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I decided to make an amplifier that’s hopefully close to realistic. The transistor configuration (gain and internal resistances) are based on what I’ve found in amplifiers from @thebugger. I also added 100mΩ resistors to the emitters of the power transistors to prevent a transistor with a slightly higher gain from delivering too much more current than the others to prevent thermal runaway. I’ve calculated that with a 48.5V sine-wave input (about 48.2V output) this amp consumes 426W, delivers 290W, dissipates 136W, and has an efficiency of 68%.
Also, this, being a class-AB amp, has an idle current of about 100mA which means an idle dissipation of about 10W. Also, I measured a THD of about 50 to 100mV, or 0.1 to 0.2%. Mostly cross-over distortion. A higher idle current will reduce the THD. Upping it from 100mA to 200mA reduces the THD to about 35 to 70mV, or 0.07 to 0.14%.
What are your thoughts on this amp? Is it realistic? Does it have appropriate thermal runaway protection? Does it have too few output transistors? Is it just a bad design? Or is this somehow actually just right? I’m open to any and all thoughts about this circuit, especially constructive criticism!
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