A Copernican View of the Turntable System


Once again this site rejects my long posting so I need to post it via this link to my 'Systems' page
HERE
128x128halcro

Showing 30 responses by t_bone

Halcro,
Regarding your last post of 1/27, I think the 'theoretical proof' that Ralph offered earlier in the thread more than covers the issue regarding the desirability of having the tonearm mount absolutely stable in space vis-a-vis the turntable platter axis/level. Any movement between the two will show up as distortion. There is no getting around that.

If I were going to decide to 'go nude' with an outboard tonearm pod... I would...
1) build a tonearm pod (or three) like yours - I think it is a great design - VERY heavy with threaded bottom allowing one to spike it to a platform,
2) mount the nude TT to the same platform that the tonearm pod was mounted to, probably using the same spikes as on the tonearm pod,
3) I would put pneumatic footers, if any, between the 'platform' and whatever it was mounted on.

Banquo,
As regards putting 'light' objects on pneumatic footers with very large weight limits... I think the value of using pneumatic footers is to reduce the resonance frequency of the mounting to as low as one can in both the horizontal and the vertical. If one mounts a 10kg object onto 3 footers which can EACH carry 10-20kg, I expect that would be a problem. I have found when I have used platforms and pneumatic/magnetic isolators that it is always better to be at the heavy end of the range rather than the light end.
Halcro,
I think Ralph would say we are all three in agreement. To me, a 20kg armpod spiked to the same platform that the TT is spiked to means they are strongly 'coupled', even if you can take them away and walk them with your two pet snakes, separately.
Dgob,
I think it was mostly stainless steel by mass but I will try to dig up that information. I have a copy made by a metals engineer who tried to copy the SAEC plinth, and the thing has three layers of different metal with slightly different resonances. It does weigh a short ton.
Banquo,
The point of weighing down the armpod is to couple it to the surface below (which in turn should couple it better to the TT). Putting separate AT616s under the table and the armpod separately negates the effect of adding on the weight to the armpod. At least in the SNL case the rabbi and baby were 'coupled' to the same backseat. Your proposed method suggests the rabbi is better off leaning through a window of another car alongside. If it were me (and it is not), I would suggest putting all four footers below a rigid layer to which both TT and pod are coupled.

Your method may work in practice, but it will limit the improvement you get and increase distortion in other ways. First, if you put ONLY the TT on 616s and leave the armpod spiked, AND that is an improvement, it indicates the footers worked. If only the armpod was on footers, and the table were not, and that also improved things, either you have a separate component-led problem to the first one or you have the same problem of resonance coming into everything from below. If your tonearm is resonating, you need to fixt that separately. If it is resonance from below, you want your tonearm and table on the same decoupling platform or the different load presented by armpod and table vis-a-vis their respective isolations will cause weird distortions.
Dgob & Banquo,
I wish you the best of luck. I may try to do something similar just to see what happens. If I eventually do, I will also try it with a single plate underneath which could be mounted on pneumatic/magnetic isolation footers. As I have repeatedly stated in these fora, I am a BIG fan of adding isolation footers underneath turntables to lower any resonance to very low frequencies. I remain skeptical that I want my arm and my turntable platter on separate axes of isolation. I cannot see how that would be a good thing as it negates everything one learns about speed stability and controlling the tracking of the cartridge in the groove. All this said, I wish you the best of luck and results.
Dgob,
Does that mean your TT is on pneumatic footers and your armpod is on spikes?
Good on you! I think getting a great result from experimentation is wonderful. I'm very happy for you that it worked. I'm going to venture out on a limb and say that you would not keep the same sound if you spiked the table and floated the armpod on the footers. I expect there is resonance in the TT you are dampening/sinking (the reason why people in plinth-world make bigger/heavier/better plinths for the SP-10Mk2), and the improvement on the armpod came from a) switching from blutack to spikes, and b) taking out the symposium (two isolation methods next to each other is usually worse than just one in my experience) - both of which should have improved things.

