I went through Mark Kelly's extensive teachings. Good research and explanations, but he is not focussing upon the center point.
Some people will hate me for this, but I want to postulate a short and clear statement ( and I ask everybody to give it some deep thought before telling me I am wrong....) regarding ANY principle in turntable drive (idler, dd or belt):
The motor of a turntable has ONLY 2 jobs to handle.
1.) bringing the platter on speed
2.) preventing the platter to slow down once it has reached that constant speed
There is nothing else the motor / drive has to do.
Physics and logic will result in a huge inertia ( = huge mass of platter) providing an extremely constant speed by its own rotation. It will too result in a coupling which does allow some slip at BOTH ends of the drive system - platter AND motor (such that little variations in speed generated by the motor itself will NOT make it onto the coupling device (string, belt - whatever). A say 35 -50 lbs platter on 33 1/3 rpm rotation has a VERY constant speed (much better in its constant speed stability than almost all motors in use in todays high-end turntables).
It is not about control between motor and platter.
The platter will not get any "faster" once it has reached its determined speed.
It gets slower due to air resistance, stylus drag etc. But those are constants in real world application.
So - all the motor and its coupling device have to do is preventing the platter from getting slower.
This automatically does lead us to a definite slip coupling and a huge inertia.
The way to get ultra constant speed and practically zero derivation in as much inertia as possible (in real world application).
Give it a deep though before jumping to the keyboard telling me a stupid, narrow-minded fundamentalist.
Its all about masses in motion.
Again - its all physics.
The trade-off is a long time to arrive at stabilized (2-4 minutes) speed. |
Micro Seiki has a kind of tape (SF-1 Series) with an enormous grip, it is very sought after these days. It was in my comparison among the best. (After 25 years a quite impressing result) There are more options with the Seiki units out there. Seiki "Shot Gun 1"Seiki "Shot Gun 2"I was influenced from the original Micro Seikii HS-Inertia unit Seiki InertiaAnyway, the way I do it works quite well and there are differences in sonics with/without. A good "tool" for comparisons. But depressing. For the others. |
Syntax, In that third photo, is the platter on the right driving the platter on the left, as it appears? This is in keeping with some of Mark Kelly's teachings on "belt creep" and how to prevent it. Anyone interested in this topic should search on the Vinyl Asylum archives for Mark's ideas. He is a brilliant guy who applied math and physics to belt drive and who compared the different qualities of idler-, direct-, and belt-drive to each other, also on a math and physics level. Far be it from me to speak for him, but based on my understanding of his findings, a very long thread between a very narrow diameter pulley and a distant platter is not a good idea, likely to result in significant belt creep compared to other arrangements, such as using one platter to drive another, using capstan type devices to force the driving string to conform to as much of the circumference of the driven platter as possible, etc. |
So this futzing-about with various types of belt media and such . . . I take it that this is pretty much "de rigueur" to get the best from any turntable that uses the thread-drive approach? What did i.e. Micro Seiki originally intend for the RX/RY-5000 system? |
Ah, yes!
a = (2*f*sin(x))/mass
Thanks for the trig review. ;-) |
we can not achieve perfection - we can only try. The long string is no compromise at all. Yes, the string has no stretch at all (a special kevlar derivate). The point is not control of the platter rotation. The point was to prevent the platter from loosing any speed. Control is futile. Some months ago I tried different belts after reading the article from Conti (BASIS Audio) about it. I bought a few from different Manufacturers and made some test runs with the Micro Seiki 5000 (Belts from Raven, Basis, DaVinci, Amazon, Kuzma, Roksan, Transrotor, Seiki original....and even various ) Strings..... The result made me curious, because there were big differences in sonic presentation (smeared Details, dull bass, different depth of soundstage etc.) Even with string was different among themselves (slip, grip, noise etc.) This was a very interesting experience for me. Some belts are really lousy, I was dissapointed, there are much discussions about more motors, or powerful motors...after all, I am smiling about that. The goal should be to find the few, who do it right. I mean, really doing right. No talking about that (most "manufacturers" today prefer doing this). When one or he other reader want an upgrade, before selling the whole Turntable, try this first. Could be interesting :) Belt Test 1Belt Test 2String Test 1 |
Dear Dertonarm: Thank you about your system, very nice. No public comments from me other that : yes, for me is of some help to understand ( between other things ) part of your whole audio " thinking/mind ".
Regards and enjoy te music.
Raul. |
Dear Kirkus, I know that these were not your motivations - I just wanted to set some points clear as the turntable sure looks like a "mammoth" in the picture and thus the above mentioned suspect might easily arise. But - thank you.
As for the string - just briefly and preliminary, as I have to leave the computer soon:
The basic idea / principle is to have a homogenous mass put into constant rotation and then let the inertia do the job. The string in its kind of "slip-coupling" (which is kind of tricky to set-up and needs a calbrated spring gauge to ensure the perfect "non-grip") does have only one job (after bringing the platter on constant speed once):
- prevent the platter from getting slower.
All I can say - and this time I just plain ask you to take my words for granted - is: it works extremely well. We made long period measurements in MTU in 1992 and the derivation from 33 1/3 was (short-period as well as long-period derivation measurements) as close to zero as possible (measurements were taken with laser beam and calibrated circular stroboscope foil).
And - yes, the measurements were made while stylus was in the groove.
This is a huge inertia (the platter is 326 mm in total diameter - 108 lbs) in motion.
Once in motion on the desired speed, there are no derivations. The air resistance, the bearing friction (...the stylus drag..) these are all constants and thus the rotation stays constant.
It however takes about 2:35 minutes to reach constant speed........
The string just have to be dyneema or kevlar derivate and the coupling has to be precise.
But it works marvelous and watching it work, you get a certain "feel" of "completeness" and "natural move".
Audio phrases......
Time to get off.
Good night for now. |
I wasn't on a field campain just to bring as many troops as possible on the battlefield as to crush the enemy by simply overwhelming him by sheer number and brute force.
