A Copernican View of the Turntable System

Dear Henry, I just stumbled upon this revival of your interesting thread. I think in your post of March 6 you have accomplished a well known rhetorical ploy; you've raised a "red herring". My argument (and Dover's) was never primarily about plane parallel mounting of tonearm with respect to the platter surface, although I would never argue that this is not important. My argument for a fixed relationship and a physical connection between the tonearm base and the turntable bearing assembly had mostly to do with preventing motion of one relative to the other in response to external or internal sources of vibrational energy. One wants the combined structure to dissipate mechanical energy as a unit. My metaphor about trying to cut a diamond resting in a rowboat whilst sitting in a second rowboat vs performing the same task while having the whole operation in one boat (easier, obviously) was meant to illustrate the point. That's the "bad thing" that I fear could come into play when a tonearm is mounted on an entirely separate support system and dissociated from the platter/bearing. Disparate vibrations of the platter vs the tonearm generate spurious signals from the cartridge.

I would also posit that the problem of "parallelism" (for want of a better single phrase) exists for both types of systems. A less than astute user of an outboard arm pod could screw up the parallel relationship between tonearm bearings and LP surface even moreso than could a poorly executed turntable design. As someone else with a lot of experience in tonearm design once remarked regarding azimuth adjustable tonearms, having the capacity to adjust azimuth endows one with the capacity to really mess up azimuth adjustment, as well as to get it right.

Dear Lew,
For a ‘man of science’…..I am surprised by you?
You posit a phantom condition……and then proceed to create an argument and case around it.
Nikola would be less than impressed with your logic?

My argument for a fixed relationship and a physical connection between the tonearm base and the turntable bearing assembly had mostly to do with preventing motion of one relative to the other in response to external or internal sources of vibrational energy.

Preventing “motion” of one relative to the other”??
What “motion” is this exactly?
Other than a fully suspended deck (which is outside the Copernican view of this thread)…..can you please explain this “motion” and present some evidence of its existence?

You appear to equate “vibrational energy” with “relative motion”?
The most fundamental aspect of supporting a turntable system IMO…..is to create a base for it as free from “vibration” and structure-borne feedback as is possible?
If “relative motion” exists…..all bets are off….unless you are playing one on a moving vessel such as a ship, yacht, train or plane….in which case……gulp!?

If one is successful in creating a ‘mounting shelf’ free of structure-borne feedback……there should be no “vibrational energy” transmitted to the turntable system.
Air-borne feedback is rarely an issue in an audio system unless one’s cartridge is ‘microphonic’. Cartridges work by translating ‘motion’ into electrical energy whereas microphones work by translating ‘airwaves’ into electrical energy.
Many listeners assume that when they detect ‘feedback’ in their systems…..it is the result of air-borne feedback whereas it is usually existing structure-borne feedback which is amplified when the volume is turned up.
If air-borne feedback was a problem in audio……the plinth would be the least of the problem areas?
The platter would be directly affected as well as the tonearm and particularly the cartridge and stylus.
Oh….and did I mention the vinyl disc itself??
If air-borne feedback were a problem……the sound of everyone’s system would….by definition….deteriorate as the volume increased?
My system’s quality IMPROVES as the volume increases.
As I listen comfortably in my home at 90-95dB SPLs and Raul claims he can approach 100-110dB!!!….air-borne feedback is a myth propagated by sheep following sheep.
The primary source of “vibrational energy” sadly……is created by the turntable itself….or rather…the motor, belts, pulleys, bearings, coils and transformers.
A ‘happy carrier’ of all these demons….is in fact the plinth which you unselfishly wish to connect with the tonearm. The tonearm! The very heart of the Copernican view of the turntable system?!

So now your ‘a priori’ proposition (devoid of any facts or evidence) has been questioned….you are left with the claim that the advantage of a plinth is that a separate tonearm base is likely to be adjusted ‘out-of-level’?
I can’t believe that you wrote this with a straight face? :-)
So let me get this straight……you are quite happy for people to get their platters AND tonearms ‘out-of-level’ by being connected on a plinth……but you draw the line at a tonearm pod being messed up?

Disparate vibrations of the platter vs the tonearm generate spurious signals from the cartridge.

So you prefer the platter and tonearm to ‘vibrate’ homogeneously?
In my system….I prefer them not to vibrate at all?

No Lew….the plinth is not a necessity.
It is a hangover from the early days of marketing a complete ‘turntable system’ as a package and few have questioned the premise of the turntable platter as the centre of this universe?
The ‘plinth’ is about as useful as tits on a bull and is the cause of many more problems than it solves.
The turntable/platter is the ‘slave’ of the cartridge/tonearm…..and the anchor of the ‘king’ tonearm must be as heavy, solid rigid and level as a rock.

