Because the booster circuit is the amplifier end of the work was too heavy components causing the rapid component of the heat. If you are wrong when install the components, that can cause fatal damaged the component , such us the installation of pin emiter, collector , and base everything must be correct.
In the circuit above can strengthen booster amplifier with maximum work and everything is evenly split, what is it evenly split ? evenly split the point here is that all components can work with the same voltage and the heat evenly , this is because at each respetive base transistor were given the same constrains and same wattage resistor. And to maintain if the power output is too large then the resistor on Re will hamper so that the transistor is not easily broken.
Part List Booster Amplifier / Final Transistor :
Q1=Transistor power NPN such us 2N3055 , TIP3055,TIP120,TIP142,2SC2922 , 2SC5200 , etc.
Q2=Transistor Power PNP such us MJ2955 ,TIP2955,TIP125,TIP147,2SA1216, 2SA1943 , etc.
X1=Voltage connector (-)
X2=PNP Base connector
X3=Speaker connecor but also must be connected from the buffer
X4=NPN base connector
X5=Voltage connector (+)
|2SC5200 2SA1943 Ex Transistor Final|
PCB Layout Booster amplifier ( Transistor Final )
For power amplifier driver you can search here : Power Amplifier Circuit