how to minimize speaker hum

[GunsMadeAmericaFree]

For about the last 20 years, whenever I built a PC, I would install an inexpensive PC stereo speaker into a 5.25" drive bay. The speaker had a headphone wire/jack that went back through the chassis, out through the back, and plugged into the headphone out jack on the back of the PC. My wife and I love the fact that you can quickly reach up and turn a physical knob to turn volume up and down whenever needed.

A couple of years back, I noticed that there started to be a hum in the speakers on one of our 3 PC's. I assumed it was the speaker itself, and old "Thor" model that was probably 15 years old, and I ordered several replacements.
Strangely enough, the interference persisted even after:

1) completely replacing the speaker and wires, and then doing it again

2) replacing the power supply

3) We also had to replace the motherboard, and doing that didn't seem to make any difference, either. (we're using the motherboard's built in sound chip)

I'm not sure what else my options might be to isolate the generated signal hum. Since I replaced the power supply, and I replaced the actual speakers twice, I'm thinking it was not either of those. I don't need anything fancy, just stereo sound. I'm wondering if there is anything else easy I can try that might give some light on why this is happening?

We don't need anything fancy, we just want very basic sound that we can turn volume up and down easily with the built in analog potentiometer wheel for volume.

Any thoughts on where we could start? It's a very small problem, but it ANNOYS me...

 

[Ken g6]

This is one reason I use a Bluetooth speaker.

 

[GunsMadeAmericaFree]

This is one reason I use a Bluetooth speaker.

I really like to stay away from wireless, since there can be dropouts, interference, etc. However, I wonder if I could somehow try some sort of USB sound solution, and run the audio out from that to the back of the speakers.... hmm.

 

[BonzaiDuck]

I just scanned post #1 and briefly the comments.

Isn't this a problem of speaker power or device power not being isolated from AC power? That's why I use UPS systems. And since some speaker systems have an AC power plug, I would isolate those as well.

 

[mindless1]

IMO, basic analog audio setups started getting noisier and noisier with each newer generation of PC hardware that had higher power state changes, due to ground noise, made worse if you have a halfway decent video card in the system.

Easiest solution is external DAC, or USB audio box/dongle/etc.

Without changing anything else, it can sometimes help to turn the PC's volume mixer up, and the speaker volume pot down. That doesn't get rid of the noise, just reduces it's volume.

Then there's the long-shots... once upon a time ago, I had a land-line, cordless phone handset a foot away from a standalone PC speaker amp that was in an unshielded box. Every few minutes, without even using the handset, it would communicate with the base station located dozens of feet away and cause humming in the speakers for those events.

 

[sdifox]

Move the low level speaker source wire away from power wires. Also check ground loop.