From the plain dimensions this may look as just another gigantic egomatic turntable where weight and money were the driving forces and the brain was replaced by the big wallet. I didn't mean to insinuate that these were at all your motivations, my apologies if it came across that way. I was simply trying to give a little counterpoint to the general discussion, and make the point that the consideration of cost isn't necessarily anathema to the pursuit of perfection. Lewm did bring up the string . . . I'd appreciate it if you could explain some of the dynamics involved here, as I don't have much experience with thread-drive turntables. While the mid-1980s Micros and such are designs I've always admired and enjoyed listening to . . . I've always been a bit mystified as to how such a thing as the alignment of the pulleys, the tautness of the string, etc. (which strike me as critical parameters) were left up to the end-user to get right, when there was obviously so much effort into removing variability from so many other aspects of the mechanical design. Also seems really inconsistent with regards to temperature, and wear/stretching of the string itself. Are these significant factors, and does it ever bug you that maybe with sub-optimum setup and maintainance, your designs over the course of the years may not be delivering the performance you designed them to have? |
Dear Kirkus, yes, I have put some money in that project back then, but I got paid back and in the end I did not loose any money on that project.
As I usually do like to link philosophy with my audio discurses, I must however admit - not today . I am not in the mood - I am afraid. Most likely it will brighten up again tomorrow... ;-).
So rather plain and straight speak now.
So far my odessey in audio has been - on the large scale - cost neutral. I rather wanted to illustrate my point that all too often we do give in too easy. All the money I did put in that project in the early 90ies did not come easy. As I certainly always had to work for my money I wasn't too tempted to throw it away. I did put lots of work into that project - much more than money.
I wasn't on a field campain just to bring as many troops as possible on the battlefield as to crush the enemy by simply overwhelming him by sheer number and brute force.
From the plain dimensions this may look as just another gigantic egomatic turntable where weight and money were the driving forces and the brain was replaced by the big wallet.
Certainly not so.
Cost was an object indeed.
Sadly enough - I do not have money to burn.
Not back then - not now.
Being self-employed means you work everyday and on your own (your own risk too....).
I am certainly much more on a budget regarding my audio passion compared to several other Audiogoners.
Thats why I designed my own turntable, amplifiers and speakers.
Because I am on a budget AND because I did not find what I was looking for.
There was much more research put into that project than my mere words and the picture can tell.
It may however give some reason why I am not too impressed by the "state of the art" turntables of today.
Maybe I just want to say:
I know what I am talking about ............ nothing else.
BTW Raul, one sample of the turntable was in Mexico City from 1993 to 1998. The owner was (and still is...) the former director of BMW Mexico. I sat up the table in your impressive city.
P.S.: agreed on the ET2 - it was just mentioned to clarify the point why the TT had several individual adjustable air supplies for the many different designs in airborne tonearms around in the early 90ies - all having different needs. |
Wow, thanks for the picture, Syntax. Very, very cool work, Dertonarm. Since we're hitting on the subject of "how do we pursue perfection" . . . this is of course a difficult question, both in the defining and the persuing. I think that there are several of us here who are frequently travel on this obsessive road in one way or another, and it seems to be ultimately a reflection of one's concept of their own mortality. And I've always enjoyed how much audio and music parallel each other in this capacity. But to lighten up a bit (I attended a funeral yesterday), there are always a couple of big obstacles in the pursuit of "perfection", the first of which I'll call the "Hubble telescope phenomonon" . . . where a focus on the tiniest of minute details causes one to completely miss the end goal -- that is, a telescope mirror with an amazing level of polish on a micro-level, and a huge macro-level flaw that goes completely unnoticed. Dertonarm metioned the Eminent tonearm, and I'll use this as an example -- great low friction, but horribly excessive horizontal mass (not to mention dirt-sensitive). The other common problem occurs with high-budget, limited-production projects. . . where from a true perfectionist standpoint, the contribution of every single design, material, and manufacturing decision must contribute maximally to the performance of the end unit. But the "cost no object" attitude actually can work against this, as there's the temptation simply to throw money at a given problem, because after all . . . what's mere money when perfection (and ultimately immortality) is at stake? And in reality, the assumption frequently gets made that simply because a problem has received great financial attention, that it is therefore solved. Thus, the input of cash has distracted the builders/designers from the required process of analyzing its contribution. Both of these are what I feel are some of the currents that drive up the cost of our hobby, without necessarily driving up the quality of the experience . . . and that's very much away from what I'd consider perfection to be. As Dylan Thomas said: The force that through the white thread drives the platter
takes my green dollar; that blasts my bank account
Is my destroyer. |
Dear Raul, right now I am in the process of building the successor of the turntable Syntax has pictured. This project will be finished in autumn this year. I will include some thoughts and technical features I either could not include back in the early 90ies - or which came to mind in the last years.
I did not post any pictures of my system, as it would not help people to get an idea. Aside from tonearm and cartridge none of the other parts of my system are commercial products. However - I will briefly describe the system.
The preamplifier is all tube. Split passive RIAA. First 2 stages are full differential stages (1st time constant of the RIAA is equalised here). Between 2nd and 3rd stage the other 2 time constants are eq'ed. The 3rd stage is a pure plate follower. All triode. The line stage is full passive with transformer attenuator made by friends in Japan. Output impedance is pretty constant 120 Ohms. It drives several meters cables and 3 different pairs of amplifiers in parallel (and live athmosphere, rich colours and live-dynamics are my prime focus in playback audio). The preamplifier is full hand wired with all silver. All tube sockets are mounted on individual PTFE platforms in open frame architecture. All resistors are Shinko Tantal. All capacitors are silver foil in oil. The whole open frame arcghitecure of the Phono circuit is itself suspended inside the 2 cabinet preamplifier by special soft rubber anti-vibration poles. The powersupply is full dual channel with 4 rectifiers (double single wave) and all PP power capacitors with dual bifilar choke LCL filtering. All selector switches are massive silver TKD. Total 6 phono inputs with various transformers to accommodate and match any given source impedance and inductance by any moving coil and MI or MM.
