Subwoofer buzzing (ground loop?)

[josdes]

Hey guys,

So I recently got a car subwoofer with a car amp to add to my current audio setup (which is an amp with 4 speakers). I'm using an old PC power supply to power the amplifier for the subwoofer. I'm using a Y-splitter to connect the audio source to the subwoofer amp and the other amp.

Everything was working fine until I turned it up quite loud. The power supply for the subwoofer failed when I did this. I replaced it with an identical power supply hoping this would fix everything. But now there is a him coming from the subwoofer (with everything identical).

I disconnected the audio source from the subwoofer amp to see if the hum persisted. Luckily the buzzing sound went away. I then tried connecting the audio source to just the sub (not with a Y-splitter to the other amp). This also worked fine, no buzz, sound was good. I did the same with the other amp and that one worked fine on its own as well.

But whenever I connect the audio source with a Y-splitter to both amps I'm now getting a hum in the subwoofer. I suspect it has something to do with a ground loop? But then why did the exact same setup have no buzz before? What can I do to fix this?

Thanks in advance for any advice

 

[weltersys]

1)But whenever I connect the audio source with a Y-splitter to both amps I'm now getting a hum in the subwoofer. I suspect it has something to do with a ground loop? 2)But then why did the exact same setup have no buzz before?
3)What can I do to fix this?

1) Given your test procedure, likely.
2) Something was not identical in the audio ground path in the failed PSU to the one in current use. A bit too much resistance between audio ground paths and earth grounds is the usual culprit.
3) Try removing the audio ground (or shield/pin 1) on one leg of the "Y" cord.

There are many sites that can give more in depth explanations, such as this:
Ground Loops - Eliminating System Hum and Buzz | Audioholics

Good luck!