Subtractive synthesis: the whole chain
Oscillator, filter, two envelopes, an LFO: every module from this course, finally working together as one instrument.
Every part in this lesson is already familiar. What you have not done yet is hold them as one instrument. An oscillator makes a bright recipe of harmonics. A filter carves that recipe down. One envelope shapes how loud the note is over time, and a second shapes how bright it is. An LFO keeps something moving underneath, so the sound is never quite static. That whole chain — source, then filter, then amplifier, with modulators aimed at the last two — is subtractive synthesis. It is the floor plan of nearly every synthesizer ever built, hardware or software.
The five modules, with their real ranges
- Oscillator — saw or square, the two richest recipes from lesson 2. Tune it to A2, A3, or E4.
- Filter — a resonant low-pass sweeping the full 40 Hz–12 kHz range lessons 4 and 5 were building toward, resonance running from a flat 0.1 up to a near-ringing 18.
- Amp envelope — the lesson-3 contour, controlling loudness: attack and decay each up to 1.5 s, sustain 0–100%, release up to 2.5 s.
- Filter envelope — the same ADSR shape aimed at cutoff instead, bipolar this time: its ENV amount runs ±100%, which this instrument maps to ±4 octaves of filter travel.
- LFO — the lesson-6 range, 0.1–16 Hz, wired to the filter's cutoff with depth reaching ±2400 cents, two octaves either way, at full depth.
The signal path, left to right: oscillator into filter into amplifier, the same order as the list above. The dashed arrows are modulation, not audio — two envelopes and an LFO stand beside the path with a hand on FLTR and AMP, exactly like lessons 3, 5, and 6 described them.
Why this order
The order is lessons 2 through 6 played forward. You can only carve harmonics that already exist, so the source has to be rich before the filter can do anything interesting to it — which is why this instrument defaults to a sawtooth rather than a sine. Loudness is the last thing a listener meets, so the amp stage sits at the end of the chain. The envelopes and the LFO are not part of that audio path at all; they stand beside it with a hand on a knob. That is the whole reason the same envelope shape could drive loudness back in lesson 3 and cutoff in lesson 5 without any of the audio wiring changing: a modulator does not care what it is turning, only when and how far. It is also why a patch gets described by naming its modulators rather than redrawing its wiring: "filter envelope" or "LFO to cutoff" points at which hand is on which knob, not at a different instrument underneath.
Three presets, deconstructed
- Bass — sawtooth at A2. Cutoff parked low at 220 Hz with resonance at 3. A strong +70% filter envelope snaps it open and shut fast: 4 ms attack, 180 ms decay down to a 15% sustain, 120 ms release. No LFO. Almost the entire character comes from that one filter envelope.
- Lead — square at A3. Cutoff opened to 900 Hz with resonance at 6 for edge. A medium +35% filter envelope, a light LFO (5 Hz, 12% depth) for a subtle cutoff wobble, and a plain amp envelope: 10 ms attack, 250 ms decay, 55% sustain, 300 ms release. The wave choice and the cutoff position are doing the work here, not the envelope extremes.
- Pad — sawtooth at A3, the same note as the lead but a different everything else. Cutoff at 500 Hz with a gentle resonance of 1.5, a soft +25% filter envelope, and a slow, deep LFO (0.4 Hz, 50% depth) for a constant wash. The amp envelope is what sells it: 1.2 s attack, 600 ms decay, an 85% sustain shelf, and a 2.2 s release that keeps ringing after the note lets go.
A complete small synthesizer, the same three presets just deconstructed above. Load one, hold a note, and change exactly one control at a time to confirm what the list above claims about it. Then push a preset until it breaks — an unmusical extreme on one knob — and dial it back to where it starts sounding like the instrument again.
This chain is why every Elektron device's page row reads the same way, left to right: TRIG, then a source page, then FLTR, then AMP, then LFO/MOD. The machines below are each device's answer for the source slot; everything downstream of it you already bridged in lessons 4 through 6: