If you have read the books that syn08 mentions more than once and still don't have a clue, maybe you should buy a TOPPING amplifier.
1. with a 100p shunt C it should not oscillate, but as syn08 says a shunt C is not optimal when it comes to the performance (THD wise) of the amplifier, and the zero that R43 creates is quite meaningless.
2. The LM334 is a adjustable CS (Current Source) and it sets the current in the LED's which sets the BIAS current in the IPS and "VAS"
3. The servo loop is a DC servo that is meant to keep the DC at the output close to zero and as syn08 says "as it is designed" it is designed wrong.
4. About the TT transistors I copy and paste what syn08 is writing
" And the deal killer: the temperature compensation of the output stage NJL thermaltrak devices won't work properly. The NJL internal diodes are poorly DC and tempco matched with the power transistors, and will either make the whole output stage thermally unstable, or overcompensate, with nasty thermal induced distortions. " and he is absolutelly right.
Edit: I see that syn08 recommended diyaudio.com maybe a better place for you to ask for help.
Stein
There more I read the more confused I get and I get as much out of it as reading multiple recipe books more than once. I much rather watch people cook and explain why and how they are treating the ingredients and then try it myself.
1. Audio Power Amplifier by Douglas Self is really good intro, the other 3 books are much more detailed and still the shunt compensation is described as a cap going from collector to the emitter and negative rail in that example and there was no resistor in series either. Visually it's nowhere near that R43 and C12 looks like and I discarded it as "some filtering". At a second glance it connected to T16's collector but not to it's base - so it's really not that obvious to me.
2. All I remember from all these books is that VAS needs a good/perfect current source and it's mostly explained with discrete components, so seeing an IC I was wondering if that would compensate for the missing buffer stage.
3. The DC servo loop is on the input stage and I've never seen that before. I've seen it output stages due to nonlinearities between PNP and NPN transistors in combination with thermal drift between the two. I haven't put any energy into DC servos since there is a lot of negative comments about DC servos in amps. I felt that I would never need one.
4. First time I've ever seen ThermalTrak and until now I didn't know such a device existed, let alone what impact it has on amps.
There are threads on diyaudio already:
Did anyone check out the recent article in Elektor Electronics? There's a class A/B amp, very low noise, discrete and through hole design. https://www.elektormagazine.com/labs/fortissimo-100 To my eyes it looks kind of interesting. Symmetrical and pleasing to the eye. I can't judge the design...
www.diyaudio.com
I need comments about "100W power amp. elektor april 1982" Someone built it for sell he change the power transistor to new one maybe for improvement. I had listen to it. Its sound better than gainclone! I need comments.
www.diyaudio.com
PS. I've built two Amp Camp Amps monoblocks so far and soldering skills are decent (always have been) and I'm looking for next DIY project. I have commercial amps, not sure I want to spend more money there. I don't think there many analog guys alive in my city and the few people I know in hardware are mostly into digital design and there is limited milage out of pure theory and books. Nevertheless this kit seems like a lot of hustle and most people seems to have had problems with it. It's been around since 1982, but a few people seem to like it.
I strongly doubt anything commercial (in the $1000 range) is going to be much better/different than wiring up some Hypex modules into an enclosure don't you think?
www.elektor.de
what do you think about this system? 
