41Hz Audio's AMP4
I've been looking for the ideal bicycle audio amplifier for a long time. The key requirements are very high efficiency at reasonably high power rating but with relatively low voltage supply requirements. 41Hz Audio's AMP4 project seems to fit, so I decided to try it out.
The kit is nicely put together and assembly was surprisingly easy. I have lots of threw hole experience, but I haven't done much surface mount, so when it came time to solder the PowerSO36 package, with its 0.65mm (0.023") pitch pins, I was a little worried. It turned out to be no problem, even with the metal slug effecting heating of the pins.
More generally, the very sensible PCB layout definitely helped make the assembly go smoothly - no via's too close to pins, and lots of room to place parts and access leads. There is a minor layout error on the rev 1.02 boards (41Hz Audio forum discussion), a couple of pins on the voltage supervisor chip are reversed. I don't need that function, but fixing the problem isn't hard, just solder the part upside down.
(warning, the full size images are very large)
Now all I need is a mini sonotube subwoofer! I'll be able to produce a pretty impressive thump, while keeping weight low.