🎛️ Synthrilla Bass Box is now available — and the story behind it is unlike any other plugin we know of.
In the late 1950s, legendary recording engineer Bruce Swedien built himself a passive DI box. Inside: a single UTC LS-10X transformer, wired backwards. This was not standard practice. Nobody did this. And the result was something nobody expected.
That metal enclosure with its incorrectly wired transformer became the defining piece of equipment on Michael Jackson’s bass tracks — from Off the Wall in 1979 all the way through Invincible in 2001. Thriller. Billie Jean. Beat It. The bass on all of it ran through this box.
The reversed wiring created a magnetic resonance between 900 and 2100 Hz — a frequency-shifting, level-dependent snarl that gave bass instruments a presence and character that no other piece of hardware could replicate. And here is the thing: when Swedien later ordered a new UTC LS-10X transformer and tried to rebuild the box, it sounded completely different. The original core had a specific batch composition, a specific magnetic history built up over decades of use. That combination could never be recreated. Not even by Swedien himself.
What We Did
We spent months analyzing original Thriller-era audio material — studying the snarl resonance across different recordings, mapping how it shifts with signal level, understanding the physics of the UTC LS-10X core. We used transformer physics calculations, FFT analysis of real recordings, and iterative DSP modeling to capture what made this box unique.
The result is the first and only software emulation of this specific device. Transformer drive, magnetic hysteresis, impedance coloring, and the level-dependent snarl — all of it, in a plugin. A sound that no hardware can reliably reproduce anymore.
Available Now
VST3 and AU for macOS (Universal Binary). VST3 and Standalone for Windows 10+.
