Low Powered Car Amp

[JustinG]

Sorry for the long post, this is my first time here so I'll give a bit of background and then on to my questions...

This is my first post over here at diyAudio, I've been creeping/poking around for a little while now and have been pretty active over at PE Tech-Talk for the last few years (same tag). I'm pretty good at wiring things up and have worked a a bunch of electro-mechanical projects in school (I've taken a few EE classes but graduated as an MechE).

I will eventually want to build a hefty home audio integrated chip amp using a PIC micro controller to control visual output and maybe source selection, etc, etc, but for now I'd like to start out small/simple and eventually when I get acclimated to the water move on to bigger and better(badder) things.

SO, actual question(s):

I'm looking at using a small(ish) tapped horn for subwoofer duties in my car that will have a sensitivity of 96 dB 1W/1m so I don't need a lot of power. I thought it would be really cool to have a really small packaged amp driving the speaker. I'm looking to get as close to 20 watts as possible into an 8 ohm load. It is my understanding that I can't get more than 25 watts into an 8 ohm load (assuming 14V) because of that whole P=V^2/R issue, is that correct, or is there something that can be about this with bridging/paralleling a chip amp since I only need one output. I would like to do without a SMPS since I'm still quite a novice in this game.

Summary:
1 channel
8 ohm load
20 Watts wanted
14 VDC power supply (alternator)

Any suggestions or am I going about this in the totally wrong way?

-JustinG

[JustinG]

So looking around I partially answered my own question. Would something like the 41Hz AMP6-basic or AMP3 kit work for this application or can it not run in a mono configuration?

[danielwritesbac]

Hi Justin,
We're playing with the inexpensive car chips over here: 12V DC gainclone? <--link Maybe you can find some ideas.

[JustinG]

Originally Posted by danielwritesbac

Hi Justin,
We're playing with the inexpensive car chips over here: 12V DC gainclone? <--link Maybe you can find some ideas.

Thanks Dan,

I was going for the "wow" factor or rather the "really?!" factor with this build telling someone that the 105+ dB they just heard was coming from this little case (amp) and a 7" woofer would be great, but maybe I'll start off with something a bit simpler/conventional for my first build. I'll take a look at those pages and see if anything pops up. My other option is I have a few old amps I no longer use that I may be able to pull the PS out of. After I make my next move ~2 months from now I'll start looking at this stuff more seriously, until then I'll be actively looking around for some good ideas.

-Justin