The year: 1966.  Enter Thomas Organ Company engineer Brad Plunkett, an engineer tasked with coming up with a tone circuit. While testing, he discovered that he had accidentally invented something way beyond a normal tone control. Plunkett put it into a volume pedal housing, and, although there was no way he could have known it at the time, he changed the world. That device, which would soon be dubbed the Cry Baby, found its way onto history-making tracks by Jimi Hendrix and Eric Clapton, and those sounds would profoundly influence subsequent generations of guitarists like Stevie Ray Vaughan, Slash, and many, many others.

WHAT IS DISTORTION, ANYWAY?

First, let’s talk about harmonics. When you play a note on your guitar, the sound you hear is made up of a fundamental frequency—the pure note—along with multiples of that frequency, which are called harmonics. If you feed your instrument’s signal into any device that changes the signal’s harmonic content in a certain fashion, you get the sound that we call distortion. There are numerous ways to change the harmonic content of your signal, but for our purposes we only need to look at three of them. Each changes harmonic content by generating additional frequencies.

The first and most basic way to generate harmonic content is to push your instrument’s signal, which is the voltage generated by your guitar’s pickups, beyond an amp or pedal’s headroom.

As a sound wave, your instrument signal sits between two boundaries called rails. Headroom is the space between the rails. If you crank your amp so that your signal’s peaks push against the rails, those peaks start to get clipped off of your signal. This is how tube amp distortion is created.

Pedal distortion is usually achieved by the other two methods: using the circuit to clip your signal before it runs out of headroom or using transistors, which generate extra harmonics because of their nature as imperfect amplifiers.

Each of these methods creates distortion, an umbrella that covers overdrive, distortion and fuzz. The difference is a matter of degree—how much are you clipping your signal?

OVERDRIVE

Overdrive is the sound you get when you crank a tube amp to that rich, gritty sweet spot. This clips your signal some, but not too much. Overdrive pedals are designed to both emulate and complement the sound of an overdriven tube amplifier.

For example—running an OD pedal through a clean amp will provide smooth, mellow grit while running it through a slightly overdriven tube amp will stack the gain from both and produce a very thick and saturated sound that’s closer to distortion but still retains the tubey warmth of your amp.

Overdrive pedals typically use a two-step process. First, hi-fidelity amplifiers called op-amps are used to boost to your signal. At a certain point, diodes are triggered to soft-clip the boosted signal, generating harmonic content. The type of diode used can have a dramatic effect on the pedal’s tone—LED—which has a wide open, transparent sound—and silicon—which is more biting with a bit of compression—are the most common.

The MXR^® Double-Double^™ Overdrive is the perfect example of an overdrive circuit—and it’s got Lo and Hi Gain modes for extra versatility. Let’s see how the signal for each looks on the oscilloscope.

The Lo Gain signal has fairly round peaks, which indicates fairly soft clipping and a smoother sounding overdrive.

With a bump in gain, the peaks get sharper, and the overdrive has a more aggressive sound. Notice, however, that the peaks are still intact. We haven’t completely slammed our signal against the rails—yet.

DISTORTION

Distortion is the technical term for all the different sounds you get from clipping a signal, but in common parlance it refers to the middle ground—a signal that’s clipped harder than overdrive, and is therefore much more aggressive, while retaining more articulation than fuzz.

Distortion pedals produce much more gain than most overdrive pedals, so players generally use them with a clean amp. As with overdrive pedals, distortion pedals tend to use op-amps and diodes to clip your signal. The MXR Super Badass® Distortion is one such pedal.

Notice that the peaks are just starting to get shaved off. But we’re still not smashing into the rails yet—we’ve got one more type of dirt to cover.

FUZZ

Fuzz was the first type of distortion to appear in pedal form, originally designed to sound like your amp was faulty or your speaker was damaged. Amp settings don’t matter much at this point—your signal is getting totally clipped.

Unlike overdrive and distortion pedals, fuzz pedals use transistors to instead of op-amps to add gain to your signal. Where op-amps are hi-fi, transistors are by nature very lo-fi—they add a ton of harmonic content to your signal as soon as they start to amplify it. The type of transistor a fuzz circuit uses can drastically affect fuzz tone. Generally speaking, germanium transistors produce a warmer and smoother fuzz while silicon transistors produce a brighter, more aggressive fuzz.

