As for heat there’s virtually none.
"
Again, no heatsink due to high efficiency.s for heat sinking it runs so
cool there’s no need for it. Practical MOSFETs take time to switch and
during that time, they generate losses in the form of heat and limit how
fast you can switch them. GaN transistors aim to solve this problem as
these few slides from GaN systems show:"
This statement is false as anyone who has actually worked with GaNFETs knows. Sure, you can make an amp that does not use heatsinks (we didn't add any until we got very close to production) but the simple fact is that GaNFETs do produce heat and if you can't get rid of it, they will fail and often quite dramatically when they do. And you might think that you don't have to worry about shoot thru current heating up the output devices since they switch so fast, but you'll find out differently if you don't include deadtime circuitry to prevent that. But if you're just doing demo and don't run the amp at full output you can get by without heatsinks.
We expect people to abuse our products. So we built the amp so it can be at full output into 4 ohms and it can sit that way all day. That would not be possible without heatsinks!
But for evaluation I'm sure this circuit board is fine. You don't need heatsinks for evaluation applications!
Distortion at high power for a Class-D is incredible
"We see that the distortion is still under control instead of shooting through the roof.!!"
"I
don’t think I have ever tested a switching amplifier with this level of
frequency independence. Even Class AB linear amps struggle to produce
such an absolutely clean response. Amplifiers with high amount of
feedback run out of gain at higher frequencies and hence distort more.
Not this design."
This has nothing to do with GaNFETs and everything to do with the design. What is being referred to here is sufficient Gain Bandwidth Product, which most amplifiers lack in order to have feedback and consistent distortion numbers at any frequency in the audio spectrum (this BTW is a requirement if the amplifier is expected to sound musical). I've made comments about this aspect elsewhere on this site. What this says is that Amir hasn't tested a lot of class D amps; Bruno Putzeys' designs share this property of consistent distortion at all frequencies, and his designs use MOSFETs.
I know sometimes it's difficult to look past the person based on their
comments and interactions with others, but George designed and built the
Lightspeed Attenuator which I've owned for over 10 years and consider
one of the best values in audio.
@clio09 I agree the Lightspeed is one of the better examples of a passive volume control. To make the devices inside do what they do (which is to say, operate in a linear fashion) takes design skill. Why do you think George designed it- doesn't that seem a bit odd?