The whole system is tri-amplification. E
ach woofer is sealed cabinet, 18 to 80 Hz with 500 Watt amplifier with active DSP. The woofer driver is a 18" unit with an BxL of 32 and maximum excursion of total 28 mm in sealed 70 litres. Mid bass and mid-highs is a 2 way system with 8" field coil paper driver with huge choke power supply and 80 000 µ filtering. 12 V supply. The tweeter is a 28 lbs unit which goes from 800 to 45 000 Hz. A ribbon / planar hybrid with 100 dB efficiency (past crossover). These two are mounted in an inverse ultraflex cabinet with a combination of 1st order electrical x-over (1 coil in low-mid - 1 capacitor in mid-high) in conjunction with approbiate mechanical filtering in low-pass (pre-chamber) and high-pass (super short tactrix). The cabinet itself has a special adjusted build-in mechnical high-pass with -3dB at 80Hz. Thus giving a pretty smooth melting between the active 18" woofer and the 8" mid-low driver. The whole system has measured 99.5 dB efficiency. Max. SPL 128 dB. Phase never worse than 8°. Pretty flat response whole band.
The amplifier for the tweeter is a special 8 Watt 1 single pair bipolar concept designed by STAX/Japan in 1980 but never commericalised. It has a double 12V - 2 000 000 µF power supply, soon to be put on complete battery supply. It is capable to deliver 5000 A for short moments. The amplifier for the mid-low (80 - 800 Hz is a single ended MOSFet design with OPT. 11 Watt. The shortest signal path of any amplifier. Very similar to the Western Electric type 25 amplifier of the 1920ies, but build with a special MOsFet and matching huge Output-transformer. No input stage, no driver stage.
Tonearm is - no surprise - FR-66s and cartridge is a very special FR-7f modified. Cables are Audioquest SKY w/144v DBS all in NF and flat ribbon pure silver for the mid-high and mid-low.
But honestly - I do not think that this description is of any help.
It rather illustrates the point that I am not too impressed with the offerings of the industry but like to go my own ways. |
Dear Dertonarm: Do you still has in use that TT with you>?, btw: which analog rig/electronics/speakers are you hearing/playing/enjoying?, could you share with us?
Thank you in advance.
Regards and enjoy the music.
Raul. |
Dear Halcro, thank you very much.
To speak in the words of an era in architecture we both do favour: .....form follows function..... ;-)) |
Dear Lewm, we can not achieve perfection - we can only try. The long string is no compromise at all. Yes, the string has no stretch at all (a special kevlar derivate). The point is not control of the platter rotation. The point was to prevent the platter from loosing any speed. Control is futile. The platter must be stablized by inertia. Control and correction in speed will always result in a constant error-correction-loop. Thus creating instability and a constant change in speed. I think this is a clear fact - everybody into technical affairs and physics will agree in this after giving it enough thought. The inertia of the rotation platter is so stable - you can't even dream getting that stability with any direct controlled (= speed control both positive AND negative by the motor via direct coupling ) platter (dd, idler or belt drive).
I certainly do not want to start any philosophical disscusion here, I just tried to illustrate the point that all too often we go for a compromise WAY TOO EARLY and WAY TOO EASY.
Compromise in our culture is a positive term - because it helps to accept unpleasant facts and things the way they are.
For me compromise is another word for surrender.
I think we should not accept surrender (=compromise) too early - without trying our very best. |
The string "belt" on the mammoth turntable in the photo is WAY too long for optimum control of platter rotation, even if the string has no stretch at all, but I guess the inertia of the humongous platter mass compensates for this problem to a degree. I am also guessing that the very long distance between motor and platter is an exteme attempt to isolate the platter from motor vibration, a la the Verdier on a grand scale. Nevertheless, it is a "compromise". IMO, it is impossible to avoid all compromises in any design and in any other human endeavor. Wherever there is a choice between two options that each has its own justification, there will have to be a "compromise" with respect to some feature of the desired outcome of the project. God help the perfectionist. |
Dear Dertonarm,
My compliments.
Being the son of an architect has certainly paid off with a design that even the Bauhaus would be proud of?......but I know that only the laws of physics determined its appearance? :-) |
Ghosts of the past.........that particular unit is from 1993.
The base plates are corian on dural with polyurethane layer.
80% of the technical periphery is inside the integrated "stands" of turntable and motor unit (including active air suspension, surge tanks, automatic leveling.
Dimensions were 4 feet wide x 2.2 feet deep and 4 feet high. Total weight approx. 580 lbs.
Every wife's nightmare.
The motor unit does feature selective air supply for up to 3 airborne tangential tonearms (adjustable pressure and amount of air - these were the days of Air Tangent and ET 2 back then.....), adustable air supply for active suspension and radial / lateral air-bearing. All speeds 33, 45 and 78 are precisely tuneable.
And this was 1993........ |
Here is one of these 15 units, a pic from a High End Show, it was bought right away, when I remember right. Probably to a Single :) WAF free Zone |
Dear Raul, yes - a different room is the one and only way to isolate any turntable effective from SPL radiated by the speakers. No doubt. However - this has nothing to do with the turntable design itself. It is a matter of the enviroment/position. Put the turntable in the next room and drill a hole through the wall to allow exit of the tonearm cable or the NF-cable(s) from preamplifier to poweramplifier(s) - è voila!
But - a turntable can be designed to "near perfection".
"Everything possible to be believed is an image of truth " (William Blake , end of 18th century).
Its a matter of consequence, effort and energy put into the task.
However - a "near perfect" turntable can NEVER be a commercial design.
A space shuttle will never be a commercial product either (not as comparism here, but to clarify the point...).
Neither can the "near perfect speaker" and its cousins the "near perfect preamplifier, poweramplifier (always in close relation to the crossover and efficiency of the speaker) etc "(well, the pivot tonearm and the cartridge - that could work in the narrow frame of market-conformity). Any other commercial audio product will be - and was so far - always a (often more and rarely less) dreadful bundle of compromises (god - I hate that word since childhood!!).
