JJ (Tesla) 6550 Tubes Matched Quad
The JJ 6550 is musical in every sense of the word and will improve the sound of your high powered bass and guitar amps with punch and clarity. Many older Marshalls were fitted with 6550 tubes and it has become a favorite with metal players and others. JJ has been producing quality amplifier tubes for decades. This is a matched quad of JJ 6550 tubes.