Bet you never knew this existed.. Supposedly inspired by the original line of Mesa-Boogie amps, the Bolt Series was a short run production from 1979-1984, and was the only series of tube amps Roland ever made. The Bolt 60 is called a “hybrid” tube amplifier because it does not use preamplifier tubes. The Bolt 60—a 60 watt amplifier—uses a pair of 6L6s for the power section, and one 12AT7 as a phase inverter (PI) tube. The preamplifier section itself is entirely solid state. This makes for an awesome platform for all you pedal junkies. Unique, clean sound.