After I had finished studying electronics at university I understood a bit more about transistors. During my final year I had been using a second (slightly less minimal) Class B amplifier (with a 5532 opamp, darlington output transistors, and simple diode biasing arrangement) and some wonderful Bandor full range metal cone speakers in an enclosure free enclosure, and a subwoofer. When visiting home at christmas I dug out the emitter follower amplifier, and found it sounded much better than my class B amplifier. I decided that class A must be the way forward and started work on a more powerful Class A amplifier...

I was impressed with the performance of this amplifier. It was however a collection of PCBs resting on a book. So I had to build it a box...

It consists of a Transformer, a power supply board providing +/- 4.5v +18v and - 5v, the voltage gain stage and the output stages. Note the blackening of the veroboard around the supposedly 0.6 watt rated emitter resistors (running at 0.25 watts each) and the main rectifier bridge(parallelled 1N4004s!!!). These components have since been replaced with 0.75 watt rated resistors and 3 amp schottkys, which run much cooler.

Developments over the first emitter follower amplifier included; replacing the emitter resistor with a current source (biased to 1A) and a buffered collector follower gain stage, direct coupled to a complementary feedback pair type of output driver. This gives 2 Watts RMS in to 4 ohms !!! The sound is sweet clean detailed, dynamic and loud enough. Initially the gain was set so the amplifier was on the edge of clip when fed from the 2 volt CD player output.