Don_c55: "Just buy a strobe disc and illuminate it with a light bulb. The 60 Hz AC frequency does not fluctuate enough to worry over." I wish that's true but using your method and comparing to a KAB strobe, there is a noticeable visual difference, even when your turntable is accurate the light bulb frequency will drift and you end up adjusting to the wrong speed. Not only the speed should be accurate but, more importantly, no wavering or no intermittent irregularity. To me cogging or analog jitter has the worst effect on the sound of playing a record. DD gets the speed accurate but often suffers from motor cogging. When done right then DD sounds great. Belt is good at filtering the jitters but the elasticity on the belt creates another set of problem. Sigh, what a circle jerk of a hobby! Don_c55: "If your platter is heavy, playing a record will not affect the speed." Didn't Halcro just said he tested the TimeLine on the TW Raven, which has a heavy platter? ---------------------------------------------------------------------------------------------- Below is an excerpt from the long winded and thought provoking piece that Lewm and Halcro was referring to in the below analogy. Good read, if you have time. :-) Peter Moncrieff in International Audio Review, issue # 80:
Consider the following analogy. Imagine first that you want to draw a music waveform, like the ones you've seen in previous IAR articles. Draw it on a square piece of graph paper. Note that you can freely move your hand in two dimensions on the graph paper, so you can simultaneously draw both the varying amplitude (height) and progressing time (horizontal axis) of the waveform on the graph paper. Next, imagine that you're doing the same thing, but you've turned the piece of graph paper sideways, so that your wrist moves from side to side (instead of up and down) as you're charting the waveform's amplitude variations.
Now, imagine that you can only move your wrist from side to side, and can't move your hand up and down at all. Your hand holding the drawing stylus has now become just like a phono cartridge holding a stylus that can only read the side to side variations in a record groove. Your hand holding the waveform drawing stylus is mounted on your arm, the same way that a cartridge holding the waveform reading stylus is mounted on the pickup arm of the record player.
If you were to try drawing a music waveform, while limiting your hand to only this side to side motion, you couldn't do it. There would have to be a further mechanism for moving the drawing stylus in your hand along the time axis of the graph paper where you want to draw the complete music waveform. You could for example rely on a strip chart recorder, which could dispense the graph paper in strip form at a fixed time rate (you've probably seen strip chart recorders in the form of earthquake recorders, where the side to side needle motion indicates earthquake amplitude, on a steadily unrolling strip of graph paper; if you're unacquainted with this, imagine a roll of toilet paper unrolling at a steady rate). The strip chart recorder makes the graph paper move along under your hand at a constant speed, thus creating a steady time axis for the waveform you wish to draw. And the strip chart literally creates this time axis. Your hand is limited to reproducing (accurately we hope) only the amplitude axis of the music waveform, since you are now limited to side to side motion.
That's exactly what a turntable does. It literally creates the time axis half of your music waveform, while the cartridge, which is restricted to side to side motion, reproduces (accurately we hope) the amplitude information that the grove contains. _______ |
All I know is that the wavering on the decaying note of a piano is REALLY annoying and that usually happens on belt-drive suspended turntables with stretchy belt. I may not know what I like but I know what I don't like.
