I have procured a PDF of the above book, which is a technical approach to designing efficient, low distortion circuits for audio. It mostly details the studio side of things such as preamps, tone controls, gain staging etc, but I am consulting it in an effort to find an amplifier topology that is suitable for driving a small 3.2Ω speaker.

This book, and lots of forum lurking, has led me to the conclusion that 2 gain stages are likely required. I need a low output impedance to drive my speaker, but high current and somehwat medium voltage gain. Some testing (using a common collector topology) has shown that I can achieve very low volumes out of a speaker if I care little for distortion, but tables like the one shown below have made me realise that two stages is the way forward. A first stage that is suited to the output charicteristics of my VCA’s, and a second stage that is suited to the characteristics of my speaker cone.

The output impedance of my VCAs is currently an unknown – I am also considering using a lowpass gate instead. But, regardless, it looks like I need 1 stage to do voltage gain, and another to do current gain. There’s also lots of talk on forums of using a transformer to connect to the speaker, but I need to do more research and find out exactly why this keeps getting recommended. I have 1 or 2 transformers lying around from having ripped apart old portable tape decks… I wonder if those were used as speaker drivers….? Or, power conditioners…?