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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 2 responses by clio09

clio09
3,345 posts
 

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.

I own both sets of amplifiers. I have owned the M-60s for over a decade and purchased the Class D around the time they came out. The Class D gives up very little to nothing compared to the M-60s, simplifies ones set up quite a bit, and if you care about saving the environment and some cash on your utility bill there's that too.

From the average audiophiles perspective the description of the M-60s by @tvad might sound nice, although I wouldn't use the term "pleasingly warm in tone" myself. From my perspective I would say both the M-60s and Class D have low coloration characteristics due to their low distortion, especially in regard to higher order harmonics which tend create unnaturally bright tones. They are both well balanced amplifiers (with AES48 compliant balanced differential circuits) that will pass the "truth" to your speakers. You will most likely find your speakers and components upstream from the amps introducing more coloration. The amplifiers themselves not so much.

As a long time Atma-Sphere customer and authorized dealer feel free to take my comments with a grain of salt.

 

clio09
3,345 posts
 

@mapman +1, I also own the Bel Canto REF1000Ms and use them to power my distributed bass array for a bi-amp set up. No shortage of bass there and it's very fast and articulate.

When speaker designers of yore were making speakers with 32 and 16 ohm impedance damping wasn't quite as important. Back then tube amplifiers, zero feedback SET in particular known for high output impedance, were by far the norm. Nowadays with speakers being of lower impedance things have changed. It's been said by a few people I know who make tube amplifiers that the popularity of solid state amplifiers using feedback came about due to speaker designers making 4 ohm impedance speakers. Makes sense when you think about it as damping should be higher with that type of load. However, these same tube amplifier makers have said to me that anything over a damping factor of 20 makes very little if any difference. So the damping factor spec should be taken with a grain of salt as well.

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