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My Dual turntable has a built in AC light bulb to check the strobe marks on the platter rim. It drifts over time while the KAB strobe light is stationary. So there is a discrepancy between using AC line frequency and quartz locked frequency. Jeez, I am such a KAB sucker. From the Dual manual:
"It can happen that the stroboscope lines appear to move slightly although the exact speed setting with stroboscope lines stationary has not been altered. This apparent contradiction is explained by the fact that the electronic central drive motor operates fully independently of the line frequency whilst the only relatively accurate line freqency of the AC current supply is used for speed measurement with the light stroboscope." I am happy that some people found their perfect turntable without worrying about these things. Us neurotics just have to suffer. _______ |
Dougdeacon: "Implementation, implementation, implementation. :)" I love it when I see people doing experiment like that. My friend owns one of the earliest version of Teres turntable before it went commercial. His motor failed couple years ago so I sent him a Papst motor salvaged from the Empire 208 with pulley diameter slightly tweaked to get accurate speed. It worked well and liked the sound and used it for a more than a year. I suggested him to try driving the Teres platter with a Technics SL-M3 direct-drive turntable via VHS tape. After some tweaks he liked it even better than the Empire that it's quieter and "overall sound wise, image is focused and sharp, more forceful with muscle, very nice." Of course, the downside is that the whole set up takes up much bigger space. Yes, it is indeed quite easy to tell the difference when you only change the drive system. People should try something like this with a belt drive table just to get an idea how much the sound can change with a different motor. It's all reversible so it's harmless. Try it. You might like it. :-) _______ |
Davide256: "Direct drives are very difficult to isolate (vibration) vs belt drives" Really? What if there is little or close to no vibration in direct-drives to isolate to begin with? Not sure you understand how direct-drive system works... ______ |
I found a random picture of a turntable online that looks like the kind of thread drive turntable Dertonarm would make. :) Any idea who made that? _______ |
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: "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. _______ |
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." _______ |
Dover, that was funny. :-D The thread " TTWeights table and Timeline accuracy" is mysteriously closed but at least we still have this thread to talk about speed issue. I don't want to stir up the pot and point fingers at certain brands but I still enjoy discussing speed issues in turntable designs. We are still waiting for Lew to report back on his Timeline experience. :) _______ |
Regardless of the accuracy of the Timeline as long as it is consistent then it still demonstrates there's inconsistency when the laser mark moves off target so there is a CHANGE due to stylus drag. It proves there is a change in rotation and it may or may not change the sound but the fact is that there is a change. What is so hard to get? If the Timeline cost only $50. Everyone would just get one and start questioning and addressing the speed issue of the turntable.
I love the KAB strobe and it's a useful device but it cannot show me stylus drag visually the way the Timeline does.
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A fast start up direct drive turntable does not necessarily have higher torque. Some DD tables boost the torque only at the first couple seconds to get the platter up to speed and then lower the torque to just enough to keep the platter running. The image that DD has higher torque is due to the popularity of Technics turntables, especially the SL-1200mk2 and SP-10mk2. But Technics is, of course, not the only name in the DD game.
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Syntax: "Tweaking a dead cow to a horse is interesting, no doubt, but other Designers made better work." That reminds me of an old Chinese saying, "ride a cow before you find a horse." For some people their turntable of choice is the cow... for the time being. :-) Or they think they're riding a horse? Or they are just "cowhide lanterns." :-D ______ |
Ketchup: " That seemingly "slow" result could simply be because of the LP slipping on the platter, not the platter slowing down due to the stylus drag." That's easy to figure out. Simply stick a piece of tape with, say, a pencil mark on the edge of the record line up with another mark on the platter and then check their alignment after the speed test to see for any drift or slippage. This was proposed by a smart forum member (Dertonarm) before. _______ |
