Effects Basics: Overdrive, Distortion, Fuzz, & Boosters

Tech Tip: Effects Basics—Part 3

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Adding crunchy goodness to your guitar sound with distortion, overdrive, fuzz and boost effects.

In Part 1 we explored time-based effects like reverb, delay and echo. Part 2 delved into modulation effects such as tremolo, phasers, flangers and chorus pedals. With Part 3 we jump into the huge universe of stompboxes that produce everything from the subtle harmonic warmth of a slightly overdriven vintage tube amp to the seething slabs of distortion high gain amps churn out in the service of rock’s extreme heavy metal territory.

Distortion versus overdrive—there is a difference

A lot of ink has been spilled in trying to come up with a clear distinction between these two terms that are often used interchangeably. Marketing copy often plays fast and loose with them. And the fact is that by tweaking the parameters of many effects boxes along with the rest of your signal chain, you can induce sounds that replicate what we commonly think of as overdrive and distortion sounds from the same stomp.

In searching for a workable distinction, looking at the signal chain as a whole to see how electronic signal inputs and outputs affect the sound that emerges from the speaker cabinet is a useful way to do that.

From a circuit designer’s standpoint, overdrive occurs when input gain exceeds a device’s ability to handle it. The classic example is an electric guitar played hard with its volume pot cranked to its maximum setting. The resulting electronic signal sent to the preamplifier section of a tube amp that in turn has its gain turned all the way up causes the tubes in its preamp to become overloaded and clip—that is, square off the waveforms as it attempts to handle the signal overload. The resulting signal that is then amplified by the amp’s power stage and sent to the speaker reflects that overdriven signal in the form of audible distortion. In turn, depending on the power handling capacity of the speaker and its degree of sonic transparency, another layer of distortion is added to the signal.

Waveform clipping, at least where tube circuits are concerned, occurs in a range from soft to hard clipping. With soft clipping, the top of the wave, as seen on an oscilloscope, is slightly less rounded at its peak. The sonic effect is generally one we associate with the terms “warmth,” “sustain” and “crunch.” With hard clipping, the top of the waveform is more abruptly squared off. Words often used to describe that sonic effect include “grind,” “grit” and “breakup.”

Digital circuits are another story. There is no gray area between hard and soft clipping. When a digital circuit is overloaded, it generates ugly noise beginning right at the upper threshold of the circuit’s ability to carry the signal without distortion. This is why digital amps and effects processors use digital signal processing to simulate the musically useful tones of tube distortion. Stompboxes with analog circuitry also sometimes aim to overload the amp’s front end, but more typically they color the signal to emulate tube breakup.

OK, so what kind of pedal do I want?

Well, that depends on what you’re going for. If you’re a blues guitarist seeking the mid-rangey, throaty tone with plenty of compression that’s a hallmark of modern electric blues guitar sound, you’ll be looking at a range of stomps that’s vastly different from those that a death metal guitarist would consider.

A good place to get started is by looking at the stompboxes and effects processors used by guitarist or bassists whose sounds you admire. Reading gear reviews by both pros and fellow guitar geeks will also help narrow down your search. Another resource is the huge library of video and audio clips you’ll find online posted by everyone from effects manufacturers to those guitar geeks who love demonstrating the capabilities of their latest stomp.

Distortion Effects and Their Boost, Fuzz and Overdrive Relatives

To help get you headed in the right direction, what follows is a rundown of effects organized by type with some video clips to give you a more concrete sense of what each does.

But if you’re feeling brave and want to dive right into the fray, Musician’s Friend offers a mind-boggling selection of overdrive, distortion, fuzz and boosts effects.


As the name implies, they boost the the signal ahead of your amp’s input. As such, boost  pedals are essentially a preamp circuit designed to goose your amp into overdrive, especially at lower volume settings. Guitarists often use them to give solos extra high-end emphasis and bite without necessarily dirtying up their tone.

