A Copernican View of the Turntable System

Lewm,

And the humour was appreciated.

As always...

Lew, you just described what I have evolved to with my own design. Hopefully now my local woodworker can turn it out for me.

2 1/2 years since the last contribution and yet nearly 1.3 million views...😎
In the time since my first enthusiastic proclamation, I realise I may have been a little cavalier in my concentration on the arm-pods at the expense of the platter/motor itself.
As most of us have realised after decades in audio......EVERYTHING matters....
I initially designed and had made, the solid bronze arm-pods and merely placed the platter/motor on tiptoes
 http://i.imgur.com/Xp97BF8.jpg
Whilst the sound produced by this arrangement seemed to prove my thesis....others looked to improve on my platter support
http://i.imgur.com/sPdkMWn.jpg
http://i.imgur.com/8BTXLIL.jpg
Realising that the flimsy metal shroud protecting the motor unit was able to 'flex' as the platter spun....I designed a stainless steel cradle to more rigidly hold the turntable
http://i.imgur.com/UuEyECm.jpg
http://i.imgur.com/Ui6trXd.jpg
This was an immediate improvement and I discovered that the Victor DD decks actually sounded better 'nude', without their protective metal shroud.
In the intervening years I became a little frustrated at the tendency for this lightweight 'cradle' to be moved whenever I re-aligned a new cartridge (which was rather often 👅). The arm-pods at around 11Kg each, would NEVER shift on their spiked feet.
I needed a 'cradle' with more mass, and thus was born the polished granite cylinder
http://i.imgur.com/S97uGns.jpg
http://i.imgur.com/qUyVNA2.jpg
This change was as much a revelation as the bronze arm-pods....
It seems that even the SS cradle was able to 'twist' under the constant centrifugal forces of the spinning platter and this resulted in a loss of ultimate transparency and lower register control.
No wonder the latest 'rave' turntable (Kronos) utilises counter rotating platters to neutralise this twisting force.
https://s-media-cache-ak0.pinimg.com/736x/62/64/dd/6264dd2057a9132a141c8cfda552102d.jpg
I feel a little foolish to have overlooked what must have appeared obvious to many for all these years....but the lessons have been learned.
Not only must the arm-pods be massive and immovable....the platter/motor must also be held in a vice-like grip. Mass is one method of achieving this but there are obviously others.......

A few problems were discovered during this last design exercise and they may be peculiar only to the Victor decks...❓
Whilst the 'nude' motor unit sounded better in my system....when I mounted it in the first granite cylinder
http://i.imgur.com/xIGWxmM.jpg
electrical feedback of the 50/60Hz became apparent with the two tone-arms which were not in the 'normal' platter/arm universal relationship.
http://i.imgur.com/ieD1q6s.jpg
Here you can see the DV507/II tonearm/cartridge passing directly over the motor transformer. This was the most affected tonearm.
The solution was to screw on the metal shroud which apart from protecting the delicate electronics and circuitry....acts as a Faraday Cage to block the RFI/EMI for the cartridge
http://i.imgur.com/UAEMFj7.jpg
Another important cure for this feedback problem is to connect the ground wire from the chassis to the preamp.

With all systems go.....time to sit back with a good Scotch and enjoy the fruits of my journey...🍹🎼

halcro

Another important cure for this feedback problem is to connect the ground wire from the chassis to the preamp.

Are you referring to the ground added to the pcb board or the external cage connection point?

 

Are you referring to the ground added to the pcb board or the external cage connection point? 

The ground wire attached to the PCB did nothing to mitigate the RFI/EMI interference.
With the Faraday Shield (metal shroud) in place and the ground wire attached.....the problem appears to have vanished.
I'm not electronically/electrically savvy so can only report the effects.....it appears that the Faraday Shield 'absorbs' the electrical energy emanating from all the electronics (particularly the power supply) and the ground wire dissipates it from the screen.
I used to keep the motor 'powered on' (but not operating) when mounted in the SS cradle as it tended to sound better than fully 'cold'.
Within the constricted enclosure of the granite cylinder.....I found that the build-up of electrical energy if the motor was left on (without the Faraday Cage) totally destroyed the sound of the turntable rendering it unlistenable.
As a precaution to the bouncing around of this electrical energy off the reflective granite enclosure.....I lined it with cork sheeting in the latest version to try some absorption.....🤔