Chiptune

What it is

The 2A03 inside a Nintendo Entertainment System has five channels: two square waves, a triangle, a noise generator and a one-bit sample player nobody could afford the ROM for. That is the whole orchestra. Melody and counter-melody take the two squares, bass takes the triangle, and every drum in the track has to come out of the noise channel, which is monophonic. So the snare and the hi-hat are the same voice taking turns, and the moment you write a hat under a backbeat one of them vanishes. Composers worked around it by putting the kick on the triangle as a fast downward pitch sweep, which steals a bass note for a sixteenth and is audible as a hole in the low end. Modern chiptune keeps all of this on purpose, either on real hardware through FamiTracker and a flash cart or in a plugin that models the same chip.

What it sounds like

Thin, loud and completely dry. The snare is white noise through a short decay envelope, somewhere around 40ms, with the noise period set high so it hisses rather than rumbles. The hat is the same generator with the envelope cut to about 15ms and the volume four or five steps lower. The kick is a triangle note dropped roughly two octaves across three frames, which reads as a thud with a pitch in it. There is no reverb because the chip has no reverb, no stereo because the NES sums to mono, and no compression because nothing is being recorded. Everything sits at the volume it was written at, and the mix is decided entirely by which channel gets to speak.

Key elements

• One noise channelSnare, hat and crash all live here and cannot overlap. This constraint writes the drum part for you more than taste does.
• The triangle kickA pitch sweep on the bass channel standing in for a bass drum. It interrupts the bassline every time it fires, and that gap is part of the sound.
• Four-bit volumeThe 2A03 gives each channel sixteen levels between silence and full. Accents exist, but they land on a coarse ladder rather than a continuum.
• Arpeggios instead of chordsTwo square channels cannot voice a triad, so the chord is played as a very fast three-note cycle, one note per 60Hz frame.
• Tracker rows, not a piano rollFamiTracker counts in rows and frames. Tempo is expressed against a fixed refresh rate, so old NES tunes run slow on PAL hardware.

How to get them

• Write the drums as one linePut snare, hat and open hat in a single monophonic lane before you do anything else. If two of them want the same step, one has to go, and choosing which is the composition.
• Build the snareWhite noise, amp decay 40ms, no sustain, band-pass around 2kHz with a wide Q. Add nothing else. The absence of body is what makes it read as a chip.
• Build the kickA triangle oscillator with a pitch envelope falling from about 200Hz to 45Hz in 50ms, no filter, no click layer. Mute the bass part for exactly the length of that note.
• Quantise the volumeSnap every drum velocity to a multiple of eight. That is what four bits actually gives you, and the coarse steps are audible as a slightly stepped groove.
• Stay monoSum the whole track to mono and leave it there. Widening a chiptune is the fastest way to make it sound like a plugin rather than a console.
• Arpeggiate at frame rateCycle chord tones at one note per frame, roughly 16ms each. Slower than that and they stop fusing into a chord and turn into a melody.

Reference points

Hirokazu Tanaka, Koji Kondo, Rob Hubbard, Tim Follin, Anamanaguchi, Disasterpeace, and the 8bitpeoples and Ubiktune catalogues. Named as reference points for the sound, not as endorsements.