To come anywhere close to the "near perfect" in audio components means in plain simply words:
- leave commerical audio products and the idea to bring that "near perfect" designed audio component to a "market" behind.
It will not work.
You have to do compromises to bring ANY product on a "market".
There is no free lunch in high-end audio neither.
Well - theres an old saying: nature knows no compromise.
Compromise may be indispensable to keep our past zenith society working as long as possible.
If we accept all too easy compromise in the development of audio components we will always get what we deserve and have gotten so far:
.....mediocrity...... |
and that's is " simple " task because there is only one person on the design but what if there are two-three-four persons on the design and everyone with the same " right " to make an opinion valid.
I know the big " trouble " here because some times in the design one or more opinions goes against each other and we have to be very very open mind to make the " final " decision on the subject below discusion. Not easy at all.
We " face " many other issues: exist the technology to build what we " think " on the design ? are there the build materials/parts in a precise way we need it? can we manufacturer if not?, questions/answers like these have its own trade-offs.
The design/build of any audio item is a real and hard challenge for everyone but big corporations like Matushita Harman and the like.
Regards and enjoy the music.
Raul. |
Dear Kirkus: I agree with you on the subject.
A TT design are develop on many " factors/characteristics " that have an intimate relationship that makes almost impossible to build the " perfect " TT and like in almost any audio item design we have to choose the best trade-offs and these trade-offs are the ones that make " the difference " but almost every TT designers have its own trade-offs priorities and to be more complex that TT designs comes to a different customers that have its own sound reproduction priorities.
Yes, we can make a TT design near " perfection " according our own technical trade-offs and the ones are not so technical but that have some kind of influence.
About, isolation: how can we aisle the TT from the SPL of speakers in the room?, maybe looking for the lower SPL in that room or taking the TT in a different room where means a different kind of trade-offs. In a TT " perfect " design we have to think about and in many ther obvious factors and other no so obvious ones.
Here we are talking on macro-isolation but there are micro-isolation that are way important too, we have to remember that the cartridge is a very strong " micro ". You point-out the importance of the arm board and I can add ( example ) the importance of a TT mat and we can go on and on. Interesting.
Now, we can put the best technical know-how on the TT design but we have to test on laboratory ( truly expensive ) and in a second step ( critical ) we have to test it in our own laboratory: ears/brain, not an easy task, each one of us has a different " approach/attitude " in the same subject!
Thank's to those human been " differences " exists different/many TT designs out there, good thing.
The subject is how the TT designer can improve ( near perfection ) its own design, it want to do it? are enough TT customers that could pay the price for that " near perfection " TT to make commercial business? can the market/customers understand the advantages on that " near perfection " TT?, I think that exist too many questions and too many different answers to each one question.
As we can try to go " in deep " on the subject as more questions come " alive " and this is almost with any audio item design.
I know ( like Detornarm ) what I'm talking about because in our Phonolinepreamp we already be " face to face " with all those " problems/trade-offs " ( and many others ) and we stay right now in our tonearm design: complex for say the least
Regards and enjoy the music.
Raul. |
Dear Kirkus, - well a Micro RX-5000 on a (specified for the Micro 5000's weight load) Minus-K is already a different beast.
The one vital point is, to really use a platform only, which is specified for the exact weight of the turntable in question.
One problem is however, that all the benchtop isolators do only perform their best with fairly heavy load (at least heavy for a turntable...).
As the better ones are designed to work with fairly big (= heavy = expensive...) microscopes and similar costly technical measurement equipment (= the users have little limit on spending extra to get their instruments show their best....... as always - they are all "in it for the money"...).
However your proposal to carefully tailor laboratory-instrument technology hits the point. It is exactly what I am doing in my spare time the past 2 months. |
Thanks for the info, Dertonarm . . . I enjoyed reading about these products.
But it's not a matter of "re-inventing the wheel", its a matter of understanding the exact requirements so as to make sure we understand how well the solution fits the application, and the problems we're trying to solve. Because (to use a silly example), putting your tomato plants in the finest laboratory glassware doesn't mean their fruit will taste any better.
Most of these off-the-shelf devices (i.e. the MK26) appear to have a low-pass characteristic that somewhat resembles a Chebyshev response, which trades some pass-band ripple or peaking for increased performance in the stop-band . . . I'd speculate that this is an excellent trade-off for most of the laboratory applications for which they're sold. But for a turntable, the low-frequency peaking of these products may indeed cause some problems. I'm sure they still sound excellent . . .
. . . but if you truly want to do a turntable "right" as you say, then simply sticking i.e. an RX5000 on an off-the-shelf Minus-K platform doesn't cut in my book. Using existing laboratory-instrument technology might be a good approach . . . but if you want the BEST performance like you say . . . a custom-designed product that had its stopband/passband performance tailored specifically to a turntable application is what you should be after. |
Well, we do not have to re-invent the wheel here. All this research about suspension has already been done by industry with huge amount of manpower and technical resources. These problems are solved.
We just have to apply them to the turntable system and/or its benchtop / stand platform.
The only problem is: they do not come cheap (as any "good" turntable cannot come cheap....) .......
Have a look at the website of Minus-K and/or Kinetic systems or any of its market competitors.
What will do the work for an electron microscope will do the work for a turntable.
The better of these benchtop platforms will isolate from vertical AND horizontal vibration.
Foot-falls and usual household vibrations from washing machines and in-house motors are not the problem.
The problem is the all-present buliding resonance.
It was an eye-opener for me to actually "see" what isolation from enviromental vibration really means - and what it can do.
If we can agree, that the idealized working conditions are very similar for both turntables and electron microscopes (both "working" in very similar nanocosmos dimensions) - then we already have the solution.
