Oli

@Antonio51, I have tested it with 1uF caps to with the same result, so I don't think that's the problem. I have 4.7uF because that's what I had lying around at the time.

@bobflux, Sorry for the confusion I said that it blows when connecting a load ; Unfortunately I blew my drivers by mistake too, I have ordered new parts and thanks to chip shortages it will take 2 weeks to arrive. Thank you for the recommendations, as soon as I get the new parts, I will update the post with all the tests and results and requested information.

@Aaron, Thanks, I'll take some scope plots and update the post.

@user_1818839, Yes it is.

@bobflux, Yes it blows up when connecting any load, I tried large motor, small motor and no motor 5 ohm power resistor.

@Andyaka I'm really confused, when the MOSFETs are not connected all the PWM signals are valid on the gate of the MOSFETs but as soon as they are connected the high-side MOSFET fails short. I'll add a bulk capacitor and build the circuit on brand new PCB with new parts. I have already burnt 6 MOSFETs :(

@Andyaka, Thanks for the recommendations, I have updated the post.

Sure, thanks for helping me out.

Thank you, I'll read that too.

I have learned a lot too

Thank you so much

someone in the comments recommend a book by Douglas Self about audio amplifier design. I have started to read it, and I think I'll need way more study to be able to design a "standard" high power audio amplifier.

I have got this one OPA454AIDDA

but seeing how complicated it is to drive it otherwise, I'll go with an op-amp

I didn't want to because they are really expencive

I'll use an op-amp

I know I'm forcing it do what I want, but I really don't have much option other than buying one. I am a beginner when it comes to amplifier design or even analog electronics

also gain of each BJT is around 50 minimum

there is absolutely no distortion any where at any frequency from 1Hz to 20kHz

I'll upload some screen shots of my scope so you can see it your self

no that happens when there is no input connected

I'm only saying what I saw on my scope

the thing is that the gain is so high even me touching it makes it go loud

I can upload scope screen shots if you need

me too :D

YES

well it did have some problems near the rails at first but after adjusting the pot it got fixed

Yes I did and it worked really good with no problems near the rails

As this is my first design of an audio amplifier I was expecting it to be bad

I know don't worry

Also I have built the AB stage physically

As I said it doesn't need to output full power all the time, as long as it sounds good and loud, it'll do the job. I guess I'll try my stupid design with a high-voltage op-amp as driver stage with negative feedback and see if it works.

I just wanted to make something that "works", Apparently it's not gonna happen :(

@jonk, Okay Thank you for letting me know. The voltage rails of the of the "of the shelf amp" are provided by it's own DC-DC converter which converts 12 volts to +- 32 volts.

@jonk, I'm trying to do it with a class-AB amp. I have looked at my other of the shelf amp it also works by using a AB output stage

@jonk, Thank you. I am driving a 2 x 2 ohm subwoofer at 800 Watts, I need +- 32 volt at output to be able to push the current through 2 x 2ohm coil of the subwoofer. I have written them in question too.

@Jonk, How can I fix the problems? This is my first amplifier design. Can you point me in the right direction ?

@Audioguru, I'm not using the class-A because of the distortion. There is no negative feedback because there is no driver stage for my class-AB Amp.

@jonk, I know it's bad which is why I'm asking for help, sorry if it's terrible but somehow it works. My load is 2x2 ohm subwoofer at 800W RMS, and I have tested it with all the frequency range at max power and there is no distortion.

@jonk, I had totally forgotten, those are supposed to be 10uF not 10 farad. My bad, I will fix them right away. I'll also update the post with class-AB stage schematics.

@DaveTweed, No It's not homework and I'm not a student. I'm trying to build a high power Class AB amp and I have made it and tested it with my scope the only problem is that my Class AB amp requires the input signal voltage to be amplified since it is a emitter follower.

@Colin, Thank you for helping and recommending the book. I'll try to make one out of discrete components. and update the post with results.

@Andyaka I have changed the voltage values so all of them are the same. I believe I have mentioned what is my input voltage level and what I require at the output.

@DaveTweed, I knew it would be inefficient but not as much. Is there a better circuit that I could use to amplify the input ? besides using high voltage op-amps.

@user_1818839, Yes I forgot to include that in my calculations, Thank you. but it doesn't solve the problem.

Does any one have any idea why the current is 180 degrees out of phase with the voltage ?

@winny, peak current rating is 40 amps. I did add a snubber with C=330 nf and R=100 ohms but it still failed. In your circuit was the resistor in series with the TRIAC ?

@TonyStewartEE75, The cap is in parallel with the air compressor motor, I think it should be the same with the AC unit because I think they are there to improve the PF of the motors. I will have a look at the voltage and current phase on the scope and update the post.

@Kartman, Thanks for the recommendations on the code I wasn't sure if Arduino had changed anything or not and wanted to be sure. I did end up adding a crude snubber on to it with R = 100, C = 300 nf but I don't think that is the problem since I cannot see any voltage spikes on the scope with the air compressor also, I don't think I'm exceeding the TRIACs specs since I cannot see anything on the scope. I measured both the AC and air compressors resistances and they where both around 6.5 ohm. maybe there's something else that is happing with the AC and not with the air compressor but I doubt it.

@ErikR The problem with that idea is that it requires a huge resistor. For example to get around %50 less amps by having 11 ohm resistor passing around 7 amps through it would be 539W of power loss for couple seconds!