On Mon, 6 Mar 2017, Bill Purvis wrote:
Not strictly Linux Audio: I've had problems with ground loops in our church
PA system.
Been there done that :)
That amp is powered by from a mains socket in the adjacent room and we had
very significant
mains hum with it until I interposed an audio transformer. Thus no direct
ground connection
between the amp and the rest of the kit.
I have just made it my policy to use an isolation transformer between any
two units with power. I have 6 for outputs (board to FOH and monitor) and
3 for inputs (guitar, bass, kb). This is a small setup. The hall has two
power entrances and the grounds seems to be at odds. I have made sure the
board and the stage use the same power (so a mic holding performer doesn't
get buzzed when touching an amp) but one of the FOH speaker/amp units is
not... we had one blow before I isolated it. I think it has a
transformerless PS so I am not sure if it is related or not... it went
back for repair at no cost.
The idea with USB is to have power included, this is great for USB memory
sticks and things, but for audio, a USB port that has no power and is
optical would be wonderful.
--
Len Ovens
www.ovenwerks.net
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