In easy words: you do not have to worry about suspension at all if you put the turntable in question on top of a professional vibration isolation benchtop platform precisely resonance-adjusted to the weight of the turntable in question (and for god's sake - do NOT place any standalone/detached motor-drive on the same platform!).
Borrow one or try to get one from technical scavangers (there are enough companies around selling of the remains from technical-orientated companies getting out-of-business). I bought a good benchtop from Kinetic used via ebay for 1/20th of the list price (o.k. the transport from North Hollywood to central europe was a few bucks too, but not that bad).
Well - a really "good" new isolation platform will cost the same as any of the "avarage" turntables alone.
If the technical aspect and waypath alone are not enough proof, I recommend to all (for once..... to support the technical outline) following Raul's advise: listen to it.
The immediate apparent difference in sound-presentation will tell the story.
As I still am sure that we do work with techincal facts and issues only in the design of a turntable - the turntable "done right" will never come cheap.
If you are into off-shore boats or high-end rifles or high-end motors - no matter where - if you are looking for the "best" in those they won't come cheap either.
You just can't fool around with physics.
In the design of those topics just mentioned - are we dealing with taste or guesswork ? Maybe in the outlook, the cosmetics - but never in the technical design.
In turntable technical design (NOT cosmetics or appearance) its all physics - and honestly, there are moments when I do not like that fact either ........ |
That implies that the suspension should go as low as 0.5 Hz to ensure isolation from building resonance. I'm not so sure on this -- after all, at 0.5 Hz the relative stylus-to-record motion *should* be fairly well attenuated simply due to the fact that it's now several octaves below the basic cartridge/tonearm resonance, which is acting as a 12dB/oct high-pass filter. From emperical evidence, the cartridge/tonearm resonance envelope definately affects the sensitivity of a boingy suspended turntable system to foot-falls and such. So I'm thinking that the primary suspension mechanism of importance is its Q, and flatness through its transition region . . . so it doesn't add any additional peaking to the tonearm/cartridge resonant peak . . . the exact rolloff point for the suspension simply needs to be a bit (an octave should easily do) below the that of the tonearm/cartridge. The best results will then be acheived because the slope of the attenuation (provided by both the suspension and tonearm/cartridge working together) is smoothly increased, without increasing the peaking, and the ultimate attenuation at very-low frequencies could be similar to the system you describe. Another huge issue is how the suspension behaves with horizontal shock, in addition to its vertical behavior. I think that this is THE main flaw in the Linn/AR suspension, and just about every turntable suspension that uses compression springs. In these systems, since the mass of the subchassis sits above its support points, it's inherently unstable with regard to external horizontal motion. This fits with the long-time Linn recommendation of the Sound Org stand for floorstanding applications . . . something will minimise the addition of horizontal energy, yet cleanly transfers vertical energy to the turntable, where the suspension does its job the best. Ideally, it seems that the subchassis should be underhung with respect to the fixed chassis, resulting in a stable, predictable horizontal resonance . . . and there's probably some perfect relationship between the horizontal and vertical resonant frequencies that would allow horizontal shock to be converted to vertical spring deflection (through pendulum action). |
Dear Kirkus, there was no way to put that design into a commercial product. Too big (the Caliburn, Goldmund Reference, Micro 8000, Raven etc. were all dwarfs in size), too heavy, too much periphery, your wife would have shoot you and divorce (not sure which first...) upon the sight in teh living room.
And no way for trickling down in more convenient size and financial frame.
Anyway - I will do it once more this summer and autumn and will include a few technical devices which I could not integrate 20 years back. I will post the pictures and specs of the turntable in late autumn here on audiogon.
For all to share. |
Dear Kirkus, indeed. Suspension of ANY turntable from vibration (if possible from air vibration = sound pressure too........ but that is another story...) is elementary. It is not a question of idea, philosophy or sound preference. It is vital to isolate the turntable from any seismic vibration. That implies that the suspension should go as low as 0.5 Hz to ensure isolation from building resonance. ANY vibration will falsify the groove modulation and alter its amplitude.
Again - we have the picture of the active or passive (if possible... air) isolated work bench for electron microscope. The working conditions for that electron-microscope are almost identical to the ideal working conditions of a turntable (at least of a turntable trying to go for anything near maximal possible performance). Both dealing in similar dimensions too.
Every owner of a decent turntable - already with built in spring suspension or not - can easily check this for himself. But a Vibraplane or a Minus-K or similar benchtop platform underneath any given turntable of at least some merit. You will notice the difference right away (no - I do not hold any shares from either company mentioned....). These platforms were designed for small elctron microscopes and vibration sensitive measurement equipment. No high-end nonsense, but straight industrial devices.
Well worth a try before you spend the next grand on a 3 feet NF-cable.....
There is one other vital aspect I want to point out: energy transfer between two masses. One mass in active movement - the other serving as the (static) floor. Picture a billiard table and the ball in motion. Ever wondered why the billiard ball does roll longer on certain tables? Because there is a direct relation between the mass (= thickness of stone platter underneath the green wool) and the energy transmission between the ball and the table. The ball stops earlier on the cheap (= rather thin marble stone platter) and lighter table. Energy transfer. More of the energy of the ball rotation is transfered into the mass of the table. If the differences between the 2 masses is increased, the ( unwnated !!) energy transmission gets less and less. The ball has a longer run - it can use more of the energy given by the qeue's poke for its motion.
