Roland BC TC-UB Ultimate Blues Tone Capsule (For Blues Cubes)The Tone Capsule is a modification circuit unit that changes the tube circuit characteristic of the original Blues Cube The Ultimate Blues Tone Capsule produces the sweet and deep compression feeling of a fully cranked up small amp with 6V6 tubes Tube Logic technology Developed by Roland engineers under the supervision of blues guitarist Kirk Fletcher The Ultimate Blues Tone Capsule fine tunes the amp capturing soulful clean and sweet crunch sounds