Mains hum in audio system

[rong1]

My sound system hums in varying degrees depending on what appliances are running. I have 'earth bonded' my reel-to-reel recorder, mixer desk, computer and amplifier without affect. Should I build a power box with a number of huge capacitors across the mains? Any suggestions welcome.

 

[karesz]

Hi,
If it humms as stand alone equipment_yes, you need to check the owns power supplies & internal eliminate eventuel GND-loops for humms...
Was it ever OK, or is it a "new effect"?
K.

 

[rong1]

The equipment is new to me, the hum occurs when I connect stereo phono cables between 8-channel mixer and my computer. I have tried new cables without success. I was considering building a power box with perhaps 12uf capacitor across the mains. It sounds like an induction hum.

 

[karesz]

If its only after connecting some external source:
I think its a clear earths loop problem_assumed; its not to eliminate with a extra filtering...
You can try to check these system supplied per isolations transformer, but because PC supplies are switcher/mains isolated_i dont understand it to first
K.

 

[rong1]

I'll check the internal earths of the mixer first. Thanks for your help.

 

[karesz]

You can try it so that you will drive with your mixer a HI-FI system/PA or an oscilloscope on the mixers output?...
K.