A Copernican View of the Turntable System

Dear Chris,'Such passion over a hunk of metal.' You should
check the gold price at present. BTW never heard about fetishism?

Regards,

Dear Henry, dear Chris, dear Nikola, "such passion" - really?
I rather perceive this tread and discussion about the pro and cons of "free" arm pods as being moderate and kind of "in cool ( if not cold ...) blood".
In any case - I certainly do not want to discredit the whole topic and the " free arm pod" pro-camp .
Everything is fine, as long as a separate arm pod is used for a limited period of time and/or to test a given tonearm quick and without drilling mounting holes in a precious plinth.
Aside from the "relative movement", there are other issues going with - any - separate arm pod ( energy transmission and reflections et al ).
Given equal care and smart design, a separate arm pod will ( .. sorry about that, Texas! ...) be 2nd choice - quality-wise ( if - of course - more convenient ).
It nevertheless has it's merits and does ease tonearm testing.
The armboards originally invented by Micro Seiki and copied by many others since can be seen as "cantilevers" - but at least they keep strict distance.

The molecular point of view is not applicable here - the derivations in atomic structure and surface are there in any case.
We have to cope and deal with them anyway.
This however does not affect the relative movement of two fairly lightweight bodies (everything is lightweight here - everything under a ton ) relative to each other caused by building resonance and energy transfer - sorry, but these are different "animals".
Furthermore these movements aren't in Microns nor Angstroems - they can approach 1/100 mm and more quite fast.
If we might not "detect" it by worsening sound nor derivation on a tangential template which line is already 1 mm thick does not alter nor deny the physical phenomenon.
A free arm pod will wander - so why do not use a adhesive tape to secure it in place ?
Easy to detach again and eliminating - or at least lessening - the "relative wandering".
Best,
D.

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.

Dear Ct, Henry, and anyone else who is disturbed by my occasional digs at your approach to tonearm mounting: Believe me when I say you have my blessings in whatever you do, and I enjoy reading about the construction of the various pods. The fact that I have not tried it and may never try it is not a sign that I am a troglodyte; it merely shows that my plate is very full with other projects that have to take precedence, not to mention going to work every day. Altho you know quite well my theoretical objections to arm pods, which are largely the same as Dertonearm's, I am sure that an outboard arm pod can sound perfectly wonderful. I also think all of us can tolerate much more in the way of imperfections in our music reproduction than any of us cares to admit, so I doubt I would hear it if my arm pod were to "walk" a few mm in one direction or another with respect to my tt. I am very happy with what I have in the way of tt's right now.

Nandric, Did you tell me that you own a Kuzma 4-point tonearm? After reading Fremer's review, I am interested in that device.

Dear Lewm & Daniel,
We are all thick-skinned enough to take the occasional barb :^)
I started this thread because of my surprise at the results of both the 'nude' DD turntable approach and the isolated 'armpods'.
They far exceeded my expectations and the implementation of both approaches is relatively easy for others to try.
So far, we have seen no negative responses from anyone who has actually sampled the approach but we have several 'naysayers' who haven't?
It seems rather odd to be offering opinions based on 'theories' when the 'proof of the pudding' is so easily abled to be sampled?
Rather like commenting on a cartridge without having heard it?:^)

If this advice follows the logic of Rauls recommendations
( not p but q)some of us will get fantastic arm pods for cheap. My only worry is the high cost of postage from Australia to Europe.
T_bone, Everything seems to be better in the USA. This of course apply also to the cats.

Regards,

Dear Lew, I expected some euphoria about the victory of your galleons. But instead your are chalenging my nationalistic feelings. Slovenia and Kuzma are my ex brothers and I already own Kuzma's TT. There are boundaries to any kind of tolerance,you know.
But If Kuzma offered one for free as a token of our reconciliation I am willing to (re) consider my tolerance.

