A Copernican View of the Turntable System

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.

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.

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!

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?