ZenTube models the physical behavior of a dual 5670 triode — not a sample library, not a neural network trained on recordings — with full circuit modeling at 4x oversampling to keep harmonics free of aliasing even with Drive pushed all the way.

Drive is gain-compensated by design: turning it up lowers the fundamental and diverts energy into harmonics, exactly like real hardware. The Drive meter reads tube push, not raw distortion.

AIR adds high-frequency lift (a high shelf), Low Cut clears low-end rumble before it reaches the tube stage, and dry/wet MIX is phase- and delay-compensated so it never cancels content in the high end.