Shielding: well worth the effort
The Analogue Device Noise Crisis** is only set to get worse…
There is a constant battle against noise
So, unless a humbucker or similar cancellation technique is used, there will always be pickup of some noise from that device.
Countermeasures
However, there are plenty of other places where measures can be taken.
The basic principle is: all metal objects can become pickups for stray potential, and hence need to be solidly connected to a ground plane, which by virtue of being static, will avoid noise being induced in the signal wires.
If they can’t be connected, mainly because they are part of the signal chain, they can be surrounded by a grounded shield, which helps a lot. The only fiddly part is getting the ground connection to the right places.
When the guitar is plugged into an amp or interface, that ground plane should be the canonical ground and will achieve the best noise rejection.
The pickup body cavity
This is rarely done, maybe for cost reasons, but is all upside — no impact on pickup characteristics. It is quite often attempted using conductive paint, but I am dubious as to how effective this is, as I yet to observe a strong effect.
The control cavity
Some guitars have a metal box containing the electronics — kudos.
Others have little (paint) to none. This exposes any switches to the ambient noise.
The bridge
This really has to be connected, if you want to avoid popping noises every time the player takes their hand off the strings.
The Project
In this instance, the guitar with a very standard Strat style wiring setup had only a metal backed control cover and frankly bad noise rejection.
A simple plan is to create a semblance of a Faraday cage around the controls.
Copper tape is available with a conductive adhesive, so simply layer the tape inside with some overlap, and there will be a decent conductive shell around the sensitive controls.
The metals casings of the switches will make some kind of contact.
In some cases, there is a tag specifically designed for this, so I make an improvised ground bus and connect those to it. If the wires for a pickup have a shield I connect those for an added bonus.
When the guitar is plugged into an amp or interface, that ground plane should be the canonical ground and will achieve good noise rejection.
Here we can see the volume pot and the pickup selector have been explicitly connected. The reverse phase switch is in contact with the shield, and the pickup wiring from the single coils is firmly “Olde Skoole”, i.e. the best that can be achieved is twisted the wires together, but otherwise there is no provision for shielding.
Results
I tried getting a convincing setup to show before and after, but there are so many variables, it would have been a video of myself [waves guitar around] saying “see? Much better!”.
However I can vouch that my band mates noticed, in the typically cramped and electrically noisy rehearsal room environment.
With exception of shielding pickups, there are no reasons to refrain from making these fixes, as the only sonic effect is to eliminate noise. So, get taping!
** a panic that I have just invented, (if you ignore all guitar message boards on the internet ever)
