Sorry... I had this detailed elsewhere, but have forgotten where
The valve amplifiers are known as Mullard 5-20, i.e. 5 valve, 20 Watt PP per channel and I built these some 35 years ago from plans released by the (then) Mullard Valve Co. in order to promote their valves.
I stripped these down a couple of years ago and had the chassis powder coated before rebuilding them with a few circuit changes which is supposed to get some 30W per channel out of them. Some of the components have been replaced with more modern versions, in particular the interstage coupling caps, which had gone leaky over the years. I also had to lower the amplifier sensitivity, to accommodate modern pre-amps, which have a somewhat higher output level than the original valve pre-amps which were originally in use with these amplifiers.
Spurred on by the two restoration jobs, I decided I liked building valve amplifiers and then built another three units. These are the ones in the Equipment rack. At the time I took the photo, I used a Denon AVR2803 as a means of controlling the equipment, for a Home Theatre system. A lightning strike K'O'ed the Denon, which I have since replaced with a similar AVR 2802. The DVD player I use is sometimes a Denon 2200, or a Marantz (forgotten the Model #!).
This is the rear view, with original Bulgin AC Connector, Octal Socket for applying power to any accessories should I require to do so.
Top view of 5-20... The square O/P transformer has since had a coat of black matt paint.
Rack mounted for use as a HT system