Years ago I bought a computer case because my other one was getting too small for the components. After moving all of the parts and booting up, one of the first things I noticed was that my guitar would very noticeably pick up interference (typical magnetic hard drive clicking sounds and so on), increasing in intensity and volume as I moved my guitar closer to the case. This never happened with the old case.
The interference is audible both through the speaker of the amp and through headphones connected to the amp. It occurs when the pickup is in the 1st, 3rd, and 5th position (cheapo knockoff fender electric guitar so 3x single coil pickups).
One noteworthy thing I suppose is that this new case material was labeled as "SECC" material, the old case simply listed "Steel", if that makes any difference.
The main issue is described above, below are just some more details.
This is a pretty big nuisance as I can't record anything without constant hissing unless I have my computer completely powered off.
I am looking to buy yet another case (I've been sitting on this one for a few years now) and want to understand whether it's a problem with the case material or if there is an alternative cause.
No new hardware was added initially when I switched cases so it could not have been a new component. In my unprofessional opinion I am leaning towards blaming the case material for the issue… honestly the material feels extremely flimsy, and bends easily compared to the rigidity of my old case.
I'm sorry if this is the wrong place to be asking such a question since it's a bit computer heavy however it involves concepts that aren't generally discussed on conventional computer boards. Thanks if you've read this far and I hope there's a concrete explanation behind the phenomena I'm facing.
Best Answer
Any type or thickness of steel will form a "Faraday Cage" shield to keep digital hash from escaping from the computer case.
HOWEVER. many cases have large holes in them for "windows" where you can look through and see the hardware (and the internal decorative lighting). I have no idea why this fascinates people, but who knows?
They also have large holes in the front for places where you can put extra floppy or optical drives, little panels with I/O connectors, etc. etc. The front panels are made of plastic which offers ZERO shielding.
You could experiment with some aluminum foil from the kitchen and just cover the entire front of the case to see if that might be the interference leakage path. Be sure to connect the foil to the case ground at some point. An ungrounded shield is worse than no shield at all because it becomes a re-radiating transmitting antenna for the interference!