hook the motor back up to our platter. The motor is either clocked to the 60Hz line frequency or is feedback servo controlled. So it holds the platter at 33.33 rpm. Any perturbation in the platter speed causes the torque output of the motor to change in order to restore 33.33 rpm. The motor could do it's job regardless of the amount of inertia in the platter. The stability of the platter speed is based on the control loop and torque of the motor combined with the system inertia. That means the designer has to couple a motor and platter as a system. The platter is designed to be a mass damper. We use mass dampers in dynamic systems. We use mass to tune System Natural Frequencies and keep them out of certain operating ranges. A bigger platter requires a higher torque motor in order to be stable. Perhaps the youtube example is a tt design with an undersized motor. I would say as a rule of thumb, the motor in a tt should be able to accelerate the platter up to speed within one rotation. To me that would indicate that the motor has sufficient torque to maintain a stable speed. btw- I just checked my tt and it is up to speed within one rotation. |
Chris, Your wish is my command :-) Please forgive the amateurish state of the movie but it was taken on my iphone4.....my first film..... and my first upload to utube! TT-101 |
While there is tremendous value in technical explanations for some of the perceived problems with vinyl playback, I think it is important to remember that those possible explanations are incomplete, and don't fully address the fact that what we are ultimately concerning ourselves with is an impossibly complex and fragile thing: the FEELING in music. Small speed stability problems that affect the perceived feeling of the music, wether caused by run-out errors or rotational speed error, are probably beyond the capability of any known measuring system. I have (like all of us posting on this thread) struggled to make my expensive belt-drive turntable as speed-stable as possible. Thread drive and a motor controller have improved the situation to a barely acceptable point. I say barely acceptable because I can still hear problems compared to the rock solid stability, and fabulous swagger that live music can have. In addition, the very same LP that has no perceived run-out issues when I use thread drive, will sound speed unstable when played using the rubber belt. This, in spite of my strobe showing that the speed should be rock solid. NOT! |
Keep in mind that the effect of the vinyl record runout is worse at the inner groove. As the needle is further out from the spindle the radius of the runout is proportionally smaller so Wow will be less at the outer groove of the record. So effectively another problematic issue when playing the inner grooves of records. Does anyone notice a rhythm/timing difference in the music from the outer to inner tracks? |