There is a very similar relation between the stylus and the platter. |
I heard in the last 15 years more average sounding units than I wanted to. Some are good looking, some are heavy, some are extremely expensive but at the end of day, well you know...average. Couldn't have said it better myself. And I think that one of the reasons why the audio community tends to make deities and martyrs out of certain designers is because their dream of making i.e. the ultimate turntable is something we can all respect, love, and identify with. And yes, the story behind a product is a very powerful (and legitimate) incentive to buy . . . but whether or not the dreams have actually been realized in the product is of course another question entirely. And there's also the question of what are exactly the objectives of a turntable "done right"? The story that Dertonarm tells of his ultimate turntable pursuit would be a frustrating one for me, because after that amount of work . . . I would personally want to see more than 15 people able to enjoy the pleasure of owning one. I think a truly successful product should put just as much innovation and excellence into the effecient use of materials and resources, and the financial model that allows it to be produced, purchased, and enjoyed to a significant degree. But anyway, I'd like to steer the discussion more toward what we think are the biggest weaknesses in most current high-end turntables, in a general sense across the industry. Personally, I feel that the suspension/isolation systems are the huge weak spot, along with the proper control and dissipation of resonant energy between the platter and tonearm mount. |
Well, I didn't read every post, but I agree, that Turntable construction is pure Physics. And like in school, not everyone is good in this, there are differences.
I am very careful with those arguments, that this and that Designer is godlike, because he is doing this "job" (whatever it is).
I heard in the last 15 years more average sounding units than I wanted to. Some are good looking, some are heavy, some are extremely expensive but at the end of day, well you know...average. Unfortunately.
Marketing can replace knowledge and when I read such stories "... sleepless nights the last 10 years because I never had a turntable here which met my expectations .... so I tried it .... and I got it ...."
A.J.Conti is one of those who do a better job, Verdier was one of those guys, too and a few others
But not everyone. |
Dear Halcro,******......."Surely Dertonarm, if pure physics made it all 'black and white' and "I have yet to see a turntable design done right."?.......why have you not yet......done it!? "******
I did.
Almost 20 years back. Together with 2 collegues I have designed and built (and they have been sold) 15 units and it did costs me alone approx. 230 000 US$ back then.
However - it was a turntable you simply could NOT sell through any High-End store due to size, weight and technical periphery needed.
The infamous WAF was way below zero. The technical features - brief summarize: a 100 lbs (very complex design internally) compund platter with a still unique approach of clamping the LP - suspended on radial AND lateral air bearing with 4 bar pressure. Whole 400 lbs turntable suspended by active air springs with 0.5 Hz resonance frequency. The motor drive - in the last incarnation without any force vectors on the bearing!! - was the big capstan from the professional Studer tape-machines. This design was backed up in the research and the tests by a division of a technical university.
Believe me - I have done it the hard way. For several years. There are good reason why my former remarks were the way they are.
As for stylus drag: - stylus drag is mainly the result of the downforce on the groove (vertical vector on the groove wall). That downforce is a result of the size of the polished area of the stylus and the VTF. Frequency modulation does vary that force only ever so lighhtly. So there is a varaition in that force, but only very faintly. AS the majority of the force is constant, it does add to the "friction" - however, it does not require correction during operation (which is impossible anyway ..... as you would create an error-correction-loop resulting in anything but certainly not constant speed).
Dear Halcro, I am familiar with all the above mentioned turntables. All those people need to SELL their turntables. Thier turntables need to fit into the living rooms of fairly well doing customers (at least if bought new in the store...) with some taste and expectations in design and a better half which sometimes does have a vote too. Furthermore their is an importer (sometimes) and a dealer (soemtimes) who need their part of the financial cake too.
In the very first all these turntables were designed and built for 2 purposes:
** unique selling proposition (by design or unique technical feature) to support the 2nd purpose:
** to make money....
A turntable "done right" will be huge, very expensive, extremely heavy and will feature some technical periphery aside the turntable itself. Imagine the working bench of a large electron microscope....... then you get an idea. |
Dear Raul - I do agree with you 100%. We - the customers - are indeed responsible for the products we get. Unfortunately we are a very small group inside the whole market for audio playback. As our buying power is way too small for the (global players..) industry to focus on, we do only get attention from companies which are small enough to be able (and are forced to...) to focus on a small niche of the market: - us, the audiophiles willing to spend fairly large amount of money to get satisfaction for their endless task for perfection and beauty in musical reproduction. And another "yes" - we will get mediocrity a plenty as long as we continue to buy it.
Only market behaviour will change the quality of the product. Nowhere as true as here in "our" market. |
I'd be interested in the discussions and ideas about turntable design and the 'pure physics' involved, yet at the same time, I'd imagine the 'real' turntable designers, those who have done the physics and actually produced a saleable commodity, laughing at us 'amateurs' wasting our time and efforts without the prospects of reaching any meaningful conclusions or resolutions?
Do we really believe that Mark Doehmann of Continuum Audio has invested 10 years of his life together with a team of 7 experts in various fields of mechanical, aeronautical and advanced systems engineering without understanding the physics involved and then testing the prototypes and manufacturing a finished workable product?
Or the Suchy family who have years of experience in turntable, arm and cartridge design?
Not to mention Harry Weissfeld, Lloyd Walker, Andy Payor, A.J. Conti, Roy Gandy and even Ivor Tiefenbrun?
And yet, for every turntable designer, there is a different solution or variation?
It is so easy for us to 'surmise' and point to the 'weaknesses' of various design philosophies but as the saying saying goes......"those that can, do and those that can't......?
Surely Dertonarm, if pure physics made it all 'black and white' and "I have yet to see a turntable design done right."?.......why have you not yet......done it!? |
Dear Dertonarm: +++++ " If the NASA had handled the Apollo - Mission that way, man would have never set his foot on the moon. " +++++
there is no single doubt about, everything must be " perfect " for that " job ", you can't have/make mistakes or " guesswork ".. science is the law.
In the analog audio " stage " science is still the law but the analog " world " is an imperfect one ( everywhere in the analog chain. ) that tolerate some " guesswork " in order to achve desirable targets.
There is not much research on the subject and not because there are not good audio item designers ( there are ) but mainly because there are too many " conformist and non know-how " customers: why a designer has to worry on a " perfect " design when no one is asking for? when almost no one cares about?
Almost all the analog audio item designs are more a commercial subject ( $$$$, in some ways it has to be, between other things. ) that a top quality performance to bring a top satisfaction to the customer, even the very high price items.
