This is the 50-watt version of the classic Hiwatt head.
Pictures courtesy of Jim W.
1975 Hylight DR504
This is another example of the 50-watt classic Hiwatt head. This one still
has the "early 70's" preamp circuit.
Pictures courtesy of Ronnie B. (aka hiwatt_luvr)
Two Input DR504 (1981)
The two-input 50-watt Hiwatt head. These heads best match the widely
available hand-drawn schematics in Pittman and elsewhere.
Pictures courtesy of John R. (aka JR)
1978 Hylight DR505
This is another example of the 50-watt classic Hiwatt head, Canadian
flavour. This one was apparently modified from stock, and looks like an early
70's circuit with a split cathode added to V1.
Pictures courtesy of bbolero