Subwoofer buzzing, but silent when (disconnected) AVR & TV turn off??

[Vict0r]

Hey guys,

I think I have a power issue in my cinema room. I recently hooked up a second BK XLS200 Mk2 subwoofer but I'm bumping into something I can't yet wrap my head around. I hope this is the right place to ask for advice and learn. Thanks in advance!

The new subwoofer I added has a noticeable buzzing when it's stand-by. The strange thing is that it buzzes even when there's no RCA connected to the AVR. I thought the sub's internal amplifier was damaged and was ready to return it, but then I noticed the buzzing stops as soon as I turn my TV and AVR off. This boggled my mind, since they weren't even connected to each other. The only thing hooked up to the subwoofer is the AC cable. The buzzing doesn't change when I connect the RCA cable. Also, the buzzing changes tone and volume depending on what's on the TV's screen. I thought it had to do with brightness, but the buzzing changes just when browsing through the TV menus. And this is still with the sub not even connected to the AVR/TV.

What can I do to fix this? My other subwoofer (the first one) doesn't have this issue and is relatively silent when powered on. They both aren't connected to the same outlet but they are pretty far apart, so I'm using one wall socket for sub 1, and another for sub 2. I tried connecting both of them to the same extension but one still buzzes when the AVR and TV are on, while the other doesn't. And the second still goes silent when I turn the TV and AVR off, despite none of them being connected.

Insert "in-way-over-my-head-I-have-no-idea-what-is-going-on-help" smiley.

 

[sandymc]

Yes, I've had this issue with an LG smart TV and a set of active monitors - it is very likely high frequency noise coupling from the power supply of TV via the power cables to the speakers. There are only three solutions - different AC lines, a noise filter for the AC line, or replace either the sub or the TV.

 

[Vict0r]

There are only three solutions - different AC lines, a noise filter for the AC line, or replace either the sub or the TV.

Different AC lines? I can't rewire my apartment!
Replace the sub? Won't another sub have the exact same issue?
Replace the TV? It's a 65" flagship OLED TV. I don't want to lose it!

I guess the noise filter would be a sensible option. Could you link me an example of a product I could try?

 

[sandymc]

Different AC lines? I can't rewire my apartment!
Replace the sub? Won't another sub have the exact same issue?
Replace the TV? It's a 65" flagship OLED TV. I don't want to lose it!

I guess the noise filter would be a sensible option. Could you link me an example of a product I could try?

Well, another sub probably won't, if it's from another manufacturer. (!)

The first thing I'd try, because they're cheap, are ferrite rings e.g.:

Pienoy 20 PCS EMI RFI Noise Filter Cable Ring/Noise Filter Suppressor Cable Clip for 3mm/ 5mm/ 7mm/ 9mm/ 13mm Diameter/Video Cable Power Cord (Black)
by Pienoy
Learn more: https://www.amazon.com/dp/B07GKBPYB9/ref=cm_sw_em_r_mt_dp_QFYAQJRR9VZPHC5PWRJG

 

[Vict0r]

Well, another sub probably won't, if it's from another manufacturer. (!)

The first thing I'd try, because they're cheap, are ferrite rings e.g.:

I think I have some of those laying around somewhere. Will give 'em a shot. Thank you!

 

[Speedskater]

Different AC circuits often increases these types of problems. Plug everything into the same AC wall outlet.
But cable TV or internet cables often cause these types of problems.

 

[Chrise36]

Hey guys,

I think I have a power issue in my cinema room. I recently hooked up a second BK XLS200 Mk2 subwoofer but I'm bumping into something I can't yet wrap my head around. I hope this is the right place to ask for advice and learn. Thanks in advance!

The new subwoofer I added has a noticeable buzzing when it's stand-by. The strange thing is that it buzzes even when there's no RCA connected to the AVR. I thought the sub's internal amplifier was damaged and was ready to return it, but then I noticed the buzzing stops as soon as I turn my TV and AVR off. This boggled my mind, since they weren't even connected to each other. The only thing hooked up to the subwoofer is the AC cable. The buzzing doesn't change when I connect the RCA cable. Also, the buzzing changes tone and volume depending on what's on the TV's screen. I thought it had to do with brightness, but the buzzing changes just when browsing through the TV menus. And this is still with the sub not even connected to the AVR/TV.

What can I do to fix this? My other subwoofer (the first one) doesn't have this issue and is relatively silent when powered on. They both aren't connected to the same outlet but they are pretty far apart, so I'm using one wall socket for sub 1, and another for sub 2. I tried connecting both of them to the same extension but one still buzzes when the AVR and TV are on, while the other doesn't. And the second still goes silent when I turn the TV and AVR off, despite none of them being connected.

Insert "in-way-over-my-head-I-have-no-idea-what-is-going-on-help" smiley.

Are you sure it comes from the subwoofer not the tv? TV psus are known for buzzing.

 

[Vict0r]

Are you sure it comes from the subwoofer not the tv? TV psus are known for buzzing.

100% the subwoofer buzzing.

 

[Chrise36]

Try to increase the distance from the tv or put some thick metal panel change ac outlets i have the same problem with my crown xls driving the sub i changed the outlet and put the crossover filter at low pass under 200hz whatever you like not full range or pass through.

 

[raindance]

Move the sub to another room and plug it in with no source. Does it hum or buzz? This will eliminate a faulty sub.

Also, how are you connecting the two subs?

 

[audiofooled]

2. I tried connecting both of them to the same extension but one still buzzes when the AVR and TV are on, while the other doesn't. And the second still goes silent when I turn the TV and AVR off, despite none of them being connected.

If I understand correctly, both subs are the same make and model? Is the buzz you explained in the sentence I quoted interchangeable? I mean, have you tried swapping the connections for the subs to determine weather it's always the same one buzzing?

What you're having is a ground loop, i.e this:

In an electrical system, a ground loop or earth loop occurs when two points of a circuit are intended to have the same ground reference potential but instead have a different potential between them.

Culprit is usually hard to detect but there are things you can try. Besides swapping the subs as I mentioned, you may try swapping the HDMI ports on the TV and AVR and adjust accordingly. If you have a spare HDMI cable, you may try that. Also, you may observe, when both subs are in standby mode, do they "wake up" simultaneously or is one lagging behind, i.e needs higher input to kick in...

I'm no expert so I hope someone over here would have a better advice. I'm just saying you could try determining weather both of the subs are acting the same or the second one may be faulty. Also, HDMI ports, connections and cables are fragile and may develop "a cold joint" somewhere so swapping the ports and cables is a good way to detect this. Nowadays, having latest and greatest equipment may not do any favors to its reliability. Hope this helps.

EDIT: Does your AVR have one or two LFE outputs? Can you try connecting both of the subs to the same LFE output by means of a simple RCA splitter?