Hello,
I am trying to identify the circuit configuration of Q11 and Q13 (Q12 and 14 by extension). It looks like a Sziklai pair but I've never seen a resistor (R50) attached where it is. Is it a Siklai? and is R50 for temperature stability/negative feedback. Thanks.
Scribble

 

Yes, they appear to be. Don't know about the resistor. Normally the outputs would be capacitively coupled to the output. What are the resistor values?

 

Yes, they appear to be. Don't know about the resistor. Normally the outputs would be capacitively coupled to the output. What are the resistor values?

They are 47 ohms so thermal compensation is all I can think of.

 

They are 47 ohms so thermal compensation is all I can think of.

And their is a 470uF cap after the TP19 output.

 

My only other thought is to prevent an overlap in on-times from produceing a power supply short. 94 Ω for a shot period of time won't affect the AC performance. The Sziklai pair only requires a single diode to prevent crossover distortion unlike the Darlington pair equivalent.

 

My only other thought is to prevent an overlap in on-times from produceing a power supply short. 94 Ω for a shot period of time won't affect the AC performance. The Sziklai pair only requires a single diode to prevent crossover distortion unlike the Darlington pair equivalent.

That hadn't occurred to me but makes sense. Thanks.

 

Could it be some form of overcurrent protection?

 

Output connected to power?

 

The 47 ohm resistors should not be used. do the amplifier like this: