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Ok, so you want to install aftermarket subwoofers and an amplifier on your Chevy Cobalt. I will first give you a little background on my Cobalt, and then I will show with pictures what I did to bring everything together. My Cobalt is a 2008, LT/SC in black. I do not have the premium Pioneer system. Beginning this project, everything about the car was bone stock, and the kick from the 4 stock speakers wasn’t even enough to keep me awake while driving.


What I put in my Cobalt so far is 2 12” Sony Xplod Subwoofers, and a Sony Xplod 2 Channel Amp. (Not the greatest system, but an upgrade is coming).

12” may be a little bit of overkill, because I definitely had a difficult time squeezing the box into the trunk. (Actually had to drop the back seats and slide it in that way…still was a very tight fit. So measure first!)

Another goal that I wanted to reach out of this project was not tapping into the factory harness at all, and still gain control to turn my amp on and off with ease.

NOTE: BEFORE MESSING AROUND WITH ANY ELECTRICAL ON THE CAR, PLEASE REMEMBER TO REMOVE THE POSITVE (RED) TERMINAL SO ANY ELECTRICAL MISTAKES WILL NOT FRY YOUR CAR!

So, I started off with the two subs already wired and installed into an enclosed box. I found that putting the subs in first before anything else was the easiest way for me to go about it (you will see why). As I said early, the subs had to be slid in through the back seat. Next, I used self tapping screws to securely fasten the amplifier on the top of the box (again, check measurements and make sure you have enough clearance under the rear deck. If not, maybe another mounting location will be acceptable).

Now, obviously the stock radio does not have RCA jacks, so I did a little homework and purchased a line output converter from Crutchfield. It was a $20 dollar item that was well worth it. Now, if you look at the way the LOC is, I did tap into the rear speakers to make a set of RCA jacks available to put into the amp.

Next I picked up a just a simple amp wiring set from Wal*Mart that had a 500k farad capacitor in it. I mounted the capacitor on the right side of the box (originally on the left, but found that it would be more difficult to run the power and ground from that side).


Next was wiring up the amp for juice. The amp kit came included with everything that I needed, including the inline fuse. The only thing that didn’t work from the kit was the massive terminal to connect onto the positive terminal (as GM has engineered a brilliant terminal…). So instead of using the kit’s terminal, I just took a standard battery terminal that would accept a 4 gauge wire, and crimped it on with vice grips, solder, and then electrical tape. I then placed the terminal over the post that lay on the battery terminal.


From here, I ran the wire under the carpet, looped it in the capacitor and then placed it on the amp. (The terminal for the amp’s ground and power were minorly customed also. They needed to be ground down a little bit to fit in the designated spot). When doing this, only use the amount of wire that you need to make it from battery to capacitor to amp. Extra wire can result in loss of sound quality. And remember the good rule of thumb, measure twice, cut once.

From here, I found a good ground on the rear deck of the car.


I mounted the ground wire, looped it through the capacitor and into the amplifier. (Same applies as above. Only use what you need)

From here I just made simple connections from the amp to the subwoofers to power the speakers. I still had to get a way to get the amp to power on. This is where I got a little creative. I from here ran another 16 gauge wire (with a 15 amp inline fuse) under the carpets and kick panels all the way to the front of the car where I had drilled a small hole to mount a switch under the heater controls (if you are going to do this, be very conscience about drilling the right spot or you will hit something that isn’t meant to be drilled into). Ran the wire back again into the amplifier. With the flick of a switch, the amps turn on and you don’t have to chop your harness at all!

Total completion time: 1-2 hours

Pros: I really like the factory H/U in the Cobalts. XM Radio, AUX input, 36 presets…can’t go wrong. My reason for doing it this way was to keep the factory look, and if I ever had any problems and needed a warranty service, then the items can be just as easily removed. I never tapped into the harness (only the rear speaker wire…and who is really going to notice that). Great sound, even with budget friendly equipment.

Cons: The pros definitely outweigh the cons. The only con that I really had was losing the ability to control the amp from the H/U. But once I tuned the amp, and the LOC, the sound is great and I rarely find myself tinkering with it at all. The only other thing that I felt was a pain was that I do have to remember to hit the switch every time I leave to the car or it will drain the battery. So I ended up buying a lighted switch ($2.50) so it will actually light up when the switch is on.

Just a few tips for little problems I ran into. On my car, the positive and negative wires were not labeled on the speaker wires. I did some investigation, and found that on the left rear speaker, the positive is the brown (looks almost black) with the yellow being the negative. On the right speaker, the dark blue is the positive, and the light blue is the negative.

Any questions? Feel free to ask me, and I will do the best that I can to answer them. As soon as I receive my new speakers, I will put up a (hopefully) much shorter How To on the speaker installation of both front and rear speakers, including door panel removal.
 

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very nice, i was just thinking about a system for mine too but didnt wanna lose my cd changer so this works.
quick question tho. Is the battery located under that box where the totally craptastic jumpstart terminals are or somewhere else?
 

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The battery is in th trunk.


And inzandity you don't need to modify or drill holes for switches. Just run the remote wire to the fuse boxe and slide it under a fuse that is acc. controlled.
 

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Discussion Starter #4
Well, I knew that I could run to an acc line, but I wanted to be able to turn the subs on and off, especially when I parked my car for college (bad neighborhood). But here is what the switch looks like.

 

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I have the pioneer system in my car already, I have a box with 3 10's in it from my truck, is there a way to wire this in through my stock sub?
 

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I have the pioneer system in my car already, I have a box with 3 10's in it from my truck, is there a way to wire this in through my stock sub?
To be honest with you, I am not too sure about the set up for the 7 speaker pioneer system that is in some of the Cobalts. To the best of my knowledge, the amp is only 170w. Now, I am not sure if thats just powering the sub, or any of the speakers, but either way, 170w is far from enough power to get the bump out of three 10's that you want to put in. My recommendation is just to either buy an amp and set it up the same way that I have it, or buy an aftermarket H/U with preamp outputs (Harley has a thread with great pictures on how to do this).
 

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I have an amp as well and a nice alpine deck...my problem with that is that i have the xm in my car and I dont know if i can hook up the stock xm antena to my alpine deck.
 

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something better is to run the line output converter or whatever its called from the input wires on the sub, did it myself, a little harder but since the sub is already getting low bass signal, your amplifier will boost that low signal, rather than have any treble coming from just running a regular speaker
 

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Discussion Starter #11
I would try it, but I actually traded my first cobalt for a manual and got the 7 speaker system and don't really need all that much kick anymore...putting all my money into my other project.
 
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