Buzzing sound coming from my Bluetooth Speakers when PC is OFF

I use bluetooth speakers, (but not connected via Bluetooth), but directly connected using the AUX cable to the Motherboard panel at the back.
When my PC is switched on, there is no buzzing sound.
But as soon as i switch off my PC, there is a loud continuous buzzing sound.
The Bluetooth speakers run on battery.

What could be the problem and how to fix it
 

icebags

Wise Old Owl
or you can switch off speakers also, when shutting down computer.:chinscratch:

(edit: i donno what's wrong with my signature though )
 

whitestar_999

Super Moderator
Staff member
or you can switch off speakers also, when shutting down computer.:chinscratch:

(edit: i donno what's wrong with my signature though )
Something is broken with default emoji size,I tested with inserting an emoji in post & it was entered at same huge size by default. For the time being I have edited your signature to replace emoji with older classical smiley type. @Raaabo @Anorion
 

patkim

Cyborg Agent
  • Since when this issue started? Was everything good before with the same setup at the same location?
  • Are you plugging it into the Line-Out port on back of your motherboard?
  • What if you disconnect the BT Speaker and plug in your headphones into Line-Out of your PC? Does the noise come? If yes when?
  • When you switch off PC, do you mean to say that you shut down the OS thru its interface and SMPS is in stand-by state or do you switch off the mains?
  • What if you give output of your mobile phone audio-out to BT Speaker over Aux-in and then shut down phone?
  • What if you use the front Audio Out of your cabinet (If you have one)? How is the behavior?
  • Do you use a surge protector /extension box for your PC? What if you plug the Cabinet SMPS directly to wall socket?
  • Since you are running BT Speaker on battery, what if you take the speaker away from the PC (another room) and try with your mobile phone output? What if you try brand new batteries, or recharge them if they are rechargeable?
  • When you plug in your headphones to Line-Out of PC, do you hear stereo sound or mono? You need to use some free Stereo Testing MP3 available on the net to test the L & R Channels or use the built in audio interface if available by the audio vendor. E.g. Realtek Audio Manager.
  • What if you plug one end of Aux-Cable to BT Speaker and leave the other end hanging (not connected anywhere)?
 
OP
mikael_schiffer

mikael_schiffer

Padawan
  • Since when this issue started? Was everything good before with the same setup at the same location?
  • Are you plugging it into the Line-Out port on back of your motherboard?
  • What if you disconnect the BT Speaker and plug in your headphones into Line-Out of your PC? Does the noise come? If yes when?
  • When you switch off PC, do you mean to say that you shut down the OS thru its interface and SMPS is in stand-by state or do you switch off the mains?
  • What if you give output of your mobile phone audio-out to BT Speaker over Aux-in and then shut down phone?
  • What if you use the front Audio Out of your cabinet (If you have one)? How is the behavior?
  • Do you use a surge protector /extension box for your PC? What if you plug the Cabinet SMPS directly to wall socket?
  • Since you are running BT Speaker on battery, what if you take the speaker away from the PC (another room) and try with your mobile phone output? What if you try brand new batteries, or recharge them if they are rechargeable?
  • When you plug in your headphones to Line-Out of PC, do you hear stereo sound or mono? You need to use some free Stereo Testing MP3 available on the net to test the L & R Channels or use the built in audio interface if available by the audio vendor. E.g. Realtek Audio Manager.
  • What if you plug one end of Aux-Cable to BT Speaker and leave the other end hanging (not connected anywhere)?
  1. been there since ALWAYS
  2. Yes, plugged into the Line Out of the motherboard
  3. When using headphones there is a slight hissing sound
  4. By switch off i mean everything, including the mains. Sometimes, even when i switch off everything, my monitor LED lights still blinks as if electricity is still running
  5. i Use a 6 plug SURGE PROTECTOR Power strip and a UPS. UPS is connected to the surge protector since i want to connect my Printer to the surge protector.
  6. I hear stereo sound, sound is fine...just the slight hissssss
  7. if i leave it out hanging then there is no sound. Its as if the computer cabinet has its own electricity
 

patkim

Cyborg Agent
For testing purposes, remove the UPS and surge protector and try plugging in Cabinet & Monitor directly to wall outlets. Already mentioned as one of the checkpoints in my previous post. I have personally experienced faulty extension boxes that sometimes even leak minor current being detected on the metallic parts of the cabinet.

Get the earthing in your house checked by a qualified electrician.

As you hear hissing even after mains off, how long does it last? What if the PC is completely off for 3 - 4 hours? Generally SMPS may hold some charge for 30 - 40 mins after full shutdown.
 
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icebags

Wise Old Owl
do you get hiss when computer is totally powered off, i.e. ac power off.

^ it's most likely ground loop issue, if there is no noise in motherboard audio o/p, since you are powering with isolated power supply, i.e. battery. in ground loop issue, input isolation transformers are best way to solve the case, but easiest would be to switch off the speakers before switching off computer.
 

topgear

Super Moderator
Staff member
Here's a good read to understand the issue in depth :
 
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