Manntis

so I've installed a PC/Windows XP based carputer in Carmen, and want to hook up the sound. Right now it's coming out of the standard green audio jack, going to a short splitter that turns it into standard red and white RCA connectors.

I've two possible amps; a 2 channel Sony and a 4 channel Rockford. The 2 channel one is meant to hook to just a left and right speaker. The 4 channel one, left and right, front and rear.

So:

Is there a way to send sound to the front speakers as well as the rear using the 2 channel amp? I don't care if the front speaker sound is amped or not - the front only used the internal amp from my deck before and sounded fine.

If not, and I use the 4 chan, I won't be able to balance front and rear to my liking unless there's a way to set that in the amp - there's only the single left and right RCAs going into the amp.

Another option, though, is I could tweak the carputer to output sound through both the audio and mic ports for surround sound, but then I'd have no mic input for hands-free bluetooth cellphone use connected to the sound system (that'll automatically turn down the stereo if I answer or place a call)

suggestions?

rotor vs. piston

If you don't care about fader, you can just wire both front and rears to the the 2 channel... just make sure you correctly match the ohms to what your amp supports.

Personally if you have room in your case I'd get a multi channel sound card... M-audio seems to be the best non gamer 3432.1 sound cards. just good ol' stereo... I plan to get one for my PC, but the MB sound really is good, not great, but close.

maxcooper

First things first, you must use some kind of amp for all the speakers you want to run. The computer does not have an internal amp that will provide enough output to drive any speakers at a volume level that will be appropriate for the car. When you had the fronts running off your head unit before, the amp in the head unit was driving them. You need an amp.

Yes, it is possible to use the 2 channel to power both speakers. If the amp is 2-ohm stable and both your front and rear speakers are 4 ohm, you can wire the front and rear speakers in parallel and the amp will drive them. If the amp is not 2-ohm stable, you could wire them in series.

PARALLEL:
FL+ to amp L+
FL- to amp L-
RL+ to amp L+
RL- to amp L-
(and do the same for the right speakers)

SERIES:
FL+ to amp L+
FL- to RL+
RL- to amp L-
(and do the same for the right speakers)

However, you won't be able to adjust the level of the fronts are rears independently. And if one pair of speakers is significantly more efficient than the other, the efficient pair will play louder (potentially much louder, since 3 dB is twice as loud). So, despite having explained this, you probably don't want to do it.

I do recommend using the 4-channel amp, so that you can control the level. The amp itself may have a level adjustment for each channel, which would be all that you need to adjust the level of the front and rears independently.

If the amp does not have a level adjustment, you can use a line-level attenuator to change the level. You will need 2 attenuators, to use only on the front (or rear). Try the system without attenuators first, and then see if it is the front or the rear that you want to play quieter than it does without the attenuators. Remember that, due to differences in speaker efficiency, it won't necessarily be the pair of speakers that you seek to be quieter. For instance, if you want the rears to play quieter in general, you may still end up using the attenuators on the front speakers if they are substantially more efficient (and thus play much louder) than the rears. So try it without the attenuators first to be certain which pair of speakers you want to attenuate the level for.

You might be able to find some fixed attenuators that work acceptably for your application. Fixed attenuators are relatively inexpensive, like these:
http://www.partsexpress.com/pe/showd...number=266-230
http://www.partsexpress.com/pe/showd...number=266-232
http://www.partsexpress.com/pe/showd...number=266-234

I found some adjustable ones that are fairly inexpensive, too, though I haven't ever purchased anything from this shop:
http://www.installer.com/item/display_item.php?it=prc1
http://www.installer.com/item/display_item.php?it=attn

Assuming it is indeed possible to configure the computer this way (which I am not certain about)...

PRO:
* No need to purchase and install attenuator
* If you have some multi-channel media (DVD movies, SACD, DVD-Audio, etc.) it might be cool to have discrete surround output channels.

CON:
* You lose the mic.

It might be worth trying, but I suspect you will want the mic and abandon this configuration.

I would use the 4-channel amp and get an attenuator.

-Max

maxcooper

Good point, r.v.p. A different soundcard may have several advantages:
* you will have discrete FL, FR, SL, SR channels, AND a mic input
* probably a better signal than your current soundcard (lower noise floor, etc.)

If you can't fit a "normal" soundcard, a USB soundcard may be a viable alternative. (I have a cheap SB Live! USB soundcard that I use with a laptop for home theater sub EQ tuning. The USB soundcard has a line-in, and my laptop doesn't.)

On a separate note, if you hook it all up with the current soundcard and it is noisy (dirty signal), and you don't have the option of using a better soundcard, I thought of a possible solution for that: use the SP/DIF digital audio out (if the card has one) and feed it to an external DAC. It will still be 2-channel, so you will need to use the 4-channel amp with attenuators for one of the speaker pairs. But this could be a solution if you hook it all up and find that the soundcard line-level output is dirty/poor.

-Max

rotor vs. piston

Also... you can get a equalizer (I have a kenwood) that you can run two channels into and it splits it to 6 channels, two front, two rear, two sub... it has fader control and control for the subs. You can find them on ebay for a decent price and I think without getttin to fancy on the computer side would be a good options. I think Max and I are in agreement really though, not going to be happy with just the 2 channel amp if you want front and rear.