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1 Watt Amp (updated) (alien.top)

submitted 1 year ago by coffeecalmsmedown@alien.top to c/diy@hi-fi.community

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Thank you all so much for your help yesterday. I've made a number of design adjustments, and it definitely looks more manageable (at least to me).

I'm hoping to get approx 1 Watt at 8 Ohms out, using a 12v supply. The design is based off of a number of other amps, including the Leak 30, El Cheapo, Z30/50, etc. As I made a few adjustments yesterday, I also realized the topology is becoming closer to a 60s Fender Princeton, though using BJTs.

Stage 1: peaking current/gm-compensated Stage 2: buffer (emitter follower) Stage 3: quasi-complementary output, driven by a unity gain phase splitter

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[–] fomoco94@alien.top 1 points 1 year ago (1 children)

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.

[–] coffeecalmsmedown@alien.top 1 points 1 year ago (1 children)

Actually, I changed the entire right side, minus the fact it's quasi-complementary. I also added a Zobel network, NFB, and another voltage gain stage. But ok, thank you for letting me know. I don't want to do an AB output for this project 🤷🏻

[–] fomoco94@alien.top 1 points 1 year ago

it's quasi-complementary.

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.

I don't want to do an AB output for this project

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.