OK. I read the first paragraph or two and then ran out of energy (vibrational and otherwise). Why can't you imagine that two wholly independent structures could react differently from one another to, lets say, a heavy footfall on one hand or the 1812 Overture blasting into your listening space, on the other? (I see that you don't believe that the energy put out by a loudspeaker can cause damaging mechanical feedback. This is your right, just as it would be your right to believe the earth is flat.) If you can't imagine that two structures mounted on your shelf might respond to energy coming into them by any of these and several other various routes in different ways (different resonance frequencies, longer or shorter time to dissipate the energy, etc, etc.), and if you cannot imagine that there is some advantage to having a single combined structure that responds in unison to extraneous disturbances, so as to minimize relative spurious motions of the cartridge vis the LP groove, then I cannot help you, but it is not I who is ignoring or not understanding the science. By the way also, you CANNOT stop all energy from entering into your turntable/tonearm. No one can. Unless you want to send your system into gravity- and friction-free outer space and cut rocket power thereafter. (Good luck setting VTF out there.) So, it's nice that you prefer a totally isolated system, we all would, but it ain't gonna happen on earth.

By the way, the PLINTH has nothing to do with this discussion. That is a different obsession of yours and the subject of a different thread.

You also wrote, "So now your ‘a priori’ proposition (devoid of any facts or evidence) has been questioned….you are left with the claim that the advantage of a plinth is that a separate tonearm base is likely to be adjusted ‘out-of-level’?" Did you really read my preceding post? That is exactly what I said I did NOT say. We've never discussed that issue before, so far as I can remember. It's pretty obvious that any design that gets the tonearm bearings and the platter surface plane parallel is OK, regardless of how it's done. This has nothing to do with our subject.

I think you want this thread to be read and contributed to only by those who swallow your line of thinking hook, line, and sinker, and who come here to kiss your butt.

Dear Halcro: ++++ " So you prefer the platter and tonearm to ‘vibrate’ homogeneously?
In my system….I prefer them not to vibrate at all? " +++++

of course that we prefer not to vibrate at all but this is only in a perfect world.

The TT always vibrate/resonates and the stand alone tonearm board too bacause tehre is no way to isolate 100% of where is seated or for what is surrounded. As a fact the tonearm/cartridge are in continuous vibration way.

You said that air borne feedback does not exist on stand alone tonearm towers but you don't have any test that could prove it. I don't have on hand but exist studies that proves that every single system and especially the analog source is affected by air borne feedback.

Maybe at very high SPL we can't detect it because that high SPL but exist no doubt about. Yes, the cartridge is more sensitive to that air borne feedback.

In the other side you have to take in count that the cartridge is extremely sensitive to tiny very tiny microscopic motions that for us are non-detectable but this IMHO does not means does not exist because exist.

The ships/water example by Lewm is very good and self explained to be against stand alone tonearms towers.
The problem is that what " happen " in theory unfortunatelly in this regards can't be duplicated in our systems so we are unaware of it and unaware of any single sound degradation coming from that subject.

I know you are a wise person and there is useless to ignore something that exist and ignore it because we can't here it.

I promoted the stand alone tonearm towers years ago and still think is the best way to go till exist a better way to isolate from the TT the tonearm/cartridge unit.

In this same thread I speak very clear about what that UNIT means and why is the cartridge the King and all other links the slaves. The UNIT is not the King as it's not IMHO the tonearm.
A tonearm design goes around from the begin to satisfy the cartridge needs not the other way around. That the tonearms designs don't take that statement at 100% does not means those designs are right.

Example, today and in the past people/designers/reviewers suddenly vote for the 12" tonearms against 9"-10". IMHO the 12" makes more harm than help to the cartridge works.

A cartridge between other things moves in the grooves at random for the tonearm with suddenly direction changes where the tonearm has to be and has to has a fast response on what the cartridge is asking for, a longer tonearm respond slower than a shorter one ( everything the same. ) so the longer tonearm goes against the cartridge needs and can't fulfil those needs where a shorter one makes it in better way.

There are many other disadvantages and the " only " in theory advantage that a longer tonearm has is that the tracking error is lower but is only in theory.

In other threads we already discuss about and the real subject is that no one can hear the difference for the better because a tonearm is longer.

But as this " stupid " myth there are many in audio.

The tonearm and cartridhe form a UNIT but the tonearm is a slave of the cartridge and the real King. Just an opinion.

regards and enjoy the music,
R.

Halcro/Lewm/Raul

You are all arguing the same points but at cross purposes.

We are measuring the groove and to measure it accurately there must be no movement between the tonearm mounting point and the platter/bearing.

Lewm's argument is simply that a rigid plinth connecting the arm and platter will minimise the risk of any differential movement.

The requirements for a nude TT approach are no different really - there must be no movement between the tonearm coupling and the platter/bearing. Placing the platter bearing on a shelf and placing the tonearm on a pod on a shelf simply means that the shelf becomes the plinth.

There are crappy plinths and there are crappy nude turntables.

Examples of crappy plinths are the Tin Sondek and the SME hollow plinth of the 60's built for the Garrard 301/401 ( they built and sold a shaker table ).
Examples of crappy nude TT's are the plethora of Garrard 301/401's running separate arm pods mounted on spongy feet that provide no rigid coupling between arm/platter.

An example of a good plinth is the Final Audio. The Final Audio has the inverted bearing/platter and gunmetal arm pod both bolted to a 40kg slab of superplastic zinc alloy that is inert - at room temperature this slab cannot be excited below 100hz, energy in this material is dissipated at a molecular level through grain sliding, it will be better than any shelf that is not of the same material.

Halcro - what category do you place the AC Raven - plinth or no plinth ? Are you going to fully nude the Raven ?

I would argue that the Record is King. That is the centre of our particular inverse.