DIY Guitar Effect Pedals
For those of the TL;DR meme, click here to jump to the Guitar Effect Pedals/Circuits Table
Studying the guitar, as with most rewarding skills, has a considerable "learning curve" (particularly for those such as I that have an abysmal lack of talent). Bashing away on an acoustic guitar, grinding out practicing chords and screeching through scales requires considerable persistence and the desire is just to "play some songs".
Simple "beginner" songs are generally "lame" and usually rely upon vocal accompaniment to sound "good", which is a big problem if your voice sounds like a bag full of cats being attacked with a chainsaw. This is the beauty of learning the electric guitar (rather than starting on an acoustic), and being into hard-rock, hammering away on some power-chords (i.e., only two note/fingers required!) is not a problem and can sound like the real deal. HOWEVER, this requires some type of distortion (i.e., effect pedal) - unless the "lame" is "amplified".
Thus the fortunate juxtaposition of learning the electric guitar and being an avid electronics hobbyist. Building guitar effects pedals is not particularly difficult (myriad sites with schematics etc) and since having the basic electronic tools and skills already, "happy days" the pedals are actually cheap as well.
Other benefits of making your own effect pedals is that you can add features and try customisations. But best of all, it sounds better if you make it yourself!!
Details of the various effect pedals I have tried are available by clicking the links in the following tables which list projects by either category, project title or ID number.
Prototyping ("Beavis Board")
There are numerous "standard" components that comprise any guitar effect pedal such as the input/output jack connectors, various potentiometers, power supply etc. Rather than having these "lashed" to the benchtop and/or "floating around" it is recommended to mount these on a suitable enclosure together with a standard breadboard, along the lines of the "Beavis Board" (1), (2). This enables circuits to be rapidly prototyped and debugged (and helps avoid errors, "doggy" connections etc). Since these "Beavis Boards" are no longer available, I have a home-brewed version with build-details listed.
Guitar Effect Pedal Types (who's who in the zoo !)
There is a palpable interminable plethora of guitar effect pedals provoking dumbfoundment and lingering flabbergastation. Huh WTF? Oh, I mean too many types and variety of effects, pedals, which one does what, need this one or that, what to do, where to start? Especially if you are going to put the time and effort into actually making them DIY.
I found the basic classification based upon the pedalboard-style approach (3) to be helpful. This also is along the lines of the four divisions of guitar effects used in "Rock Guitar for Dummies" (4). This gives the following classification (assuming the most common pedalboard arrangement) of guitar → gain stage → frequency → modulation → time → amp, as recommended by Sweetwater Sound.
1. Gain Stage/Based Effects
"Gain" is just another way of saying making the input signal from the guitar larger. Therefore, "gain" based effects range from "clean boost" through to "overdrive" then to "distortion" and eventually "fuzz". This is roughly in order of the amount of gain, but also the "amount of clipping" and how the "clipping" is done. "Compressor" type effects also can be thought of as "gain based" as the signal is boosted and or decreased as necessary to make the output signal between the set thresholds.
A "clean boost" is basically a pre-amplifier. This can be used to correct signal loss through a long effect pedal chain and or long length of cables. A boost pedal can also be used to increase the signal to an amplifier (or other effect pedal) to induce "clipping" or "distortion" - which brings us to the topic of "distortion".
Distortion means modification of the input guitar signal that leads to "significant" alteration of the signal. This is a rather "subjective" definition, but that is maybe why there are so many different distortion/fuzz pedals!
"Distortion" comes from "clipping" of the signal (well at least in terms of what a guitar effect pedal circuit is trying to achieve). Using the normal analogy of a simple sine wave, see this reference for a more detailed explanation with diagrams (5), the "top" and "bottom" of the sine wave (i.e. input signal) is cut-off (hence "clipped"), the more the "clipping" the more the distortion. Thus "distortion" circuits change the input signal to mimic the effect of over-cranking the input signal to an amplifier/speaker. This "clipping" (if done correctly) rather than just "cutting some of the signal" produces a bunch of harmonics which gives a "pleasing sound" in terms of narly, grungy, fuzzy "rock'n roll".
This leads to lots of potential variation as the "gain" can be produced using op-amps or discrete transitors (either silicon or germanium) whereas, the clipping can be done through "straight" gain or using various types of diodes (again either or silicon or germanium) either as feedback (soft clipping) or at the output (hard clipping). Hence, the wild plethora of "distortion" and/or "fuzz" circuits/effects.
2. Frequency/Tone Based Effects
Circuits that affect the frequency of the input guitar signal include equalizers (EQ), wah-wah, pitch shifters and harmony (octave up/down), envelope filters etc.
3. Modulation Based Effects
Modulation effects include tremolo, vibrator, chorus and flanger/phasor.
4. Time Based Effects
Time based effects range from the simple "delay" (repeating the input signal at some set time or times) through to "reverb" or "echo".
Where I encountered new components, circuit ideas and or concepts I have not previously used, often I produced small test circuits to focus on learning the new item. Details of such experiments and learnings can be found on the Component Testing pages.
Guitar Effect Pedals/Circuits
| Project Title | Description | Difficulty |
|---|---|---|
| Bazz Fuzz Box Effect | Fuzz Box Effect - 1 transistor, a diode and 2 capacitors! | Easy |
| "Angry Charlie" pedal | A high gain distortion/overdrive pedal with 3-band tone stack | Medium |
| Pedal prototyping board | Prototyping breadboard with standard pedal components (à la "Beavis Board") | Medium |
References
ref 1: http://beavisaudio.com/techpages/SchematicToReality/
ref 3: https://www.sweetwater.com/insync/guitar-pedal-buying-guide/
ref 5: https://www.howtogeek.com/64096/htg-explains-how-do-guitar-distortion-and-overdrive-work/
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