Hi everyone... just made this quick video about making my PRS S2 quiet! There has been a long-standing argument among guitar players that hum is caused by ground issues... if the hum goes away when you touch the strings or bridge it IS NOT A GROUND issue. It drives me crazy every time I hear someone say "have you checked the ground?". GRRR!!!
Anyway, here is a video, hopefully it helps people in the future!
I have fought with this kind of noise before and sadly, it is not solved by shielding the guitar electronics. That kind of noise is generated when your body picks up environmental energy and radiates it into the guitar pickups.
The reduction in noise could as easily been related to there being less noise in the envirionment. That kind of noise comes and goes based on time of day, appliances running, phase of moon, etc.
Also, certain guitar pickups are more susceptible. You can't say "this guitar is shielded, its making less noise, therefore the shielding is responsible." Some pickups are less susceptible, ones with less presence. More likely the guitar that was buzzing more had higher value pots.
The solution I have found to solve this when it arises, is to run a wire ground from the amps input, and attach that ground to your body (wrap around ankle or similar). This will ground you body to the amp and not the guitar. The problem when relying upon the guitars ground is that frequently when playing you aren't grounded to the guitar, so that kind of noise will seep through. If you ground your body to the amp's input, that solves the problem. Remember, its not a problem with the guitar, its your body picking up noise and radiating it to the pickups.
You can see this is true because when ungrounded and your hand is close to the strings, the noise increases. If the noise increases when your hand is close to the strings and not touching, shielding the cavity won't make a shit of difference. its better to have a wire handy so you can ground your body to the amp input when the issue arises, and you dont have to shield all your guitars.
I have a wire like this attached to a metal strip on the floor. If my environment is acting up, I just step on the strip. (Playing without shoes or socks at home.) Having read this, I bet you still think shielding the guitar cavity is a "first line" solution for this kind of noise.