Rerurn to Romy the Cat's Site
In the Forum: Analog Playback
In the Thread: The last phonocorrector: “End of Life" Phonostage
Post Subject: Route(s) to GroundPosted by Paul S on: 11/20/2011
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The ideal "star" grounding plan is seldom realized in practice, for lots of reasons. For one thing, it takes serious concentration to really think it through. As I have said many times, it is often useful to have a "bleeder" on the chassis, and this works better if it runs uninterrupted to a dedicated ground rod rather than via the mains neutral or ground. Again, neutral and ground share a bus at the main (service) box, in any case, and often before that in a sub-panel, or even in outlet or junction boxes, even though this is not good for hi-fi (nor is it safe...).
The phono [pre]amp exacerbates both parasitic and self noise both just because it boosts a small signal so well. Sure, any EMF can harbor and/or effectively generate noise that gets picked up by the gain circuitry, in addition to generic EMI and RF. Likewise, current may be "stacked" internally due to varying ground potential, especially between gain stages, not to mention the loops we always figure out the hard way.
Lastly, not saying it is this way for you, but I have also been quite peeved when replacing a special $$$ tranny with someting "less special" cured the hum immediately!
Best regards,
Paul SRerurn to Romy the Cat's Site