Where are the customers? where are we? how can the analog audio market really grow-up if we are " satisfied " with what we have? we are satisfied with the same/similar audio item designs of " 50-100 " years ago ( many times lesser designs. ), where we leave the " emotion " to explore to discover to think in a " new " way?: almost no one cares about and IMHO that's why: ++++ " I have yet to see a turntable design done right. " +++++ ( or almost any other audio item. ) we are " down " here " ( in a deep hole ) and not because there are not good " professional " designers ( there are: several. ) or people with the enough knoledge to do it.
This is not the first time that I point out these subjects and if we continue to pay for " mediocrity " that's will be exactly what we will have: " mediocrity ", IMHO I think that we need a customer " revolution ", we need to shake all those talent people out there for they give us what today we deserve, we are " the one " to make things change for the better we need to be active part of the changes.
Regards and enjoy the music.
Raul. |
Hi Raul . . . were you able to get any comparisons of stylus drag between a modulated and an unmodulated groove? I think that's one of the central points of most of the discussion of stylus drag. |
Dear friends: I'm not on the TT design ( tonearm/cartridge is my priority. ) but this discussion could help to everyone in some way or other, at least to understand what is happening.
Some of you " speak " about specs and IMHO this subject could be very controversial for say the least.
Many of the " standard " specs/measures on audio items ( any ) can't explain per-se why we hear/heard what we hear/heard.
My opinion on the subject is try to define what/where/how to measure and its relationship with what we hear/heard or our targets about. IMHO not an easy task: whom will fix/decide those " true/new spec standards "?. Anyway a good " exercise ".
A second subject: stylus drag. During our tonearm/cartridge research/design I made several tests and still doing ( for different reasons that TT design. ), one of them was this:
I choose seven different cartridges ( different stylus/compliance/MM-MC design, VTF, etc. ) and five different LP's.
The test was over the same TT and same tonearm ( at the same time. ) where the " only " variable was the cartridge ( well more than one variable due that each cartridge has different parameters. ).
The test was a " home test " not a strict controled and scientific one but interesting.
What we want to measure was how the stylus drag ( well the tonearm/cartridge. ) could change with different cartridge in different LP in different velocity recorded tracks that I choose.
What we do?: we put " that " cartridge in the tracks ( each one at the same time ) I choose ( running the TT at 33 rpm. ) and suddenly switching-off the TT and measure how many seconds take the platter to stop. I choose three tracks on one side in the LP: one at the outer of the LP one at the middle and one at the inner of the LP.
The tools I used was a cronometer, eyes and very fast " brain reaction ".
Not an easy test, I have to train for several hours ( two days ) till I " show " good " constant " response ".
This test show us that that stylus drag " exist ", that its behavior is cartridge/stylus/VTF/position on the LP dependent, that is different on different tonearms and TTs, that a heavy platter ( 20 kg. ) in rotation has an influence on that stylus drag when you swtich-off, etc, etc .
I know that maybe this almost " hobby-test " does not help on the TT discussion due that the TT was/is switch-off and that was not made it in a scientific/tools way but the test opened my " eyes " for our self tonearm/cartridge design.
It is not to easy the desing/research on " mechanical " devices ( like tonearm/TT and the like . ) specially the tests of those devices because it is not only a subject to have the know-how what/which/where/how but to have the precise scientific tools to do it: we need a laboratory and we need a lot lot of money to have that laboratory.
This issue is/was one of the reasons that bring us ( on the tonearm design ) to find where to do it, finally we meet our friend at the University and even here is not easy because is something " new " where the " scientists " does not have many experiences: it is an easy task for them nothing difficult but " new ".
Like always, I say every single day is a learning one to anyone in different areas/topics on our day by day life. There are more knowledge to discover to experience that our self ( each one ) know-how.
Regards and enjoy the music.
Raul. |
What I wrote was that any effect of stylus drag on speed will in part be a function of the distance of the stylus from the spindle (not "distance from the stylus"). I was referring to the mechanical advantage gained by applying a force some distance from the center of rotation vs near to the center of rotation. Kirkus got it right. |
Dear Kirkus, Lewm, (Teres ??) and Dan_ed, if we all join forces in this discussion I am positive that it will become a really worthwhile discurse.
Of course - stylus drag is rather a very variable force and can not really be called a "constant".
So - how do we proceed?? Do we carry on in this thread or is one of you starting another focussing on the turntable design in general, maybe with stylus drag and its influence on stability as a sidematter? Any suggestions? I am happy to participate in a real good discussion when we focus on technical aspects. |
Dan_ed, I think Lewm is talking about inner tracks vs. outer tracks on the disc. This will of course vary the amount of stylus drag torque that is applied to the platter, by a simple difference in leverage. |
Lewm, "distance from the stylus"? Why would there be component that varied with this distance? Unless we're jumping to AS? |
Dertonearm, You wrote, "Stylus drag is a very small sliding force in constant motion and is - coupled with any serious platter (of course not if the LP lays just on the platter and is not firmly clamped down) - really neglectable. Its a force smaller by several magnitudes compared to the energy the stylus puts into the platter while modulating the groove information. A force smaller by several magnitudes compared to any motor generated vibration."
In writing thus, you are implying that you know the approximate magnitude of the force of stylus drag. I would be interested to know what that is, so I can compare it to the magnitude of the other forces you mention. I tend to agree with you, that the force of stylus drag cannot be THAT great, since, if it were, cantilevers would be ripped from their insertions into the cartridge.
I don't think anyone would take issue with your definition of the function of a turntable. The problem is that many of us have heard or think we hear deficiencies in LP reproduction that are attributable to "something" that is at least partly overcome by the use of direct- or idler-drive, as opposed to belt drive. In this tiny little world of vinyl audiophilia, that "something" has been identified as being the result of stylus drag, because there are no data to indicate what else it might be. By the way, I don't think you meant to infer that stylus drag is a constant. Would it not be expected to vary according to groove tortuosity and distance of the stylus from the spindle? |
I'll second the motion for some discussion on these topics . . . regardless of where we stand as individuals, the enthusiast audio industry these days is very much threateaned by the stagnation of ideas, and open discussions are an excellent way to combat it (or each other:)). |
Absolutely. Start another thread on TT spec review, or something like that and let's see where the discussion goes. |
Hey Dan_ed, really ? I expected my post would provoke something like this. After all nobody likes big mouth with no proof behind...........
