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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?


128x128Ag insider logo xs@2xcelander

Showing 7 responses by erik_squires

erik_squires
5,268 posts
 
I just wanted to pop in and say I too look forward to first hand listening experiences, as well as direct comparisons with other Class D and other types of amps.

Best,
E
erik_squires
5,268 posts
 
I’ve noticed a pattern, that the only ones whinging, or finding invisible problems to turn people off with the GaN technology. Are the ones with "some

Hahahahaha, hahahahaha.  Hahahahaha. Hahahahaha. OMG. 


Hahahahaha.


Thank you very much for your continued contributions.
E


erik_squires
5,268 posts
 
Eventually EPA will stop the production of Class A as an energy waster, just wait and see..

I'm pretty sure they'll want to ban bit coin mining long before they pay attention to the nearly extinct audio enthusiast.

Best,
E
erik_squires
5,268 posts
 
The overshoot is a common cause of the hard edge found in a lot of solid-state equipment.


Not even apples and oranges, this is apples and couches.

What evidence or experience do you have that this particular issue is indicative of this audible problem in a linear amplifier?

Next, since these overshoots are at an even higher frequency than the switching speed, maybe by 10x as much. A 400kHz switching speed, with some ringing, would probably be in the 4 MHz range. Based on what experience do you attribute this particular issue to a particular sound quality in what exact Class D amp?

Because the last thing my Class Ds have is hardness, did I get lucky?

Best,
E
erik_squires
5,268 posts
 
I',m back, after just completely putting the GaN amp at a disadvantage. Its 100W at 8Ohm and I put one amp each channel whereby I took the midrange driver lead from my outboard crossover and put a full .7 Maggie on it rather than going to the 3.7i panel. My purpose was to find the line of the AGD and I did of course. Whats nice it the channel just stops music, when you turn it down it comes back.



I have no idea what this paragraph means.

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.


erik_squires
5,268 posts
 
I thought it was a taboo to use negative feedback in a class D design.

Nope, it’s inherent in a lot of Class D. It doesn’t work quite the same way though. Some uses local feedback, which does not include the output, and some do.

Feedback and a triangle wave oscillator is how the analog input is converted to PWM output.
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