The Concrete Sound Lab Slab is an all-transistor gain pedal designed to produce a range of tones from cleanish overdrive to saturated fuzz.
Its circuit combines a JFET-based preamp with a James tone stack—a configuration that allows precise control over frequency response before the signal hits the gain stage. This feeds into a silicon bipolar transistor output section, which provides dynamic response and harmonic complexity.
The design prioritizes responsive, lo-fi distortion with usable tone shaping at any gain level.
The preamp’s tube-like response works well with both guitar and bass, while the post-gain filter ensures the distortion remains usable even at high gain settings.
Features:
- Boost footswitch adds extra saturation
- Pre-gain tone stack shapes the character of the distortion
- Post-gain low-pass filter tames high-end harshness