Fender Twin Reverb amplifiers use four output tubes, of the 6L6GC type. They use six preamp tubes, consisting of four 7025/12AX7 types and two 12AT7 types.
The Fender Twin Reverb amplifier features four output tubes, specifically the 6L6GC variety. It also utilizes six preamp tubes: four 7025/12AX7s and two 12AT7s.