I dismounted them from some rejected PCB from Samsung. It wasn't an amplifier, nor an SMPS, I guess it was a driver of some kind of big display, or vehicle. They seem to be new development indeed, but unfortunately not especially for audio.
Thanks! Sadly this has too high fall time for audio.
I've tried some of them (RJ...), and they weren't good enough (eg. too high switching loss -> damaged at about 25...30 A peak current), but I think if I saw the datasheet, maybe I could figure out what to modify to reach a little higher efficiency.
I saw so many potencial in RJP3043! Vcebr=360V, Vce=1.5V @ 16A, tdon=20 ns, tdoff=60 ns, Qg=~30 nC... but current "tail" seems to be too long.
Unfortunately the switching freq was not fixed, so I can tell only the idle freq: 200 kHz, but this is somewhat irrelevant.
I didn't try IXGP70N33, mainly because the isolated package can dissipate very little power. I'm planning to remove isolation from the bottom... This has an ultra low saturation voltage (1V @ 16A), so I'm going to use in (resonant) power supply instead of in amp. I don't think it would be fast enough.
RJ...s are usable in sub amp, but worse than the previously used HGTG12N60A4D.