grounding scheme

[Leolabs]

When building some sort of preamp/intergrated amp,with a few pairs of input RCAs,a selector switch or a bunch of relays,what kind of grounding scheme is more suitable,by system or by channel???

[parsecaudio]

Hi leolabs
the better system is to use a bunch of relays that switch (on each input) both ground and signal from the connected source moreover if a tape(or CD)recorder is present, and grounding like only one input present.
The relays must to be connected as closely as possible to the RCA(or XLR)inputs.

[AndrewT]

Hi,
since I have never built an integrated nor a pre-amp, a bit of guesswork here, so this is a suggestion.

keep each channel separate.
keep low current, clean grounds separate.
keep higher current clean grounds separate
keep dirty grounds separate (decoupling and relay power).
keep power supply ground and zero Volt commons separate.
keep safety earth separate.
keep each RCA ground insulated from the chassis.

Bring all the grounds (EXCEPT the safety earth) to a single audio ground (central star ground).

You will need to experiment with the order of bolting the various grounds together, but I recommend that the dirtiest grounds start at one side moving progressively through the high current to the cleanest ground at the other side. I use soldered earth tags on the end of each ground, that way way I can add extra grounds to the bolt, or change the order, or remove for maintenance.