Sounds like a Tesla turbine.

jh

Actually I was more thinking about skin friction drag. Did you throw the stones to slide off the water? All that is necessary is speed of rotation of this thing…

http://en.wikipedia.org/wiki/Skin_friction

In fact if this thing reaches own cruse high-speed rotation then the vertical bearing might be even dropped as it would hold itself strictly vertically under the principles of angular momentum. It is similar to the old sea navigation systems that maintained orientation in gimbals…

The Swiss company Da-Vinci Audio that use to make very interesting LC phonocorrector it looks like trying to hit the jackpot with TT design. I look at all the TT that are being made I never stop wondering what the ultimate from my point of view shape of Micro Seiki 8000 never was embraced by other companies. The way how Micro did the bases was the simples possible and that allow putting in the same footprint max among of arms with unlimited design, since the arm-boards allowed spinning on their pivots. Well, it looks like the Da-Vinci has gone there:

http://www.da-vinci-audio.com/Turntable/reference_turntable.htm

They use a heavy platter with vertical magnetic bearing. The same design only with this older model according to them was 100kg – it already a solid mass. I hated their older design - it is what people do for stupid visual appeal instead of the best implementation of the functionality. The new design, it looks like it is a prototype right now is very good and it should make a TT that is very convenient to deal with. I hope then will make it with a reasonable price and I hope it will sound well. Yep, the reasonable price it is exactly what should be expected from Swiss manufactures and this US distributors!

The only criticism that I would express about the new Da-Vinci TT idea is that they allow only 2 pivots for armbords – it should be 3 as there is one extra space that is not being used. In the rest I applaud the direction the Da-Vinci Audio has gone with this new TT objectives.

I still feel that there was nothing more elegant in the disc/platter interface invented then the negative curve and all those vacuum or “no-vacuum” solutions are half-ass solutions. The negative curving is longer to engage but it takes time until vacuum builds up as well….

I would personally discard the whole subject, as I do now, and would play the records without forcing them to do anything then just freely lay atom of platter. But I am a freak in it as I do not like even the records camps. I have camp but I hardly ever use it….

Romy, what do you mean by "the negative curving is longer to engage"?  I picture a platter that has been machined to the negative trace of the LP face but without any means to "engage" the LP unless there are further stipultions, such as weights, clamps or vacuum; in other words, the negative trace itself is just a "mirror" resting place where the disc sits +/- , according to how flat it happens to be, unless and until the disc is made to conform and sit perfectly tight by other means.  Of course Micro did have high-tech vaccuum TTs available, too, although I know nothing about them, nor do I know anything about their propritary clamps, if they had them.

It appears however that I am the oddball, with the vacuum, since the vast bulk of TTs are sold and used without any means, let alone any effective means, to couple the LP to the platter, negative curve or no, and most people who use the clamps believe they are just flattening the warped LP with them.  While many people want to think they are coupled, most of that lot basically does nothing active to ensure that it happens.

If anyone following along has used low-pressure vacuum for a while and then gone away from it, please speak up and offer some intelligent reasons for your switch.  Although Lloyd Walker makes some very interesting observations during his clamp versus vacuum arguments, the "tap test" and subsequent listening comparisons have convinced me of the generic fact that well-done coupling is very beneficial.  In my comparisons I hear no advantages in loose discs.  Needless to say I am curious to hear the Walker, although it could be pretty scary, given the ancillary equipment they all seem to use.  Even so, as I laid out in my "Balls to Shop" thread, there might still be some There there.

Best regards,
Paul S

Paul S wrote:

Romy, what do you mean by "the negative curving is longer to engage"?

Paul S wrote:

Although Lloyd Walker makes some very interesting observations during his clamp versus vacuum arguments, the "tap test" and subsequent listening comparisons have convinced me of the generic fact that well-done coupling is very beneficial.  In my comparisons I hear no advantages in loose discs.  Needless to say I am curious to hear the Walker, although it could be pretty scary, given the ancillary equipment they all seem to use.

I am NOT a big fan of Lloyd Walker, I do not pay a lot of attention to what he says and I genially am not happy with what he does or willing to do.

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.