Finding a hum

[SS Minnow]

More like a com line on a lighting snake... Is that OK. or would the speech get slurred?

 

[TimMc]

More like a com line on a lighting snake... Is that OK. or would the speech get slurred?

Only if the snake has been drinking...

Most of the stories you'll hear about mixing DMX and analog audio in the same cable jacket are not recent - we and the cable companies have learned that 1 common shield and drain wire is not sufficient.

In my shop we routinely bundle analog 6 pair with DMX and CAT5/6 cables and an AC service feed for the LX dept without negative results.

Ditto for strapping an AC line (10/5 3 phase) to the analog audio drive snake, which is on top of or next to the 54 pair analog audio multi... no problems.

 

[JimP0771]

Always make sure you never have any Lighting and sound cables next to one another. That will create a hum I learned that the hard way years ago. Will never do that one again.

 

[RonHebbard]

Always make sure you never have any Lighting and sound cables next to one another. That will create a hum, I learned that the hard way years ago.
I will never do that one again.

I should know better than to loosen the lid on this can of worms (But apparently I don't).
In your broad and sweeping generalizations, are you speaking of balanced or unbalanced audio cables and at what signal voltages, impedances, and levels?
Similar queries regarding your lighting cables: DMX or networked lighting control cables and / or 120 / 208 volt single and multi phase load cables?
@TimMc Wanna wade in, I suspect the water's gonna get a little choppy?
Toodleoo!
Ron Hebbard

 

[jkowtko]

Here's a fun one and a quick lesson learned ...

Early on I had a PC with M-Audio Revolution 7.1 PCI sound card with (unbalanced) outputs going to my board ... worked fine for a while, then after reconfiguring some equipment in the booth I started to hear a hum, even when I turned off the PC completely. Only if I unplugged the audio cables connecting the computer to the board would the humming stop. So the hum was coming from the computer ... but how could that happen when the computer is turned completely off?

Turns out I had plugged the monitor for the computer into another outlet under the table, which was on a different electrical circuit, which evidently had a ground differential (not sure of the exact term here) from the circuit that the main equipment was on ... when I plugged the monitor into the same outlet as the computer and board the problem was resolved.

-- John