This is a Tube Pre-Amplifier and Zero Watt Amplifier for electric bass based on Fender® Bassman designs. The Organic Lab BASS preamplifier uses the actual high voltages found in classic amplifiers and adds a "BIAS" bias adjustment, which allows the bias of the 12AX7 triodes to be varied between 220VDC to 320VDC. This allows you to adjust the working point, taking it to the Organic Lab BASS from more linear places to more non-linear places, obtaining a whole range of valve colors, from the most crystalline to the most compressed, reaching a soft overdrive that reacts organically with the dynamics at the time. tap.