Now, the actual build in the article uses a TPV3100 dual transistor (it's 2 devices in one package - I think). Being somewhat clueless about transistor characteristics and equivalents; I've ended up using a pair of 2SC1971's.
I've built the amp here:
And the bias is currently set to minimum which is 0.748 volts. With just the bias connected the current draw is about 70mA. If I then add power to either transistor (not both) via T2 the current draw increases to 1.85A. This seems rather excessive.
What I don't know is a) if the transistors I have used are suitable for this application and b) what sort of standing current I should expect.
Nothing is getting excessively hot, and no smoke has come forth, so it's not a total disaster (yet).
All this has been possible with the assistance of my second in command:
Can anyone help?