Dgob, Sometimes I go for humor ahead of substance. Just kidding. We all know where I stand on the issue of plinths. I have done the work to reach my conclusions, so I feel ok as regards my own preferences and my own system. However, I am beginning to think about an inert plinth that provides a lot of mass mostly under the platter/motor assembly, so there is a minimal "deck" extending out around the platter periphery. Then a pod for mounting the tonearm, like the ones some of the guys have built, that would be firmly mated via a structural member, back to the main plinth. A few commercial products are built that way. I do not back off my contention that a closed loop connection between the tonearm bearings and the tt bearings is desirable, as Dover mentioned.
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
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Lewm, It sounds interesting and I'd be interested to hear about the outcome of your experiment. The closed loop arrangement is precisely what I'm trying to test while optimising the isolation in light of other decoupled approaches. Experientially, (as everyone is probably aware) I am convinced by the performance of an SP10 on pneumatic footers with a decoupled tonearm arrangement: the sound is exceptionally good and greatly exceeds all of my prior analogue experiences. However, I am really only interested in obtaining the optimum performance from my gear and that could very well lead me to share your beliefs - even though I remain quite dubious. I will give it my best shot and see what that brings. As always... |
2 1/2 years since the last contribution and yet nearly 1.3 million views...π 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 Β 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 π ). 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...β 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...πΉπΌ |
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