For players who love the big, bold sound of the Thunderbolt 1 x 15" amp, but need a lush all-tube reverb to fill out their sound, Supro introduces the 1675RT Rhythm Master amplifier. Rooted in Supro tradition, this vintage-inspired model features independent bass and treble controls, a six-spring reverb, output tube tremolo, and switchable power. The Rhythm Master's 35-watt Class A (Cathode Bias) mode offers a spongier, vintage character, while the 60-watt Class AB (Grid Bias) mode offers a faster transient response with maximum headroom and volume available.