Early booster pedals such as the Vox Treble Booster employed a germanium transistor—a solid state device that’s still used in modern stomps to produce a boost that both sweetens up treble frequencies while also subtly fattening up your guitar’s midrange. Guitar heroes like Page, Clapton and Beck counted on these devices to add some edge to the output of their Marshall stacks and Vox amps.

Today’s booster units offer a range of sonic options from those that aim to simply add a clean boost to those others that thicken up mid and top-end frequencies with harmonic complexity. Many incorporate elements of overdrive by adding a little “hair” to upper frequencies.

The TC Electronic Spark Booster is one of the latter class of pedals that can operate as a pure level boost effect adding 26dBs of gain in the top end. But it delivers much more on request. Tweaking the active Bass and Treble EQ knobs in combination with the Drive knob helps you center the frequencies you want to affect while introducing a modest amount of breakup to overly clean amps.


The TC Electronic Spark Booster has EQ and Gain/Level knobs for dialing in the frequencies and degree of boost you want. A 3-way toggle with Fat, Clean and Mid settings further pinpoints how the Spark Booster works on your tone.


One of the most iconic uses of fuzz tone came along early in the Rolling Stones career. Keith Richards had begun messing around with one the earliest fuzz boxes—a Gibson Maestro Fuzz Tone—when he started sketching out his idea for what would become the memorable guitar riff on “(I Can’t Get No) Satisfaction.” Originally intended to denote the places where a sax part would later be overdubbed, the effect made it onto the released version leading to a run on fuzz boxes.

Other fuzz units quickly showed up including the Dallas Arbiter Fuzz Face used by Hendrix as well as the Mosrite FuzzRITE also used by Hendrix and Carlos Santana to add a furry edge to their tone. Paul McCartney also got in on the fuzz frenzy using a Vox Tone Bender to add fuzz-laden distortion to his basslines, notably on “Think for Yourself.”

The MXR Classic 108 Fuzz reproduces the classic sounds of ‘60s and ‘70s hair-laden hard rock with some modern improvements. One of these is a buffer switch that allows it to get along with wah-wahs placed ahead of it in the signal chain, avoiding the unwanted oscillation that can plague that combination while also curbing muddiness.


MXR’s take on the vintage Fuzz Face, the Classic 108 Fuzz, improves on the original with a wah-friendly buffer switch and true bypass circuitry to keep your signal chain clean when you don’t need fuzz. The compact case conserves precious pedalboard real estate.


As we said at the outset, most overdrive pedals are designed to mimic the sound of an overdriven tube amp. Many will hasten your amp’s natural tendency to get into musically attractive distortion—a handy thing when you want that breakup to happen at volumes which don’t involve falling ceiling tiles or neighbors calling the cops.

Beginning in the late 1970s, overdrive pedals started showing up that did just that. Leading the pack were the Ibanez TS9 Tube Screamer and the Electro-Harmonix Big Muff. Both have withstood the test of time and continue to be among the most popular overdrive stomps on the market. Both companies have spun off variations to serve specific performance needs and tonal objectives.

Electro-Harmonix has capitalized on its original Big Muff design with models tailored to the dynamics of bass guitar. The E-H XO Bass Big Muff Pi preserves the natural bottom end of the instrument while adding a very tweakable range of distortion sounds that go from mild to hairy.


The Electro Harmonix XO Bass Big Muff Pi combines standard Volume, Tone and Sustain knobs with a handy Boost switch when you’re ready to put your bass in the sonic spotlight.

One of the more recent incarnations of the Big Muff guitar stomp lineage is the Electro-Harmonix Germanium 4 Big Muff Pi. It doubles your sonic possibilities with two foot buttons; one engaging its overdrive circuitry, the other bringing on full-blown distortion sounds. True to its name, at the heart of its electronics is a germanium transistor—the same solid-state device that’s been powering such stomps since the 1960s. Both sections have a Bias control that allows you to dial in the amount of gain that pushes the transistor circuit. A Volts knob on the distortion side of the box controls the current reaching that circuitry, setting up myriad tonal possibilities.


The E-H Germanium 4 Big Muff Pi rewards a thorough exploration of its control panel with a seemingly endless array of overdrive and distortion sounds.

