The Electro Harmonix 7591A tube is renowned for its smoothness and has often been difficult to acquire. If you're weary of the usual "fuggettaboudit," "can't get 'em," or "UNOBTANIUM!" responses when inquiring about a 7591A, your search may be over. These tubes are now available and they're authentic! Known for their smooth yet punchy sound, with a sweet harmonic finish, this year's vintage is sure to please. Owners of Ampeg amplifiers, celebrate!