What is FET Distortion?

Bryan Clark Author

Learn about what FET distortion is and how it is used in foot pedals.

Well hello everyone! I wanted to take a little bit of time and explain what FET distortion is, the acronym, and some classic pedals that use this type of technology.  

FET distortion is a type of distortion that is produced by a field-effect transistor (FET) in an amplifier circuit. This type of distortion is characterized by a gritty, high-gain sound that is often described as "fuzzy." The distortion occurs when the FET is operated in its non-linear region, which causes the transistor to amplify the input signal in an unpredictable way. This can create a range of harmonics and other distortion products that give the sound its characteristic "fuzz" quality.

FETs are a type of transistor that uses an electric field to control the flow of current through the device. Unlike bipolar transistors, which use a current to control the flow of current, FETs use voltage to control the flow of current. This gives FETs some unique properties that make them well-suited for use in distortion circuits.

One of the key advantages of FETs is that they have a high input impedance, which means they can amplify signals without loading down the source. This is important in distortion circuits because it allows the input signal to remain intact and retain its character, even as it is being distorted.

Another advantage of FETs is that they can be operated in a wide range of bias conditions, which allows for a wide range of distortion sounds. When a FET is operated in its linear region, it will produce a clean, transparent sound. However, as the bias is increased and the FET is operated in its non-linear region, the distortion will become more pronounced. This allows for a wide range of distortion sounds, from subtle to extreme.

FET distortion is used in a variety of musical genres, and is particularly popular in guitar amplifiers. Many guitar players prefer the sound of FET distortion to other types of distortion because it has a natural and organic quality that is well-suited to the guitar. The gritty, high-gain sound of FET distortion can add a sense of power and intensity to a guitar performance, making it a popular choice for rock, metal, and other high-energy genres.

BTW, One of my favorite new pedals that combined FET as well as silicone and Germanium fuzz is the Chase Bliss Pre Amp MKII designed with Benson amps. It's on my pedal board bottom right (with all the sliding faders).