Slab

The Slab is Concrete Sound Lab's debut pedal, a lo-fi gain machine built around a tube-like JFET preamp section feeding a responsive silicon bipolar transistor output stage. The gain range runs from clean-ish through overdrive into fuzz territory, all with a lo-fi character baked into the circuit architecture.

A pre-gain James tone stack lets you shape which frequencies hit the clipping stage, making it a powerful texture tool rather than just an afterthought EQ. A post-gain passive low-pass filter dials back harshness on the output. A footswitch-activated JFET boost overdrives the preamp stage for additional gain and harmonic saturation when you need to push things further.

All-transistor design, hand-soldered with through-hole construction (surface-mount JFETs excepted). Every transistor is tested before soldering and each pedal is calibrated after assembly. Mono in/out. 9V center-negative only.