Computer power supply noise

[Gibsonman63]

Sometimes it takes me a while to catch on. I have two computers in my studio, one strictly for music apps and my internet computer that I do everything else with. I had a power supply failure on my internet computer a few months back. Shortly after, I noticed that my Express was starting to hum and was generally not behaving as well as before. I did not connect the two until last night. At the end of rehearsal, I fired up my internet computer, which is usually on during rehearsals because I tend to practice with youtube videos to warm up before the guys get here. As soon as I turned it on, there was a very noticeable hum coming from my guitar amp. Somehow this computer is putting noise back into the power wiring.

Suggestions? I am thinking that I either need to change the power supply again or put some kind of filter between the computer and the outlet. I keep an outlet checker in my gig bag and I have tested all of my outlets to confirm that they are wired correctly.

It is really good to know that my amps are fine, though.

[davebolden44]

sometimes the proximity of electronics can induce hum into an amplifier. are they side by side?

[Gibsonman63]

Actually my amplifier is on the opposite side of the room. The two computers are stacked one atop the other. One induces noise, the other does not. The entire room is on the same circuit.

[Leo_Gnardo]

Actually my amplifier is on the opposite side of the room. The two computers are stacked one atop the other. One induces noise, the other does not. The entire room is on the same circuit.

Some electronic items cause noise on the AC line then it's not a matter of distance between say a computer and guitar. Computer power supplies are notorious for this, and other modern digital appliances using SMPS power supplies not far behind.

In some instances I've seen a simple isolation transformer sort it out. But that's no guarantee an iso will do the trick. Some years ago I sourced one for a local muso who had problems with neon signs in clubs putting buzz in his system. He found running the neon's transformer off the iso cut the noise.

In extreme cases a serious line filtering circuit PLUS iso transformer system is what's needed, those big heavy $1500 Furman rackmounts. Another possible solution is the UPS, "uninterruptible power supply", intended to run office computers & medical equipment through blackout & brownout conditions. A UPS has batteries and in inverter to create its own 120VAC supply. Possibly a relatively cheap UPS to run your noisy computer will sort things out in your studio/rehearsal room.