Designing a simple analog kick drum from scratch

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If you look at my backlog of videos, you’ll notice that I never tackled any percussion circuits before. This is mainly because percussion circuits are quite complex and dense. They mash a ton of different functional blocks – oscillators, envelopes, VCAs, filters etc. – into super efficient little packages.

And they achieve that by taking shortcuts left and right, in sometimes surprising and unintuitive ways. Which makes them even less approachable.

So I decided to cut my teeth on simpler single-purpose circuits first. Now that I’ve covered all of the essentials though, I felt it’s time to give percussion a proper go. So in this video, we’ll try our hand at a classic, Roland-inspired analog kick drum. If you want to build along, here's the bill of materials:

Resistors
1M x2
470k x1
120k x1
100k x5
47k x2
39k x1
33k x2
14k x1
10k x2
2k x1

Potentiometers
1M (lin) x1
100k (lin) x3
100k (log) x1
50k (lin) x1
10k (lin) x1

Capacitors (all film/foil)
220nF x1
15n x3
10nF x1
3n3 x1

Semiconductors
1N4148 diode x7
BC558 (PNP) transistor x2
BC548/547 (NPN) transistor x3
TL072 dual op amp x2

Chapters
00:00 Intro & Kick Drum Basics
03:15 Bridged-T Oscillator
08:30 Gate-To-Trigger Converter
10:55 Manual Pitch Mod
12:24 Manual Decay Mod
17:15 Pitch Envelope
24:21 Smoother Pitch Envelope
27:26 Pitch CV
29:52 Accent CV
33:26 Tone & Distortion
37:18 Final Demo & Outro