Regards,

Dear Henry,
it is not disputed at all - at least not by me - that a "nude" turntable paired with an "isolated/free" armpod(s) can sound very good.
For a limited period of time.
With certain arm/cartridge combination (the higher the compliance - the better).
Even I have tried separate arm pods as long back as 1986 (if I remember right they were pretty hefty - approx 30 lbs each) in conjunction with a Le Tallec and a Micro Seiki skeleton TT.
Neither Lewm nor I do offer opinions based on theories here.
What we did was acting as advocati physici.
Technically - and ultimately sonically - there is no single advantage of isolated arm pod versus firmly attached armbase.
If isolated arm pods can and do - undisputed by me - sound so good in comparison with so many plinth-based tt, then the explanation is easy, logic and showing that there still is a lot of work to do in many integrated turntable concepts.
In any case - where is the problem, why not simply prevent an isolated arm pod (but by all means do at least place arm pod and tt on the same ground/shelf, whatever ) from moving by means of adhesive tape or similar.
Easy to remove, easy to alter.
But it is not just "movement" - it is too energy transfer and reflections.
That's why it works comparatively well with high compliance MMs - they but very little energy into the tonearm.
Peace on earth .....
Cheers,
D.

Dear Daniel,
I understand your point about 'fixing' the base via tape or blu-tak and that is easy to do.
There is however another philosophy to the 'support' of the armpods.....and indeed the nude TT itself......and that is, to de-couple both elements from structure-borne feedback via the supporting shelf.
I know some folks insist that spikes actually 'couple' rather than 'de-couple' and that 'isolating' feet made of rubber or visco-elastic material are better and there may be some truth in that. Nevertheless, I believe that bolting or fixing the armpods to the substrate without 'decoupling', may cause problems from structure-borne feedback?
It may not be a big deal in the overall scheme of things....so let's keep our minds open :^)
Cheers
Henry

Hi D – Does your Uni tangential alignment tool differ from the manufacturers one at all ?

The tool I actually use for measurement is a customized one that has a fine thin line etched into the material. The stylus fits into it or it doesn’t. The pic I posted was the manufacturers one as u know. Thought it looked like a nice two lane highway per post reference ? I have found with the sp10 chassis 7.5 inches is the "middle of the road" when measured from the left side for the ET 2.5.

Hi Lew – if you choose to order the Kuzma 4 point tonearm online with a computer – pls be careful when checking off the options boxes. You don’t want to end up receiving one of Mr Kuzma’s brass arm pods in the mail too ? But I have to admit I would pay to see a picture of your face if you opened up the box to find one inside? :>)

All
I am going to have a plate welded to the bottom of my brass arm pod to accept the DIN connection right at the pod. Can anyone tell me if I better off to use a different metal other than brass for this plate. (sonically speaking ) Anyone have any thoughts on this ? Was planning on brass ?
Much appreciated.

Cheers Chris

If this advice follows the logic of Rauls recommendations
( not p but q)some of us will get fantastic arm pods for cheap. My only worry is the high cost of postage from Australia to Europe

I already called dibs on those Nikola – sorry – right Henry ?

Hi D – I apologize – should have posted my question in the Uni-Protractor thread about the tangential alignment tool.
Chris

Chris,
FWIW, a friend swears by phosphor bronze.

Hi T Bone - An all Phosphor-Bronze POD ?

That's what my armpods are made of.....phosphor bronze.
Sounds good to me :^)

Dear Chris, If I understand Freud well this is how 'it'
should work: 1. first step is the denial (= your post);
2 second step is the doubt; 3. third step is insecurity
and 4. seling the demn thing to get some night's rest.
In the meanwhile I should be able to get a second 'nacked
TT'.
Sleep well till the second 'step'.

Regards,

That's what my armpods are made of.....phosphor bronze.
Sounds good to me ==========Halcro

Now that is a man who has chosen one of the right materials for an armpod.

Hi Audpulse, If I am able to count this make at least two
man 'who has chosen the right material(s)'. But there are
others who have chosen for the 'acousticaly dead' arm pod
made as a sandwich from: two layers of steel,two layers of
cork, two layers of granite and one of acryl. This abundance of materials combined with the scientific reaserch regarding the acoustical death imply a different kind of animal. So it is more about the man than the material if you get my meaning.

Regards,

IME, not only the choice of material, but how the material is processed has a significant effect on the sound.

Again IME, the descending order of sonic quality is: 1 machined from solid billet, 2 extruded into approximate shape then machined, 3 forged, 4 vacuum or pressure-cast, 5 sand cast.

