Posted 25th April 2014 at 10:13 PM byrjm (RJM Audio Blog)
Updated 26th April 2014 at 07:19 AM byrjm
As a companion post to the GeminiPS I thought I'd throw the amplifier circuit out there too...
It's not something you'd have any reason to built today I think, but some of the ideas are worth revisiting.
The output stage is what is normally referred to as a complimentary Sziklai pair. The LTSpice circuit below uses the same output, but with the diamond buffer type bias, with it all scaled down to headphone-amplifier voltages and loads. It would be interesting to compare it against i.e. the conventional diamond buffer used in the Sapphire headphone amp. Maybe I'll get around to it. The simulation shows a bit more transient peaking than the straight diamond buffer, ideally there could be some way of adding compensation / reducing the bandwidth to more reasonable levels.