Any other Agoner interested in this ?
Specs including given reasons - or plain specs ?
Including material selection?
If some interest for this I will gladly unfold a brief but detailed enough "roadmap".
Let me know your mind.
On the other hand this is far going beyond the original thread about the bearing friction.
Maybe we should start a new thread ?? |
Hey Dertonarm! Show us how it should be done right. Let's have a spec review. |
Dear Teres, yes, I could grant your last post with some technical counterpoints and facts, but the only result will be argument.
But I can not resist.
****Thankfully, turntable design is not pure physics. A good design also includes compromises, tastes, experimentation and even some guesswork. Otherwise turntables would all look and sound the same. Really boring...*****
Well - turntable design is pure physics.
A turntable is a rotating machine.
That rtation has to be constant and its dynamic forces have to be that large that the extraction of the modulation by the tonearm/cartridge system have no side-effect on the constant rotation.
Furthermore the whole machine has to be suspended from building resonance.
Period.
Would you argue about a wheel and its function??
Stylus drag is a very small sliding force in constant motion and is - coupled with any serious platter (of course not if the LP lays just on the platter and is not firmly clamped down) - really neglectable. Its a force smaller by several magnitudes compared to the energy the stylus puts into the platter while modulating the groove information. A force smaller by several magnitudes compared to any motor generated vibration.
It is not a magic stone nor does it inhibit mystery unknown physical energy which puts it outside the Einstein Continuum ( however - many audiophile seem to believe just this and are supported by commercial audio advertising....).
The fact that "taste, compromises, experimentation and even some guesswork" is included in the design of turntables is the reason why almost all turntables do indeed "sound" different and most do sound pretty boring.
If the NASA had handled the Apollo - Mission that way, man would have never set his foot on the moon.
I have yet to see a turntable design done right.
I have yet to see a turntable with written standard specifications to start with.
So far we have a few good amateurs, but no professional anywhere. |
Dertonarm, we are talking about physics. The issue of stylus drag has been hotly debated before. It is a fact that any drag, regardless of how small will slow a platters rotation. A large platter mass spreads the variation over a longer period of time, but does not and cannot eliminate it. It's basic physics. Any amount of energy added or removed to the system will directly affect speed.
Now what can be debated is the audibility of such a small effect. Logically it seems quite implausible that a force as tiny as stylus drag could be audible. The audibility of the things being discussed here certainly are in the realm of opinion and theory.
Regardless of the theory there is a great deal of evidence that techniques that target stylus drag (like bearing friction and intimate coupling) produce positive, audible results. This would suggest that the theory of audible stylus drag is correct, but it certainly falls short of proof.
Thankfully, turntable design is not pure physics. A good design also includes compromises, tastes, experimentation and even some guesswork. Otherwise turntables would all look and sound the same. Really boring... |
Dear Teres,
stylus drag is only an issue if the record is not firmly clamped down to the platter.
If the record is not firmly clamped down, we do not need to talk about correct application or technical issues anyway. This is basic parameter. If securely clamped down it becomes part of the moving system and its mass - hence: heavy platter with high inertia.
As I said before - this is only one approach and certainly not the only one in igh-end audio, but it is the approach of physic and technical engineering.
A heavy platter will have no variation once it is on speed.
Any possible loss in speed is avoided before it occurs - by correct allpied coupling with string (= very low grip but enough to avoid loss of constant speed). Thus the error does not occur but the only task for motor and string is to hold the speed - nothinh else.
Stylus drag do only have an effort when the record itself "slips" on the platter surface (and believe me - I do use a cartridge which really can "drag". But of course it is only going on a record which is firmly - really firmly - pressed down on the platter).
Sometimes it really helps illustrating forces in motion with vector diagrams on a sheet of papaer. Visulising what really is going on does set some points clear really fast.
This is physics - thus it can fairly easy be determined when you allow the facts to spread.
Trying to correct any variation in speed as fast as possible ............
The result is constant back and forth in speed.
In other words - you implement unstability by doing so.
Every technical engineer into dynamics or constant torque will tell you that this is futile.
Turntable is pure physics - not taste, not opinion.
Too often in High-end audio people get the impression that physics laws have been invented during the development of audio components.
Not so.
Extremely few audio components - mechanical ones like tonearms, cartridges and turntables - do really take correct applied physics into account.
Otherwise we would have much more better components around. |
Dertonearm, I don't know whether you have already done so, but you might like to go over to Vinyl Asylum and search on the musings of Mark Kelly, a very smart fellow, on the various platter drive mechanisms and their pros and cons. Of additional interest is his work to develop drive systems for AC motors that reduce motor noise and cogging. |
Dertonarm, the heavy platter, slip coupling approach focuses on only the issue of motor cogging. This approach does not deal with the issue of stylus drag, or any other variability in drag. Contrary to popular beliefs platter mass changes how stylus drag affects speed but does not correct it. A massive platter will reduce the magnitude of the variation but extends it over a longer period of time. A light platter will conversely allow a larger speed variation but it enables more rapid recovery. Heavy vs. light platters exhibit different sounding degradations but they are still degradations.
Intimate coupling of the motor to the platter is the only way to effectively deal with stylus drag. But intimate coupling also makes problems from cogging worse. So in the end a compromise between the two is needed. A DC motor needs less isolation than an AC motor so the compromises will and should be different. Personal preferences also will dictate the ideal compromise. For example idlers with AC motors have poor isolation from cogging, but more intimate coupling. The result is excellent rhythm and timing but finesse and low level detail are sacrificed. Some like the idler compromise and others don't.
If you start with a very low cogging motor then a better compromise can be achieved. |