I should also point out that the phosphor bronze alloys used in machining are different from those used for casting (higher tin and lead content).

hth, jonathan carr

Has anyone tried making their arm tower with brass? Do you see any advantages/disadvantages with this material?

Cheers

Thanks for the input Jonathan.
If I may ask.......how have you managed to determine this grading and for how many materials?

Dear Halcro, Jcarr's "table of material's sonic quality" is correct. The key is the decreasing ability/speed to transmit energy in the different processed materials. Cheers,
D.

Hi Henry.

By building, listening and measuring, not only to my own designs and prototypes, but those of other designers also. Subsequent discussions with yet other audio designers and retired designers have suggested that we generally agree about the ranking.

Compared to machining, casting is cheap if large numbers of parts are to be produced, and therefore would be most attractive to a manufacturer such as myself. This is particularly true when the shapes get complex, which drives machining costs up, up, up. Unfortunately, so far I haven't been able to convince myself to use casting for anything more demanding than an active digital cable enclosure.

How many materials? Off the top of my head, aluminum(s), magnesium(s), brass(es), bronze(s), iron(s), copper(s), titanium(s), stainless steel(s). Probably more if I jog my memory.

BTW, none of the above necessarily means that you and I would come to the same conclusions. It very well could be that your audio system and listening habits are different enough from mine that we'd have to agree to disagree.

cheers, jonathan

Hi Jonathan,
I imagine though, that the 'processing' of the material and the 'significant effect on sound' due to that, would vary depending on 'where' in the signal-processing chain that material was applied?
For instance, I can imagine a tonearm headshell or arm-tube having a more 'significant' effect on the signal than say......an isolating spike or cone, or an arm-pod or a shelf bracket?
Cheers
Henry

Jcarr,

As I was posing the questions you were already answering. Synchronicity,

Thanks

May I ask all of you if a very heavy outboard armpod as I am using it for the FR-66fx on my Continuum is moving despite the fact that I connected it with a plastic part between the TOHO armpod and the heavy Continuum body - in this way creating a sandwich constellation. I for myself don't believe the TOHO stand will move but I am eager to learn if this is possible anyway.

best & fun only

Dgob, One advantage of brass: it is pretty soft and therefore very easy to machine. It also looks nice.

Can someone point out to me where (in what post) JCarr listed his preferred materials in order of goodness? I only see where he listed first the preferred methods for creating objects out of solid metals and in a second post the metals that he personally has auditioned. Or Jonathan? Thx.

Daniel (DT): Do you equate speed of the propagation of energy in a material with goodness of the material for use in arm pods, plinths, arm boards, platters, or what?

Dear Lewis (Lewm), IMHO the "conductivity of energy" is a key feature/issue in tonearms and turntables (and associated arm pods, plinth, platters). It is at least if one tries to get the most dynamic, live-like and uncolored sonic results.
It is a key issue - not the only one, but very important and most often overlooked.
Cheers,
D.

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.

Lew, when it comes to choice of material rather than choice of processing, it is harder to say what is better, and what is less so.

While audio design is predominately about engineering (or should be, IMHO), there is also an element which is similar to cooking, or matching clothes.

You pick a design direction which you think is technically correct, decide on a building method (including materials) which you think is likely to bring you the benefits in a cost-effective manner, listen to the results, then assess what needs to be added, subtracted, or changed. If you make a wrong decision at any stage, chances are that the resulting product won't do particularly well in the market. Build it, and they will laugh (grin).

What the above also means is that, the design direction affects the choice of materials, and vice versa. My preferred material choices are affected by my design direcions, and undoubtedly the same is true for other designers. There are some materials which, when used as structural materials, don't particularly sound good for my ears and my designs or operating environments. But these same materials seem to work fine for other designers and how they operate these materials.

When it comes to subjective choices, there is no "right" or "wrong", in the same way that chocolate isn't "better" than tomato, nor the reverse. You may listen to a material or component and like it, I may disagree. But if it produces the sound that you are aspiring to, that is what should matter the most to you.

