Loud Buzz On Speakers

[transformer8]

I want to listen to audio files on either of my four PC metal towers. I discarded the sides on all four of my PC towers because they aren't necessary. I use either a Radio Shack MPA-250B 250 watt amplifier or a Radio Shack PA amplifier 40 watt and either a set of Pioneer bookshelf speakers or a set of Polk Audio bookshelf speakers. The problem is that there sometimes is a loud buzzing sound that completely disappears when the PC is shut down. The PC towers are placed on a 24" wide NSF shelf with 3/8" sheets of HDPE used to create a smooth surface to place the towers on. The four towers are placed very close to each other with just inches separating all four. I use the top tower that is nearest to my person and I get a very loud buzz on either set of speakers using either amplifier and using either one red and one black 22AWG solid or the Radio Shack brand speaker hook up wire that is sold as paired strands with the white stripe for orientation. The power outlet is a Belkin all metal ten plug power tap with ground. The same buzzing is identicle on either amplifier and on either set of conductors aka wires and on either set of speakers. I disconnected the Radio Shack TRS audio cable from the PC tower to either amplifier and the buzz continued in identical pitch and volume. When I turned the PC tower off the buzz disappeared. However, having shut off the PC tower nearest me and turning on my PC tower that sits on the bottom shelf and is blocked by my PC tower that I do not use there was no buzzing sound on the speakers. In summation, the PC tower near me with exposed guts seems to make the speakers buzz. The PC tower with the exposed guts that sits on the lower shelf and is blocked by another PC tower with exposed guts that is out of use does not cause my speakers to buzz. Any idea what is happening? I sure would appreciate an analysis. Thank you in advance.

 

[Nightwisher]

I want to listen to audio files on either of my four PC metal towers. I discarded the sides on all four of my PC towers because they aren't necessary. I use either a Radio Shack MPA-250B 250 watt amplifier or a Radio Shack PA amplifier 40 watt and either a set of Pioneer bookshelf speakers or a set of Polk Audio bookshelf speakers. The problem is that there sometimes is a loud buzzing sound that completely disappears when the PC is shut down. The PC towers are placed on a 24" wide NSF shelf with 3/8" sheets of HDPE used to create a smooth surface to place the towers on. The four towers are placed very close to each other with just inches separating all four. I use the top tower that is nearest to my person and I get a very loud buzz on either set of speakers using either amplifier and using either one red and one black 22AWG solid or the Radio Shack brand speaker hook up wire that is sold as paired strands with the white stripe for orientation. The power outlet is a Belkin all metal ten plug power tap with ground. The same buzzing is identicle on either amplifier and on either set of conductors aka wires and on either set of speakers. I disconnected the Radio Shack TRS audio cable from the PC tower to either amplifier and the buzz continued in identical pitch and volume. When I turned the PC tower off the buzz disappeared. However, having shut off the PC tower nearest me and turning on my PC tower that sits on the bottom shelf and is blocked by my PC tower that I do not use there was no buzzing sound on the speakers. In summation, the PC tower near me with exposed guts seems to make the speakers buzz. The PC tower with the exposed guts that sits on the lower shelf and is blocked by another PC tower with exposed guts that is out of use does not cause my speakers to buzz. Any idea what is happening? I sure would appreciate an analysis. Thank you in advance.

The power supply of the PC is likely the issue. Amps can have a tendency to pick these up.

Common suggestions:
Move any wires that are close to the PC as far away as possible. Especially if they are on or near a power cord or the PC power supply itself.
Use higher gauge speaker wire, such as 16 or 14 gauge. That's a recommendation I would make anyway. That adds more shielding and better conductance.
Use shielded cables for RCA cables, etc. That's also a recommendation I would make anyway.
Try using a power conditioner (which can get pricey) to try to eliminate the issue.
Manetic Ferrite Core Cord Noise Supressors can help.

 

[DaveVoorhis]

... However, having shut off the PC tower nearest me and turning on my PC tower that sits on the bottom shelf and is blocked by my PC tower that I do not use there was no buzzing sound on the speakers. In summation, the PC tower near me with exposed guts seems to make the speakers buzz. The PC tower with the exposed guts that sits on the lower shelf and is blocked by another PC tower with exposed guts that is out of use does not cause my speakers to buzz. Any idea what is happening? I sure would appreciate an analysis. Thank you in advance.

I'm not clear what's running and what's shut down when you get the buzzing, but it sounds like it might be power supply noise from one or more flaky power supplies.

Have you tried putting the sides back on the PCs? They're partly there to reduce electrical interference.

 

[transformer8]

The power supply of the PC is likely the issue. Amps can have a tendency to pick these up.

Common suggestions:
Move any wires that are close to the PC as far away as possible. Especially if they are on or near a power cord or the PC power supply itself.
Use higher gauge speaker wire, such as 16 or 14 gauge. That's a recommendation I would make anyway. That adds more shielding and better conductance.
Use shielded cables for RCA cables, etc. That's also a recommendation I would make anyway.
Try using a power conditioner (which can get pricey) to try to eliminate the issue.
Manetic Ferrite Core Cord Noise Supressors can help.

Thank you. I will try that.

 

[transformer8]

I'm not clear what's running and what's shut down when you get the buzzing, but it sounds like it might be power supply noise from one or more flaky power supplies.

Have you tried putting the sides back on the PCs? They're partly there to reduce electrical interference.

I discarded the four sides many years ago. I have no kids or cats to worry about. I'm going to move the amps to a secluded area to see if they produce distortion. Wish I had a Faraday cage. Thank you.