Posted 12th February 2014 at 04:10 AM by fas42
Updated 12th February 2014 at 09:55 PM by fas42
I mentioned in a thread a while ago about doing an exercise of engineering an amp capable of delivering 2k watts into a 1 ohm load, with distortion aiming at the magical ppm figure. This is still happening, and making progress ... key problem as I saw it was managing crossover distortion intelligently - I'm looking at a conventional class AB output stage at the moment - and it didn't make sense to try and control it using a classic global negative feedback approach.
By nature I'm an excellent scavenger, I look to see what ideas are already out there - so I'm trying out some concepts in using local negative feedback. This is evolving, step by step - and showing promise: in a simulation of the output stage only, getting effectively 2kW in 1R, at 200kHz with reasonable stability - and the waveform at this stressful frequency looks pretty good, there is still some crossover glitching, but I'm reducing the visible level of it steadily.