FWIW, I also agree fully with Daniel and Travis regarding outboard arm pods. When you play a record, what you are actually doing is measuring it against the platter and spindle. Mounting the tonearm on a separate pod allows relative movement to occur between the tonearm pivot and the platter / spindle, and this will interfere with the accuracy of measurements.

I acknowledge that in some situations the tonearm may be picking up environment vibration, which will affect the sound, and some listeners may be reacting to that. However, what this strongly suggests is that the plinth design offers inadequate environmental isolation. I suggest that a more elegant, and technically correct solution is to mount the tonearm pivot and platter / spindle onto a single rigid structure that allows everything to move together at the same rate and same distance (and phase), then isolate the complete system from the environment by means of an isolation platform (not footers). Even better would be to add an acoustic shield around the turntable so that it doesn't get affected by the sound pressure from the speakers.

Lastly, you may find it interesting to study grounding theory in amplifier designing. There are strong parallels to what is being discussed here.

hth, jonathan carr

Jcarr,

I appreciate your comments as usual and recognise the logic (indeed a Japanese technician who used to produce tonearms in the 80s has pressed the same logic on me for some time) but can only say that my experience of isolated tonearm and turntable does not accord with the theory. Whatever the reason, the results really do speak for themselves.

Lewm,

Thanks and its machinability and aesthetics are key reasons why I am considering using brass for my arm towers. This will be important as I intend to do all the work myself. The other reasons are its relative price to bronze and its decent mass.

Now I just need the time and opportunity to try this out

Lewm,

Thanks and its machinability and aesthetics are key reasons why I am considering using brass for my arm towers. This will be important as I intend to do all the work myself. The other reasons are its price relative to bronze, its decent mass and of course its not being magnetic.

Now I just need the time and opportunity to try this out

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.

T-bone, thanks for your helpful comments. if the plastic piece does not link the arm pod with the TT what kind of material will do it? I always use isolation platforms: the TOHO stand is placed on one, the motor on a separate one, the turntable on three isolated feet with platforms and the whole system again on a special Copulare isolation table (platform structure as well as feet).Following JC's suggestion to shield the TT i should build a surrounding shield for allover wave protection around the Continuum. This I can do. What is the best material and how much of the turntable needs to be covered, 100 mm above the highest point (tonearm)?

best & fun only

Thuchan,T_bone is referring to the "cantilever effect". A separate armboard/armpod should be linked to the plinth by means which are as rigid and as stiff as the material of the plinth itself.
Otherwise you would create an "elastic joint" similar to a cantilever.
In the very same sense a separate/free standing arm pod in it's relation to the plinth/turntable is "connected" to the plinth. With inevitable effects on energy transfer and resonance behavior of the "closed circuit" mechanical system (here: stylus/cantilever - tonearm - arm pod - common ground - plinth - bearing - platter - record - stylus/cantilever).
That's what Jcarr meant when he was referring to the "grounding principles in amplifiers".
Cheers,
D.

Dear Thuchan, It is impossible for me to resist the temptation. You can probable also use the shild surrounding to protect yourself from radiation in case of an nuclear war.

'Peace',

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...

Dear T-Bone, Dear Dertonearm. Oh yes theory is a wonderful thing but are there any experiment documentations available which support the "cantilever-theory" as well as the "isolation theory (of different platforms)".

Funnily I made the experience when I put the motor drive and the three legs (feet) of the Continuum on extra platforms the sound is quiter and dynamically better. I would never return to a non isolation concept.

Nandric is right he knows how to handle the issue seriously ... :-)

best & fun only

Hello Jonathan Carr – I want to say that I find your posts on this public forum always very informative and helpful no matter what the thread topic. As a manufacturer you are quick to point out any biases and I appreciate that you usually recommend to us to use our own ears for the final call.

THEORY PART

Jonathan Carr stated.

A) Mounting the tonearm on a separate pod allows relative movement to occur between the tonearm pivot and the platter / spindle, and this will interfere with the "accuracy of measurements".

This sounds very technical and something that would come out of a white paper. It is a statement that would give designers/manufacturers a direction to take in the manufacture of TT’s. It also sounds very logical to me at the macro level. I have no problem with it.

-----------------------------------------------------------

Now here is another broad statement that I have read about Armpods on the internet. Original Author unknown.

