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?
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