Yes you are right. The load is not a resistor. But it just OK to be a simplified way to explain why the higher the impedance the higher the power.

Hi Rowdy,

Actually there's no "impedance match" problem for class D audio amplifier at all. The internal mosfet is working in on-off mode. When it's turned on the equivlant resistance is only about 0.1Ohm. The max power of class D amp is depend on the maximum current it can drive. When the current is fixed the bigger the load impandence, the bigger the power. That's why the output power is larger for 16Ohm than 8Ohm. Of course the max power is limited by some other factors such as supply voltage.

The power can be up to 15W with 24V supply on a couple of 16Ohm speaker. This is strange when comparing with traditional analog amplifiers.

http://www.v-module.com is the manufacturer's website. It's seems to be a site that is being constructed.

page of VMA2016: http://www.v-module.com/info.aspx?id=20
datasheet: http://img.v-module.com/datasheets/ds_vma2016.pdf

The price is about $7 to $8, depend on the order quantity. I paid $75 for 10pcs. The system cost is quite cheaper than most ICs (such as LM1875) because there's no heatsink and other components.

I found a nice part to building a guitar amplifier. It's a all in one class D audio amplifier module, the size is only 0.6" x 1" x 0.15" (the size of a stamp). But the output power is 10Wx2, really amazing! No heat sink and external components (except power bypass cap) needed. I bet it's the simplest audio amplifier circuit you can find. Due to it's high efficiency there's no much heat generated even when the speaker is very loudy. It's ideal for battery powered applications.

Sound quality? pretty nice comparing to it's size and cost.

the part:


the board I made with VMA2016


reference circuit provide by v-module