B) Isolated Armpods break the rumble feedback “loop” as it happens through the plinth as it contacts the arm at both ends - through the arm pillar and cartridge via the platter.

This also sounds very technical to me again and "also" something that I think could come out of a white paper. It is also a statement that would give designers / manufacturers a direction to take with the manufacture of their TT’s and also their Armpods as a package together or separately. It also sounds very logical to me at the macro level. I have no problem with it.

FACTUAL

This vinyl hobby is a very “crude hobby” no matter how “pretty” we make the components look and how technical we make our language about it. Such expensive mechanical or structural components whose job together is to send “vibrations” along picked up from a crude piece of vinyl plastic, of which NO TWO ARE ALIKE.

I have watched how these lps are made. All of vinyl’s inaccuracies 1) warps, 2) not centered spindles, 3) varying thicknesses, 4) varying grooves 5) fill in others …
This has led to a plethora of devices out there to help mitigate these inaccuracies. Look at all the devices trying to get the best alignment out of just two specific points on this piece of vinyl. The remaining points on the lp become even less accurate. All of this makes words such as "accuracy of measurements" start sounding to me on this public chat forum, like square pegs being tried to fit into round holes? No matter how accurate the process is in building the actual TT player itself and its components. You are still dealing with that piece of vinyl as your source.

SETTING THE RECORD (no pun intended)

I am in no Pro camp here – never have been. I am only Pro sound for me in my room/s. I am a user here – I am not a manufacturer, designer, dealer, distributor or anyone that benefits in any way from having someone’s equipment in my room like some others here. My latest TT has a 100 pound plinth. I have multiple TT’s that I own and of the three in my modest sound room, one uses Armpods.

For the last 30 years my occupation has been in the field of RISK Management Planning and Mitigation. I get dropped into companies and my team needs to come up with solutions to their specific problems. This work involves macro and micro analysis, design and solutions.

Now if I was being asked my professional work opinion here based on all this theory and my real listening tests, my professional response back would be that both of the above statements (A) and (B), make logical sense at the macro level and the ultimate micro TT detailed solution must take in and incorporate the advantages of both.

PHILOSOPHY

I am a big believer in the BIG ROCK theory. Not just for this hobby, but for my family, and my occupation. I consider myself a music lover first then an average audiophile. I have only myself to please. I have been told I am a very stubborn person.

SUBJECTIVE PART

My opinion as a user and after real testing and real experimenting in my own room are that even though A and B are I believe, both logical statements. For what I am actually hearing (B) represents a bigger rock than (A). I believe I am hearing the advantages of (B) and they overcome or cover up any problems with (A) - or if not - someone here should stop with the theory and tell me what I should be listening for to indicate (A) problems.

In the meantime I have not completed all my planned testing, but so far I feel the isolation this Pod provides helps to move me closer to my nirvana. I am content and having a lot of fun listening to music, not worried if my 16.6 lb Brass Pod or Platter and Motor are moving on me.

Cheers Chris

Dear Jonathan, I guess I am in good company. When you wrote, "...a more elegant, and technically correct solution is to mount the tonearm pivot and platter / spindle onto a single rigid structure that allows everything to move together at the same rate and same distance (and phase), then isolate the complete system from the environment by means of an isolation platform (not footers)", you pretty much echoed my position on the subject. Thanks very much for taking your valuable time to respond.

One thing though.... chocolate IS better than tomato, except at this time of year when our tomato plants are producing great tomatoes faster than we can eat them, thanks to my wife.

Ct0517,

It would seem that our experiences defy the theory. As a certain phiilosopher once said, in that case, the theory needs revision/refinement.

An old Chinese saying: black cat or white cat, the right cat catches the mouse!

Mounting the tonearm on a separate pod allows relative movement to occur between the tonearm pivot and the platter / spindle, and this will interfere with the accuracy of measurements.

It is hard to argue with this statement and, like Lew’s ‘Galleons on a stormy sea’ analogy, it would seem to preclude further development of the ‘isolated armpod’?

