Boost, Overdrive, Distortion & Fuzz Pedals – What’s the Difference?
Wednesday January 10, 2018. 09:57 PM , from Sweetwater inSync
This is far from a new question: it’s one that’s been asked countless times and will no doubt continue to pop up, as the line between this quartet of pedals — especially OD and distortion — is often a blurry one. And to make matters even worse, I’ve seen many answers that confuse rather than clarify.
To add further to this age-old query, there has never been a wider array of boost, OD, distortion, and fuzz stompboxes to choose from than there is right now. I mean, here at Sweetwater, we offer in excess of 350 such pedals! That means that if you ran just one of them through its paces each and every day, it’d take you over a year to complete this seemingly simple task! Overwhelming? Confusing? Mind-boggling? Based on the aforementioned number of choices, all three boxes are ticked for me!
So to hopefully help clarify any muddy water that may lurk, here’s my take on the differences among this big four. And for what it’s worth, what follows is not only based on over 30 years of personal tone-searching trial and error, but it also draws on the wise words of countless great guitarists, their techs, and their producers. Plus, it also uses the wisdom I’ve gleaned from pedal designers and experts who are all way, way smarter than I am — not that that’s a difficult feat!
In a nutshell, all of these types of pedals have the same end-game objective — to make your guitar tone bigger, bolder, gnarlier, edgier, heavier, nastier (in a good way!), and just more better! And all of them, when used correctly (duh!), can and will do all the above — but they all do it differently and in varying degrees, too.
In terms of their desirable signal-altering abilities, I’d liken the boost, overdrive, distortion, fuzz quartet to the four heat options I once encountered in a great restaurant that specializes in spicy food — mild, medium, hot, and insane — with every single option being tonally tasty: providing that the chef is a good one, of course!
Historical Distortion Trivia: The first-ever pedal to generate distortion was the fuzz. Before that groundbreaking unit of harmonic-mashing mayhem existed, though, the often criminally overlooked Link Wray recorded an instrumental in 1958 called “Rumble” that featured a gratingly distorted guitar sound. How did Link achieve this landmark of loud? By poking holes in his speaker cones with a pencil (don’t try this at home kids — it will void your warranty!), that’ how! The aforementioned single was banned by US radio but inspired the likes of Pete Townshend of the Who to pick up the guitar. Link may not have been the first to record with a distorted guitar sound, but his influence is irrefutable.
Right, let’s cut to the chase. First though, folks, there’s one critical factor we need to have somewhat of a grasp of, and it is this…
Distortion: A guitarist-friendly explanation — allegedly!
Yes sir: distortion is a word we guitarists throw around all the time, but what does it actually mean and — more importantly — how is it created?
Part I: What is distortion?
To address this, I immediately went to “the Googles” (© Henry Rollins!) to get the “dictionary definition” of the word. Here it is:
Distortion: The act of twisting or altering something out of its true, natural, or original state.
Even more relevant to us axemen, this statement was also included in the definition:
Audio Distortion: Falsified reproduction of an audio signal caused by change in the original signal’s waveform.
Some of the “distortion synonyms” offered were pretty cool and telling too. For example: deformation, contortion, disfigurement, defacement, and even torture!
To get a better understanding of what distortion is and does, let’s take a quick look at the “true, natural state” of a “clean” guitar note’s signal, before it is tortured and deformed into distortion. To that end, Figure 1 shows a simple sine waveform image I’m sure you’ve seen countless times.
The way amps or tubes or pedals or speakers distort this nice, smooth, symmetrical wave is by chopping off (a.k.a. clipping) the tops (peaks) and bottoms (troughs) of it.
Furthermore, this can be done in a gentle (soft clipping), not-so-gentle (hard clipping), or barbarically brutal (a.k.a. fuzz!!) manner. The latter of the three basically totally beheads the peaks and troughs of the sine wave, thus turning it into a square wave — so-called because that’s exactly what the once-smooth, curvaceous wave ends up looking like.
Each one of these three levels of distortion/clipping — soft, hard, and brutal — also changes the harmonic content of a note by adding new frequencies to its fundamental (namely the pure, undistorted note) frequency. And when these additional frequencies are added to the fundamental (plus, to be 100% correct, multiples of the fundamental that also lurk harmoniously within the undistorted note), a new tortured and deformed sound is created. And this is the tone that we guitarists (and fans of rock guitar) know and love as distortion or overdrive or fuzz. Got it?
The above is, as already stated, a very simple, basic overview of a much more complex sonic subject. For example, oftentimes the clipping involved is far from symmetrical (i.e. the deformation of the peaks and troughs caused by distortion is asymmetrical) or pretty to look at, but hopefully this quick, er, peek has proved helpful thus far. Right, back to it…
Figure 2 and Figure 3 are two overtly simplistic diagrams of the three types of clipping just discussed.
Figure 2: Soft & Hard Clipping
Figure 3: Brutal Clipping (square wave — a very simple diagram)
Part II: How Do You Distort a Guitar Note?
