[wlai]

I would like to build a simple amp to drive a simple 8ohm speaker housed in a small box, for very casual listening from an iPod. The considerations are that it's cheap, small, and battery powered.

I researched turning a CMoy into such a beast, but in an old thread AMB pointed out that you may as well start with a speaker amp design. Anyone know of a place to start? I've looked at Gainclones but their power requirements tend to be higher than 2xAA.

Thanks for any pointers.

 

[threEchelon]

Umm... T-Amp?

SLA batteries might be too big for you but just one 12V goes great with a T-Amp.

 

[GTroy]

2nd the T-amp

 

[ericj]

This is what tripath chips are *for. So, yes, the T-Amp is a good way to go.

Just for kicks, and since we discussed the lm317 as an audio amp recently, another possibility is the TL431 shunt regulator:

http://www.techlib.com/electronics/audioamps.html#TL431

Yes, a single TO92 part can drive a speaker. You probably want a higher value output cap than the schematic suggests, though. 2200uf for good bass response.

 

[wlai]

Oh, SLA battery is way too big. The box itself is about 4" cubed. I am thinking 2 to 4 AA's to power, since I can barely squeeze in a 4AA holder. I suppose I can DC-DC boost to whatever operating voltage is, but would prefer not having to worry about power supply side too much.

 

[amb]

For a small, cheap, easy, battery-powered, non-hifi speaker amp, you can use a jellybean LM386 chip. Very few external parts are needed.