How to Make a Synth Bass: Sub, Saw, FM, Acid and 808

Most synth basses start from the same settings: mono (one note at a time), notes below about C3, and an amp envelope with a near-zero attack, full sustain and a short release. The wave and what moves it then decide the style: a bare sine for a sub, a saw through a closing low-pass filter for the classic synth bass, a fast FM envelope for a slap, high resonance and slides for acid, and a sine with a pitch drop and a long tail for an 808. Every recipe below works on almost any synth, hardware or software.

A few settings hold for almost every bass. Mono mode stops low notes piling up into mud, since each new note cuts off the last. An attack of 0 to 5 ms keeps the bass on the beat with the kick drum, and a release of 30 to 100 ms stops notes smearing together (the 808 breaks this rule on purpose, with its long tail). Check every patch on a phone speaker too, where almost none of the lowest octave comes through.

How to make a sub bass

A sub bass is a sine wave played low. A sine has no harmonics above its fundamental, so a sub sounds round on big speakers and can disappear on small ones.

1. Start from an init patch with one sine oscillator. If the synth has no sine, a triangle with a low-pass cutoff around 100 to 150 Hz gets close.
2. Set the amp envelope. Attack 2 to 5 ms, sustain full, release 30 to 80 ms. A 0 ms attack can click on synths with free-running oscillators, because each note starts partway through the wave; a few milliseconds of attack or an oscillator reset (often labeled key sync or retrigger) fixes it.
3. Keep it dry and centered. Leave the filter open and skip reverb, chorus and stereo widening, which all smear a sub.
4. Play in the right octave. E1 is 41.2 Hz, A1 is 55 Hz and C2 is 65.4 Hz. Most sub lines sit between E1 and E2 (41 to 82 Hz). Below C1 (32.7 Hz), many speakers and headphones barely reproduce the note.
5. Give small speakers a clue. Add a triangle one octave up at 10 to 20 percent of the level, or a touch of drive. Either one adds harmonics high enough for a phone speaker to play, and the ear fills in the low note from them.

A sub also works as a layer, an octave under any of the brighter basses below.

How to make a filtered saw bass, the classic synth bass sound

The sound most people mean by “synth bass” is a saw wave through a low-pass filter that opens bright at the start of each note and settles darker while you hold it.

• Oscillators. One saw. For weight, add a square one octave down (minus 12 semitones) at about half the level. For movement, detune a second saw by 5 to 10 cents. Push that detune to 15 to 25 cents and you are heading toward a Reese, the growling bass of drum and bass.
• Filter. Low-pass, 24 dB per octave if you can choose, cutoff 250 to 500 Hz, resonance 10 to 25 percent, and key tracking at 30 to 50 percent so high notes are not duller than low ones.
• Filter envelope. Attack 0, decay 200 to 400 ms, sustain 10 to 30 percent, release about 50 ms. Raise the envelope amount until the cutoff leaps two or three octaves at the start of each note.
• Amp envelope. Attack 0 to 3 ms, sustain full, release 40 to 80 ms.

The filter envelope’s decay changes the character more than any other control. Around 100 ms gives a tight, plucky funk bass for busy sixteenth notes. At 500 ms and up, each note opens with a slow “bwow”. Routing velocity to the filter envelope amount makes harder notes brighter.

To turn the patch into a synth bassline, take Am, F, C and G in A minor, one bar each. Play each root (A1, F1, C2, G1) in steady eighth notes, and on the last eighth of the bar jump up an octave before you land on the next root. Once that feels solid, replace the octave jump in the first bar with G1, so the line steps down A, G, F into the F chord.

How to make an FM bass

FM synthesis builds a bright tone by letting one sine wave, the modulator, wobble the pitch of another, the carrier, so fast that you hear a new tone instead of vibrato. More modulation means more harmonics, with no filter involved. For bass, make that modulation fade fast, so each note starts with a bright snap and settles into a round tone. Yamaha’s TX81Z, a four-operator FM module from 1987, shipped with an FM bass preset called LatelyBass, one of the most famous presets in synth history.

