10 Watt Valve Guitar Amplifier

A novel design that gives around 15W power output from a pair of EL84's. The driver stage is a bit unusual in that it employs a long-tail pair of ECC83 triodes, the tail provided by a constant current transistor source. This is followed by a pair of cathode followers to provide a very low impedance drive for the output pair. None of it is necessary but it seemed like a good idea at the time. In fact, the idea was to design a driver stage that would drive almost any output pair. The output stage operates in fixed bias and is directly coupled to the cathode followers.

I love the sound it makes on overdrive: Bluesy and British sounding, breaking up gradually as the drive increases.



Blue Box

This is a speaker cabinet made for a Celestion Alnico Blue speaker. It is a closed back design constructed from 18 mm plywood, glued and screwed. It is covered with carpet, cheap stuff from Maplin, glued on with PVA wood adhesive.

The speaker cloth is fitted to a wooden frame which is attached by screws from the inside.