Which Class D Amplifier? PS Audio, Ghent, Nord, Merrill or other???

I found some interesting You Tube videos of the new ADG Vivace GaN mono blocks:

1. A pair of the new ADG Vivace GaN monos driving the mids/treble of a biamped speaker with the bass driven by an older pair of Rowland Model 12 class D monos compared to 2 pairs of Rowland Model 12s driving both.

2. A pair of the new ADG Vivace GaN monos driving the mids/treble of a custom biamped Magnepan speaker without the bass being driven at all compared to 2 pairs of Rowland Model 12s driving both the mids/treble and bass.

Here are the links: https://www.youtube.com/watch?v=KJb3pOY4tGA
https://www.youtube.com/watch?v=KJb3pOY4tGA&t=392s

3. B&O ICE Module 250ASX2 with tube input. (500wpc@8) vs. Jeff Rowland 535 (250wpc@8) vs. AGDProductions Vivace monos.

Here’s the link: https://www.youtube.com/watch?v=b-HFVPvWHTw

It is true that the comparison is limited by the audio quality on a You Tube video, but I found the audio quality sufficient enough to still convey the clear superiority of the GaN amps. Of course, I’d prefer comparing the sound quality in person.
I also thought the ADG Vivace amps, with the gimmicky large tube shell containing the GaN FETs protruding from the top of the amps, actually looks much less goofy in action than I originally thought it would. My current opinion is that it’s a good tip of the hat to the fondness most tube lovers, including myself, have for the warm glow of tubes in a darkened room that is remininscent of good music flavored with a touch of euphonic joy.
These videos struck me as satisfying confirmations of the benefits GaN FET technology can contribute to the sound quality of virtually all solid state amps.

Tim

Correction:  I mistakenly stated the older Rowland Model 12 amp is class D in my last post.  It is actually a class AB amp.

Sorry,
 Tim

   I'm also curious about how your development of a class D amp is progressing and whether it will utilize GaN or any other newer technology.  

@noble100
Right now we're not using GaN transistors but they are certainly on the radar. So far we've been building our modules by hand. GaN devices are much smaller than what we are using, which makes the assembly a lot more difficult (or easier, if we farm it out). Otherwise progress seems to be pretty good.

Hello atmasphere,

Thanks for the update. Very interesting and surprising, too. I’m not surprised you’re building your class D modules by hand but I thought you’d decide to utilize the faster switching GaN FETs in your amp. I would think not using them would handicap your amp’s performance in relation to the competition. I assumed you’d choose the best parts for each amp function in order to optimize overall performance.
I’m just an enthusiast of good music played through high quality audio equipment but even I can hear the improvement in sound quality of the ADG Vivace mono blocks despite listening to them on a YouTube video on a laptop via headphones. I think the improvement would likely be even more obvious and impressive heard in person.
I may be attributing too much credit to the faster GaN FETS, rather than the typical silicon MOSFETs , for the improvement in sound quality I hear in the new ADG amp. I know there're many other design factors involved in determining an amp’s ultimate sound quality.
But I understand that you’re an amp designer who’s also responsible for running a successful company and there’re very important factors involved in your choices that I’m not aware of. You certainly don’t owe me an explanation, I think I’m just a bit perplexed and disappointed.

Best wishes,
Tim

^^ The reason we aren't using GaNs yet is we are in a prototype stage. We developed a means of eliminating the need for dead time circuitry in class D amps (for which we have a patent pending).

The main reason to use GaNs is to minimize dead time (dead time increases distortion). So you are seeing GaN-based class D amps right now that have no dead time circuits simply because the transistor is so fast that with conventional switching speeds no dead time circuits are needed.


We're able to switch at the same speeds with conventional devices.


What this means is that for any given semiconductor tech that comes along (GaN and whatever **will** follow) we'll always be able to switch at higher or equivalent speeds with older technology (which is less expensive, although GaNs are already pretty inexpensive, being only about $3.00 each). Of course the flip side is that we can use the latest tech and switch faster. But in a prototype that sort of thing isn't necessary.