That is a whole another subject all together. I truly have no strong opinion on the subject but I do hear a lot of talking noise about the “quality” of motors for heavy belt driver turntables. My idea is that with a sufficiently heavy platter and proper tension of belt the influence of motor should not be issues for sound. Some people disagree and invest a lot of efforts, or at least talk into the motors. Go figure….

AC motors, DC motors, synchronous, asynchronous, brushed, brushless, big and powerful motors, under-powered motors, and motors with heavy flywheel… whatever people use. A friend of my a few years ago wanted to manufacture extremely advanced TT and he invested months of searching and huge financial efforts into founding of a “perfect motor” for TT. He calmed that it is virtually imposable to found a “right” motor for TT. Eventually he found some in Austria I believe some old new stock motors that he claimed “are the only one type of TT he have seen that could do the job”.  I have no idea what his problems with motor were, as well I am not exactly compostable with his technical justification but he did invested a LOT into the notions of “perfects” TT motor.

Interesting that I have purchased from him one of those outragesly expensive “unique and perfect” TT motor, more expensive then the cost of some turntables in many hi-fi installations. I made that “unique” motor to drive my Micro 8000 TT and… I heard nothing different. There was literally no impact if it was a different motor, so the “unique” motor is sitting in my storage….

Actually it is surprisingly interesting. It is a German company and they do a fascinating and it appears to be appealing turntable

http://www.soundscapehifi.com/tw-acustic-raven-ac-pics1.htm (you can click the images to enlarge them)

I like the configuration: simple and with no-nonsense. The base looks like polymer presumably with solid mass. The platter is steel-type, presumable non-magnetic. The TT has not too overlay sophisticated bearing but the top layer of platter – the brose layer is decoupled from the bottom steel layer with polymer layers. I am sure that if the density and mass of that polymer layer to tune properly then the design might yield very interesting results. I like the idea quite a lot.

The same company does the 3-motor version that I believe is foolishness…

http://www.soundscapehifi.com/tw-acustic.htm

…but the initials direction of the TW-Acoustic I found quite fascinating. I never seen it or heard it but it looks like it is $10K turntable - very much worth attention.

Paul Costa wrote:

Aparently the new powersupply for the motor makes it sound even better, but I have not heard it or the three motor.  I would like to hear the three motor but really do not have any interest in owning it.  Much debate on the synchronization of the three motor tables, some folks say it deos more harm than good.  But TW uses only one belt and the belt has minimal surface contact with the platter perimeter.  How it makes any sense I do not know.  They say it has a bigger sound and better pitch stability and more torque with less belt contact.

Paul, I have a lot of attitude toward it and I believe that 3 motors, 5 motors, 543 motors is very idiotic direction. Why a minimal surface contact with the platter shell be better? A belt applies moment to platter only in the area of initial attack of platter. The rest of the belt juts lay on plate with no effect at all. Why we need more torque in belt moment? We need opposite - as soon the platter hit it;s cruise speed we need less torque. I also do not know how all that PS paranoia for TT motors makes any sense. You see: those types of the tables, with platter of over 10kg have absolutely enough stability from a passive, regulated low-torque motor. They are stable and do not worry about the stability. Then the designers introduce the sophisticated systems of the motor management, with servo, with sensors, with feedbacks… you name it… all those extra intelligence in motor make a bad damage to sound of TT. When a single belt drives a relatively heavy platter with low BUT CONSTANT torque then the micro-beating in the bearing is stressed on one side and the TT is in a perfect dynamic equilibrium. As soon the torque begin to fluctuate then the TT’s bearing jumps out cruise beating and all hell get loose. The CONSTANT torque in a way biases the platter bearing. So, I see all conversations about better PS in TT as marketing BS the has absolutely no relation to actual sound

I'm not convinced a constant side load on bearing is good.  It causes assymetrical wear.  Just seems to me a center balanced bearing with no lateral loads would be better.  Merely an intuitive hunch.

As for the copper, yes, it will ring all by itself.  But reaction is much different when sandwiched or clad.  I think what the designer is trying to do is an impedance match or translation.  We go from soft vinyl to a hard and damped sink.  Putting the vinyl directly onto the mechanical sink is not right.  The idea is to convert from one impedance to another in a broadband manner.  Same as with a horn!  That is what rubber or felt mats do on most tables.  The copper on the Raven replaces the mat.

jh

hagtech wrote:

I'm not convinced a constant side load on bearing is good.  It causes assymetrical wear.  Just seems to me a center balanced bearing with no lateral loads would be better.  Merely an intuitive hunch.

