 Unlike all the earlier Hammond organs, which used vacuum tubes for preamplification, amplification, percussion and chorus-vibrato control, the T series used all-solid-state, transistor circuitry, though, unlike the L-100, it did include the scanner-vibrato as seen on the B-3.Other than the T-100 series models, all other T-Series models included a built-in rotating Leslie speaker and some included an analog drum machine, while the T-500 also included a built-in cassette recorder.It was one of the last tonewheel Hammonds produced.