Many plugin developers have tackled the famed TB-303 Bass Line, whether it’s the Roland-inspired Imaginando TV3, Ronan Fed’s RF-AB303, or Roland’s own direct software emulation.
Now, The Crow Hill Company is taking its turn to pay homage to the TB-303 with Acid Synth, the latest addition to the free Vaults series.

Roland’s TB-303 is an example of the many happy accidents in music, like the Phil Collins gated reverb story (any version of it). Despite some early chart success with Rip It Up by Orange Juice in 1982, the TB-303 was out of production around a year later.
Roland aimed to create an electric bass in a box; it didn’t quite work out, and few artists found a need for the TB-303’s unique sound.
Fast forward another few years, and the group Phuture, led by DJ Pierre, launched the Acid House genre by creating a sound even further removed from Roland’s original intentions.
DJ Pierre found his new sound by “misusing” the TB-303, although when so many signature sounds and processes come from ignoring the user manual, incorrect definitely doesn’t mean wrong.
The Roland TB-303 is the defining sound of a genre, sub-genres, and an entire cultural movement.
Acid Synth utilizes the same Vaults plugin GUI as always, with the first of the two large dials, Cutoff, being a 24 dB lowpass filter.
The second of the large dials is Resonance, and it’s key to that iconic DJ Pierre sound.
The smaller controls start with Mod and Decay.
Mod controls the level of voltage sent to the filter, and Decay controls the decay length for the envelopes.
The demo video highlights staccato and legato playing, specifically the lovely glide effect that occurs when playing legato. In addition to that, the Decay knob is a good way to get a really crisp and clean staccato-like performance more easily than playing it in.
As usual, the last two controls are Echo and Splosh, which are delay and reverb effects.
Although these last two effects are present in every Vaults release, the Splosh effect differs for Acid Synth; it’s an algorithmic imitation of a cave that works perfectly well with the transcendent acid-house vibes.
The Crow Hill app is available in AU, VST, VST3, and AAX formats for macOS (Big Sur – 11 and higher) and Windows ( 10 – 11).
Download: Acid Synth (FREE)
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