I expect that if you do not hear any issues with the fact that the table/platter is now theoretically resonating at a low frequency in relation to the tonearm pivot point, that the experiment has been successful. Once in position, the table itself has a great deal of inertia (in 3-dimensional space), which should help keep most of the resonance transfer in the domain of heat generation rather than low frequency movement. Remaining theoretical issues might remain just that - theoretical.

I have a couple of motors like that and some great footers made by Sony way back in the day. I could try that relatively easily if I could make an armpod. I'll have to think of a way to get one done...
Halcro,
Just because you asked... ...there is a back story...
JVC/Victor of Japan was originally owned by Victor (US).

Victor was formed when Emile Berliner (inventor of the gramophone and then first owner of The Gramophone Company) lost a suit brought by Columbia and Zonophone early on, and wasn't allowed to make records anymore. The guy (Mr. Johnson) who was making gramophones (I think on an OEM basis) for Gramophone Company filed suit to allow him to sell the gramophones he had made, he was victorious in court, and he named his company Victor Talking Machine Company. That company partnered up with the original British Gramophone Company to sell gramophones, and the British company found the painting, got it changed slightly (from wax cylinders to discs). EB asked the original artist to grant the US picture rights to VTMC. That was 1901. As a result, they also got some other jurisdiction rights by default it appears. A few years later, VTMC started exporting equipment to Japan. In the 20s, after the great Kanto Earthquake destroyed most of Tokyo (1923), Japan raised import taxes dramatically, causing VTMC to decide to set up a local manufacturing and sales company, called 日本ビクター (Japan Victor). Then RCA took over Victor TMC in 1929 and RCA's corporate philosophy was to run overseas businesses on a RCA-local JV basis, so they JVed with Tokyo Electric (at the time a company in the Mitsui keiretsu, but better known now under a different name, created when it merged with Shibaura Electric Mfg - Toshiba). When relations between Japan and the USA got worse in the late 30s (as Japan was embarking on its Greater East Asian Co-Prosperity Sphere efforts), RCA no longer wanted to be involved with a Japanese JV so sold the rest of Japan Victor to its JV partners. After the war, during which Toshiba and Victor had both suffered greatly (in the bombing of Tokyo and 'burbs), but had significant debt remaining, and GHQ decided that banks couldn't own big parts of companies anymore, both Victor and Toshiba needed new partners. RCA raised its hand, but so did a long-time fan of talking machines, records, and the "HMV logo", the president of Matsushita. He decided he wanted to be in the record-making business and put up a boatload of money to buy out the debts of Victor from banks. Later Matsushita Konosuke would actually be chairman of Victor. In any case.... in Japan, most people referred to the company as "Victor" rather than "Japan Victor" and the brand used in Japan was, in the 60s-80s, "Victor". When Victor started selling VHS machines globally in the early 80s, they used the "JVC" brand outside of Japan. Later, "JVC" as a brand was re-imported and all the Victor-brand A/V products made by the Japanese company were branded JVC. And that's all she wrote... Back to armpods!
Halcro,
For clarification for those who may not know the history/linkages, Victor and JVC are/were the same company (though a few years ago they merged with Kenwood). In Japan the brand was usually called Victor whereas abroad it was JVC (Japan Victor Company, called that, rather than Victor, because of trademark issues I think). Later, JVC (the company) also moved to use the JVC brandmark in Japan for local market products. FWIW, Panasonic had a similar issue where Panasonic was the brand name used for items sold abroad and Matsushita Electric Industrial (the listed company) used 'National' as their brand in Japan. Only recently did Matsushita retire the National brand and convert those items to Panasonic. At the same time they changed the company name. Many Japanese companies used 'brand names' for their audio component lines which were different than their company names. Matsushita was responsible for Technics. Toshiba was responsible for Aurex. Mitsubishi was Diatone. Sanyo was Otto. Sharp was Optonica. Kenwood was Trio. Pioneer was Exclusive. Hitachi was Lo-D. Teac is Esoteric (and TASCAM). NEC was Authentic. Kensonic was Accuphase. Nagaoka was Jeweltone. Dynavector was On-Life Research. Akai was A&D. Aiwa was Excelia. And Sony was briefly Esprit (and more recently, Qualia).
I am happy to have the seismic protection for when earthquakes come along. But the resonant frequency of those is quite low :^)

