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In the Forum: Analog Playback
In the Thread: The last phonocorrector: “End of Life" Phonostage
Post Subject: EMF and "Split" "Grounds"Posted by Paul S on: 11/23/2011
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If you can do it, try isolating both cases/chasses from your "ground plane(s)". Use one inclusive "ground plane" for both the PS and the gain/RIAA sections, and ground this "ground plane" to the house "neutral" wire. Do NOT connect any shielding to the "ground plane". Then ground the cases/chasses, all internal shields, the IC shields, TT/motor, arm and step-up ground lugs to a special, dedicated ground rod (not the house neutral or ground!). This special ground rod is the "bleeder" I keep referring to.  Make sure any un-used inputs or outputs are covered/shielded. If you have noise from the bridge, consider using the (Fairchild?) "Stealth" diodes; they are VERY quiet. I posted about these in my K&K thread.

Maybe the above will work to quiet your rig. The big, strong trannies throw big, strong "fields", however, and they do tend to make their own problems. Surely you have the trannies on isolation pads of some kind, with fasteners tightened "just so", to quell vibration, and tranny axes at right angles when they are adjacent?

I don't remember now if you said your step-up tranny is in the phono stage case/chassis. It might be quieter if the step-up tranny is in its own shielded case that is grounded to the special, dedicated ground rod. Certainly, it should not be connected to the house neutral or ground wires.

Good luck.

Best regards,
Paul

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