Cracking inductance

[halfbackstrat]

Has anyone ever experienced a desktop computer 2/3 feet from an amp causing a prominent crackling in through the speakers?
Is it possible that the dc current in the computer could induct into the amp?
The reason I draw this conclusion is my amp crackles and the volume drops when my pc is on!

If this is possible how could I counteract this problem?
Shielded tape?

[Structo]

Sure computers are known to be picked up by some amps.
I think it is usually the monitor that can add noise.
Maybe a fan is sparking which would send out noise.

But if you have WiFi or a cell phone nearby, then you could get all kinds of noise.

The volume dropping part is a puzzler unless it is overwhelming the guitar signal.

You might try a small cap on the input to ground.

Does your amp have a grid stopper on the input tube grid?

[vibratoking]

I agree with Tom. That problem is usually caused by the monitor and not the PC. Switch off just the monitor and see what happens. IME, the coupling usually happens through the pickups...single coil or humbuckers. You can change guitar orientation to determine this. If it is coupled through the pickups then modifying the amp won't help.

If the coupling is indeed directly to the amp, then distance is your friend.

On the other hand, I have never experienced volume drop...your problem may be completely different from what I have experienced.

[Zippy]

Volume drop is reminiscent of parasitic oscillation - the amplifier is amplifying signals of frequencies that are beyond your hearing range.

Got a 'scope? It'd be interesting to see what's going on.

Beyond that, start trying to eliminate the source as others have described.