SD21 Bass Driver, based on the popular SansAmp Bass Driver with an improved 4-band active equalizer, allowing you to have two independent mid controls, Contour switch that switches between the vintage sound (mid cut at 450hz used in the first versions of the SansAmp) and a more modern touch (full frequency sound used in the latest version of the SansAmp), it has an elegant design and also has an independent DRIVE switch for the saturation stage of the effect. It has a balanced XLR output and CabSim.