How audio circuits work, one question at a time, each with its circuit playing on the page. https://synthmaker.com/circuits/ 2026-11-11T00:00:00Z SynthMaker https://synthmaker.com/circuits/voltage-divider/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

Two resistors in a row give Vin × R2/(R1+R2): two equal 10 kΩ ones halve it, −6 dB. A volume knob is the same. Play it in your browser.

https://synthmaker.com/circuits/volume-pot-taper/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

An audio-taper pot gives −20 dB at half way, a linear one only −6 dB, so the audio taper turns loudness down evenly. Hear both. Play it in your browser.

https://synthmaker.com/circuits/rc-filter/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

An RC filter cuts treble above f = 1/(2πRC), 6 dB per octave: 10 kΩ and 10 nF give 1.59 kHz. Turn it like a tone knob. Play it in your browser.

https://synthmaker.com/circuits/wah-coil-resonance/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

A wah is a coil and capacitor ringing at one frequency; the pedal moves that peak from about 530 Hz to 2.6 kHz. Play it in your browser.

https://synthmaker.com/circuits/diode-clipper/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

Two diodes facing opposite ways flatten a loud wave's tops: here a 6 V peak is held to 0.63 V. That's distortion. Play it in your browser.

https://synthmaker.com/circuits/hard-vs-soft-clipping/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

Hard clipping stops a wave at a flat ceiling, here ±4 V rails; soft clipping bends it through a knee. Hear both, peaks matched. Play it in your browser.

https://synthmaker.com/circuits/clipping-diodes/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

With 6 V in, silicon diodes clip at 0.63 V, germanium at 0.34 V and red LEDs at 1.63 V. Hear them level-matched. Play it in your browser.

https://synthmaker.com/circuits/octave-up-rectifier/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

Flip a wave's bottom half up and a 110 Hz note comes out at 220 Hz: a full-wave rectifier, the heart of an octave-up pedal. Play it in your browser.

https://synthmaker.com/circuits/diode-wavefolder/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

A wavefolder turns a wave back on itself past a threshold instead of flattening it: here at 0.41 V, 1.58 V and 3.46 V in. Play it in your browser.

https://synthmaker.com/circuits/op-amp-rules/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

An op-amp makes its inputs equal and draws no current into them: a buffer (×1), gains of 1 + Rf/Rg or −Rf/Rin, and a mixer. Play it in your browser.

https://synthmaker.com/circuits/op-amp-headroom/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

An op-amp can't swing past its rails. At 18 V instead of 9 V it swings ±9 V, not ±4.5 V: 6 dB more headroom before it clips. Play it in your browser.

https://synthmaker.com/circuits/op-amp-overdrive/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

Two diodes across an op-amp's feedback resistor round off its output about 0.5 V past the input: soft clipping with a mid hump. Play it in your browser.

https://synthmaker.com/circuits/op-amp-slew-rate/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

At a gain of 100 a 741's top is 3 dB down near 10 kHz, a TL072's near 30 kHz. Slew rate matters only on big, fast swings. Play it in your browser.

https://synthmaker.com/circuits/tone-stack/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

A passive tone stack only cuts. With bass, middle and treble at noon it scoops the mids, 12.9 dB down at about 770 Hz. Play it in your browser.

https://synthmaker.com/circuits/sallen-key-filter/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

Two resistors, two capacitors and one op-amp make a 12 dB/octave low-pass. Gain sets the peak, Q = 1/(3 − gain); at 3 it sings. Play it in your browser.

https://synthmaker.com/circuits/state-variable-filter/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

Two integrators and a summing op-amp give low-pass, band-pass and high-pass at once, plus a notch; one resistor sets Q. Play it in your browser.

https://synthmaker.com/circuits/ladder-filter/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

Four stacked transistor pairs and capacitors make a 24 dB/octave low-pass whose cutoff is a current. Feedback makes it sing. Play it in your browser.

https://synthmaker.com/circuits/transistor-gain-stage/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

A transistor's current grows ten times for every 60 mV at its base, so biased mid-range it turns 5 mV into 0.7 V, a gain of 140. Play it in your browser.

https://synthmaker.com/circuits/treble-booster/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

One germanium transistor behind a 4.7 nF capacitor boosts 5 kHz by 34 dB and 100 Hz by 10 dB, so a driven amp bites. Play it in your browser.

https://synthmaker.com/circuits/germanium-fuzz/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

Two germanium transistors amplify a guitar about 1,000 times until the wave squares; a 2.5 kΩ input makes it clean up. Play it in your browser.

https://synthmaker.com/circuits/crossover-distortion/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

A push-pull stage's NPN and PNP each need about 0.6 V to conduct, so 1.2 V around zero is lost. Two diodes of bias close the gap. Play it in your browser.

https://synthmaker.com/circuits/exponential-converter/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

A transistor's current doubles every 17.9 mV at its base; a 100 kΩ and 1.82 kΩ divider makes that one volt per octave. Play it in your browser.

https://synthmaker.com/circuits/differential-pair/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

Two transistors share one current, split by tanh of their base voltage difference: straight for a few mV, half squashed by 100 mV. Play it in your browser.

https://synthmaker.com/circuits/ota-vca/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

An OTA's gm is its bias current over 2 Vt: 0.2 mA gives 181 into 47 kΩ, 10 µA gives 9. Keep its input under 30 mV or it growls. Play it in your browser.

https://synthmaker.com/circuits/ota-filter/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

Two OTAs charging two capacitors make a low-pass whose cutoff follows a current: 120 µA gives 810 Hz, 435 µA 2.9 kHz. Play it in your browser.

https://synthmaker.com/circuits/low-pass-gate/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

A filter and VCA in one: an LED lights a resistor in an RC low-pass, and as it goes dark the cutoff and level fall within 100 ms. Play it in your browser.

https://synthmaker.com/circuits/slew-limiter/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

A resistor filling a capacitor makes a pitch voltage glide: with 100 kΩ and 1 µF, each step goes 63% of the way in 100 ms. Play it in your browser.

https://synthmaker.com/circuits/sample-and-hold/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

A switch turns on for 50 µs per clock tick, so a capacitor grabs the input and holds it. Noise in gives random steps. Play it in your browser.

https://synthmaker.com/circuits/envelope-follower/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

A diode and a capacitor turn a sound into a voltage that tracks its loudness: 2 ms to charge, 100 ms to let go. It opens a filter. Play it in your browser.

https://synthmaker.com/circuits/how-circuit-simulation-works/ 2026-11-11T00:00:00Z 2026-11-11T00:00:00Z

One equation per node, a step rule for each capacitor, Newton's method for the diodes: 2–3 guesses a sample. Hear aliasing too. Play it in your browser.