The circuit design for the Classic amplifiers is about as simple as possible, employing just seven vacuum tubes in the Classic Sixty-Two. Single-ended triode voltage gain and inverter stages are coupled to an output stage comprised of a single pair of ultra-linear operated EL34 tubes for each channel. The Classic One-Twenty adds a second pair of output tubes to each channel to achieve twice the output power. Simple but highly effective discrete voltage regulators supply rock-solid stable DC voltage to the critical voltage gain and inverter stages. And speaking of simple, maintenance of the Classic amplifiers could hardly be easier: the owner need only make a simple bias adjustment using the built in bias indicators when installing fresh output tubes.