[LAU] ground loop hell

[Len Ovens]

On Mon, 16 Feb 2015, Roger wrote:

> On 16/02/15 11:51, Len Ovens wrote:
>> 
>> It seems even with all power coming from one outlet, I have one amplifier 
>> with some hum. It is way less and by playing with levels I was able to make 
>> it so low as to not be noticed. However my plan of isolating everything 
>> should fix it completely.
> Look at the signal cabling or even nearby EMF sources. I recall ages ago

Over 100 ft of unbalanced input. The hum was not there with the power 
ground lifted (now fixed). I will be Changing things so I have balanced 
out of the mixer -> through snake -> one to one isolation transformer -> 
unbalanced to amp.

My final setup will be: all stage powered instruments or unbalanced 
sources will have a DI (transformer with ground lift), All returns to 
stage will have isolation transformers. Mics go straight.

Anyway the hum was low enough that I had to tell people it was there, so I 
am at "good enough". I do have two pots at max and one very low to get it 
to work that way though. I will see what my isolation box does.

--
Len Ovens
www.ovenwerks.net