Mullard three-three

Mullard 3 Valve 3 Watt Hi-Fi Amplifier

This one was bought on ebay with no valves.  It's a home made amp, even the chassis is hand made.  The ouptut transformer is a Parmeko P2641 as used in the 1956 prototype.  I reckon this amp was built soon after the Mullard circuit was originally published.  Even so, I've decided that the chassis has no merit and the Elstone mains transformer isn't ideal, so I'm going to make a new chassis and fit a different mains transformer.

The Elstone mains transformer is interesting though, and quite likely an old item (in 1956) reused.  It has a 5V winding, with tapping at 4V, for the rectifier heater.  Whilst 5V heater rectifiers were common in 1956 I reckon that 4V heaters were pretty much obsolete except in equipment designed a decade earlier, e.g. some test equipment.  I'd like to use the smaller EZ80 rectifier for this project, so a 6.3V heater winding for the rectifier is required.   

 DiyAudio thread on merits of circuit