Another marketing gimmick?

That’s just an aesthetic take on a what reviewers say is a great sounding amp. It’s a Gallium nitride power FET device that only the maker has access to, since he designed it. All other GaN devices are for radar and if used for audio, are modified or backward engineered. It replaces silicon devices as it’s way faster.

No, he designed the circuit, not the GaN FET used in it. He had some involvement when he was in the semiconductor industry, but it was not designed for his amplifier. It appears to be obsolete as well as he bough the remaining inventory and is changing to a different FET for newer designs. Your comment about all GaN are designed for radar is simply not true. Switching devices in power conversion (which is what a Class-D amplifier is), is a primary market for GaN and there are numerous devices designed specifically for this from a growing number of vendors. They are not even very expensive any more with low quantity orders under $2.00, and volume much less.


The switching FET is just one aspect of Class-D as well.

While Class-D is efficient, there is still heat generated. Putting it inside glass is going to maximize the temperature swing from turn-on till it reaches operating temperature. If you like to keep your amplifiers off, till used, it may not be ideal for consistent performance.

Marketing? .... Definitely, but the upgrade path is interesting and this method ensures the unit does not have to be opened. I wonder if those contacts are audiophile grade? $20-100 speaker binding post, $0.25 cent tube socket contact ..hmmmm.

audiozen, hopefully the tube socket has been 'improved' in some fashion unknown @ this point.  Time (and a curious purchaser) will tell the tale.

If the tube has been evacuated of air, I wonder if heat will be (or not) an issue.  The elements within the typical tube we're used to referring to 'glows' with it's current; IC's do employ heatsinks and fans to varying degrees and applications.  I wonder if using a noble gas within the tube might make a difference.  Nitrogen, used to inflate auto tires, makes them 'run' cooler, perhaps?

I would think that would be touted in the specs....I would.  "Exotica" such as this, esp. at that price point, could allay 'heat concerns'.

Just musing...

2034 @ your local Best Buy:

The GaN FET 'tube tester'....*L*

(You can say you saw it here, first...*L*)

Don't know if you're old enough to know or remember the 'tube testers' that were occasionally at local markets.  The better versions had a meter to give one an idea if it was 'marginal enough' to make it through the next football or baseball broadcast....

It'd generally punk out 3rd quarter.....*L*

If evacuated of air it would get hotter. There are some gases that would improve thermal transfer to the glass, but thermal conductivity of gases is inversely proportional to molecular weight, and they escape easiest .... i.e. helium and hydrogen. Neon may be a reasonable compromise. There are some more esoteric ones out there. Most of the heat transfer is because of the gas moving due to diffusion and chimney effects from the hot electronics.  With the electronics in a sealed enclosure like this, most of the heat transfer will be radiative.


Nitrogen is not a noble gas. It also does not make your tires run any cooler. That is an old myth. It may from a practical standpoint in that it escapes slightly slower than plain air so better chance your tire is properly inflated, but that's it.

The device I use was developed very specifically for class D audio, not for power supplies, low voltage points of load or RF circuits.

Yes, others use GaN devices but not the ones he worked on with the supplier and he bought out all the inventory. I don't know where you got the notion that the circuit is obsolete unless it was meant to demean. 

He's devising a new one to deal with the increased power of his next amp. Going back down in power doesn't appear to involve modifications. That, and although other makes use some form of GaN device, they're not intended for audio, like his are.

And, yes, I took some poetic license in saying that it was for radar as I was lazy to not list all the other applications. You're quite the pill, aren't you?

All the best,
Nonoise