Lewm: "The engineers of the 1970s and 80s were well aware of all of these issues that we are now still obsessing over. The L07D may turn out to be my all-time fave, and it's not the highest torque in town." Good point and good write up. At one point I thought the higher the torque the better and forgot about the increase in cogging. Torque for torque sake does not a good turntable make. I agree that Kenwood knew what they were doing back in the days. Recently I recommended a Kenwood KD-770D, one with a rather low torque coreless motor by DD standard, to an acquaintance and he is so happy that even his wife thinks the sound is smoother and that's with a cheap cartridge. I really think the reduction of cogging by using a good motor is a worthy effort in DD designs. And a precise but "gentle" servo is less harmful to the sound than some brute force detecting system. eg., someone in a DIY forum did the below to his modified Technics SL-Q3: "I modified the negative feedback loop network to make the whole thing underdamped. As it is from the factory, it is overdamped and after doing some A/B test by switching instantly between the factory network and the new one, it is obvious the change in sound. The modded version is much more relaxed and clear and all the distortion (similar to jitter in digital) in mids and highs is gone." Some of that sterile DD sound may be caused by the "overdamped" servo, a kind of "analog jitter" Mosin and others mentioned before. It all comes down to execution, I guess... _______ |
Ketchup: "You would think that at least one of them was an audiophile today and maybe even posts on an audiophile forum, but I have never seen one of their posts." You must be kidding me, right? _______ |
Can anyone name one brand that is not Japanese, not German, and not Swiss origin that made direct-drive turntables in the 70's, 80's, and 90's before the Rockport Sirius III, which was reviewed in Stereophile in 2000? I certainly cannot think of one. So for 3 decades in the USA and UK that were dominated by Linn, there was no manufacturer making DD tables. Are audiophiles really that monogamous? That statistic is frightening, considering the two audio powerhouses in the world did not make a single direct-drive turntable in the heydays of analog! Click here for some direct-drive history and brands. _______ |
Geoch: "I feel that the Hi-Fi market's turning point at '80s with the Japan giants leaving the field to some hungry animals, it is still our torment today after 3 decades and we owe it to our love for this hobby to realise and accept the influence which has upon us the marketing status. After the shrinkage of the hi-fi market, the industry turns its back and left the designers to seek for the wealthy victims among us. There is so little progress and so much BS today that the buyer is usually go for the more beautiful as a statement of his life style. But unfortunately TTs are not cars and so, his "Bugatti" is only for the eye and refuses to spin properly a vinyl. Are we going to feed this monster again?" Great post, Geoch! And great question! _______ |
Dover, a laugh is all you need.
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Ketchup: "Hiho, I'm not sure how to take that." Sorry, Ketchup. Your post was legit but cynicism got the better of me. My initial reaction was that we audiophiles really like to flatter ourselves and why would any Japanese engineers who worked for these corporate giants would waste time on a forum like this and most of them likely not fluent in English, which Lespier alluded to. Knowing how engineers sneer at and dismiss audiophiles, and I knew quite a few, I am skeptical they would ever respond to forums like this. Again, your post and question was totally legitimate and I sure hope we will get a response from these pioneering engineers one day. ______ |
Dev: "I tried it on a "DD" SP10 MK2 and it was off, no way to correct like the MK3 offers speed adjustments so the owner has to send it in." I believe there are trim-pots inside the chassis that can vary the speed minimally but I just don't know which ones. Maybe the trim-pots are for other functions. I don't have my SP-10mk2 or the manual anymore to verify that. Perhaps other more knowledgeable owners can comment on this. Good luck. ______ |
Sarcher30: "Unfortunately bringing the motor closer to the platter also brings it closer to the cartridge as well. Which on the TT's I have had with that arrangement caused hum on most of my cartrides. There may be some TT's that sheild the motor well enough to pull it off." Perhaps you can try grounding the motor housing? _______ |
Lewm: " I believed that firmly and permanently anchoring the distal end of the idler arm was preferable to using the external adjustment mechanism, wherein the pivot of the idler arm rides on a rail across the motor drive shaft, as you select speed." I agree. All Lenco tables in stock form have speed issue. Not the fault of the motor, idler wheeel, nor the design. It is in the sliding mechanism that holds the idler arm that is always loose. You can hold it and feel it with your fingers and it's loose and it is this looseness in holding down the idler arm that's preventing the speed to be spot on. You can lock it down of course but then you lose the speed adjustability, hence the PTP approach but adjusting speed would be, indeed, a pain in the arse. Only by keep the opposite end of the idler wheel solidly in place will the speed be stable. It's a very mechanical turntable and if the idler wheel is allowed to move even microscopically on the tapered pulley the speed will change. I have several stock Lencos and they all have the same issue. It's no wonder some diyers made a micrometer to slide the idler arm in keeping in position and having the adjustment ability. Part number 14 is the culprit._______ |
Dev, I hope I did not discourage you to pursue the Lenco. It's a great sounding turntable although I never had the time nor effort to set it up properly but I have friends who got good results from adding a little elbow grease.
