1. Home
  2. amps-preamps
  3. 142893-45726

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
teo_audio
932 posts
 
Let me just say, that if the problem of non linear distortion generated has been fixed from the fet based class-D of the now..then I’m all for it.

I’ll jump of the dang cliff and dive so deep I hit the bottom and nearly die.

I wanted class D to do a new thing, to be the new better kid, but it was not. Not even close. Efficiency was there but the audio essentials, the reason for it to exist -- all of that went into a meat grinder.

The world of audio needs/desires -outside of perfectionist audio- made it so that the music was sacrificed for financial/business/sales efficiency.

It’s the same reason we ended up with digital and it took over 20 years to try and find out how to fix it after the fact. And we’re still not there.

I spent two years working on extant class D designs and correcting their flaws, inch by inch.

It all got tossed, as no matter what I did, they could not equal the amplifiers of old and current linear design. The flaws were and are fatal and endemic to the device design criteria/operation itself.

If GaN can cut the core of that flaw out, then I’m probably in with all limbs, again.
guidocorona
4,114 posts
 

Some of us have had a more nuanced experience with Class D than TEO_Audio.... I have been listening to class D since 2006.... I have heard class D purgatory, hell, and class D heaven since then. Have been experiencing musical nirvana in my own system with class D amps since 2008.


I have also experienced for several days one quite promising GaN-based prototype amp in my system, which, because it was incomplete nd not well broken in, was still displaying some minor audible artifacts in the treble region... Yet, was in spite of this, as I said... Very promising.


So, my ever cautious inclination is to say that GaN may be, if not the only way to create excellence with class D, at least one of the emerging technologies with high potential.


As more GaN amps are released in the next few years, we might have a better idea if the potential for generating nirvana is inherent to GaN transistors, or if GaN technology per se has instead an average chance to be inside superior amps.


Guido









celander's avatar
celander OP
1,036 posts
 
Looks like ADG Productions Inc will be showing off gear at APOXNA 2019.
http://www.axpona.com/exhibitors.asp
Schaumburg is a short drive from Evanston. 😎

erik_squires
5,268 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.


georgehifi's avatar
georgehifi
4,966 posts
 
celander OP767 posts
@tweak1, Early adopters pay the heavy price.


Just like with all new topologies, the old become door stops, and unsalable, when the new topology takes off.
Just like CD's early days with brickwall filters, like Sony's 16bit 101's and 701's have a listen to those, they are listenable, I got rid of mine as soon as I heard Marantz's 14bit without brick wall filter.

tweak1
I contacted Paul McGowan (PS Audio) about his Sellar dac/pre, and also asked whether they are playing with GaN.
 "The Stellar S300 is a dual mono design,  based on a modern Class D ICE module, designed in Denmark."

The Stellar S300/700 used Ice modules.

EG: If all three below had the same RRP

PS would wait for maybe a Chinese Class-D manufacturer to start making the complete Class-D boards using the GaN technology. (high profit low manufacturing cost)

For PS to design and make their own Class-D boards based around the GaN transistor would be a major undertaking for a company like them to do. (medium profit high manufacturing cost)

AGD is another story, being a "boutique manufacturer" maybe a one man show, can afford to go the hands on hand made route. (low profit very high manufacturing cost, but very low overheads)

The middle one's the disaster if things go wrong.

Cheers George      
 
More to discover