However, I notice the difference between having an isolation platform and not having one. And I notice the difference in loading one differently. And I also notice acoustic feedback from time to time. Wish it weren't so, but I do... But that's just me and if noone else has a problem with sound waves in their listening space, I guess I'm just unlucky... :^(
Nikola,
If cats only have seven lives in Holland and you need a few extra lives out of your cat, you need to import some from the USA where they have nine.
Thuchan,
The Toho base is an excellent, heavy base. The issue is not so much one of moving by hundredths of a millimeter as the fact that it may flex or resonate at a different frequency or 'offset' (the timing of the when the wave crosses the zero point) than the table does. Thebase (and its footers) may react differently to flexion or resonance of the platform that it shares with the Continuum than the Continuum does. The plastic thing - whatever it is - between them will not link them so that they share whatever internal resonance they have.

At least that would be the theory of the downside to separates which were nonetheless supremely stable in their own right - the problem which Micro Seikis and the Kenwood L-07D, to some extent the Exclusive P3, and other tables sought to address.
Thanks Jonathan - I was searching for that word "phase" in my head, when noting the possibility of similar resonances having an "offset" through different coupling or whatnot. I think it got lost rattling around in there - probably a "just-ate-a-Ku'a-Aina-burger-on-a-Friday-afternoon-after-a-long-week-so-brain-is-not-all-there" kind of thing... decent burger though...

I agree the right way to do it is to make the armpod/mount as rigidly associated with the spindle as possible, and then isolate (preferably a magnetic floating platform loaded on the heavy end (grin)) the whole.
Thuchan,
This is, as Dgob points out, only theory. However, following that theory, one would say that having armpod and turntable on different isolation platforms would be sub-optimal. One could see this by having the table be absolutely, perfectly stable and putting the arm pod on top of a sponge-y material - the arm-mount/arm bearing is isolated/coupled to a different extent than the table bearing. Any movement anywhere (the ones your isolation platform is supposed to counteract) will lead to distortion because of the mismatch in response of the bearing surfaces. Putting both on separate isolation platforms does not necessarily improve things as trying to match the resonant frequencies of the two isolation platforms in both frequency AND phase is almost impossible (primarily due to differences in platform loading leading to both different frequency and different reaction time to a given impulse). Or so the theory goes...

Halcro,
A couple of thoughts...

I think we will all agree that just because the 'theory' is not borne out in 'results" does not mean the theory is wrong. In many cases, the 'not-as-good-in-theory' concept is far better implemented than the theoretically-correct. My Micro Seiki belt drive sounds far better than my Technics SL1200 but my Exclusive P3 sounds better than a Rega P3.

I too am not 'religious' about audio. Personally, I think several of the arm pods developed here are probably capable of permitting excellent sound (arm/cart/implementation permitting). Reading this thread has given me some ideas. And it makes me want to have a crack at something similar too. A 10-20kg arm pod is a prodigious weight, and in practice, that kind of weight will couple the pod and therefore the arm bearing to the surface below the arm pod. Pods are not necessarily like galleons on a stormy sea in practice. That said, if I implement pods, I will seek to couple the pod and the motor to a single rigid surface, and then isolate that rigid substructure. Doing so will get me somewhat close to Jonathan's concept.

Many of us, myself included, are firmly in the camp of improving our systems any way we can. That necessarily requires experimentation. And in many cases experimentation is assisted by forming a hypothesis, which for practical purposes, until proven, is really all a theory is. In many cases, there are practical obstacles to going down the road of perfect theory. Your point about MCs vs MMs is an easy case in point. The theory that MCs are intrinsically better than MMs requires that the pre-pre stage (head amp or step up transformer) be capable of not limiting the effective performance of the MC. I think in practice that aspect limits the performance many get from their LOMCs.

As to your points on air-borne sound transmission and its effect on turntables... All I can say is that if you have never noticed it, you have been extremely lucky, or extremely good, in your room set-up. I have not been either and have heard the effects. Even when my P3 is well away from my speakers, listening with top up or top down is different. If you have an ADC, testing the effects of sound transmission on analog playback, and of the effect of greater volume, is relatively easy.

