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oh yeah, your right. sorry about that. i was supposed to add the message to my post regarding audio amps. anyway, we were tasked to make an audio power amplifier (class B) on final stage to drive a load of 4 or 8 Ω to output power of 30 W. its just that i do not know how the pre-amplifier should be. thank you. i'm still confused on how to make our project. we are to use a dual power supply to be connected to the pre-amp then to the power amp. whew! i still got lots of things to learn. so if you could help me please. thanks a lot.
A class-B output has severe crossover distortion. Audio amps use class-AB which has no crossover distortion.
An audio power amplifier has a certain amount of voltage gain. You must tell us the sensitivity of its input for 30W output into 4 ohms or 8 ohms.
You also must tell us the input voltage from your source which determines how much gain the preamp needs. It might have a very low level microphone or a very high level CD player as its input so the required gain is very different for them.
You can use the old TDA 2020 or any similar IC directly from national or ST Microelectronics.
The surprises you can find and the time used to improuve the circuit are long higher than to use a dedicated IC.
Overall in this way you can garantee the repetebility of the project