Thread: Car Amp Help!!

Originally Posted by thepurser

I am stripping out my headunit and from reading and research It appears I need an Amp to get the sound from the PC to the speakers via a soundcard.

correct, if you not be using a HU then you will need to feed your computer's low-level audio signal directly into an amplifier.

Originally Posted by thepurser

Am I correct in assuming that the sound comes out of the pc as stereo into the amp either as stereo or split into 2 sets of stereo streams

the first rule you have to learn before you even start your carputer project is... NEVER ASSUME ANYTHING!!!... now to answer your question; it depends on the computer/sound card and your software settings. if you're using a laptop or an OEM PC (HP, Dell, etc) then it will most likely have a single 3.5mm stereo output jack. if you're using a dedicated soundcard then chances are it will have at least 4.1 surround (4 separate channels plus a subwoofer output). using all 4 channels can be a pain to configure. even if you have 4+ channels available, it is often times preferred to set your sound card's settings to "2 speaker stereo" and simply use a y-adapter to split the 2 channels into 2x2 outputs (2 lefts and 2 rights, front and back play the same sound)

Originally Posted by thepurser

Is there an issue with using a 2 channel amp into 4 speakers?

no, you simply wire two speakers to each output. remember to keep the speaker impedance within the amp's tolerance range. when you wire speakers in parallel you cut their impedance in half, when you wire speakers in series you double their impedance. when you lower the impedance you raise the amp's output power, when you raise the impedance you lower the amp's output power.

most amps are 2-ohm stereo stable, so if your speakers are 4-ohms each you can wire them in parallel and the amp will see a 2-ohm load. since you are using your stock speakers, you need to find out their impedance before you can determine how to wire them up. if your amp is 2-ohm stable but your speakers are 2-ohms each then wiring the speakers in parallel will give the amp a 1-ohm load (which may burn the amp out), wiring the speakers in series will give the amp a 4-ohm load (which is fine).

Originally Posted by thepurser

Do I need a 4 channel amp?

no.

Originally Posted by thepurser

Could I use 2 2channel amps?

yes.

Originally Posted by thepurser

Found this on Fleabay.
http://cgi.ebay.co.uk/Mnew-car-boat-...742.m153.l1262
Would something like this work

it would work, but don't expect spectacular or powerful sound from it. that 180W x 2 rating is complete BS (it is an unrealistic rating based on input/environmental conditions that your car cannot provide)... basically, the peak output rating is used purely for marketing reasons, it is a useless number in determining the actual performance of an amp. cheap amps emphasize the peak output, while good quality amps emphasize the RMS/continuous output. notice how they don't include the RMS/continuous output rating on that little amp?

Originally Posted by thepurser

or am I being a complete moron

no, you're just learning. as long as you are willing to learn then there is no shame in not knowing something. I tried to explain everything as clear as I could, but if you still don't understand something, don't hesitate to ask