As we’ve just learned in Part I — the deed of distorting is done via clipping a note’s waveform and so adding extra harmonics to it. There are two basic ways this can be done:
Method 1: Crank the signal up (to 11)!!
The dotted, horizontal line at the very top of Figure 4, labeled Threshold, is the Maximum Output Level of your signal. The space between the peak of the signal’s waveform and this Threshold line is known as ‘headroom’.
And just like the floor and ceiling in a corridor, these two lines are immoveable objects. Consequently, when the signal’s waveform gets taller than the headroom, the wave has to morph itself to fit between those two lines — not vice versa.
So to clip the wave, we merely need to amplify it so it’s bigger than the threshold. And the bigger we make the wave relative to the headroom height, the more distorted the signal becomes. Figure 5 shows the creation of soft and hard clipping in this way.
Method 2: Create a circuit that clips the signal as is.
This could be equated to asking a 6-foot-tall man to walk down a corridor where the ceiling is only 5 feet high — he’ll have to “distort” his body in order to fit!
Furthermore, the lower the ceiling is made, the more distorted the chap has to make his body in order to walk down said hall. As a picture (or four) can paint a thousand words, Figures 7a–7d will hopefully cement my feeble attempt at this visual anecdote.
Makes sense. Any questions?
As a general rule, the fundamental way boost pedals differ from their OD, distortion, and fuzz brethren is this: they usually do NOT contain a clipping (i.e. distortion-adding) circuit; whereas the others do. A boost pedal’s function is normally to add pure gain to your guitar’s signal — namely make it bigger (and therefore louder) but not change it (i.e. distort) in any way. They’re effectively sonic magnifying glasses, if you will.
To emphasize/underline this fact, manufacturers will often use the term clean boost when describing such a pedal’s function.
With the above stated, a clean boost pedal can and will overdrive an amp into distortion, if the boost level is such that the signal that hits the amp is bigger than the preamp’s threshold. This is often referred to as front-ending an amp and is highly desirable to many. Because of this, boost pedals are often used by rock guitarists to push an already overdriven/crunchy amp over the cliff.
A boost pedal can also add a desirable edge or grind to an OD or distortion pedal when placed in front of it and both pedals are engaged. Hence the reason certain players chain pedals that are seemingly the same, because the distortion created by the combination is desirable. To this end, a few overdrive and distortion pedals have switchable “boost” options built into them. Two examples of this are the Wampler Plexi-Drive and the EVH 5150 Overdrive pedals.
A literal “clean boost” pedal will invariably just have one control for level (boost). Some, however, have a switch or tone control (or three!) for tonal tweakage of the desired boost.
Treble Boost Trivia: It is worthy to note that the “Godfather of Heavy Metal” in the minds of many — Tony Iommi of Black Sabbath — often used a roadie-modified (Dallas Arbiter Rangemaster) treble booster to front end his overdriven tube amps to help create some of his unique, signature sounds. A lot of folk assumed a fuzz pedal was involved — that was not the case.
These bad boys normally have at least three controls — one for volume (or level), one for drive (or gain), and one for tone. Some go as far as having controls for bass, middle, and treble — allowing further tonal tweakability.
As already mentioned earlier, overdrive pedals will add distortion to your signal, in addition to boosting it (if you desire, of course). Because of this truth, the following question is often, understandably, asked: “as a distortion pedal does the same thing, what’s the darned difference between overdrive and distortion?” Well, my friend, to revisit my earlier analogy — the difference is determined by the “spiciness” or “heat” of the distortion the pedal adds to your sonic dish. Overdrive is mild/medium; distortion is spicier — and hotter!
Another difference is this: while an overdrive pedal pushes your signal pretty darned hard, it doesn’t change your existing tone much. Distortion pedals, on the other hand, not only add more saturation (or spice), but they also tend to alter your sound.
Generally speaking, overdrive pedals add that soft, rounder clipping we discussed earlier. Furthermore, while remaining general — the purpose of an overdrive pedal is to (allegedly!) give you that desirable warm, fat, round sound of a tube amp that’s been, er, overdriven — but not to extremes. Think cranked Marshall Plexi rather than a Diezel VH4, Friedman BE-100, EVH 5150, or Mesa Rectifier. Or if you prefer, think more Cream, Free, or AC/DC, rather than Slayer, Slipknot, or Metallica!
To achieve this desirable soft clipping, overdrive circuits usually use a 2-stage process. The first step is to boost the guitar’s signal using IC (Integrated Circuit) op-amps (operational amplifier). The second step occurs later on in the circuit where diodes are employed to soft-clip the boosted signal and also add harmonic content. The type of diodes used (and also how they’re used) can have a profound impact on the sound an OD pedal creates, incidentally. And that’s another reason why there are so many different options out there. “One man’s meat is another man’s poison” is an old adage that certainly rings true here.
To the ears (and fingers) of many — including some of the most revered tone-smiths out there — the sound of an overdrive pedal being used to push (front-end) an already crunchy tube amp over the edge is a highly desirable one. And part of the reason is that the combination of pedal and amp overdrives is more complex and can’t be achieved by either unit alone. It should be pointed out that this is often done with the overdrive pedal’s volume control cranked and the gain control nearly off — thus effectively making it a clean boost unit of sorts.