You can explore the entire range of Electro-Harmonix stomps here, including other variations of the Big Muff.

For many tone freaks, the instantly identifiable green case of the Ibanez T9 Tube Screamer spells classic overdriven tube tone goodness. Unlike more extreme OD stomps, rock and blues players appreciate the way it works with your guitar and amp’s native sound rather than overwhelming them. Its modest gain levels push your preamp into breakup that’s always musical. If you’re looking for massive levels of high-gain crunch levels, continue on to our discussion of distortion stomps below. But if you’re looking for an effects pedal that can be dialed in to work with your amp’s natural harmonic distortion, the TS-9 is a likely contender for your pedalboard.


The Tone, Drive and Level controls on the Ibanez TS9 used in conjunction with your guitar’s volume pot and amp’s gain knob provide a broad palette of overdriven tones.


We saved the discussion of this category of stompboxes for last because they're the big kahuna when it comes radical tone tweaking. If overdrives are the polite society of the effects world, then distortion stomps are their unruly, kickbutt cousins from the other side of the tracks.

That said, distortion pedals come in a huge range of sonic flavors from relatively mild to mind-shatteringly wild. Many are aimed at the hardest-edged realms of rock including extreme genres such as grindcore and black metal that wed trebly tone with enormously distorted output.

In the earliest days of rock, distortion came from applying excessive voltage to the front end of the guitar amp, producing harmonically complex overtones. Generating feedback loops by jamming the guitar’s pickups into the face of the speaker cabinet added to the overall distortion as did taking advantage of the “faulty” preamps of guitar amps that had taken a beating on the road. As the music grew increasingly electrified, artists began seeking more extreme forms of distortion with guitarist Dave Davies of The Kinks famously slitting the speaker cone on his amp to achieve the dirty, proto-metal tone heard on the band’s 1964  single “You Really Got Me.”

As rock grew ever louder, bands such as Led Zeppelin and Deep Purple emerged laying the groundwork for the heavy metal sounds that would follow. Answering the demands of these bands, companies like Marshall Amplification began building increasingly louder and bigger amp heads and speaker cabinets that generated seriously distorted waveforms.

Beginning in the 1970s another approach to achieving distortion appeared: the stompbox. Depending less than their overdrive cousins on the front end of the amp they were electronically chained to, these early distortion effects aimed to achieve massive breakup

within the modest confines of their own cases. Leading the charge was the BOSS DS-1 Distortion Pedal that remains in production to this day. While its Tone knob may not have all the sophistication of units sporting more elaborate EQ controls, the DS-1 is capable of an uncanny range of tones that go from the leading edge of tube breakup to unadulterated filth and beyond.


Take a sonic tour of the BOSS DS-1’s range of tones and sample its ability to reflect your playing dynamics.

One of metal guitarists’ favorite techniques for achieving tonal nirvana involves scooping out midrange frequencies while applying a treble boost to combine heavily distorted rhythmic chording with screaming, single-note lead tones. The Electro-Harmonix XO Metal Muff with Top Boost is designed to achieve that and more with its six-knob tone-shaping control array.


Dialing in screaming leads and chunky distorted rhythms is child’s play when you’ve got an E-H Metal Muff with Top Boost at your feet.

A word about pedal order

Although the order in which you chain effects together on your pedalboard is the subject of lively debate, most guitarists ascribe to the theory that distortion, overdrive and fuzz boxes usually should be placed up front in the signal chain. If you’re using both a milder OD effect plus a more radical distortion stomp, it’s generally felt the overdrive should precede the distortion electronically.


We recently prevailed on shredder extraordinaire Steve Vai to share his insights on perfect pedal order.

Stay tuned for Effects Basics—Part 4 in which we’ll look at the effects that work on dynamics: compressors, expanders and limiters—tools that can have a profound impact on your sound.

Want to dive deeper into effects? Our Guitar and Bass Effects Buying Guide looks at the entire spectrum of stompboxes and effects multiprocessors.

Tags: Electric Guitars

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