Removes part of the sound: low-pass keeps what is below the cutoff, high-pass what is above, band-pass what is around it. Slope is how sharply — at nothing one stage, twelve decibels an octave, and at one a second stage behind it doubles that, which is the steeper slope the Oberheims and Junos are known for. Resonance lifts whatever is sitting at the cutoff, and for low-pass and high-pass the number is decibels rather than a bare ratio: at thirty, what sits on the cutoff leaves thirty decibels above what sits below it, which is loud enough to drive whatever comes next. It reaches the first stage and only the first. Two stages both carrying it would add in decibels rather than share the number, so the steeper slope would be a peak twice as tall instead of a skirt twice as steep — and a note with a harmonic landing on the cutoff would arrive a thousandfold, which is a different sound played in one octave and not in the next. Level is what leaves, for taking back what resonance adds or making up what the cutoff took away. The cutoff is an input as well as a knob — an envelope patched into Cutoff opens the filter as a note starts, an LFO sweeps it — and Cutoff depth is how far, in cents, so the sweep is even to the ear wherever the cutoff sits. Below nothing that depth runs the other way: the same envelope closes the filter as the note starts instead, which is the polarity switch those instruments put beside theirs. Key tracking moves the cutoff with the note played, at one rising with the pitch, so a phrase keeps its brightness as it climbs rather than going dull at the top — it needs the note routed here as well as to the oscillator. Shelf gain is for the three shapes that lift or cut a region rather than remove it, low-shelf, high-shelf and peaking, and does nothing to the others; at the steeper slope it applies to both stages, as the shape and the cutoff do. Resonance is an input too, and its depth is how far, in decibels. What reaches the filter is held inside the knob's own range however hard the input pushes, because a resonance past thirty decibels is a peak loud enough to hurt rather than a sharper filter.
Four notes played on Keys, passing through it on their way out.
‘filter’: Filter · filter type low-pass (knob ‘Shape’) · into ‘one’ · into ‘filter2’ · cutoff turned by ‘Cutoff (Hz)’ · boost turned by ‘Shelf gain (dB)’
‘filter2’: Filter · filter type low-pass (knob ‘Shape’) · into ‘two’ · cutoff turned by ‘Cutoff (Hz)’ · boost turned by ‘Shelf gain (dB)’
‘one’: Gain · into ‘level’
‘two’: Gain · into ‘level’ · level turned by ‘Slope (12 to 24 dB per octave)’
‘level’: Gain · into ‘out’ · level turned by ‘Level’
‘slopesrc’: Constant · into ‘slopegain’
‘slopegain’: Gain · into ‘slopeinvert’ · level turned by ‘Slope (12 to 24 dB per octave)’
‘slopeinvert’: Waveshaper · modulates the level of ‘one’
‘cutoffin’: audio input · port cutoff · into ‘cutoffdepth’
‘cutoffdepth’: Gain · modulates the cutoff shift of ‘filter’ · modulates the cutoff shift of ‘filter2’ · level turned by ‘Cutoff depth (cents)’
‘note’: note input · port midi · into ‘trackdepth’
‘trackdepth’: Gain · modulates the cutoff of ‘filter’ · modulates the cutoff of ‘filter2’ · level turned by ‘Key tracking’
‘out’: audio output · port out
‘resonancein’: audio input · port resonance · into ‘resonancedepth’
‘resonancebase’: Constant · into ‘resonancescale’ · value turned by ‘Resonance (decibels, for lowpass and highpass)’
‘resonancedepth’: Gain · into ‘resonancescale’ · level turned by ‘Resonance depth (dB)’
‘resonancescale’: Gain · into ‘resonanceclamp’
‘resonancescaleset’: Waveshaper · modulates the level of ‘resonancescale’
‘resonanceunity’: Constant · into ‘resonancescaleset’
‘resonanceclamp’: Waveshaper · modulates the resonance of ‘filter’
The finished blues trio from a zine that builds a 12-bar blues one instrument at a time. Two choruses: the first with held organ chords, the second with a…
Stage 6 of a 12-bar blues built one instrument at a time. The whole trio from stage 5, now arranged into the full twelve-bar blues: three lines of four bars (A…
Stage 5 of a 12-bar blues built one instrument at a time. The organ from stage 4 through a homemade Leslie (a spinning speaker): a Tremolo pulses the volume, a…
Stage 4 of a 12-bar blues built one instrument at a time. Drums and walking bass from stage 3, plus an organ built from three sine waves, the note and two…
Stage 3 of a 12-bar blues built one instrument at a time. The drums from stage 2, plus a walking bass: one note per beat, stepping through the chords A, D, A,…
Stage 2 of a 12-bar blues built one instrument at a time. A drum kit made from scratch: a sine-wave kick with a quick pitch drop, a snare from a burst of…
The Ricoh 2A03 as a band of four, which is all the Famicom and the NES ever had to make music with. Two pulse channels, whose only choice of tone is how much…
The OB-Xa brass stack of the keyboard riff everyone knows from 1984, rebuilt out of the library: four sawtooths spread sixteen cents either side of the note,…
ATMOSYNTH built-in module
