As some of you may already know, I live in Toronto, Canada. Generally speaking this part of the world is well known to have a dry climate. While there are many incredible guitar manufacturers inside Canada that deserve recognition (foreshadowing), lots of popular models and brands of guitars are built in climates that are comparatively humid like Japan, Indonesia, Mexico, even California and Tennessee.
While this fun fact may seem at first to be of little consequence, owning a guitar in a dry part of the world brings to the surface a problem that is not unique to dry areas but is certainly made worse in them. I'm talking about electro magnetic interference. Electro magnetic interference occurs when radio waves, static electricity, or other forms of electrical stuff (that's a technical term) interfere with the magnetic field of your pickups and get amplified through your guitar speaker. Personally, it drives me nuts.
The ProblemI first learned about electro magnetic interference when I bought a new guitar back in 2014. I was thrilled with my purchase, a 2013 SG standard that I still use often today and I couldn't wait to show it off at my next gig. That weekend I had my chance to try it out with a wedding band in the city and I showed up looking sharp in my suit and tie with my brand new purchase slung over my shoulder, ready to rock. It didn't take long before my unbridled excitement morphed into a deep guttural concern over what the hell was happening with my shiny new instrument. All night long my every move against the body of the guitar was converted into an obnoxious static rattling like a radio looking for a signal broadcasting through my amplifier.
After I went home that night, I spent a sleepless night researching endlessly through reddit threads and online forums trying to find somebody else who shared my experience. I came to learn that I was dealing with something called electro magnetic interference, and what was causing that horrid noise was actually static electricity generated by my shirt rubbing against the guitar's control cavity that was getting amplified by some dark magic through my pickups. The general consensus online was that my expensive new guitar was seasonal, and I should pick up a box of bounty dryer sheets to soak up the static that builds up, and learn to cope with this unavoidable consequence of owning a guitar in a dry climate. If this is really the case, I was curious as to why none of my other guitars suffered from the same problem. The explanation I found again and again was that Gibson doesn't "shield" their guitars.
What does it mean to "shield" a guitar?!
The Faraday CageWhen we talk about shielding a guitar, we are talking about a concept in electrical engineering called a Faraday Cage. The general idea behind it is that if you encase an electrical circuit in a conductive material, it will protect that circuit from outside electro magnetic interference. Police use this exact same concept to protect cell phones collected as evidence from outside manipulation by placing them in a "Faraday Bag". I've also heard of Faraday Bags being used to protect car keys that can remotely turn on cars from functioning erroneously.
An example of a Faraday Bag like those used by law enforcement or the military.
An example of a Faraday Pouch used to protect car key fobs.
For guitarists, by encasing your guitar's control cavity in a conductive material you will protect your circuit from electro magnetic interference. In my case, this means that although my shirt rubbing against my control cavity may still generate static electricity, that static electricity is blocked from interacting with the electronics of my guitar by the Faraday Cage that I built around that circuit. This can also help to reduce noise in particularly noisy pickups that is generated by electro magnetic interference.
How To Shield Your GuitarYou can definitely visit your local guitar tech if you plan on getting your guitar shielded, and I'm sure that they will do a great job. However, it can be an expensive modification due to the fact that all of the electronics must be removed from the guitar, and depending on how busy your guitar tech is, it can also take a long time before you get your guitar back. The truth is, shielding your guitar on your own is not that difficult as long as you have a little bit of confidence with soldering.
First, you need to open up your control cavity and remove all of the components, and remove the pickups as well. For the love of God, take a picture of your electronics or make notes or do something before removing everything so that when you are putting everything back, you put it back in the right place and wire it all back up correctly.
Now that you're looking at a totally empty control cavity and pickup routes, you need to cover the inside walls with adhesive copper foil.
This copper foil will make things much easier because the adhesive is also conductive. If the adhesive side is not conductive, you must ensure that the conductive side of the tape is always contacting the conductive side of the next strip of tape, which can be a challenge. Using copper tape with conductive adhesive means all you need to do is totally cover every inch that you can of your control cavity, pickup routes, input jack route, and pickup switch route. Be sure also to cover the backside of any surface that contacts those cavities such as the backside of your pick guard on Telecaster or Stratocaster style instruments, or the backside of the control cavity cover and pickup switch cover on Gibson style instruments. It's important to make sure that the tape placed on cavity covers or pick guards will make contact with the tape placed inside the cavity once it is closed up. This can be done by putting a small lip of tape over the top edge of every cavity.
Next, you will need to run a wire between every cavity that is covered in copper tape. To do this, it is a good idea to use 22AWG copper wire.
To run wire between all the shielded cavities of your guitar, you realistically need around three meters of wire. This set here is 12 feet which should cover you, and is push back wire, meaning you will not need wire cutters to expose the edges of each wire. Once these wires have been cut and put into place, solder the ends to each cavity, connecting all the cavities to each other.
Once all the wires have been soldered, the next step is to check for connectivity between all of the cavities. To do this you will need a multimeter.
Place one end of the multimeter inside one of the cavities, making contact with the copper tape and place the other end inside a different cavity making contact again with the copper tape. If the multimeter registers a reading, this means that there is connectivity across both of those cavities, and your faraday cage will function correctly. Repeat this test again testing for connectivity across all cavities. If everything is connected properly and registering a reading, you're doing great! If not, make sure that your wires are soldered correctly and try again.
Now, you can reconnect all the electrical components of your guitar, and close up all of the cavities!
If you're more of a visual learner, check out this video here. This guy does a really great time lapse video of himself shielding a Telecaster style instrument and his comment section is very helpful if you have questions about what he's doing.
Thank you so much for checking out my thoughts on how to shield your guitar! I want you to know that I really appreciate being a small part of your journey with the guitar, and if you have any comments or questions please feel free to reach out!