Yep, the center balanced bearing is certainly better but dues it exists in a real word. I would say it never exists. The assymetrical wear is night not be good but… it is where the bias of a platter with a belt of constant torque makes the wearing irrelevant.  If cause they are all hypothetic theories and how it all works in a real word I have no idea.

hagtech wrote:

As for the copper, yes, it will ring all by itself.  But reaction is much different when sandwiched or clad.  I think what the designer is trying to do is an impedance match or translation.  We go from soft vinyl to a hard and damped sink.  Putting the vinyl directly onto the mechanical sink is not right.  The idea is to convert from one impedance to another in a broadband manner.  Same as with a horn!  That is what rubber or felt mats do on most tables.  The copper on the Raven replaces the mat.

I agree that it is not advisable to use copper without a mat. When I was in Japans I had a dinner with Micro-Seiki designer and I ask him why some of the identical Micro TT have copper or steel platters. He explained to me that copper platter by nature have idiosyncratic colorations that he felt was it a offset for SS electronics of 70s and 80s. I used Micro a few 1500, 3000, few 5000 and 8000. The 1500 had steel and I was able even to lay the record on the platter. Other 1500 with copper platter were too colored. I never was able to play the 5000 and 8000 with any heavy platters, in fact the 5000 need a special platter.

So, I think that TW’s copper top is not a big deal. The most important is how the TW’s people made and tuned the middle insert of the platter – here is where all hart of this TT lives in my view. If they “voiced” it interestingly then it shell be an interesting turntable. How much elections they stuffed in PS and how many motors they made their customers to buy is irrelevant and serve only the objectives of Framer-level BS literature.

Romy the Cat wrote:

What attracts me to the TW TT is the idea that it is possible to discard anything that we might consider important but to make the platter as a sandwich what the bottom of the platter care bearing but the top of the platter is decupled from the bottom by some kind of anti-resonance layer. The concept I think is superbly powerful. It to plug into the game some very serious materiallogists then I think it might be possible to make an collection of the insertion rings with different level of viscosity and energy-transfers characteristics that might be placed between the bottom and top of a platter and tune the sound of turntable to what is necessary. Very cool idea of making active turntable instead of staticly-made design. Pretend that you get a TT base with a collection of 10-20 insertion rings and you in your own room ( considering how your TT install, what arm, cartridges, and zillion other criteria that influence your sound) is able to tune the TT to sound neutral in your specific circumstances. After you done you return the leftover rings to the manufactures. I think it is incredibly powerful concept, Very liberating concept!

pretend we have the same platter at Tw has with mass-loaded bottom, light top and middle anti-resonance section. The anti-resonance section is not the polymer that TW uses but a two sandwidges of light multilayer mater similar to what Kevin Tellekamp uses - a chemical saturated foam that resonates ant temporary hardening at given frequency. Those two sandwidges are divided by air bubble. Now, we install the TT, set up and then we attach to the platter a bicycle air pump and begin to pump air into the air bubble inside the platter. The air bubble with the raise of pressure presses the side of the sandwidges, changing the frequencies where the sandwidges operate. So, we effectively implement a situation where a platter might be fine-tined for the specific ant-vibration characteristic that might take place in a given TT situation. BTW, the same sandwidges-air-sandwidges decupling might be used between a TT’s base and the tonearms….

If it works then would you like to take it further: be my guest. Let the fantasy to fry and let call the concept as Active Suspension.  Pretend a TT with Active Suspension, eclectic compressor and high precision manometer shadowing psi in the platter bubble. Then pretend an electromagnet at the bottom of the base with an anchor making a mechanical ping to the body of TT. Then a phonostage has a scope hat allows read from the cartridge the bottom base ping. By modifying the pressure of the bubble and changing the ant-vibration and damping characteristics we monitor on the scope a regular impulse response of the entire TT suspension. We can even set a desirable pressure for a given records thickness, pressing type, type of music… whatever….

newbie here but this interests me as i have the baby raven one.  the platter of the ac is hollowed out and filled with a gel and then topped with the copper "mat".  why is this important?  because vibrations exists is 2 forms, s-waves or rolling waves and p-waves or compression waves.  in a fluid, s-waves do not exist (think about it, how can a fluid roll?).  this leaves just the p-waves.  as the p-wave passes through the different materials, some will be refracted and trapped in the boundary layer, some will be attenuated and continue on it's path and some will be reflected.  reflection is what we want to control.  this design eliminates much of the vibration propagation but one needs to be careful not to make the table sound too dead or there will be lifeless sound with no dynamics.  so voicing becomes as much an art as a science.

