Looking on Info on DIY car amps.

[CptanPanic]

Is it cost effective to build your own car amp? I just built a headphone amp, and was thinking I could build an amp for my car. I was thinking about a 4x50RMS amp. Is there any sites dealing with this? Searching for DIY car audio mostly comes up with DIY installing car audio and not building.
Thanks,
CP

[mikee12345]

i dont think it is possible easily at all with DIY

you need a switch mode power supply for higher voltage amplifiers

4x22watt rms is possible with bridged Ics

25-50watts is only 3db

Cheers

[fr0st]

car amps are the same as home ones except the power supply. A 4x50 would require a SMPS. Look at http://sound.westhost.com/project89.htm fo that. It is quite simple as long as you have a testing psuy of low amperage or that has current limiting. Until you get the primary windings right you're going to have trouble.
Other than that a gainclone will give you 50w easy.

[Davide82]

Problem in car audio is low voltage: 12 V.
If you want lot of power you have 2 ways:
a) increase voltage
b) increase speakers (lowering impedance)

Car speakers are usually 4 Ohm; without increasing the voltage you can get around 30 W rms. But remember that you can add many speakers (each with 30 watt).
DIY is quite easy if you don't require to increase voltage (it is difficult and expensive); you can build simple ICs amp (take a look at http://www.st.com/stonline/products/selector/203.htm they have many 14.4V ICs made for car audio).
Remember that 30Wrns is plenty of power with good speakers...

I would build something like this:
Front: 2x30Wrms
Rear: 4x30Wrms
Using this configuration will allow 180Wrms (total) avoiding the need to increase voltage. Consider that you can probably easily fit 4 speakers in the rear of your car (stereo image is preserved enough thrugh the 2 front speakers).

[theChris]

"Using this configuration will allow 180Wrms (total) avoiding the need to increase voltage. Consider that you can probably easily fit 4 speakers in the rear of your car (stereo image is preserved enough thrugh the 2 front speakers)."

-i disagree. the rear speakers will adversly afect the stereo image. the image will no longer be from in front of the users but from different places. i've been in cars where there was no distinct right channel, sound seems to come from the front left or the rear.