Leonardo Capossio wrote:




In this case, the only thermally dependent element I see is the PTC100.
The circuit surrounding the PT100 seems to be compensating the bias
current of the power amp, though I do not understand it fully, if
anyone can point to a source that explains how this circuit work it
would be great.


** PTC100 operates the "mute" function of the power amp by shutting off Q7 and so the base voltage to Q8 - which is a 2mA current source for the input pair Q9 & Q10. This results in no current in the driver stage - transistors Q11, Q12 & Q13 and so no amplification.



..... Phil