The JMP Master Model is the direct precursor to the infamous JCM800 amps of the early 80's. As indicated by the 2204 circuit designation, this amp has the exact same circuit as the JCM800 amps, only with a slightly different transformer configuration. This amp is equipped with 6550 tubes, giving it a deeper low end presence compared to the EL34 amps. This amp has signs of prolonged storage, but still looks very good, with no significant blemishes of any kind. Also the amp is all original, which means it might be necessary to perform some routine maintenance (filter caps, etc) should you wish to use it for gigging or other prolonged use. Otherwise it sounds excellent, and stands as a great representation of the proto JCM800 design!