In any case, I applaud your efforts at experimentation thus far. It really is all about living with and enjoying the result.
Halcro,
I know my statement and Jonathan's are not the same - no 'quite' about it. My 'if I implement pods' comment involves a pod, his doesn't. I agree with Jcarr's recent comments and am on record moons ago on these fora having said something similar. But if a pod is to be used, having everything extremely well-coupled (de-coupling I assume is isolation, which should be avoided) and rigid will approach JC's suggested goal. Some pod implementations have different isolation systems under the pod and the table, which makes for a different arm-bearing-to-table-bearing interaction, and this is something I would suggest against. In the end, it all comes down to implementation (Dgob's Chinese cats and your arm pods).

'Well away' is perhaps different than what you would call 'well away' given the concept of 'distance' in a Japanese living space is probably different, but it is still out of the direct radiation pattern of my speakers. My P3 is on a large wood rack, but it does not matter much. The P3 has construction, shown here much like Jonathan's suggested method, with an isolation platform built-in. The fact that results differ slightly with the top down suggests air-borne effects, but I have no doubts my room could be improved.

Downunder,
The lid of the P3 is specifically designed to combat airborne vibration which might affect playback.
Halcro,
I don't have suspended wood floors. They are poured concrete with a thin fake wooden flooring cover. The rack in the system page is old. I haven't added pics in a couple of years.

The P3's springs are actually surrounded in an oil solution inside the rubber casing. The resonant frequency of the isolation system is set to be 3-4Hz. The effect is quite different to that of a normal suspended table like a Linn or Thorens. Other P3 owners might attest as to the isolation system's effectiveness.

I don't doubt that if one tried hard enough one might be able to create a 'capture system' as you propose. But the happy effect of mine is that closing the lid while playing often has a salutary effect, and never deleterious.

In Japan, TTs rigidly coupled to wall mounted shelves would be just as affected as rigid floors, like mine, with earthquakes. However, earthquakes/tremors are not the only thing causing building structural resonance, especially in cities. And not just in Japan.
Suspended. I don't worry about whether my floor will flex though. I know it will. Earthquakes affect the sound because the building shakes (for those not used to them, earthquakes can be 'noisy'). Having had a setup on the ground floor (concrete slab) before, I know it will move too. That's life in the big city...
FWIW... my apartment building is wide and flat and is only 3 floors high. It is certainly not designed with the same features as my office building, which is 15 times taller, and has seismic dampening foundations.

Not sure what to say... My SX-8000 sounds better with an air-bearing isolation stand beneath it than without it, as does my SP-10Mk3 in a SAEC-like metal plinth. Both weigh a short ton. I am currently listening mostly to a very heavy direct drive turntable with stillpoints for feet. The sound is excellent. But I have yet to put an air table beneath it and I am wondering...
Halcro,
Makes sense as an inexpensive DIY solution. May not be as pretty as the DaVinci solution but there is no reason why it cannot be made reasonably pretty. The question I would have is how one can make really decent Micro-Seiki-like armbases to fit in the middle of the top plate, and have the top plate look really, really good.

The only way I can think of it is to make a very fine liquid "top" by turning it upside down (so top is down) on wax paper and pouring only the first 2-3 cm (with a styrofoam blockout for where the top plate and VTA tower will be). Then after that is done and mostly dry, pour the rest in around the blockouts and let dry. The first layer on wax paper, if wet at the very bottom, should create a super-smooth surface which can be finished as one likes.
Yes, you are probably right. The nest way to deal with the top is have a full-width metal top-plate.
Halcro,
What does it mean if the feedback increases as volume increases. If airborne feedback is the ONLY problem, one would figure the effects to increase. Personally, I am not convinced that airborne feedback affecting my rack, and then feeding 'structural feedback' through an isolation system (designed to combat structural feedback) to my turntable is a more insidious problem than the same airborne feedback affecting the record, tonearm, or dustcover itself.