But ‘theory’ and ‘practice’, when it comes to audio, are often uncommon bed partners?
For instance, there are good theories for the superiority of belt-drive over direct drive turntables…..and vice-versa….yet both can deliver fine practical results.
There were (supposedly) good theories behind the superiority of digital over analogue as the ‘source’ material in audio reproduction yet in practice (according to vinyl advocates), those theories have still not been realized?
There are good theories for the superiority of Moving Coil cartridges over Moving Magnet cartridges yet in practice, (according to some advocates), those theories do not always apply?

The ‘theory’ regarding air-borne sound transmission affecting the analogue playing system is also ‘undeniable’?
All the frequencies of the audio spectrum from 20Hz to 20KHz (as well as sub-sonic and ultra-sonic frequencies), bombarding the delicate parts of the turntable/arm/cartridge system must induce vibrations within those parts which will be amplified and projected through the speakers?
If this theory is correct, then scientifically it must follow that the higher the volume, the greater the induced vibrations.
In practice this must mean, that as we turn up the volume, the sound quality decreases?

I have heard the reverse to be true. Up to the limits of amplifier distortion, speaker ability, room configuration and turntable quality, generally the higher the volume level, the better the sound quality.
I have even heard turntables which are located in separate rooms to the speakers and to my ears, the sound quality is not improved?

So ‘theories’ are great if one needs a starting point from which to commence a design, however in audio, there seem to be many other overriding factors which render many known theories of physics to play, if not negligible, then very minor roles?

Audio is not a religion and I attempt to convert no-one here. If one hears a benefit, let on-one corrupt the reality with ‘unproven’ theory.

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.

T_bone. How could anyone of impecable taste listen to their turntable with the lid down :-)
Even with my lp12 music sounds much better with the lid up, or better still off. Never even thought of playing the exclusive P3 with the lid down.
But seriously, a great thread that makes cd /digital even more boring

Hi T_bone,
I realise that you, and many others are perhaps trying to rationalize what we 'arm-pod' folk report, against what your instincts and learnings tell you and all I can really say is that until one actually tries a well developed 'pod'.......it's all just 'words'.
But I'm looking forward to your own experiments :^)

Regarding your problems with 'feedback' and my lack of any discernible angst in that region.......I must say that I have always had my turntables mounted on a shelf cantilevered from a solid masonry wall.
The fact that you state that..."even when my P3 is well away from my speakers"....... leads me to suspect that it is structure-borne feedback you are experiencing rather than air-borne?
Could you perhaps describe how your P3 is supported?

T_bone,
Re-reading your post above.......

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.

I believe that I have done just that by coupling (or de-coupling) the motor and pods to the very same 32mm laminated (stressed-skin) rigid shelf structure which is isolated from the floor and walls by cantilevered metal brackets.
Your statement and that of Jonathan's are not quite the same?

Dear Travis, Once you couple a high mass arm pod to the plinth you likely have a very good set-up. That's what I would do if I ever build an outboard pod. I never would argue that basing a tonearm firmly in a stabilizing high mass is not a good thing. Look at those optional weights made by M-S and SAEC to stabilize the vertical shaft of their tonearms where it passes through the mounting board. That seems like sound engineering to me. I have made some brass pieces like that (to go under a mounting platform) for my DV505 and I plan to do it for the Reed and/or Triplanar.

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.

The fact that results differ slightly with the top down suggests air-borne effects,

Not necessarily. If the structure-borne feedback is resonating through the metal base of the P3 (and those 'isolating' springs can often be a happy conductor of resonating frequencies) and into the motor and/or platter, closing the lid can often form a 'capture chamber' being filled with the release of the feedback into air-borne frequencies.
Sprung decks like the Linn Sondek can surprisingly be the most prone to structure-borne feedback.
Looking at your 'System' page, I suspect your floor-mounted rack is the limiting factor. Mark Doehmann of Continuum stated that it took $30,000 of engineering to provide a floor-mounted stand like his Castellon with the same isolation as a wall-mounted shelf.
Suspended wood floors such as yours, are extremely difficult to isolate from structure-borne feedback.....and in Japan, with the seismic activity constantly providing Dertonearm's micro movements.....it should be avoided at all costs.
Any chance of you trying for a wall mount........just to experiment :^)

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.