1. Pick a ratio. A modulator at the same frequency as the carrier (ratio 1) adds every harmonic, for a buzzy, saw-like tone. At ratio 2 only the odd harmonics appear, a hollow, square-like tone. At ratio 0.5 a new partial appears an octave below the note, for extra weight.
2. Shape the modulator’s envelope. Attack 0, decay 80 to 200 ms, sustain 0 to 20 percent. Raise the modulation amount until each note starts bright and buzzy.
3. Shape the carrier’s envelope. Attack 0 to 2 ms, sustain full, release around 50 ms.
4. Send velocity to the modulation amount. Hard notes slap and soft ones stay round.
5. Add grit if you want it. A little feedback on the modulator roughens the tone. A third operator at a high ratio, 7 or above, with a 10 to 20 ms decay puts a click at the front, like a pick on a string.

FM basses carry well on small speakers, since every note opens with a burst of upper harmonics. In Gelato Synth, our iPhone synth, you set Ratio on the Osc B page (x0.5 to x8) and Amount on the FM page, and Envelope to FM gives each note the bright attack and purer tail from step 2.

How to make an acid bass

Acid bass is the squelchy, talking line of acid house. It comes from the Roland TB-303 Bass Line (1981): one oscillator with a saw or square wave, a 24 dB per octave low-pass filter with its own envelope, and a step sequencer of up to 16 steps per pattern, where any step can carry an accent or a slide. Phuture’s “Acid Tracks” (1987) is often credited as the first acid house record.

• Oscillator. One saw, in mono. A square gives a rounder, hollower line.
• Filter. Low-pass, cutoff 200 to 400 Hz, resonance 60 to 80 percent, envelope amount 50 to 70 percent.
• Filter envelope. Attack 0, decay 100 to 300 ms, sustain 0.
• Amp envelope. Attack 0, sustain full, short release.
• Drive. 30 to 50 percent of drive or distortion adds bite and keeps the resonant peak from sounding thin.

Accent and slide are what make the line talk. An accented note plays louder and brighter; without an accent button, send velocity to both the amp level and the filter envelope amount and play those notes harder. A slide ties one note into the next without restarting it, while the pitch glides across. Set the synth to mono with legato (sometimes called fingered) portamento, a glide of 40 to 80 ms, and overlap the two notes.

For a first pattern at 125 BPM, fill a 16-step pattern of sixteenth notes around C2, mixing in the octave (C3), the minor third (Eb2) and the fifth (G2). Accent three or four steps, slide into two others, and leave two steps empty. Then, while it loops, slowly turn the cutoff and envelope decay by hand; those knob moves are half the sound.

How to make an 808 on a synth: sine, glide and drive

The Roland TR-808 (1980) is a drum machine, and it plays no samples: every sound comes from analog circuits. Its bass drum is a sine oscillator, a low-pass filter and an amplifier, with a decay control that stretches it into a long, low boom whose pitch sags slightly as it fades. Hip-hop producers lengthened that decay and tuned the drum to play basslines. Today “808” names that long, tuned sine bass even when no drum machine is involved.

1. One sine, in mono. The same start as the sub bass.
2. Add the pitch drop. Send an envelope to pitch so each note starts 12 to 24 semitones high and falls to the played note in 20 to 60 ms. That drop is the kick at the front of the 808. Stretch it toward 150 ms and it turns into a laser zap. In Gelato Synth, Punch on the Env page is a fast pitch drop built for exactly this.
3. Set a long amp envelope. Attack 0, decay 1 to 3 seconds, sustain 0, for a tail that fades on its own. For one that lasts as long as you hold, use full sustain and a 200 to 400 ms release.
4. Turn on glide. Mono, legato glide, 80 to 200 ms. Overlap two notes and the second slides in from the first, the bend you hear all over trap. Play them apart and each note gets a fresh hit.
5. Add drive. 20 to 40 percent of drive or saturation clips the sine softly and gives it harmonics, so the 808 growls a little and stays audible on a phone.

Then tune it to the song. In F minor, the root sits at F1 (43.7 Hz). Let it ring through most of the first bar, then in the second bar hit F1 again and slide up to Ab1 or C2, the minor third or the fifth. When the 808 doubles as the kick, keep the notes sparse enough for each tail to ring.