The MXR Super Badass Variac Fuzz uses silicon transistors, so it has a nice cutting tone. What makes this pedal unique among other Dunlop fuzzes, though, is its Variac control, which allows you to adjust the amount of voltage—and therefore headroom—available.

You can adjust the Variac control from 5v to 15v. This image shows what the signal looks like at the 5v setting. As you can see, the peaks are totally clipped off. There isn’t a lot of room to move around before your signal smacks into the rails, creating a gnarly, splatty sound.

Increasing the voltage to the default ±9v smooths out the edges a bit, but the peaks are still flattened up against the rails. At this level, the Super Badass Variac Fuzz sounds like a chainsaw in a lightning storm.

At 15v, this pedal has a lot more headroom than most fuzzes. This produces a super smooth and transparent signal that’s more akin to overdrive, but it’s more like a transistor’s interpretation of what the op-amp + diode combination produces in a pedal such as the Double Double Overdrive.

The harmonic content generated by transistors removes the need for a diode to clip the signal but that doesn’t mean you can’t combine transistors with diodes for a whole ’nother level of super hard-clipped saturation. The Way Huge® Russian-Pickle™ Fuzz, for example, combines silicon transistors with silicon diode clipping to create a thick and groovy sound with a pronounced midrange.

THE WRAP

The science of distortion can seem pretty esoteric, but in simple terms we can see that the differences between overdrive, distortion and fuzz have to do with how hard you clip your signal. Depending on the shade of distortion you’re looking for, you’ll find amps and pedals using various methods to throw your signal into dirt mode.

Equalizer

When playing out, one of the first issues you’re going to have to deal with is adapting your tone to various physical spaces or unfamiliar backline equipment. Your most basic line of defense in these situations is an EQ pedal, which allows you to fine-tune your sound by cutting or boosting specific frequencies.

MXR^® has two great options: the Six Band EQ and the Ten Band EQ. Modern classics, both have been upgraded with noise-reduction circuitry, true bypass switching, brighter LEDs for increased visibility, and a lightweight aluminum housing.

The Six Band covers all the essential guitar frequencies, from 100Hz to 3.kHz, and each can be boosted or cut by 18dB. If you’re in a mind to save space, this is the EQ for you, as it comes in at the same size as the Phase 90.

The Ten Band EQ gives you control over a wider range of frequencies, from 31.25Hz to 16kHz, which you can cut or boost by 12dB. This extended range makes it perfect for bass players as well as guitar players. For further fine-tuning, you can also cut or boost your signal at both the input and output stages. Finally, there’s a second output so you can run two separate signal chains.

Having either EQ on your board allows you to tune your guitar or bass rig to any venue in short order. Just remember to tune with your ears, not your eyes.

If you want a simpler, less transparent and more “sauced up” tone-shaper, the Micro Amp+ is another great option to consider for both guitar players and bass players. It builds on the classic Micro Amp circuit with EQ controls, low-noise op amps, and true bypass switching. This is a pretty versatile pedal—it can be used as a boost, if you have enough headroom; an OD, if your headroom is lower; and as a line driver/ buffer.

Compressor

Some players consider compression to just be a studio thing—unless you’re using a more “effect” style pedal such as the Dyna Comp^® Compressor—but compression can also serve you well on stage. It helps even out your signal, ensuring that nothing gets too loud or too soft by limiting the dynamic range.

The MXR^® Studio Compressor and Bass Compressor are perfect for this application. Their Attack, Release, Ratio, Input, and Output controls make it easy to dial in the desired threshold, from subtle peak limiting to hard squashed compression. Use the ten gain-reduction status LEDs to check reaction speed in real time. Equipped with CHT^™ Constant Headroom Technology, these compressors also provide a ton of headroom for clear and transparent performance.

Buffer

When you run your signal from your instrument to your amp though long cables and/or through a large array of effects with varying impedance, players often experience line level or treble loss. A buffer such as the MXR^® CAE MC406 addresses this problem quite nicely.

It comes in a small, rugged housing and can add up to +6dB of gain to your signal with its front-facing slider, making up for signal loss that can occur when combining effects with different impedance levels. Hi and Lo cut switches help you to fine-tune signal recovery. The CAE Buffer also comes with a convenient 9VDC power output jack, for powering another pedal, along with an extra output for a tuner, separate effects chain or amp. On the inside, you can set whether to receive a buffered or unbuffered signal.

The CAE Buffer can be placed before, after, and sometimes in the middle of the effects chains to help drive things along.

