Keeley Mini Katana Clean BoostKeeleys oldest design made smaller and with tasteful updates including an additional feature. The Katana started back in 2002 within the Time Machine Boost. It was a dual class A JFET design that gave players and incredible boost and sounded so good they never turned off. In fact they often ran two or three on stages like John Mayer! The Mini Katana boost provides over 35dB of boost. Enough for the most demanding players and sound reinforcement.