Filament Power, for larger builds

[Cqwet Dbdfte]

Right, the ground loop problem may need to be solved one way, RFI in another way. When these old texts were produced cell phones wasn't a major issue. Many "balanced" lines are not truly differential, just DC balanced. Ethernet lines have a good setup for differential signalling and transformer isolation. Stranded CAT 5/6 should work ok also for audio.

 

[ruffrecords]

Sadly, Muncy's '94 AES paper isn't easily findable free online. It is exceptional.

There are different schools as to best practices for what to do with the shields. Up to and including landing one end and connecting the other through a small cap for RF. Always sounded like a pain to me.

A place I worked 25 years ago was set up with male end lifted, bussed shields, if landed, at the bays. Mic lines excepted. Still had noise issues. I redid quite a bit of stuff there this last year, some fairly guerilla, two rooms very conventional. Landed everything, bussed at the bays, and have had virtually no problems (one issue with the monitors on a TSM aside). Don't ask me what changed. The place was built in the 70s, and redone several times since. Oddly, it seems to work best like this. Just goes to show that "ground loops" aren't always ground loops. Nowadays, I tend to land, and lift if I have problems. I find relatively few.

I once found an interesting paper years ago, I think by Clive Green of Cadac. Bottom lines, the more screens you can parallel by landing both ends, the lower any noise becomes. Basically the interference current has less impedance across which to create an interfering voltage.

e
But again, a whole different animal to the pin 1 problem.

Indeed.

Cheers

Ian