Subwoofer hum advice
Discussion
My subwoofer has an audible hum. I'm pretty sure it's mains hum as it varies with gain and where the audio cable is positioned. I experimented with different cable routing but as soon as it gets anywhere near the AVR it hums. Would getting a cable with heavier shielding be the answer? If so, can anyone recommend anything that is more substance over style? I only need 2m.
I've had this with a cable that was run too near a power lead and because the sub does it's own amplifying, if a bit of interference gets into the signal, it gets amplified too.
I just use chord company sub cabling, but I have no idea if they have any decent shielding in them, I'd suggest rerouting the cable as much as possible to minimise the problem, your AVR shouldn't be the problem, but the power running to it might be the issue.
I just use chord company sub cabling, but I have no idea if they have any decent shielding in them, I'd suggest rerouting the cable as much as possible to minimise the problem, your AVR shouldn't be the problem, but the power running to it might be the issue.
Start by disconnecting the signal cable completely at the sub end. Does the noise go?
Now plug it back it if it did and disconnect from AV amp end. If it is still here it is picking up noise from the amp. If not, feed the power to it from another socket, preferably with the power cable run across the floor and visible.
Check pots don't feel 'scratchy' when turning them up and down.
Now plug it back it if it did and disconnect from AV amp end. If it is still here it is picking up noise from the amp. If not, feed the power to it from another socket, preferably with the power cable run across the floor and visible.
Check pots don't feel 'scratchy' when turning them up and down.
LordFlathead said:
Start by disconnecting the signal cable completely at the sub end. Does the noise go?
Yes, the noise goes when disconnecting the cable from the sub.LordFlathead said:
Now plug it back it if it did and disconnect from AV amp end. If it is still here it is picking up noise from the amp.
Yes, when it's connected to the sub but not the amp it still hums.LordFlathead said:
Check pots don't feel 'scratchy' when turning them up and down.
No, they don't. Firstly plug everything into the same outlet.
If it's still there buy a ground loop isolator.
It just plugs inline with your RCA cable.
Ground loops are caused usually by using different earthing points but this can even be inside the electronic devices themselves and cause ground loop hum.
If it's still there buy a ground loop isolator.
It just plugs inline with your RCA cable.
Ground loops are caused usually by using different earthing points but this can even be inside the electronic devices themselves and cause ground loop hum.
The sub cable is just an mono RCA. I tried another (shorter but cheaper) cable but it made the hum worse. If I connect the cable to the sub, but not the amp, I can hear the hum change as I move the cable closer and further away from all the connections at the back of the amp. I'm pretty sure it's just induction mains hum. I'll try some more imaginative cable routing options before I spend any money.
marctwo said:
The sub cable is just an mono RCA. I tried another (shorter but cheaper) cable but it made the hum worse. If I connect the cable to the sub, but not the amp, I can hear the hum change as I move the cable closer and further away from all the connections at the back of the amp. I'm pretty sure it's just induction mains hum. I'll try some more imaginative cable routing options before I spend any money.
RCA cables are not balanced like say XLR cables. One side is not connected by what you describe above here so the cable just acts as an antenna for the mains hum @50Hz£5 for a ground loop isolator and just use one channel of it for the sub.
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