[LAU] ground loop hell

[Roger]

On 16/02/15 13:15, Len Ovens wrote:
> 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.
Did you try just disconnecting the shield at the amp end?