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Here we go again. Subwoofer hum problem. Please help.

Wooferhead

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Jul 13, 2023
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Someone lent me a subwoofer (Energy XL-S10). It worked fine at his location, no hum I could hear. I then brought it home. (this happened within the same day.)

First, I had it connected to my system and plugged it to the power bar (off position) which my CD player and receiver are using (nothing else). Then, I switched on the power bar (both CD player and receiver are off). A loud hum came through my bookshelf speakers immediately. I switched off the power bar right away (hum stopped) and removed the subwoofer from the system. I then plugged the subwoofer alone to another power socket nearby. A hum came out. I tried other power sockets in different rooms, same hum. It baffled me completely.

After I removed the subwoofer from the system, I switched on the power bar, CD player and receiver and played a CD. Everything was fine. No hum.

What is the problem here? Is it the power socket? Is it the wiring at my home? How do I fix it?

Thanks in advance for your input.
 
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Some power supplies can induce hum into other electronics just by being connected to the same power strip (or breaker, for that matter).

I distinctly remember another ASR member discussing a similar case with a Hypex/Purifi Amp, though please don't ask me to find it :)

Try various mains outlets and if you can't get rid of the hum, I think it's fair to just blame the subwoofer and move on.
 
Hums with no RCA cable plugged into the sub?
Maybe the sub amp is going bad (e.g. capacitor)?

Maybe DC Offset (Emotiva makes a product to combat this, believe it's called CMX2)

Any LED/Flourescent lights? Dimmer Switches? They can be a cause of hum.
 
Some power supplies can induce hum into other electronics just by being connected to the same power strip (or breaker, for that matter).

I distinctly remember another ASR member discussing a similar case with a Hypex/Purifi Amp, though please don't ask me to find it :)

Try various mains outlets and if you can't get rid of the hum, I think it's fair to just blame the subwoofer and move on.
All that I described above happened yesterday within a few hours. As mentioned, the subwoofer worked fine at its owner's place, no hum there. Only when I took it home and plugged it into the power socket did I get the hum. So, I couldn't really blame the subwoofer. It had to be something in my home. It could be the power supply as you've explained.
 
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Hums with no RCA cable plugged into the sub?
Maybe the sub amp is going bad (e.g. capacitor)?

Maybe DC Offset (Emotiva makes a product to combat this, believe it's called CMX2)

Any LED/Flourescent lights? Dimmer Switches? They can be a cause of hum.
The subwoofer worked fine at its owner place just 30 mins before. It has no LED lights nor switches.

Emotiva CMX2 was sold out at their website unfortunately. It looks like a pricey power bar.
 
All that I described above happened yesterday within a few hours. As mentioned, the subwoofer worked fine at its owner's place, no hum there. Only when I took it home and plugged it into the power socket did I get the hum. So, I couldn't really blame the subwoofer. It had to be something in my home. It could be the power supply as you've explained.
It's possible that at your friend's place, the Sub just happened to have been plugged into another breaker, therefore sufficiently isolated from the other electronics.
 
Well could be a couple of things. If you have a cable or sat box on the same system they are always a biggie. Other then that you may have dc floating around on your ac .

I would check first to even make sure you outlet is wired correctly.

After that we can move on.
 
Well could be a couple of things. If you have a cable or sat box on the same system they are always a biggie. Other then that you may have dc floating around on your ac .

I would check first to even make sure you outlet is wired correctly.

After that we can move on.
I tried five different outlets in different rooms, same result.
 
What about plugging in RCA or XLR interconnect cables?
or
Was the AC cord the only cable that was plugged in?
As mentioned, I had the sub connected to the system after I brought it home. A loud hum came out the bookshelf speakers the moment I switched on the power bar. So I removed the sub and plugged it into a different power outlet with nothing connected to it. A hum came out.
 
maybe you have sine wave generator switched on that does the 60hz sine wave
 
maybe you have sine wave generator switched on that does the 60hz sine wave
The only things on the sub that can be adjusted are the Low Pass Filter and Bass Volume. That's all.
 
The only things on the sub that can be adjusted are the Low Pass Filter and Bass Volume. That's all.
you need do yt video so we can hear the actual sound of this hum
 
I want to attach a MP4 Audio file of the sub hum here. Anyone knows how to do it?
 
You have to find out if the connection of your rca cable to the sub creates or affects this hum. My sub was humming horribly and I found out that it was because my sub cable was not shielded. I bought a new shielded sub cable and I now have zero hum.
 
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