Shielded Guitar Cavity – Is it Really Necessary?

shielded guitar cavityA shielded guitar cavity will go a long way towards preventing interference from reaching your signal.

If you live in an area with a lot of electromagnetic interference, you are going to love today’s article on the subject of a shielded guitar cavity. What we’re going to do is talk about shielding the control cavity for maximum protection from interference. It’s not hard to find a guitar shielding kit online, but there are also some excellent DIY methods you can use to get the job done.

What is a Shielded Guitar Cavity?

A shielded cavity is when we coat all surfaces inside the guitar with a shielding paint or shielding foil. There are several products available online or at the local hardware store that will work correctly.  We will also need to use the paint or foil to coat the cavity cover or pickguard. We essentially create a metal box to hold all of the guitar’s electronics.

What are the Benefits of a Shielded Guitar Cavity?

Our metal box shields our electronics from every angle, protecting them from electromagnetic and RF interference. This interference can enter your signal and create a static or buzz in your sound. Many items around the home can cause interference, including your refrigerator, microwave, washer, dryer, and fluorescent lighting. Power transformers and street lights can also cause interference.

A shielded guitar cavity will go a long way towards preventing the interference from reaching your signal. Shielded wire leaves your volume and tone pots exposed, so shielding the cavity does a better job of protecting your guitar.

How Much Does it Cost to Shield a Guitar?

The cost of shielding your guitar is going to be dependant on what type of shielding you decide to use. Aluminum foil tape for guitar shielding is not very expensive, and copper foil tape is only a few dollars more.

Shielding paint will be up to about 5x more expensive than foil tape and can cost up to $50 or more depending on which brand you choose to use.

The least expensive approach to creating a shielded guitar cavity is to use ordinary aluminum foil. Aluminum foil EMI shielding will work as well as any other shielding, and you might already have some around the house.

Tape vs Paint for EMI Shielding

Both approaches will have very similar results, and both will have pros and cons.

Tape Pros

  • There’s no mess with tape
  • It’s reversible
  • It’s inexpensive

Tape Cons

  • Might work loose over time or not stick
  • Tough to work in tiny areas
  • Can be tough to cut the perfect size

Paint Pros

  • Easy application no measuring or cutting
  • Long-lasting and won’t fall off over time
  • Useful in tiny areas.

Paint Cons

  • Expensive
  • Can be messy
  • Cannot be reversed
  • May not be as conductive

We recommend the tape, at least at first, because it’s cheap and reversible. You can easily switch to paint later if you think it is necessary.

Copper Tape vs Aluminum Tape

Copper is the more conductive metal, but it’s difficult to say if it’s a better shield. We are creating a type of Faraday Cage which might not depend on conductivity. There are examples of useful Faraday Cages made from all kinds of metals. Both metals are popular and work well, but aluminum probably has a larger market share, because of the lower cost.

Copper tape usually has conductive adhesive and is much easier to solder than aluminum. Aluminum tape has more of a general purpose that often lacks conductive adhesive. Aluminum is also tricky to solder.

We recommend going with the copper tape because of the ease of soldering and because it’s often packaged with conductive adhesive.

How Do We Shield a Guitar Cavity?

Shielding the guitar is quite simple and only requires removing the cover and electronics from your guitar cavity and coating the inside with a conductive material. You will also need to coat the inside of the cavity cover.

If you unsolder the output jack, you might be able to unscrew the volume and tone controls and leave the rest of the electronics soldered together. Carefully move them to the side while you shield the cavity. If you do need to unsolder more wires, remember to write down or take a picture of the way the wires are supposed to go so you can replace them when finished.

If you are using tape, take your time and cover the area with long flat strips. If you are using paint, apply a thick coat evenly across all surfaces. How it looks is secondary to coating the entire surface.

When your shielded guitar cavity is complete, replacing the cover should create a metal box with the only gaps in coverage being the holes for the volume and tone controls and the switch.

Replacing Your Electronics

Replacing the electronics will be a little more tricky than taking them out because the shielding that we installed can cause guitar grounding issues. The shielding will come in contact with the metal casing of the pots and the switch, creating a guitar ground loop. If you create a ground loop, it will act as an RF antenna which will be counterproductive to the work we are doing.

Install Without Ground Wires

The best solution is to re-install the electronics the way they were, including the output jack and then remove the ground wires. For instance, if you play a Gibson Les Paul style guitar, your electronics cavity might typically look similar to Figure  1.

Fig 1


With the shielding in place, you will need to remove some of these wires to make it look like Figure 2.

Fig 2


Ground the Shield

Grounding the shield is the most challenging part of this project. We need to solder a wire from the shield to the back of the volume pot. It sounds simple, but it’s tough to get the shield hot enough for the solder to stick. You will need a good connection between the shield and the back of the volume pot for it to work.

Test the Shield

The best test is to plug the guitar into your amplifier. If the guitar produces sound, the shield is operating correctly.  If the guitar is not working the shield is most likely not connected to ground. Less likely, there isn’t a good connection between the pots and the shield.

A poor connection could be caused by the paint not being thick enough, or the tape having a non-conductive adhesive.

Summary

A shielded guitar cavity is not very difficult to create, and it can dramatically quiet your sound. Is it really necessary? No, but if you play your guitar in an environment with a lot of electromagnetic interference, we highly recommend giving this mod a try. If you learned a little more about shielding your guitar, please share this post on Twitter and Facebook. And take a look around humbuckersoup.com for our other articles on guitar electronics.

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