the raven one platter is homogenous, made of one like material.  it still sounds great though.

ducatirider wrote:

a load on the side of the bearing could cause an elliptical rotation.  since we are dealing with micro-engineering the effect is likely audible.   Arthur Khoubesserian of Funk Firm uses a single motor with 2 additional pulleys to even out the lateral bearing force.  this idea eliminates the need for 3 motor synchronization.

Yep, I never was a big fun of 3-motor synchronization; in fact I feel that multi-motor idea is very bogus. If to pretend that we do have elliptical rotation then the fact itself that we have it is not a big deal. The bad thing is beating of spherical axis from one side of elliptical to another during the palter spinning. If a spherical axis has elliptical freedom but sits in one side of ellipse then it would be as good as no elliptical beating is available.

Fist I feel that an idea of a single motor itself is something that would keep a spherical axis leaned to one side of a hypothetical elliptical wearing of out bearing. The moment is continually applied to one side of platter effectively “biasing” the platter. There is way to take this presses further – introducing an artificial “brake” on another side of platter (or at any side at this meter). That brake acts like a mechanical grounding rod – it forces the spherical axis to sit very firm in elliptical corner. It also makes the driving belt from motor to work harder. By adjusting the force of the brake (mass of the pulleys, their driving diameter or whatever) it is possible to fine-tine the rotation system. Micro had this done with passive horoscope then the suggested to drive of the main platter. I like the idea but I feel it is very bulky.

What I experimented and go very good result was “suck out roller”. It was a soft rubber roller that was running off my driven by belt platter where the tension on the roller’s bearing was enough to bias out my platter. I was able to measure the fact the platter “sees” the roller. The Idea worked very well; however, I have to admit the all of it had no effect to auditable result. Eventually I returned back to just a simple and no fancy mass load platter with a single motor and loose belt…

There are several sources of relatively static and fairly variable noise and vibrations that a TT deals with, and likely there is no one way to deal with all of it at once.  A coupled fluid will likely let loose at some point where another form of anti-vibe must seamlessly take over, trap and then somehow disapate "noise".  In the case of the platter, there are broad band resonances from the environment and the TT's self noise, in addition to the mechanical interface of the stylus in the groove, and this is stuff we do not want amplified.  Some gets loose into the arm and some gets into the vinyl, and some of it shows up at the stylus - again - when it's no longer wanted, or it otherwise enters the amplification chain in an undesirable form.  Lots of interesting "proprietary" "solutions" out there, and in the case of expensive TTs they somehow tend to look like SOLUTIONS, as well.  Well, I suppose they better, after all.

The drive issue has been both way overblown and under-developed, practically speakingh, IMO, in that the theoretical forces we are talking about are miniscule in practical terms.  The "eliptical" bearing force loads are easy to incorporate in a captured bearing or bearings at both ends of a located shaft, and nothing I have seen or heard to date has convinced me of the practical worth of extra belt(s) and/or motors, in dealing with these issues, either.  My own experiments with belts show that the practical minimum is the best length, as they tend to develop vibrations and even cycles of vibrations if too long.  I just don't get, and I have never heard, how adding extra drive elements can help, in the end, when it is just more stuff to do something else, ie, it just becomes another variable (loose cannons).

Once the math starts, it just keeps going, and IMO it gets untenable, fast, and the super-engineers are left to "solve' only a few of the storm of "problems" that the "rigorous" approach generates as each factor introduces new factors.

In the end, of course, there has to be a balance between abstract science and practical application on the one hand and effective marketing on the other hand.  So far, it looks as though marketing is the biggest consideration in most cases; if not in the beginning, then certainly in the end.

Still waiting for the Ultimate TT...

Best regards,
Paul S

ducatirider wrote:

so voicing becomes as much an art as a science.

perhaps "voicing" was a poor choice of words.  but i don't think there's any designer that would put a concept into production before testing it for sound quality.  and then tweaking until the desired effect has been met.  tw spent decades perfecting his material choice for the plinth.  even a raven ac today has a different motor controller than one from a year ago. i do agree that there is no "ultimate" anything in this world.