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In the Forum: Analog Playback
In the Thread: The last phonocorrector: “End of Life" Phonostage
Post Subject: Bingo!Posted by N-set on: 2/1/2012
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 Paul S wrote:
N-set, I don't know much about the theory, but maybe you have focused on "uniform ground potential" while neglecting the effects of EMF?  (Not to mention the EXTREME difficuty of maintaining a "single", non-reactive "ground path" in the first place...)


That was it, Paul! I've ass-u-med that the all points of the chasses will be at an equal potential. How wrong (maybe right at HF)!
I've rearranged connections within the CHASSES in a starlike-fashion: now every chassis has it's
own "chassis bolt" where different parts of the chassis/screens etc meet.
The signal ground (big Cu plate) is connected to the signal chassis bolt, which is
the grounding terminal for the TT. The connection to the PS chassis and the mumetal cases of the SUT's
also meet there (the upper right corner):

Nset834_signalbox_topview.JPG


With all in place, the SUT's connected, the chasses closed, the inputs shorted
and the PS far away the ham is gone. Huray!
The latter constarined will be addressed by closing my mains transformers in steel coffins and also possibly
the SUT's--there is enough space. The earthing--my lovely Cu toilet tube does not seem to a have an
earth connection-there may be some plastic part somewhere, so I'm floating...
The next step is to cook a decent TT-pre cable and make that interface ham-tight.

Cheers,
Nset


 

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