It should also be noted that certain overdrive units, such as the highly lauded and legendary Tube Screamer, will accentuate (boost) and/or attenuate (reduce) certain frequencies too. This means that the importance of the tonal role played by a relatively cheap stompbox being used in front of a considerably more expensive, all-tube amp, should never be overlooked or minimized. Ditto literally everything else in the signal path — from strings to speakers.
As just stated, the main difference between overdrive and distortion pedals is aggressiveness. Distortion units are effectively the sonic equivalent of English football hooligans. A distortion pedal produces way more gain and also clips the signal way harder than an overdrive pedal, while remaining pretty darned tight and articulate — certainly much more so than the father of all distortion pedals, the fuzz (stay tuned!). While, as already ascertained, an overdrive pedal creates soft clipping, distortion devices add a harder, more aggressive (edgier or squarer) clipping.
Because of the sheer amount of gain a distortion pedal is capable of, a lot of players use them with a clean-sounding amp. That stated, a fair few axemen have used a distortion stompbox in front of an overdriven amp to wonderful effect — including the late, great Randy Rhoads, who used a modified MXR Distortion + pedal to slam a cranked Marshall 100W Plexi even harder.
Just like overdrive pedals, distortions typically (ab)use op-amps and diodes to achieve the desired clipping. They also tend to have three (volume, tone, distortion) or more (e.g. volume, bass, middle, treble, distortion) controls.
Unlike overdrive pedals though, due to the sheer amount of saturation a distortion pedal adds to your tone, they aren’t very responsive to subtle picking nuances.
The grandfather of distortion in a stompbox — the aptly named fuzz pedal — was born in the mid-’60s, and of the four types we’re looking at here, it is by far the most radical. If truth be told, this aptly named effect was initially created to imitate the sound of something malfunctioning or broken in the signal chain — like an amp or speaker, for example (see the earlier Link Wray note). And because of this goal, there’s often a gloriously musical randomness to fuzz.
In fact, according to the learned writings of Art Thompson (a great journalist & chap) of Guitar Player magazine, the first “fuzzy guitar” recording was one of those wonderful happy accidents! Apparently, a faulty tube-powered mixing board was the culprit, and all involved liked the resulting sound, so it was kept.
Fuzz is capable of creating gnarly, heavily clipped, and harmonically altered sounds that are often wonderfully hard to control. One big reason for this is that fuzz pedals invariably use transistors for gain as opposed to op-amps, and while op-amps are pretty hi-fi, transistors are the exact opposite — they’re lo-fi and add a heap of harmonics as they mash your signal into a square!
The transistor being used often has a huge impact on the type of fuzz created. Silicon transistors generate a bright, aggressive fuzz while germanium ones tend to be smoother and warmer sounding.
One of the true masters of fuzz (ab)use was the late, great Jimi Hendrix — and a big part of his genius was, IMHO, his incredible ability to appear in total control of the seemingly uncontrollability of said pedal.
Breaking Fuzz Fact: As the saying goes: “there’s an exception to every rule” and here’s a doozy – the Electro-Harmonix Op-Amp Big Muff reissue fuzz pedal that was unleashed in late 2017. As its name reveals — it uses op-amps instead of transistors! This unit is based on the late ’70s units made famous by Billy Corgan on the Smashing Pumpkins’ multi-platinum album, Siamese Dream. Proof positive that it’s not merely the ingredients that make a great dish (or fuzz!) but how they’re collectively combined.
Interesting Trivia: Although the Big Muff Pi is synonymous with classic fuzz tones, the term “fuzz” is nowhere to be found either on the pedal itself, or in the leaflet that accompanies it. Instead, the pedal is described as “the finest harmonic distortion-sustain device developed to date,” and its three controls are labeled Volume, Tone, and Sustain.
Like all things tonal, there is no best or right or, for that matter, wrong here. Whatever you think sounds and feels the best for your style and sound is correct, regardless of the opinions of others. Go with your gut, and don’t be afraid to experiment, either. Sometimes a seemingly outlandish or illogical pedal combination can be magical. Want an example? Well, that’s what I’m gonna sign off with.
There’s this charming and charismatic Texan fella with an impressively long beard and an equally long and impressive resume of highly lauded tones. His name? The Reverend Billy F. Gibbons. Many moons ago I had the honour (correct spelling) of mapping out his complex rig setup for Guitar World’s popular “Vulgar Display of Power” page. And part of that rig was a section with no fewer than six of the same exact distortion-creating units chained together!! His rationale? Here are his immortal words of wisdom on said subject:
The author of this piece with Billy F. Gibbons, Fort Wayne, 2017
“Combinations of multiple effects are manageable when using a slight edge from each, which avoids the unwanted collision of tones. However, at this point, sometimes the grind of excessive noise becomes its own thing!
“Experiment… just not with your medication.”
Billy F. Gibbons, Guitar World, 2005
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