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Guitar Effects Building Blocks

The analog-audio toolkit, on one page. Print me.

The compressed essence of the Guitar Effects track (Lessons 23–29). Components carry over from the rest of the course; the new idea is shaping an AC waveform.

The standard signal chain

input (high-Z + coupling cap + bias) → gain → clipping → tone → volume → output

Foundations (Lessons 23–24)

Guitar = small, weak, high-impedance AC signal; effects reshape its waveform.
Single 9 V supply → bias to ~4.5 V (virtual ground / Vref) so AC can swing both ways.
Coupling cap = in-line, passes AC + blocks DC (vs decoupling cap across power).
High input impedance (~1 MΩ) or a buffer avoids "tone suck."

Gain (Lesson 25)

Gain = output ÷ input size. Unity (1) = buffer; >1 = boost.
Op-amp non-inverting: two resistors set gain; make one a pot = drive knob.
Transistor stages also amplify (vintage character; basis of fuzz).

Clipping = dirt (Lesson 26)

	Soft = overdrive	Hard = distortion
Diodes	In op-amp feedback loop	To ground, after the amp
Peaks	Rounded	Squared
Example	Tube Screamer	Boss DS-1 / MXR Dist+

Diode flavor: germanium (~0.3 V, warm/compressed) · silicon (~0.7 V, tight) · LED (~1.7 V+, loud/open). Asymmetric diodes add even harmonics.

Tone / filters (Lesson 27)

Cap passes highs more than lows → pair with a resistor = filter.
Low-pass = tone knob (cut highs); high-pass = tighten bass.
Bigger cap → lower cutoff. Passive filters lose some volume (dump signal to ground).
Before clipping = tighter dirt; after clipping = tames fizz.

Time-based (Lesson 28)

Delay/echo: store & replay. Chips: BBD (analog) or PT2399 (DIY go-to, ~30–340 ms).
Modulation via an LFO (slow wave): tremolo (volume), chorus/vibrato (delay time), phaser (filter sweep).
More advanced — build dirt first, then layer these on the same fundamentals.

Bench habits Start amp volume low · common ground throughout · check power polarity · build & test one stage at a time.

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