The 7 cylinder started out as a chalenge to design a guitar amp using only 7 pin tubes. The result was a punchy amp with great breakup and a transparent vibe that lets the guitar's natual tone come through. The 5654 input pentode has a percussive quality that's different than anything else you've heard before. The 6J6 floating paraphrase inverter is influenced classic Supro and Valco amps from the 60s, but modified for better control when pushed hard. And the 6AQ5s power amp tubes are similar to 6V6. The 7 cylinder also sounds awesome with a tubescreamer driving the input!