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music EMI problem with guitar amp?

R

ross

I know some of you guys play guitar, and I was wondering if you have experienced this problem?

I just upgraded my computer, and apparently (after asking on a sound forum), my power supply is emitting some kind of EMI that is conflicting with the amp. They are plugged into different outlets, and my amp is run through a power conditioner. The noise heard is really shrill, like feedback, only its not feedback. It is much softer, and the farther away I get from my computer, eventually it fades out.

Is there some kind of adapter I can put on my computer? Has anyone had this problem?
 
I am by no means an expert on electronics, but sometimes an "upgrade" is not necessarily an upgrade. If you still have your old computer, check what form factor its PSU is, and if you are knowledgeable about such things, perhaps swap it into the new computer, if it will cope with your new motherboard and peripherals.

Another option, pls correct if I am wrong, would be to construct a faraday cage for your computer (I think the principle will work in reverse).
 
ring sting said:
I am by no means an expert on electronics, but sometimes an "upgrade" is not necessarily an upgrade. If you still have your old computer, check what form factor its PSU is, and if you are knowledgeable about such things, perhaps swap it into the new computer, if it will cope with your new motherboard and peripherals.

Another option, pls correct if I am wrong, would be to construct a faraday cage for your computer (I think the principle will work in reverse).
Click to expand...

The old PSU is a 480w, and its running my old computer. When I swap it in, it works but half of my computer doesnt run. The new one in question is 700w..

I will look at that cage thing when I get to work
 
imaguitargod said:
From what I understand, it sounds like bad grounding.
Click to expand...

If that is the case then why wouldnt it appear when I swap in my old power supply? Bad grounding on the computer, I assume, not the amplifier. Right?
 
Interesting thread...the EEE group (Electro-Environmental Effects - EMI )for our aircraft sit about 20 feet from me...I described your problem and they started shooting questions at me...did he get a new monitor too...does the new computer run on a different clock speed than the old one does...did he get more/different peripherals with the new computer?...are the outlets your computer and amplifier on the same circuit (that one would be easy to fix, put each one on a different circuit)?

then they said, when he changed the new power supply to the old one and it stopped doesn't mean that is the issue, the new power supply could be running another cooling fan that the old one doesn't.....soooooooooo

finally I got them to narrow it down for trouble shooting the problem...

the issue is whether it is a conductive or radiative problem....if it is a conductive problem you can get an RFI filter for your guitar amplifier power cord and that will determine if it is a conductive problem...they said you could get an RFI filter for about 20 bucks....if that doesn't solve your problem, then the problem becomes radiative...which could be numerous things....

they recommended the RFI filter first
 
I remember picking up the local college radio on one of my amps a long time ago. It was only when I plugged it into a specific outlet did it turn into a radio....fun stuff.
 
imaguitargod said:
I remember picking up the local college radio on one of my amps a long time ago. It was only when I plugged it into a specific outlet did it turn into a radio....fun stuff.
Click to expand...

If my guitar did that, could I record the sound and claim it as my own? Since TECHNICALLY it is coming out of my amplifier.........
 
well, if you have a filter for your amp, you shouldn't be getting any interference from the power source...

don't know what to tell you....they said a 'faraday' cage around your computer would work to some degree...you might try that as RS suggested
 
The old PSU is not strong enough to run the new motherboard, and possibly doesnt have enough plugs for the new peripherals.... hmmm

As AJ suggested, it could be just one element of the new equipment. Have you tried running the computer, but disabling say one fan, then perhaps something else? That would help to narrow it down.

Just to bounce some questions:
If the old PSU in the new computer doesnt cause interferance, is that because it is not running something? If the answer here is NO, then could it be the electrical shielding on the PSU itself? What about the case the computer is in? Where the PSU sits, is it constructed of some sort of metal? IS the PSU case made of metal?

Plugging the new PSU into the OLD computer, does that create interferance?

Perhaps a dose of chilli and garlic water, and a hit of Neem oil will drive the bugs out.... ;)
 
Let me answer what was just asked..

1. The fans in the computer were in there.
2. The case is the same.
3. The 480w PSU only does not run 2 fans that were already in the case anyway.

:(

Yeah.... I guess I will have to get a new PSU or something. I can kind of deal with it, but it gets annoying.
 
bentalphanerd said:
I'm pretty sure theres line filters available. Are the cables for computer & amp both earthed?
Click to expand...

I assume so, yes. The amp for certain. The PC, I dunno.. It is plugged into a surge protector...
 
if the plug has 3 pins it should be earthed...if you're using the 2 pin plugs that'd be the first & easiest thing to change.
I'd say its unlikely your PC is emitting a radio signal (of any real strength) would think you're getting wave anomalies through the house wiring. Sometimes even moving things to different power plugs can help but it depends on how your place is wired up.
Other option is that a transistor or electrolytic capacitor is starting to go on your amp.
 
If its a problem with the amp, then it suddenly happened to both of my amps :) I am going to try a few things this weekend and post what the outcome is.

It is just such a pain to get under my desk and mess with power cords.. Saving that chore for this weekend. :)
 
haha, believe it or not, it is worse with different guitars. I tried my Les Paul last night, and it was unplayable. It was so loud it was like feedback.

Sigh
 
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