Direct Input Box

This one’s a no-brainer for bass players. Chances are, the venue’s sound tech will want to run your signal to the FOH. If you don’t have your own DI box, you’ll have to use theirs, leaving your tone in their hands. Having a DI box such as the MXR^® Bass DI+ or the Bass Preamp allows you to go direct while retaining control over your own sound.

The Bass Preamp features separate Input and Output level controls and a 3-band EQ section with sweepable midrange—from 250hz to 1khz—for extensive tonal flexibility. It’s all delivered super clean with high headroom thanks to our own Constant Headroom Technology^™, and you can use the Pre/Post EQ switch to set whether or not your Direct Out signal is affected by the Bass Preamp’s EQ section. And of course, the Bass Preamp features a Ground Lift switch in case you encounter ground loop hum.

The Bass DI+ combines a three-band EQ with a switchable distortion channel, including a noise gate, a Phantom/Ground switch, an unaffected parallel output for a tuner or separate signal chain, and of course an XLR direct out.

Volume Pedal

Putting a volume pedal on your board allows you to change your output level quickly and without having to stop playing. It also allows you choose where in your signal chain to adjust volume—relying on only on your instrument’s volume control for output dynamics can result in a weaker signal being fed to your pedalboard.

The Volume (X)^™ Mini Pedal is a great pedalboard-friendly option—it’s durable and solidly built with a lightweight aluminum chassis, aggressive non-slip tread, and our patented Low Friction Band-Drive for a smooth range of motion and consistent, reliable performance. For maximum comfort and precision, the DVP4’s rocker tension is fully adjustable. This pedal can also be used for expression purposes, but that’s an entirely different function.

Two common placements for volume pedals are pre-gain, before distortion pedals, and post-gain, after distortion pedals. A volume pedal placed pre-gain is used much like a volume knob on a guitar. When the volume pedal is placed post-gain, a lot of players prefer to use it to adjust the overall volume of your signal without effecting the gain structure of any overdrive, distortion, or fuzz pedal in your chain.

A/B Box

An A/B box allows you to route your instrument’s signal to two separate output paths. With the MXR^® A/B Box, you can switch between amps or run them both at the same time with different effect configurations, which opens you up to a whole range of tonal options. You can also use this pedal to create separate chains within your main signal chain.

Noise Gate

A noise gate automatically mutes your signal below a certain output threshold. This comes in handy if you’ve got any noise—often caused by super high gain pedal or amp settings or a venue’s faulty wiring—interfering with your signal. Dial in the right setting, and your signal will be totally silent until you start playing. Noise gates are usually placed at the end of the signal chain or after any gain pedals in an FX loop.

The MXR^® Smart Gate^® Noise Gate is equipped with three selectable types of noise reduction, covering just about every noisy signal situation you’re likely to face.

It bites down on sizzle and hum but lets the smallest detail of your playing through, sensing precisely when and how fast to engage without getting in your way. It lets you can wring every last bit of sustain out of chords without being cut off, reacting gradually to long, sustained notes and quickly to short, syncopated notes while preserving picking dynamics and harmonic overtones.

Power Supply

Maybe this one is too obvious, but hey—it’s good to be thorough. Why worry about a bunch of batteries when you can power all of your pedals with a single source?

The MXR^® Iso-Brick^™ Power Supply is just such a source, and a very convenient one at that: its compact and lightweight, making it vert pedalboard-friendly, with 10 fully isolated outputs that accommodate a variety of voltage and current requirements: two 9V outputs at 100mA, two 9V outputs at 300mA, two 9V outputs at 450mA, two 18V outputs at 250mA, and two variable outputs adjustable from 6V to 15V at 250mA. The two variable outputs can be used to emulate voltage “sag,” a drained battery effect sought by many vintage tonechasers. The Iso-Brick Power Supply also features power on/off and connection status LEDs so that you can quickly troubleshoot any pedal or connection issues.

For a simpler power solution, the DC Brick^™ Power Supply is also a great choice. With eight 9V outputs and two 18V outputs, it will power just about any analog pedal, and each 9v output has a red LED that illuminates if there is a short.

Obviously, if you used all these pedals at once, you could take up an entire world-tour sized pedalboard. You still need room for your Fuzz Face^® Distortions, Carbon Copy^® Delays, and Cry Baby^® Wahs, so use this list to address your particular needs as a gigging musician. Which of these pedals might make your life easier when you step onto the stage?