GaN FET Amps vs. Traditional Class D Amps

Class D amplifiers barely scratch the surface of the capabilities of GaN semiconductor devices.  Compared to Si devices, GaN can operate a higher frequencies, higher voltages, higher power and higher temperature.  An amplifier can be designed to take advantages of these greater capabilities.  Just swapping out Si devices with GaN devices would do little to change the amplifier but if you design the amp to run a higher frequency with fewer devices then things may sound different. 

@tosnc +1

I have yet to hear any GaN Fet amp design, so can’t comment on the sound of those. My comments have more to do with my class D journey--how I proceeded amidst the pro- and con- hype.

First: I know my own sonic tastes and preferences very well. I prefer amplification that is slightly warm, definitely spacious & resonant, has a midrange that is expressive and full, and conveys the natural weight of lower frequency instruments. In short: sound that is "musical" (sounding a lot like the real thing IRL), not sound that is forensic and unnaturally detailed.

Second: I addressed my own ignorance by reading vast amounts of reviews and user comments for dozens of class D amps, new and old. At first I wasn’t much concerned with cost or availablity, but more with sound. This took months, mainly because relatively few reviews really characterized the sound of amps in ways I recognize; and even fewer user comments drilled into that side of the amp in question. Instead, there was a lot whiz/bang stuff about S/N ratio, damping fact, amperage into low impedance loads, blah-blah. Those things are obviously important, but lacking characterization of the amp’s sound, they don’t mean as much to me.

Third: I finally identified three or four class D designs that were (more frequently than others) lauded as sounding like music. The first was an ICEpower design, the Wyred 4 Sound ST-500 class D amp. I found one used and liked the sound a lot right away. I felt extremely lucky that all my homework had paid off. Next I picked up a used pair of Bel Canto 600M NCore monoblocks. Again, I liked the sound right away. Another huge piece of luck.

So I was able to find one example each of two legacy class D technologies (ICEPower and NCore) that sound really to me and were affordable. I suspect there’s at least one GaN FET design out there would fit the bill, too. My research is ongoing, but I have yet to find any affordable names to get interested in, plus the two I have (ST-500 is backup; 600Ms are in the system) are so good, I really have no need to upgrade.

PS: what started me on all this was the limitations of space I face in this home offic.e There is simply no room for an A/B class stereo amp here, much less a paif of A/B monoblocks. Class D definitely works here, with little if any heat output and far more compact case footprints.

"Basically I’m trying to understand what all of the fuss is about." 

Current flavor du jour explains the fuss. Where it goes remains to be seen. Current owners are still early adaptors. 

I fell down the Hypex NCore hole and convinced myself Bruno Putzy’s NC1200 monos sounded as good as the big Class A amps I owned at the time but, after spending quality time with them, I decided they ultimately didn’t. The NC1200 amps were simply not as natural sounding, at least to me.  As with regular Class D, advantages of GaN FET include size, cost, and lower heat.  As pointed out, there are potentially performance benefits. I am still not seeing much GaN FET with higher power ratings, although the monoblocks from Mytek do look interesting (link), and pricy. 

This isn't 1973. Today's Class D amps should be preferred by any audiophile if they want to hear what the music is actually supposed to sound like.