OT303 VST | Acid Synthesizer

OT 303 — Acid Bass Synthesizer

We all love a bit of acid. OT 303 makes it super easy to get huge, screaming acid lines, chunky distorted bass and rolling riffs into your tracks. The simple main panel and easy-to-use sequencer allows you to get an acid line going in seconds. Enable the sequencer and hit 'Random' for an instant unique pattern, crank up the resonance and distortion and tweak or automate the cutoff. 

We spent a lot of time looking at squiggly lines and listening.

OT 303’s sound was developed through comparisons with the Roland’s TB-303, studying the waveforms, harmonics, filter response, envelopes and accents. The graphic below shows some of the comparisons.

Get a pattern going

The built-in 32-step sequencer gives you independent accents and slides, editable note lengths and swing. Program a line from scratch, or use scale-aware randomisation to get a pattern going instantly. A couple of changes to the rhythm or accent placement can take the same notes somewhere quite different.

Work directly in your DAW’s piano roll, trigger a sequence by holding a MIDI note, or use DAW transport playback. You can also drag export MIDI or WAV straight into your DAW.

Work the filter

Saw and pulse waveforms feed a resonant filter, with envelope modulation, decay and accent controls for shaping the response. Keep the envelope short for a tight, percussive line, or open it up and let the notes run into each other. A sub oscillator adds weight underneath, with advanced sound controls for further adjustment.

Add some drive

The main drive section has six characters: 303 Drive, Tube, Bass OD, Diode, Hard Clip and Fuzz. Use a little to roughen up the sound, or push it harder for a more aggressive line.

The reorderable FX rack adds further distortion options alongside tempo-synced delay and reverb. Change the order, stack distortion stages or run the echoes through the drive. Delay and reverb ducking let you keep the notes clear without losing the space around them.

Give the sequence some movement

Three editable curve modulators can control synth and effects parameters. Draw in a gradual filter change, a repeating rhythmic shape or variations in drive and effects. It’s useful for adding movement over a longer phrase while you work the other controls.

Basics Tutorial:

Included

• Monophonic acid synth with saw and pulse waveforms
• Expressive accents and slides
• Resonant filter, envelope controls and sub oscillator
• 32-step sequencer with editable note lengths, swing and scale-aware randomisation
• Six main drive characters and additional distortion in the reorderable FX rack
• Delay and reverb with ducking controls
• Three editable curve modulators
• Factory presets and a browser for saving your own sounds
• Drag-and-drop MIDI and WAV export
• Resizable interface and PDF manual

Compatibility: Windows 64-bit VST3. macOS Universal VST3 and Audio Unit, supporting Intel and Apple Silicon Macs. Requires a host that supports the supplied instrument format, such as FL Studio, Ableton Live, Cubase, REAPER or Logic Pro (AU). Individual DAW versions have not all been tested. Pro Tools/AAX is not currently supported.