Exceedingly rare bigga tape recorder with interesting looks of the sci-fi kind, added later in time to the only 1976 Mitsubishi / Diatone well remembered lineup : DA-P20 dual-mono preamp, DA-C20 preceiver, DA-A10DC & DA-A15DC dual-mono powerhouses and DA-F10 & DA-F20 FM tuner.
A lot of functions, switches, knobs and buttons, even if the measured specs aren't really sci-fi.
Three heads (ferrite for record and erase, sendust for replay), three DC motors with closed-loop dual capstan for the drive motor, a mix function with independent levels fo the MIC and LINE inputs, precise VU meters with three-seconds peak hold, soft-touch buttons, two test signals for calibration (440Hz and 8Khz) and bias fine-tuning for both channels.
Added for the upcoming 1980s decade : ASPS and synchro rec/play with Mitsubishi record players.
Automatic Spacing Pause System allows to record three-second blanks - useful to later on skip from one recording to another... but that function wasn't offered on the DT-30 :)
Turntable synchro allows to launch recording of a record only by pushing the record transport pad : the DP-EC20 turntable automatically starts playing.
There probably was a japanese Diatone equivalent of the DT-30 but I haven't got anyhting on it yet.