Where do I even start?  If electronics design is my passion, audio amplifier design would be my favourite, above anything else.  I have designed many other amplifiers, and I like putting them on breadboards and PCBs, and even though I enjoy troubleshooting them if they don't work, I genuinely love hearing them when they're finished!

In August of 2013, I decided it was time to pick my favourite design and make a complete unit from it.  After all, what's the use of talking about all the amplifiers I've ever deisnged, if I've never finished one?

This little one can deliver 35W RMS of continuous power to each of two 8ohm loads, which is a comfortable amount for a small living room speaker system.

It's a class AB amplifier circuit, so it provides a reasonable tradeoff between excess power use, and clean performance.  According to the FFT on my oscilloscope (and a little math), the distortion is a little less than 0.07% at full power.  This could be lower if I had raised the slew rate from 11V/us to 13V/us, but for the sake of the intended consumer (i.e. me) it's sufficient.

The unit has a fuse and power switch on the AC line, and has fuses all throughout.  Overload protection is a must, and the sleek blue power LED is driven by a constant current source which has a few advantages.  I chose this method so that it can be driven dim enough to not be a problem when watching a movie in the dark, and it won't flicker at high outputs.  A raw DC power supply also ensures the most power delivery with the lowest component cost.