alexpigment wrote: ↑
Mon Sep 14, 2020 10:44 am
... The hum originally described in the thread seems to imply to me that the trem/bridge are not grounded. ...
But the OP's reduction in hum when "the strings or any other metal" is touched is actually a sign of a well-grounded
guitar, as @mbene085 emphasized. The guitar is grounding the OP.
Nice proof of that recently in this vid, where touching any
ground in the room reduces guitar noise, ie you don't have to touch the guitar to reduce its noise, because the source
of the noise problem is not the guitar ...
He also touches on the fact that the local noise environment will then determine how much EMR the body picks up, and thus how much of a problem the body-borne and air-borne noise mechanism will be. So if a noisy environment is the cause of the OP's noise problem, the exact same guitar setup in an EMR-quiet environment will not be as noisy.
Regarding how far you have to go to shield a guitar well
, we don't really know. We know that the resistance per unit area of shielding paint is higher than foil (and varies with paint type and thickness ... thicker ~= lower). But we don't know if that translates to worse noise rejection at typical guitar noise frequencies. We don't know if Fender's practice of running a ground wire to each cavity to ground the shielding paint is sufficient (they have electrical engineers desiging amps, so maybe it's been tested ?). We don't really know if copper foil is better or worse than aluminium foil at common guitar noise frequencies. We also don't know if a faraday cage really needs to cover the whole guitar internals and be 'watertight' .. many such cages in industry/research are actually mesh rather solid, and have openings through which cables pass. We don't know if just using shielded conductor cabling (like in many MIJs) and/or some twisted pairs makes other shielding redundant. We also don't know the exact circumstances under which shielding might
affect pickup frequency response (ie maybe only when it's too
close to a SC, affecting eddy currents ??).
So ... lots of unknowns about guitar shielding. And lots of variation in how (well) people apply it. Some of that may contribute to some people on forums saying shielding didn't make any difference for them - maybe the noise source was one unaffected by shielding, maybe they didn't ground their shielding, etc etc. One of my personal bugbears is the number of people on youtube showing "how to shield your guitar" who fail to include a before and after recording to show that it actually worked !
So the best we can probably say at this point in time about shielding is "something is better than nothing".
"I just knew I wanted to make a sound that was the complete opposite of a Les Paul, and that’s pretty much a Jaguar." Rowland S. Howard.