Multiple Altec 9440A amplifiers ground loops

[rghinton]

I am using the unbalanced 1/4" input sockets that override the Balanced High Z Inputs. Since the Balanced High Z Inputs are overridden (per the Altec 9440A operating instructions), the transformer sockets are out of the circuit. I do not have the transformers installed and I have no jumpers (jumpers are not an option with the 9440A). The first chance that I get, I will remove everything from the rack that ties the chassis of all units together and see if the hum is still there with none of the units connected to the common metal rack. Thanks for your interest bfish.

[bfish]

... (jumpers are not an option with the 9440A)...

Sure they are... just not;

...(per the Altec 9440A operating instructions)...

Gives you essentially the same thing you're doing, only with the XLR cable.

You can run more than the listed input xfmrs too, see Paul R's excellent answer to that Q. (I know, loss of sens/BW). You've got a lot of holes there to fill though...

Probably unrelated, but a prime suspect with HT ground loops is the cable/dish ground. Usually a separate ground rod, and not hooked the house AC ground. Easy enough to trace, just unhook the cable.

I'm picturing you swapping rack hardware on those beasts. :doh:

[rghinton]

I have the amplifiers and processor out of the rack. I have not had time to check for hum.
I have the 4 amplifiers, a 5 channel surround sound processor and a dvd player. I do not have cable/dish in this system.