Class D headphone amp Project

[Iain]

Hello there everyone

I am trying to make a portable class D (right class?) DAC/headphone amp that takes a single 3.5mm input and converts it over to two 3.5mm outputs or 4 mini XLR outputs - the output is 2x500 milliwatt channels 1Vrms (UP TO HD 800 headphones)
300 ohm impedance output

The unit will have gain (hi/med/low) brightness (on/off) crossfeed (on/off)
I have tried to make what I can understand in yenka, but frankly this is above what I have been taught, and wondered if I could reach out to get some help.

Currently I am using op amps for the comparitor, triangle wave generator, and everything else there on seems a bit confusing, 555 timers for the pwm.

I have no idea how I am going to get the balance the line outs or even how the gain switch would work.

Would it be better to have this professionally made, or could people here give me pointers?

thanks

Iain

 

[Raven Luni]

Interesting. I'm working on a couple of class D projects myself. If its a DAC then you can skip the triangle wave generation and comparitor stage. Depending on the format of the digital signal, you'll have to use a clock signal synchronised with the sample rate and have some way to decode it into its raw / parallel form. Then youd pass it to a counter which would determine the pulse width (with some logic ensuring that it doesnt count down past zero and that zero / non-zero sets the pulse logic level).

Because of quantisation issues, you might also want to consider oversampling to improve the quality. There are a few articles on the subject. Google is your friend.