Lowrider,
In order to prevent ground hum most have 2 different grounds, one being Chassis Ground (earth, safety ground) which should also be connected to pin 1 of all XLR connectors both in and outputs. Typically Signal ground is isolated from chassis ground with a dual diode in reverse parallel and a resistor - or something similar. Signal ground should not be present on pin 1 of the XLRs
I have referred to this paper before - it contains some very useful information about grounding
https://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf
Good Listening
Peter
In order to prevent ground hum most have 2 different grounds, one being Chassis Ground (earth, safety ground) which should also be connected to pin 1 of all XLR connectors both in and outputs. Typically Signal ground is isolated from chassis ground with a dual diode in reverse parallel and a resistor - or something similar. Signal ground should not be present on pin 1 of the XLRs
I have referred to this paper before - it contains some very useful information about grounding
https://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf
Good Listening
Peter