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sky satellite causing Amp/Sub to hum

npinks

Standard Member
i have just disassembled my av equipment to put in to a larger stand for the new tv

i have used the same HDMI cables for each input and the same cables to the new tv

What i now have is a humming noise been generated buy the subwoofer, after hour couple of hours plugging and unplugging i have found that the cause is the SKY Satellite box, the humming stops when i disconnect the hdmi lead, when reconnected the humming starts, but goes when i disconnect the sky cable from the dish and comes back when i touch anywhere on the box with these

i think its some sort of grounding issue so tried another box and still got the humming

i'm stumped in why its started and how to solve this, anyone had similar issues:(
 

Rodders53

Distinguished Member
List of other kit (TV, sub and amp especially) may be helpful if it may be brand related.
Do cables go direct to your own dish? (not communal). Any amps or loft boxes involved? Does TV UHF aerial connect via Sky box as well? any Magic eyes?

Has this all worked OK with the new TV before new stand was obtained?
 

npinks

Standard Member
Panasonic 55CX700b TV
KEF eggs 7.1 speaker setup
KEF Amp
skyHD box
aTV
All connected to a Onkyo NR609 amp

All worked perfectly, I have through process of elimination worked out the hum becomes apparent when the skybox has the twin coax cables connected, with just the hdmi lead there is a faint him, which really goes louder when I touch the sky box with the wire end of the sky coax

I have had the ladders out and disconnected the cables from the lnb on the dish, hum still there

I think it's a ground loop issue but didn't have this with old tv, but it's still there with the new tv completely disconnected from the mains and hdmi leads
 

norman bates

Established Member
Hello I am having the exact same problem when I disconnect the hdmi into television from virgin box the buzzing in the subwoofer stops !
 

JokerJack

Established Member
I had the same issue, turned out to be a ground loop issue. Ended putting a piece of wire from the back of the sub to the AV receiver to earth them. you can buy sub cables with earth leads on them or just use a separate cable.. mine is gone since doing this.
 

Rodders53

Distinguished Member
Nearly all modern kit is double-insulated with no real 'earth' or ground connection. Unless a communal feed aerial and satellite connections are allowed to float and are seldom earthed.

Thus, interconnection leads are the only way all the items outer cases are brought to the same potential, approximately... any voltage imbalance can cause small currents to flow and may result in enough signal to give hum.

Some TVs can induce problems via the UHF TV aerial connections via Sky boxes ... Decoupling Sky coaxial cable to avoid ground loops may provide a solution if that is the cause... and it seems the most likely to me as the 'new' or 'change' in your setup is the TV... and the hum is unlikely to just be coincidental?
 

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