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Gallium Nitride GaN Class D Amplifiers

In my recent research for a possible upgrade to my current amp (Benchmark (AHB2) I was reading about the new higher end design for Class D. I'm very interested in learning more about these new GaN(Gallium Nitride) designs. Three companies are offering some very well reviewed products and they are not going crazy with Watts per channel:

Orchard Audio offers a 250 watt Amp

AGD a 100 watt

Atmos-Phere also a 100 watt

What's interesting  is while Orchard is a new company AGD and Atmos-Phere have been around a while producing high end Tube amps. In almost every review it is noted how these newer designs sound like Class A or Tubes with all the benefits of Solid State. One reviewer couldn't go back to his tube amps after extended listening to the Orchard. No wonder AGD and Atmos-Phere are getting into this technology. It's very exciting as these amps are highly efficient turning over 90% of the power they draw into sound compared to about 78% with A/B designs and I believe even significantly lower for Class A. They run cool and usually weigh between 10-28lbs. I plan to do more investigation. Small size and light weight with decent power is very attractive. There are also mono block offerings for more power if needed. These are not cheap Class D products. They are well designed and constructed.

Orchard Audio's base model is around $2700and their Dual mono version with larger power supplies is $5500.

Both AGD and Atoms-Phere are $5000

Mono blocks for each are about twice the cost.

Has anyone had any experience, demos, etc ., with these types of GaN Class D amps?

 

jfrmusic

Showing 6 responses by tvad

tvad's avatar
tvad
11,534 posts
 

What SQ characteristics do distinguish from the auditioned Class D Gan amps that cause you to still prefer tubes. I suspect I would agree with you and pick tubes but for my rooms allergy to heat.

Have you ever experienced a class AB amp that got you closer to your tube preference ("soul"?) than a Class D Gan? If so, which one(s)?

#1 on the list was 3D soundstage. Depth was more convincing using a 300B SET tube amp.

#2 was texture. The tube amp conveyed a bit more.

Regardless of what chip amp I’ve auditioned, they all sounded a bit sterile and artificial compared to the 300B tube amp. The AGD Audion GAN mosfet amp was the least so.

I have never experienced a Class AB solid state amp in my system that came close to a tube amp. I have heard Class A that approached a tube amp - Pass Labs XA-30 and XA-60.

 

 

tvad's avatar
tvad
11,534 posts
 

@marco1, thank you for specifying the amps.

Interestingly, two of those...AGD Productions and Orchard Audio...were two I also auditioned about four years ago.

I arrived at the same conclusion as you did.

Nevertheless, I believe AGD Productions GAN amps (and I suspect Atma-Sphere GAN amps as well), are worthy of recommendation and audition.

tvad's avatar
tvad
11,534 posts
 

Do yourself a favor and just find the right amp.  I went the Class D route and now sorry other than it will probably be my summertime amp.

@marco1, you have made this comment in different threads.

I respect your opinion, and I made a similar decision, but I hope you won't mind if I ask you to share some details.

It's helpful to readers if specific Class D amplifier(s) are discussed, because akin to other audio components, chip amps (I use the term chip amps, because not all are Class D) don't sound the same. At least the chip amps I've heard in my system had different presentations and characteristics.

Which Class D amp(s) are you referring to that did not meet your expectations?

tvad's avatar
tvad
11,534 posts
 

@bhvf, in my system, bass was not light from AGD Audion amplifiers. It was deep, resolved and tonally balanced. More truthful might be an accurate description.

The "tube" in the AGD amplifiers contains the GAN chip, and was designed to allow easy chip upgrade by an owner without opening the amplifier’s chassis. An owner simply pulls the tube, unscrews the base, pulls out the GAN chip and installs the new chip, screws the base back on and re-installs the tube. Albert has written that he also did it because it’s reminiscent of tube components and looks cool, but it has a practical purpose. I'm not aware at this time if a new GAN chip has been designed that necessitates an upgrade.

tvad's avatar
tvad
11,534 posts
 

@jfrmusic, I have not heard the Atma-Sphere GAN amps. I mentioned having auditioned Atma-Sphere OTL amplifiers; specifically, M-60 mono blocks.

I auditioned AGD Audion mono amplifiers.

They share common characteristics of naturallness, tonal richness, excellent frequency balance (actually I think the AGD Audion had slightly better balance), and an expansive image. It’s been a few years, but my fuzzy recollection is the AGD Audion amps were more tonally neutral. The Atma-Sphere M-60 always struck me as pleasingly warm in tone, but not syrupy. This is a wonky comparison, though, because I have no idea if the Atma-Sphere GAN amps convey the same house sound. Maybe someone who has heard both will respond  

Preamp was SMc Audio VRE-1C. Loudspeakers were Audio Note AN-E/SPe HE (95db, 6 ohms).

 

tvad's avatar
tvad
11,534 posts
 

I’ve auditioned the Orchard Audio and AGD Productions GAN amps in my system. To my ears, they did not sound alike, and other than being GAN chip amps were not sonically comparable.

The AGD Audion amps were natural, extended, and transparent with a large sound stage. Not dissimilar to my SET tube amplifiers, and to Atma-Sphere OTL tube amplifiers that I also auditioned for an extended time, although both lacked the elusive 3D depth of the tube amplifiers.

The Orchard Audio amplifiers sounded sharper and more precise. They skewed away from my listening preferences.

I don’t think one can price shop in the GAN amplifier arena and think they’re getting the same (or similar) sound for less money among available products.

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