It looks like you didn’t take any of the advice that you were given on your last post, so I won’t be helping. But… I will say that while the original design would work poorly, this one won’t work at all.
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Cake day: October 24th, 2023
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With a properly designed amplifier, you’ll have no trouble getting 1 watt of output.
These are the problems I see:
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You probably don’t have enough gain in the output stage. There’s a reason why darlington outputs are used in almost every commercial design.
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The voltage divider bias you have won’t be stable. As the outputs heat up the Vbe drops. This means the bias current will increase. Which makes them even hotter. Which means bias increases more. Which means… Thermal runaway is possible. The usual cure is the use diodes (or in a typical design a transistor as a Vbe multiplier) mounted to the heatsink so that bias voltage tracks with temperature.
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Your input stage can’t swing close enough to the rails and that will limit the ability of the output stage to achieve maximum possible voltage swing.
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There’s a reason why all modern designs use a diff pair on the input and complementary pairs on the output. It’s the best way to do it. The quasi output stage was used when PNP power transistors performed much more poorly when compared to NPNs.
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In my opinion, you never omit the zobel on the output. It’s there to help prevent high frequency oscillation in the power stage.
Personally I’d just use a op amp buffer followed by a diode limiter and then an IC power amp. (Or a discrete amp using the normal modern topology.)
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No. It’s not. You’re using a unique topology that was originally used to eliminate the output transformer in shirt pocket radios.
A quasi-complementary is just like a complementary amplifier except the bottom darlington has been replaced with a Sziklai pair. It’s prone to oscillation and was only used because older PNP power transistors were exceptionally poor performers.
Come again? That output stage you have can only be operated as class AB or class A. It’s (almost) always used class AB.
Don’t be a Richard. You can use all the help you can get with this and there’s people here that can help you. So don’t be some armchair engineer when you don’t even know basic terminology and act like a complete phallus and expect people to want to help you.