In testing now...
Pedestals, plinths, and pods oh my! LOL Nandric! You are right. 'Marketing material' perhaps does not have the 'gravity' that one might wish for, though the research behind the concept seemed to be well done.
Raul,
If you look at the original marketing materials for the Kenwood L-07D from almost 30 years ago, you will find a clear 'explanation' against having the arm base be dis-connected from the bearing mount of the turntable. A similar explanation is in some of the original marketing materials in Japanese for the Exclusive P3. In fact, the P3's construction is not terribly different than some of the 'armpod' implementations. What some of the philosophical 'naysayers' bring up as an objection is not necessarily the lack of bulk-cladding (plinth) around the motor OR a heavy armpod. The philosophical issue some of us have is that of putting an isolation layer between the motor bearing and the arm bearing.

In the design of your arm, I imagine you are not going to put an isolation buffer between the armwand and the bearing - that would strike you as less than optimal, and not even worth testing. Some of us feel, perhaps to our detriment, that an isolation layer between motor bearing and arm bearing is not much different.
I meant to say in the previous comment that the P3's construction is not terribly different than some of the 'armpod' implementations of some of the people who have presented on this thread. The difference would be in how the armpod is connected to the surface beneath it.
Halcro,
I'll get there. I think the concrete idea is really kind of cool. One could even do a low cost DIY "TT pod" out of concrete. :^)
Ct0517,
A pedestal is nothing more than a 'plinth' :^)

The issue of having isolation between the arm bearing and table bearing can be illustrated, in extremis, by imagining a jack-in-the-box with an immovable armpod next to it. After jack has popped out of the box and does not bounce anymore, he is perfectly stable and unmoving at the end of spring. As long as he is perfectly still with absolutely zero resonance, the relationship between your tonearm pivot and jack's nose is always the same, whether Jack is encased in concrete (a plinth) or perched on the end of his spring (on top of a 'platform' which moves in relationship to the world around it. As soon as there is any resonance in the system however, jack will move with regard to the tonearm pivot (and therefore the stylus), and may do so in slightly unpredictable ways. In any case, the slightest movement will cause a kind of intermodulation.

If you fix Jack to the platform your armpod is resting on in order to keep the relationship between his nose and the armpod-mounted arm pivot perfectly constant, you have effectively plinthed him.

If Jack has some kind of internal resonance, the method of fixing him to the board may have more or less resonance. This is the difference between a bad plinth and a good one, but the inherent goal of a plinth is to keep the relationship between the arm's pivot/bearing and the motor bearing as stable as possible. If one removes the plinth which surrounds the motor, and mounts it naked on the same table as the armpod, one has removed an intermediate coupling material (the one which connected the frame of the motor to the bottom of the footers, but one has not changed the concept/goal, one has simply changed the method of execution.

If, however, you stick your TT motor on an isolation base which is not the same base that your arm bearing is resting on, you are effectively changing the distortion relationship. You may find that a substandard plinth will resonate unpleasantly because of a resonant frequency of the material which is in the audible range. If you change this frequency to a 3-5Hz frequency (the goal of most isolation systems), you have exchanged the plinth resonance-induced distortion for one which is like an off-center 45 record.
Oops. Writing on an iphone is a sure-fire way to make lots of typos. So please ignore those.

One can add to the last point that it is not necessarily a BAD thing to exchange one set of undesirable resonances for another set of undesirable resonances. It could be that one likes the flavor of the second better. But for people who are trying to get rid of ALL distortion, introducing an isolation layer (distortion transformer) between two points which are supposed to be absolutely fixed together with zero distortion between them is in some way 'giving up.' And while it may be better than it was 'before', it makes one wonder about the state of the 'before' and almost certainly can be improved upon.

That said, it is not a difficult thing to do, and I will try at some point. I can think that it might even be an improvement on some of my stock plinths (because some of them were not top-notch). I can probably figure out an armpod of some sort relatively easily (it could be an arm attached to an current plinth and the motor outside it, either spiked (rigidly coupled) or isolated (on magnetic levitation footers) with regard to the surface below.
I agree Henry. The FR-5 IS better than the FR-6 and sounds quite decent. I haven't tried it in that particular headshell but I imagine it would sound better than I have heard it yet. And because it is not 'audiophile-approved' in the other thread, it can be gotten 'cheaply'... :^)