 The Twin Reverb II was produced until 1986, and was available as a head (amplifier alone) or 2×12 combo.The circuits for this series of 1982 Fender amplifiers were designed by amp guru Paul Rivera; the 60w Concert amplifier was by far the most successful in terms of sales, but all models in this range and the next are now becoming highly sought-after by collectors and players.The Twin Reverb II was replaced by The Twin, commonly referred to, though incorrectly as, the "Evil Twin" (Fender has only referred to the "TWIN AMP" or the '94 Twin Amp as being the "Evil Twin", not the red knob Twin) due to the addition of both a separate gain channel and a switchable overdrive on the clean, in 1987.