For an idler design, it is very quiet, thanks to the brilliant simplicity, its quality core components: motor, bearing, and platter. Its idler wheel is also the thinnest and lightest among idler-drive designs and that might partly contribute to its silent running. The idler wheel is also quite stiff and low compliant compare to Garrard, Thorens, Rek-o-kut, etc... and consequently, I believe, less "meaty" sounding, which can be a plus to some people. Admittedly, I quite like that beefy tone on idler tables with thick fat wheels but they are also harder to tame the noise, especially if they use a huge fast running motor, eg, that monstrous Ashland motor in the ROK or McCurdy or Russco. To me the Garrard definitely has a juicier tone than the Lenco but it's not as quiet. Lenco is also, I believe, easier to obtain correct stable speed. My experience is that the thickness, compliance, and among of rubber of the wheel correlate with the tone and tonal balance. (Let's not get into the audio political correctness of neutral game, "my table is more Neutral than your table" pissing contest. I cringed whenever audio reviewer using that term. I equate "neutral" with neutered.) I still marvel at the enormous bass dynamic and heft of a McCurdy idler table with a huge motor...but, alas, it was really noisy--good luck taming that beast!
Anyway, if the noise issue is taken care of, idler tables are great musical machines and can get quite addictive with its ballsy tone... other tables (like some Scottish sacred cow) might sound wimpy as the musicians are playing with one testicle missing. If the table pass the Timeline test, would that be balls to wall? :-)
Sigh, so many toys so little time...
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Lewm: " 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." It is, indeed, a head game. Sometimes I wonder if we make rigid on all the linkages such as the idler arm, rubber bushing, to not allow any flexing, will the speed be even more stable and what will happen to the sound. The brilliance of the Lenco is in the use of tension: the idler arm pressing on the motor, the spring pulling the wheel towards to motor shaft, and 3 point suspension pushing up the motor towards wheel and then the platter. It's in this chain of tension of push and pull that makes the whole system work in unison. It's a complex and zen system at the same time. I wonder if making any one or all part(s) rigid will ruin this system of tension and its sound. Or it might improve it. I do not know... but it's a fun head game. :-) To me the idea of direct drive having only one single moving part is even more zen.... and that one moving part rotates at 33.33rpm is super cool... at least it runs circle around Art Dudley's head. ;-) ______ |
Atmasphere: "Were it not for the motor in the 208, I'm not sure I would even be messing with belt-drive at all." I share that sentiment. Lewm: " 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." I am surprised that you did not know Papst is a company that made motors. Yes, it's Papst with the P. and the same Papst model is used inside the Empire 208, Fairchild 412, various Rek-O-Kut belt-drive and idler-drive tables such as K33H and L33H. Different motor models are used in Thorens 124 as replacement, smaller motor in the Empire 598, etc... It's also possible the Audio Note TT3 three-motor turntable uses Papst motors. http://www.audionote.co.uk/products/analogue/tt-3_01.shtml#_____ |
Lewm: "no need for me to know anything more than what I have learned by casual reading." That's very zen. I need to do that myself. Bill Belichick has a sign at his team facility that says "Ignore the noise." Good advice. _______ |
Stop all these turntable tests, for now, on speed accuracy and enjoy the Super Bowl! Enjoy the food!
