 In 1972 a master volume was added, then in late '73 it was fitted with a push pull "boost" or acentric potentiometer in the master volume position.The rating of the amplifier's output power was upgraded to 100 watts and between 1977–1982 an ultra linear output transformer was used, increasing the power to 135 watts.A Hum Balance was added at this time

In 1982 the Twin Reverb II was introduced to compete with Mesa Boogie's very successful products; it had an output rating of 105 watts and a return to Blackface era cosmetics albeit with a different, channel-switching cascading gain circuit with a more modern mid-range voicing and without the 'traditional' vibrato.