chipmusic.org — What are the typical C64/SID sounds/instruments? (2015)

A keyboard player joining a video-game cover band (in the vein of Press Play on Tape or Machinae Supremacy) asks which sounds make a SID tune sound like a SID tune, and how to fake them on a rompler (Yamaha MOXF6, Korg M50, Yamaha SY85) for rehearsals. The answers are a compact description of the SID aesthetic from the outside, with one concrete lead recipe.

Key claims#

• Murenius's own list of what he had already identified: fast square-LFO pitch jumps "to fifths and octaves" ("works fine already and sounds good enough"); the same done with an arpeggiator ("still sounds too 'sterile'"); filter sweeps; "pulse width modulation with bass sounds" — impossible on a rompler because it means changing the oscillator's waveform. Still missing: "the ringing lead sound like in the Gianna Sister title track" (nobody answers that one).
• n00bstar: "PWM is a huge part of the C64 sound and you won't be pulling off realistic SID leads without it." His general tips: (1) do not go analog or "virtual analogs that try too hard to simulate tubes and warmth" — "Hash [sic], brittle digital synths will give you better results for chiptune sounds since that's pretty much what the original hardware was"; (2) "Leave that … Effect section alone" — the sound "is mostly used dry with the only effects being those you can make by hand in a tracker", namely: (3) chorus/flange/phase "if you waste 2 channels on a single sound", one of them detuned "by a tiny bit" — kept mono "you get a flanger/phaser like effect", hard-panned "a kind of chorus", "rarely used in 'heavy' sections because of the wasted channel"; (4) delay, "again, by wasting another channel for the delay taps. The classic chiptune delay is a single tap delay either 3 or 4 quarter notes behind the original signal", used in calm sections and "the first to get sacrificed" when every channel is needed; (5) the classic C64 lead: "Start with a pulse oscillator at about 10% width, and increase the width up to a 50/50 square wave and add vibrato to it all. A lot of synth leads start loud and sustains at about 80% of the volume. This gives a nice guitar/piano like attack and keeps melodies from sounding too stale." Also: solo a channel in a SID player and sample it. "Chord Arps" are out of reach of live playing because no traditional arpeggiator "is fast enough for the purpose".
• chunter: one synth covers SID tones if it can "manually sweep the pulse width" and has "one hell of an arpeggiator, something like an old Nord Lead"; Murenius's 300 BPM thirty-second notes = 160 notes per second is "more than enough"; what sets a chip apart from a synth with its filter open, "besides the roughness", is that "most can bend and switch their pitches and tones at will" — hard to emulate live, but a good rearrangement "carries the tune well enough" (as Press Play on Tape shows).
• Jellica's list: "awesome buzzy ring modulator / flabby distorted filter / weird adsr / Pulse width modulation on your leads too!"
• Murenius's solution (2015-02-05): the MOXF's common LFO accepts a hand-drawn waveform; a four-step "prime–fifth–octave–fifth" step-LFO on pitch recreates the arpeggio sound, and the option to jump or glide between steps "kinda simulates the pitch bend instructions"; the same LFO drives filter sweeps (tried on a noise waveform first). Next step: a PWM multisample recorded from a C64 emulator. He refuses to sample whole channels from other people's tunes — it "would feel like cheating".

Practical takeaways#

For a SID-style lead on any synth or chip: a narrow pulse (about 10 %) opening to a square, vibrato, an instant attack that settles to roughly 80 % sustain — on the SID about sustain $C of $F (a derived value, not the thread's). Keep everything dry; build chorus, flanging and delay from extra channels, not from an effect section (detune, fake-echo). "Chord arps" are a tracker thing: at 50 steps per second no hand-played arpeggiator keeps up.

Notable quotes#

n00bstar: "PWM is a huge part of the C64 sound and you won't be pulling off realistic SID leads without it."

Jellica: "awesome buzzy ring modulator, flabby distorted filter, weird adsr".

Relevance#

The wiki's lead recipes were table mechanics; this gives the perceptual description ("start loud, sustain at 80 %") and the dry-signal, digital aesthetic in musicians' words for instrument-design, pulse-width-modulation and chiptune. Few concrete SID values — the thread is about other synths.

Pages touched#

instrument-design · pulse-width-modulation · chord-arpeggio · chiptune · detune · fake-echo · filter-programming · ring-modulation-and-sync · adsr-envelope · chipmusic-org · multisampling