Solid-state audio amplifier complexity vs valve/tube

Elerion said:

I'd like to share my first design, to seek for tips and advices.
The open loop simulation shows plenty of gain/phase margins, and bandwith is almost flat between 20Hz and hundreds of kilohertzs.

Click to expand...

I am glad that you added C3 as a frequency compensation capacitor.
Since speakers are inductive and present a high impedance at high frequencies, add a zobel network to the output like most amplifiers have.

2n2222 and 2n2907 transistors can be replaced by cheaper bc547 and bc557.
I left the driver transistors Q9 and Q10 as bd135/bd136, even though in this circuit, they handle low current, and dissipate low power. Replacing them by smaller 2n2222/2n3907 deliver a slightly less output voltage.