Hum in system when only amp is on


I am getting a hum when the amp is turned on but not the preamp. The hum goes away when the preamp comes on. Does any one have any ideas?
My system:
Theta dreadnaught 5 channels
Cary cinema 6 preamp
audioquest jaguar unbalanced rcas
dedicated outlets

Thanks,
Ian
128x128ian_slater
The arrows on the ICs connecting the preamp to the amp should point to the preamp. The preamp AC cord should be grounded, but the amp should not (it's grounded through the ICs and the preamp) and you should use a "cheater" plug on the amp's AC cord plug so that you are only plugging two prongs into the wall, not three.

Try those two things, and see if the hum doesn't go away.
This is not an answer to your question, it's just a rule we ALL gotta follow:
ALWAYS turn your preamp on (and give it a moment to stabilize) before turning on your amp. ALWAYS turn your amp off before your preamp.
Best of luck,
Joe
Nsgarch, I don't think the directionality of the IC's would make a difference in Ian's problem, but my understanding is the arrows should go in the direction of the music -- thus, pre-amp to amp.
I agree that floating the ground on the amps, but not the pre-amp, can solve a ground loop problem. That's what I do, but I've been told it's not the safest solution, either.
Ncarv, you might want to read the description of their x-Stream power cords on the PS Audio site. They even provide their cords with a removable ground pin for that very purpose.

As for the arrow direction, Ian is using Audioquest single ended Jaguar ICs. These follow the standard Bruce Brisson "shotgun" design a la Monster, MIT, Straightwire, etc. Meaning that the shield is connected to the ground ring at the arrowhead end of the cable and not at the other end ("floated"). You want to drain the shield to the preamp, since in a star-grounding arrangement, that's the one grounded component. It really has nothing to do with signal flow since a cable will acclimate to either direction of signal flow during break-in. This unfortunate misunderstanding arose as a result of cable manufacturers wanting to give the consumer an oversimplified explanation for orienting their cables. And in fact it works when you're talking about source-to-preamp connections, but does not apply in preamp-to-amp connections -- UNLESS your amp is the only grounded component. However that won't give you star-grounding, which is the recognized best method for getting the most noise reduction.

Hope that explains it :~))