EMI, or Electro-Magnetic Interference, is a problem that can plague your guitar as well as your other audio equipment, causing a particular buzz or hum that can sometimes be impossible to get rid of depending on the source. If you’ve ever experience a particular hum or buzz coming from your guitar, amp or other audio equipment, you’re not alone. In this article, we take a quick look at what is EMI and how to keep it from ruining your guitar tone.
What Is EMI
EMI is a type of interference that affects all kinds of audio equipment, caused by either the equipment itself or the cables connected to them picking up nearby electromagnetic fields. This usually shows itself as a particular type of noise such as a hum, buzz, or static. The culprits behind these magnetic fields are wide ranging, but common causes that you will typically encounter are television monitors, computers, light dimmers, fluorescent lights, power lines, radio transmitter, TV transmitters, and even some car ignition systems. It should be said that since EMI depends on both your equipment and the environment you’re in, completely eliminating the noise caused by it can range from pretty easy to nearly impossible.
Dealing With EMI Noise
If the EMI issues you are experiencing seem to show up or get worse depending on your location and which way you are facing, the quickest method to eliminate them is by moving around or facing a different direction until it’s gone. Yes, it might not be a permanent solution but if you’re in the middle of a gig or on the clock in the recording studio, it will definitely be the quickest fix. If that doesn’t work or you want something a bit more permanent, you have several options.
The first is to install humbuckers or active pickups on your guitar. If your tone depends on traditional single-coils, that option might be too drastic. If that’s the case, you can try a suppression pedal. There are two main types of noise suppressors – gates and noise reducers. Noise reducers, like the Rocktron Guitar Silencer and the Boss NS-2, use various techniques to try and quell the offending noise. Gates, meanwhile, are like a hatchet that let you manually cut off all signals below a certain frequency. The MXR SmartGate and NoiseClamp are two popular pedal options. You can read more on noise gates in our Gates, Equalizers And Compressors article.
You should also be aware that it’s not just pickups that are susceptible to EMI. The wiring on a guitar can be also be affected. If that’s the case, you should definitely look into shielding your guitar wiring. If done correctly, it should not have any effect on your tone. If not, it can act as a capacitor, draining your high-end response. There are many videos online (like the one below) that you can follow to shield your wiring properly.
Possible Grounding Issues
Aside from light dimmers, computer monitors and the other EMI sources mentioned above, grounding issues are another common cause of noise troubles. If the tips above didn't help, there's a chance you might be dealing with ground loop problems. A good way to tell if you are experiencing grounding issues is by unplugging your guitar from the amp and seeing if the buzzing goes away. If the noise remains, you are most likely dealing with a ground loop problem.
Another way to tell is by listening carefully to the sound of the buzzing. While EMI tends to sound like a distorted buzz, ground loop issues usually come off as more of a low-frequency hum. They are pretty similar, except that the EMI buzz has more of an emphasis on the higher end harmonics. These two methods are by no means foolproof but are still a good place to start. If grounding issues are the source of your noise, check out our article What Is Dirty Power And How To Avoid It and the video below for more info.
Whether it's from grounding issues, acoustic feedback or EMI, noise is one of those issues that pretty much every guitarist will have to deal with eventually. By knowing where the noise comes from and how to deal with it, you can take the necessary steps to tame or completely remove it, allowing your tone to sound the way it was meant to.
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