On Wed, 3 Jun 2015 23:21:43 -0700 (PDT), Len Ovens wrote:
I don't know about ground switch, but some of them
had a "hum" switch
or something similar... flipped the ac lines. Sometimes the "neutral"
was connected to chassis... which with no keying on the ac plug meant
the chassis might just as easy be hot. Nobody has done that for a long
time now. The idea was old and outdated 50 years ago. (probably before)
I also think it might soft or more likely hard disconnect neutral (case
ground) from audio cable connectors ground.
Again, I want to point out, that proper ground wired equipment still
could cause issues, when the microphones ground source from the outlet
is another ground source from the outlet for the guitar amp.
On Wed, 03 Jun 2015 22:23:59 -0700, David Christensen wrote:
If this is a home studio fed from the same panelboard
that feeds your
house, you might find that all the other loads in your house (and/or
your neighbors' houses) are causing electrical noise problems for your
audio systems.
As long as electric arcs or heavy machinery aren't involved, but just
averaged home appliance it doesn't matter. Even a broken washer,
illegal baby alarm and 10 cheap switching power supplies unlikely will
cause audible issues. Indeed, even a single bad designed electric clock
in the neighbour house could cause radiointerference. In Western
civilisation detector vans seize such broken clocks.
If you're living close to a street railway or the like, than you're
screwed.
Btw. we should avoid spaghetti syndrome, but even a spaghetti
syndrome that is a mix of audio cables and main cables unlikely cause
an audible issue.
For example, separating power and signal conductors as
widely as
possible ...
... doesn't harm, but if the distance is the length of even a long
room, a few centimeters or a meter should be enough. Audio engineers
not seldom use mains and audio cables in parallel, close together over
distances that are much longer than long rooms. Just the audiophiles
tend to care about separating centimeters of cable.
Nothing should be broken, IOW audio gear and lighting should be without
flaws and your neighbours shouldn't make steel, that is more important
than separating audio and mains cables "as widely as possible".