Exactly. I was going to chime in here but you have it covered.Not an amp pro, but I know just enough about electronics to be dangerous.
GaN FETs have a lower on-resistance and switch off faster and harder than silicon. For Class D amps, this has a bunch of benefits.
First, power losses are reduced (i.e. efficiency goes up). So you need less heat sink. And because the GaN FETs conduct electricity so much better than Si, the devices themselves are smaller. This means smaller amps that run cooler at the same or higher power levels.
GaN FETs switch much faster than Si. So you can increase switching frequency without losing too much efficiency. This in turn allows smaller inductors in the power supply, EMI, and output filters. It also allows the feedback loop and output filter to reduce their effect on the audio band, for better transient response and slew rate.
GaN is harder to manufacture than Si, but it uses a lot of the same techniques and equipment. Because the conductivity per unit area is so much better than Si, devices are smaller, and you can put more of them on a wafer. This should bring costs down pretty quickly as the chip factories gain experience. EPC is already offering (or claiming) GaN devices cheaper than the equivalent Si FETs.
GaN doesn't require a new design approach in the same way that MOSFETs did over bipolar transistors, or bipolars over tubes. But GaN makes radically better power switching MOSFETs than silicon. The only real drawbacks are unfamiliarity and device prices, and the device costs are coming down pretty quickly.
I think in 15 years we'll be saying "Remember silicon MOSFETS?".
Multi-phase switcher? I always wondered why car amps never went that route. Something the computer and automotive industry use on a regular basis.I developed and in the process of patent 1.2GHz switcher and it shows 96% efficiency.
i don`t have comment on soundsdigital amplifier. So far it seems nothing more than creative marketing.
Exactly again. Mass manufacturing will drive GaN prices down significantly. I use a lot of MOSFETs in my designs. Modulated motor controllers, fuel injector drivers, etc. 10 years ago I would pay $0.43 for a 20mohm FET in 20 million piece quantities. With recent advancement in FET technology I can now buy a 1.5mohm FET for $0.11ea in 10 million piece quantities. Oh, and by the way, package sizes have shrunk significantly as well. No more D2Packs!!!My opinion? Not today. The audible differences would be slight; maybe some golden-eared folks might find them worth the money.
The EPC amp is a demo piece. It's intended for electrical engineers, not for audioheads. A mass-produced board would be cheaper, even using current parts.
I think as GaN sees wider adoption in other areas (e.g. power supplies, where efficiency and power density in space and weight are big deals), mass production will bring device prices down, and we'll start to see some radically powerful and tiny amps at a modest premium or even a discount to current silicon Class D.