The Blackjack 21™-II is based on two 12AX7 preamp stages and a 12AT7 driver stage. A surprising amount of clean headroom is available before the output stage begins distorting with an American style tone, that’s sweet and warm up and including clipping, and well into natural overdrive. Its tone provides a clean cutting rock edge, filled with a rich harmonics and just the right amount of chime. More clean headroom than Four Aces™ or Lucky-7™, but the same great tones both clean and dirty! The circuit design also is “attenuator friendly”. The Blackjack 21™-II and its siblings the Four Aces™, Lucky-7™-II and Full House™-50 have a preamp stage inspired by our ODS® and TDS® designs, which allow clean-to-mean from the guitar volume control on both the clean and dirty channels. What’s great about this power level, is that you can use the amp as a single channel amp with reverb, gain boost, and natural amp overload, as a single channel high gain amp (using the overdrive channel and the guitar volume to control everything), or run it as a traditional channel switcher amp!