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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?


celander
vt4c
27 posts
 
As the GaN is used in the non-linear stage i.e. the output, it just operates as a very fast switch, the benefit of GaN is less heat, and higher switching frequency.
GaN is a non-linear power device and really should not matter for sound quality. It may be easier to design an amp with GaN, but audible effects should be unrelated, unless a much higher switching frequency is used to advatage of simpler filtering and higher resolution A to D converter is used.
Too much sales jargon.
tweak1
870 posts
 
OP, why not start a new thread address AGDs concerns? 
celander's avatar
celander OP
1,036 posts
 
☝🏻Done. 
teo_audio
932 posts
 
I'd like to make sure that everyone understands that any harmonic distortion, ringing and overshoot at the switching part of the amp is going to be far above the switching speed.

Problems with the slew rate, switching speed,etc. here are not going to directly translate to audible issues the same way they might in a linear amp.

The shape of the square wave in a linear amp is totally audible. Class D is not going to translate the same way.

That's nice Eric, but all measurements preformed on all class d amplifiers say something that is sort of the opposite of what you are saying.
The theory is one thing, the reality says something completely different.

Explaining why what I mention is is important, is an act of teaching too may people who (currently) have no clue, how to fix things they have no idea are broken.


georgehifi's avatar
georgehifi
4,966 posts
 

Here is the PDF to the eGaNAMP2016 GaN amp.

Steve Colino said if one wants even better sound from it, you can add a heatsink to those GaN fets and take the switching frequency up to 1.536mhz and then adjust the output filter much higher.

https://epc-co.com/epc/Portals/0/epc/documents/thirdparty/eGaNAMP2016_Consumer-123115.pdf

If you want to make your own, a complete stereo eval board is available 
https://epc-co.com/epc/Portals/0/epc/documents/thirdparty/EAS_eGaN_2.0-Channel_EvalKit-010116.pdf


Cheers George
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