[xluben]

Tonight I unhooked my Marantz reciever and thoroughly cleaned it (inside and out). I hooked it back up and now there is a noticeable hum from my subwoofer when nothing is connected to the AUX input (but the cable is inserted).

Let me explain the circumstances in more detail.

No hum ("or" goes in between each item):

Reciever off
Subwoofer off
No cables plugged into AUX inputs (but sub plugged in)
Subwoofer not plugged into reciever
Input selector on anything but AUX (AUX and subwoofer connected)
Cable plugged into AUX is plugged into source (iPod, Laptop)

Hum occors:

When everything is on, sub is connected to reciever's Pre Out, reciever's selected input is AUX, and cable is plugged into AUX (but nothing is plugged into the other end of the cable>

Hopefully this is clear. Basically I have an iPod dock connected to my reciever's AUX inputs with a mini-to-RCA cable. When everything is plugged in and turned on (music paused) there is no hum. As soon as I pull the iPod out of the dock, there is a loud hum out of the subwoofer. The hum's loudness varies with the reciever's volume control.

The strange part is that none of this happened before today. I have tried everything I can think of to get the hum to go away, but nothing will work. Is this something internally between the Pre Out and AUX in signals? Or is it a grounding issue?

The reciever has a post on the back called "Chassis Ground" Do I need to hook this up to something? (I put 16ga wire in it and touched it to a screw on a light switch, and I thought this stopped the hum, but now it no longer seems to work

).

 

[jumping jupiters]

have you tried hooking up your ipod dock to another input besides the AUX? see if the problem follows the dock.

this sounds like a crazy problem! though it is not uncommon to have a hum in your sub and not your speakers...my guess is that the frequency range of the sub is more effected than that of most bookshelf or non-full range speakers. I had a problem with hum in my sub and it turned out to be coming from my cable TV connection that was hooked into the processor. the hum was there no matter if the unit was on or not...it ended up that the ground cable on the outside of my house had a poor connection...literaly the clamp from my cable tv ground to the grounding rod was too loose and needed tightening from being hit too many times by the lawn mower...that took a while to figure out!

Good luck