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Halcro: "Perhaps the key to the accuracy and consistency of many DD turntables.....is their inbuilt ability to monitor the platter speed against a quartz crystal timing device......and make instant corrections for any deviations." While I am a fan of direct-drive but I am not sure that's a good thing about servo making "instant corrections for any deviations." Any error has to be detected first before making correction so it's after the fact and sometimes if treating it with an iron fist approach it can cause unnecessary jitters and possibly that sterile sound we associate with DD tables. I think the key to good sound in DD, other than motor quality, is how the designer approaches this servo or corrective system in a sensible way. If the outside disturbance of the speed is too large, I see no need to correct it and just let it be. For example, if I were to tap the platter rim with my palm while spinning and I don't see the need for the platter trying to hold speed. It comes down to how smooth the correction is. I don't think servo response time have to be so quick. A gentle approach is probably more pleasing to the ear than a brute force one. I can be wrong and there are probably good sounding DD tables (TT-101?) out there using the quick fix approach. I understand stylus drag is not a constant resistive force, neither is music. Perhaps the torque should be set just high enough to plow through the most demanding musical passages (1812, anyone?) and leave it at that so the servo does not have to do tap-dancing all the time? Of course, it's impossible to do instant servo on belt-drive of course due to the elasticity and time delay of the belt but its gentleness probably offers a pleasing sound. ______ |
> Lewm: "The L07D is among those that use the servo feedback sparingly or gently, whichever term fits best." I don't know enough of electronics to decipher servo circuits but I do know one DIYer in another forum tinkered with the servo on a heavily modded unit of a stock Technics SL-Q3 turntable with the following: "I modified the negative feedback loop network to make the whole thing under-damped. As it is from the factory, it is over-damped and after doing some A/B test by switching instantly between the factory network and the new one, it is obvious the change in sound. The modded version is much more relaxed and clear and all the distortion (similar to jitter in digital) in mids and highs is gone." Now, I wish I can do that to my Technics table... > Lewm: "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." Maybe you can raise the Timeline above the spindle with, say, a piece of styrofoam or a roll of electrical tape, center it and hold it with double-side tape? It's a little mickey mouse but it can be done...... that is, if you have the time and energy to entertain us. :-) _______ |
Lewm: "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." I don't think the damping factor of a servo circuit is determined purely by mass, that is, higher mass = overdamped or lower mass = underdamped. It is probably preset by the electronics how responsive or how quick the response time to the load or mass deviation, I supposed there's a "reference" load much like a zener diode in a regulated power supply, which is a form of feedback. Some turntables have very "loose" or gentle response to mass deviation, that is, even without the platter it can still rotate smoothly. I think it is predetermined by the electronics in the over all design. I think sometimes by adding mass to the platter can sound "smoother" is to purposely overwhelm the servo to allow more platter inertia to do the job so it's actually underdamped (less hunting, perhaps?). I guess it's a balance between letting the mass or letting the motor/servo/electronics do the work. It really comes down to engineering decisions. Back to the same idiom that there are many ways to skin a cat, I guess? _______ |
I believe the Brinkmann Bardo and Oasis use the gentler servo speed control. Here's what they wrote in their white-paper; it's a little long but it's a good read: PROBLEM WITH DIRECT-DRIVE
Studios (radio stations in particular) demand quick start-up times turntables typically have to reach their correct speed within half a revolution. For LPs this means 0-33 1/3 rpm within 0.9 seconds. Such acceleration figures can only be achieved through use of high-torque motors and correspondingly tight coupling between the drive and platter. It isnt a surprise then that for decades idler wheel drive designs were the defacto standard in studio applications. But idler wheel turntables also had seriously high maintenance costs in order to be up and running 24/7 and to avoid rumble and other sound degrading issues caused by worn out idler wheels to affect the sound negatively. Thus out of necessity, in the late 1960s manufacturers of studio turntables began to look for low(er) cost maintenance alternatives. They came up with direct drive, whereby the platter was placed directly on the motors shaft, ie the stator was mounted around the bushing and the shaft was used as the rotor and voila, the goal was achieved; at least in theory.
