Concrete Sound Lab announces Slab JFET gain pedal
July 11, 2025 · 2 sources
Concrete Sound Lab has released the Slab, an all-transistor gain pedal, Delicious Audio reported on July 11, 20251. Guitar Pedal X described it as the company's first pedal, designed by Josh2.
Delicious Audio describes the circuit as a JFET-based preamp feeding a James tone stack, which it says allows control over frequency response before the gain stage, followed by a silicon bipolar transistor output section1. The pedal is intended to cover "a range of tones from cleanish overdrive to saturated fuzz"1. Delicious Audio states that the preamp's response suits both guitar and bass, and that a post-gain filter keeps the distortion usable at high gain settings1.
Guitar Pedal X lists six controls: Pre-Gain Low, Pre-Gain High, Gain, Boost, Tone (post-gain low-pass filter) and Level, plus Boost and Main Bypass footswitches2. It describes the circuit as JFET tube-emulating and "possibly somewhat Fetzer adjacent"2. Delicious Audio lists the boost footswitch as adding extra saturation, the pre-gain tone stack as shaping the character of the distortion, and the post-gain low-pass filter as taming high-end harshness1.
Guitar Pedal X gives the price as $200 from the Concrete Sound Lab webstore2. It notes that it is not clear whether the boost is independent2. It also states that touch-sensitivity and dynamics could not be established without hands-on use2.
"The design prioritizes responsive, lo-fi distortion with usable tone shaping at any gain level."
The Slab sits among overdrive pedals. Guitar Pedal X describes it as a "Boost, Overdrive, Distortion and Fuzz multi-gain pedal"2.