GaN-based Class D power amps


The use of GaN-based power transistor tech is now emerging for Class D audio power amplifiers. Seems appropriate to devote a forum thread to this topic. At least 3 companies have commercial class D amps in their books:

Merrill Audio, with their model Element 118 ($36k per monoblock, 400 W into 8 ohms, 800W into 4 ohms), Element 116 ($22k per monoblock, 300 W into 8 ohms, 600W into 4 ohms) and Element 114 (coming soon). 
https://merrillaudio.net

Review of Element 118 at this link:
http://www.enjoythemusic.com/superioraudio/equipment/1018/Merrill_Audio_Element_118_Monoblock_Amplif...

ADG Productions, with their Vivace Class D amp ($15k per monoblock pair, 100W into 4 ohms). (The designer emailed me indicating he has another product in the pipeline.)
http://agdproduction.com
Review of the Vivace Class D moniblocks at this link (warning: link might not work (1/11/2019)):
https://positive-feedback.com/reviews/hardware-reviews/agd-production-vivace-gantube-monoblock-ampli...

Technics SE-R1 Class D stereo amp ($17k per stereo amp, 150WPC into 8 ohms, 300WPC into 4 ohms) 
https://www.technics.com/us/products/r1/se-r1.html
Preliminary review of the Technics SE-R1 at this link:
https://www.stereophile.com/content/technics-se-r1-digital-amplifier
Technics also has a lower priced GaN-based class D integrated amp in their catalog:
https://www.technics.com/us/products/grand-class/stereo-integrated-amplifier-su-g700.html

Anyone listened to or own any of these amps?


Previewcelander
LOL @georgehifi your silly link is for an ICE Module, but nice try.

@georgehifi george do you know anything about all the differnent GaN devices used in Technics, AGD, Merrill, and your beloved eval board from EPC? Only one manufacturer uses GaN devices purposed for Audio, do you know which one? 
georgehifi,

If you believe this is the actual phase shift of the output of an IcePower based amplifier, can you explain this near perfect 1KHz square wave?

https://www.stereophile.com/images/archivesart/555Belfig2.jpg

If you have that much phase shift at 1KHz and changing considerably over the harmonics of a 1KHz square wave, then there is no way the wave would look square.
Perhaps there are holes in your knowledge that prevents your understanding of how these things work ..... 

I know I'm not the brightest bulb in the lamp but what exactly does that phase shift mean in the link from George? Compared to a speaker or room interaction it's not much or is it?  I don't know that I've ever seen a plot like that before. 
I know I'm not the brightest bulb in the lamp but what exactly does that phase shift mean in the link from George?

@djones51
Phase shift is interpreted by the ear as a tonality depending on what is causing the phase shift- a rolloff at high frequency outside the audio band can sound like a darkness, it can also sound like a brightness if there is a peak. The ear uses phase information for echo location, so it can alter the soundstage too. The ear is entirely insensitive to phase at a single frequency, like a sine wave or the like; and there are other factors it uses to sense tonality and soundstage, so even though phase shift plays a role, its not the only way the ear works. But if you really want to get the tonality and soundstage right, this is a thing that needs attention.


While some class D amps have significant phase shift, others do not, just as in traditional amplifier technology. It is a logical fallacy called 'Guilt by Association'  that is being employed here by George- he is saying *all* class D amps have this phase shift in the link he provides, when actually the curve is for a very specific amplifier. Logical fallacies are inherently false and this is an excellent example.