Harold, Tape is not a new idea. Beyond that, I know some guys who then end up coating their tape drive with talcum or other stuff, to improve its frictional contact with the platter. I've also seen discussions of just exactly what kind of tape works best.
Hiho, Your comment on using a direct-drive turntable to drive a belt drive turntable is something I considered bringing up in this discussion. If nothing else, it reduces belt creep. But it also says to me that those belt drive motors with relatively small diameter pulleys, and this includes some very expensive products, are off base. First of all, the smaller the pulley, the faster the motor has to spin, the more noise it might make as the bearings wear. Second, the smaller pulley with the motor placed far from the platter would tend to increase belt creep. The only virtue of the small diameter pulley is that it might mask speed errors to a degree. |
Harold, You never mentioned, until lately, that your rim drive is a Salvation. Vic's seems to be the best, by visual inspection of photographs, of the bunch. At least in part, I think this is because he started out from the beginning to design and build a rim drive, whereas most of the others out there are belt-drive conversions. Too bad that TT Weights went out of business; some of their offerings also seem to have been born as rim drive. However, apparently they had problems. (Please don't attack me on that; I am only reiterating what I've read here and on VA.)
Hiho, Your solution might work well too. However, I'd have to think about how the second (passive) pulley would affect belt creep. Three pulleys, like 3 motors, is just a commercial gimmick with mostly negative consequences, IMO.
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Harold, Theory is all I've got. I just look at how rim drives work, and I consider what might be good or bad about it. Rim drive itself seems to have come about as a band-aid available to belt-drive makers who feel pressure to offer an alternative. Teres led the way in doing that, I think. But in another way, you are quite correct; I would be out of line to say that I know how YOUR particular rim drive turntable sounds. It may be great, and I may be completely off base. I did not mean to slur your choice of turntable. I can speak about belt-, idler-, and direct-drive with more of a sense of authority, because I've heard more than one example of each type in my system, but even there, anyone's particular experience must be limited. I don't claim to know it all, but I may sound that way some times.
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Humans have inertia, too. Just like massive plinths. |
If the plinth is very massive, then I would think Rollerblocks would be good. With a torque-y motor like the one in the Mk2, the force spinning the platter in the clockwise direction also creates a counter-force that "wants" to rotate the plinth in the opposite direction (Newton's 3rd Law of Motion). If you mount a light structure on Rollerblocks, there might be a slight tendency that this counter-force will be sufficient to actually overcome the inertia of the plinth and twist it in the counter-clockwise direction, which is not ideal for playing LPs and also wastes some torque that you want to be applied to the platter.
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Multiple motors. What would interest me to try, if I was still interested in belt drive for my own use, would be two motors positioned at opposite sides of the platter, 180 degrees apart, so as to equalize the forces involved in rotating the platter through a belt connection. Any more than two motors only increases issues related to noise and synchronizing the motors, without enhancing any of the potential benefits associated with more than one motor. It’s a can of worms that I would rather not open. I believe the Kuzma Reference turntable uses two motors in this manner. |
Has2be, I don’t disagree with the substance of what you wrote, but I am a bit puzzled by the following phrase: "at a time when everyone was dumping belt to manufacture DD because the electronic end was at a rabid pace of growth and precision and yet , Micro Seiki went back to making high end belt/string drives." Just what period of audio history are you thinking about when you write this? The way I experienced it, in the 50s (before I really was a "player" in this game, but not before I was exposed to music in our home), idler drive was if anything the predominant mode (think "Garrard"; Garrard changers were common in even the most sophisticated systems). AR changed the game in the late 60s, when I was finally able to buy my first audio system, with the X model, which of course was the most basic belt drive imaginable. But in the 70s, when the Japanese got into the market in a big way, direct-drive was very fashionable but kind of mid-range-y in quality. True, there were some high end DD turntables made in Japan during a brief golden era, but in parallel the very most expensive turntables were BD (Thorens, Goldmund Reference, etc). By the late 70s/early 80s, DD kind of got dumped in favor of belt drive, largely due to the efforts of Harry Pearson and the Absolute Sound credo. I’m sure Gordon Holt had something to say on this subject, but I don’t recall what it was. Anyway, by the mid-80s, as vinyl dipped in popularity, BD was thought of as the only way to go among aficionados. My point is, I don’t recall any time when belt drive was eclipsed by DD, even temporarily. As for Micro Seiki, they were always basically a high quality BD company; their DD turntables were never competitive with the best of the breed, and I don’t think they ever intended them to be. It's interesting how differently we view the history. |
"The motors are located farther from the cartridge". But in a DD turntable, the platter IS the rotor. There is no separated motor assembly to "make noise"; the platter is motivated to rotate only by virtue of its being a part of the rotor, being influenced by the magnetic field of the stator. Nothing touches the platter, in other words. The only mechanical noise can come from the bearing assembly, as with any other type of turntable.
Whereas, in a BD turntable, the motor pulley bearing is under constant tension biasing it to one side as it pulls against the platter, which is likewise biased in the direction of the pulley, which cannot help but generate noise. That mechanical noise can be transmitted directly into the platter via the belt; the less compliant the belt, the more efficient it will be at transmitting noise from the motor and pulley. If you ameliorate that issue by using a compliant belt, then you have more belt creep, leading to speed inconstancy. The best virtue of a belt-drive: cheap to build.
You can like whatever you like, but keep the facts straight. IMO, the rim drive is the worst of both worlds, not the best of both. Mechanical vibrational energy from the motor is transmitted right into the platter with no belt to isolate one from the other. At the same time, the typical rubbery contact point between the drive wheel and the platter is constantly trying to rotate the motor in the opposite direction (per Newton's 3rd Law of Motion), and flaws in the O-ring result in mechanical noise and speed issues.
The big issue with DD turntables is simply electronic noise (EMI, especially) that could in theory be picked up by the phono cartridge due to the proximity between the two. Most of the time, the platter itself is an efficient shield. The other problem is motor cogging. But BD and rim drive motors are not at all free of that problem, either, and the best DD turntables have motors of far higher quality than what you will find in most BDs. Why I like coreless motor DD.
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Not to disagree entirely with Lak's point, but let's not equate rim drive with direct-drive. They are or can be as different from one another as BD from DD. Likewise, I think the Reed Muse turntable that I mentioned above offers the option of a form of rim drive vs belt-drive. In my thinking, rim drive is closest to idler-drive. On that subject, I've got my much modified Lenco sounding pretty near exactly like my tweaked Victor TT101. That was not intentional; it just came out that way.
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Sorry if I was too rough on you. You told me privately which two turntables you compared. I was interested to learn that they are both from the same company, one a DD and one a BD. That right there is a topic worth discussing: why did the one company market two technically different turntables, and how is it that they sound so different? I'll leave it to you to reveal the name of the company, if you wish to do so.
There's also that Reed turntable, the Muse, I think, which can be configured either as a belt drive or as a rim or direct-drive, can't recall which. Some early adapters seemed to prefer it as one or the other, with a very clear preference.
My position would be that the single most important job of the turntable is to get the speed right and keep it right during play. Once that job is accomplished, there are still many other factors that govern how the turntable "sounds" overall, probably related to resonance or lack thereof. I've come to believe that a really good DD does the prime job better than a BD at the same level, but when BDs get REALLY good, they can do it too.
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This is meaningful only in the sense that you have compared two turntables and found that you like the sound of one better than that of the other. Period.
I can tell you about two direct-drive turntables, one of which has an inherently more "romantic" sound than the other. I could do the same with two belt-drives. |
