Developer Born Second has released BS-203 MacroAcidizer, a component-level analog-modeled acid synthesizer plugin for macOS and Windows.
The plugin combines three switchable acid machines with a scale-aware pattern generator, and we are giving away one free copy to a lucky BPB reader. You will find the entry question at the end of this article.
BS-203 is Born Second’s first virtual instrument, developed over roughly a year by Keil Corcoran, who is also a member of the band STRFKR.
He based the plugin on three favorite pieces of hardware in his studio, and he says the modeling data was recorded through a Neve 1073 channel strip, adding warm harmonic saturation to the captured signals.
First of all, I love the website’s design. Its early-Windows vibe and pixel-art icons bring back memories of coming home from school and firing up my Windows 98 PC to make music in programs like Mixman Studio and eJay.
Those were simpler times, and, in a way, making music with those more rudimentary tools was more fun than it is today. That’s how I remember it, at least, but I digress.
BS-203 offers three machine modes. 303/Classic is based on the Roland TB-303, with its diode-ladder low-pass filter, resonance/accent interaction, and decay-only envelope. 202/Silver is based on the Roland MC-202, offering a sub-oscillator, a four-pole low-pass filter, a steeper envelope, and a brighter top end.
The coolest one is BB/Basubitchi, modeled on the Juteon-shonen BassBoy+, with a brighter two-pole filter, pre-filter Drive, post-filter Distortion, and a CSTEP parameter that quantizes cutoff movement for stepped digital sweeps.
Switching models keeps your current pattern and shared musical settings, so you can audition the same line through all three voices. You can also unlock sections that the original 303 and BassBoy lacked, including a 202-style LFO, full ADSR, PWM, and a sub-oscillator.
Although it is monophonic at heart, a six-voice Poly mode is available for MIDI and on-screen keyboard playing, while the sequencer itself always stays monophonic.
The Acid Brain pattern generator creates a bank of sixteen related 16-step basslines per Randomize press. You can shape them with density, length, gate, clock division, accent, and slide controls, and patterns snap to harmonic major or minor scales in a selectable root key.
Incoming MIDI notes can re-root a running pattern without regenerating it, and Grab MIDI drags the current result into your DAW with notes, accents, slides, and gate lengths intact.
The onboard effects rack includes SATCH saturation, tempo-synced delay, and reverb, modeled on reference hardware from the Born Second studio. GRIT blends in the measured hardware noise floor and can be set to zero.
BS-203 MacroAcidizer costs $25 and includes five activations, unlimited updates, no dongle, and no subscription. A fully functional demo with periodic white noise is available as a direct download, no account or email required.
The plugin runs in 64-bit VST3, AU, and AAX formats on macOS 11 or later (Intel and Apple Silicon) and Windows 10 or later.
The Giveaway
We are giving away one free copy of BS-203 MacroAcidizer.
Giveaway question: What’s your favorite retro synth (owned or one you wish you could own)?
Please leave your answer in the comments below to enter.
We will pick one random comment and announce the lucky winner on this page on September 20th.
Good luck!
More info: Born Second BS-203 MacroAcidizer ($25)
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Last Updated on September 8, 2026 by Tomislav Zlatic.
