: can anyone tell me what the knobs do on this amp bought in a garage sale for 70.00 but the knobs are not marked what i was told this is a 1968 contessa mini bass tube amp there is 2 large tubes and 2 small tubes Hi, I have something that might be similar, from about that time period. It says Contessa Mini Bass CA 15. It has 3 knobs on the left of the cabinet. All have settings of 1 through 10. The left one is Bass, the middle is Treble, and the next one, on the right is Volume. To the right of these are two inputs for guitars, one hi and one lo. I wonder if this is similar. david