But start-up times of less than 1 second necessitated high torque motors, which designers achieved by using motors with 32 and more poles. The penalty they paid were heavy cogging effects accompanied by high wow & flutter numbers. The cure was found in quartz locked motors and phase locked regulators; which corrected for any deviations from their preset with an iron fist. On paper at least, these corrected direct drive turntables boasted hitherto unimaginable low wow & flutter numbers down to 0.001%. But the rigorous iron fist regulation prevented the platter from spinning smoothly; instead, the regulation caused the platter to oscillate continuously between speeding up and slowing down. These start/stop motions translated into an unpleasantly rough and hard sound; odd as wow & flutter numbers in the 0.001% range are deemed inaudible.
Once the direct drive technology had gained a foothold in pro audio applications, the benefits of mass production (ie. trickle down effect) made sure that very soon even $100 turntables were equipped with direct drive and advertised as having less than 0.01% wow & flutter. This is precisely where direct drive got its bad rap sheet. Under closer scrutiny however, this assumption were based on some misunderstandings. For one, in home audio application use, turntables are not really required to reach 33 1/3 rpm in less than a second, thus 32 pole motors and phase locked regulators are not really necessary either.
THE BRINKMANN SOLUTION
Having decided to utilize a direct-drive mechanism for our new turntable, we began searching for the appropriate motor. Sadly (or luckily, as it should later prove) and despite much effort we were unable to find a motor that was up to our stringent quality requirements. We therefore decided to design and build the motor in-housewhich had the nice side effect that we did not have to cut any corners and instead were in the fortunate position of defining all relevant parameters ourselves. The motors stator consists of four specially designed field coils, which are mounted concentrically with high precision around the platter bearing. Based on listening and tuning sessions, we decided to forgo the typical 90-degree mounting angle in favour of a non-standard 22.5-degree raster, which, due to the magnetic fields overlapping, further reduced cogging. The motors rotor also acts as the sub-platter and carries a magnetic ring with 8 poles on its underside.
The drive mechanism, based around Hall sensors and an encoder disk, is designed in such a way that there is just enough power to bring the 10 kg heavy platter up to 33rpm in about 12 seconds. Conversely, only a minimal amount of energy is actually necessary to keep the rotational speed at a constant. While the drive mechanism is indeed direct, power
is actually transferred without any contact. This soft coupling via a low power magnetic field translates into a silent drive, which reduces cogging further. One of the main attributes behind the sound quality of the Oasis has to do with our proprietary motor control. It works proportionally, i.e. it transfers just enough energy to the motor for it to remain at constant speed. Conversely, due to our ultra low-friction bearing, only a small amount of energy is actually necessary to keep the motor at constant speed. Previously available regulators typically work disproportional and rather abruptly: they speed up and slow down the motor very rapidly when necessary.
During the development phase of the Oasis turntable, we spent many long hours auditioning several different regulator designs; it became quite evident that utilizing our concept of proportional regulation always resulted in better sound: typical harder motor control concepts produced a sound significantly lower in quality, with less color and drive. I suspect their decision "to forgo the typical 90-degree mounting angle in favor of a non-standard 22.5-degree raster" is influenced by Dual's design of the EDS-1000 motor, which also has the same coil arrangement... _______ |
Lewm: "Lets keep in mind that what you quote from the Brinkmann website is a commercial" Yeah, I know. It's full of their own propaganda but I was too lazy to edit the pertinent parts so I just posted the entire section on drive system.... didn't mean to impose their bias on anyone. But it's still a good read for me and for the most part I agree with them about having a gentler servo system instead of a iron-fisted one and it resembles my own experience, granted there's always exception out there. I think this is a great thread as it allows people to focus on one of the most important and underrated aspect of a turntable: speed accuracy. It's been fun. P.S. Yeah, where is Travis or T_bone? I miss him. ______ |
Peteayer: "Well, 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." Can't you hold the the tachometer steady or clamp it to something so it would not move? _______ |
