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A fine hello to one and all!

I have the Rockford Fosgate sound system which comes with an 8-Channel Digital Signal Processing amplifier and a 10" Dual 1 Ohm Subwoofer. I grew tired of listening to the horrible 10" subwoofer because it did not have great lows and almost no excursion so it did not have much 'Punch' to it. I set out on months of research and even called up Mitsubishi directly to get the specifications of the entire sound system which did not prove very effective unfortunately. In the next few days I will do an entire write up but for now I just wanted to share my excitement.

It turns out the stock amplifier is an 8-Channel Digital Signal Processing (DSP) amplifier. Each door speaker gets one channel (4), each tweeter gets a channel (2), and the subwoofer gets two channels (2). This means the subwoofer is effectively being ran off of a 2-Channel amplifier, with a 1 ohm current going to each voice coil. I used a multimeter to test each coil. The problem with a 1 ohm stable 2-channel amplifier is that there are almost no subwoofers that will work in the stock configuration. That is no problem though because if you bridge the amplifier you can get a a final impedance of 2 ohms. There are hundreds if not thousands of subwoofers that have 2 ohm impedance's. This amplifier will work with a Single 2 Ohm subwoofer or a Dual 4 Ohm subwoofer, I am currently using a Dual 4 Ohm subwoofer.

I purchased an RE Audio subwoofer that was so close to fitting it was stupid, however I got it to work. More on that later. Now that the woofer is wired and fits perfectly in the stock enclosure, how does it sound?? The new woofer is much cleaner, more punchy, louder and goes lower than the stock woofer however it is not a drastic change. Do I find the change in sound worth the price? Yes I do actually. While this is no replacement for a proper amplifier and subwoofer this is a great alternative to make this sound system more bearable for those of us who can't afford a new sound system (after paying for this stock one haha).

There is one problem though, a problem that prevents this from sounding much better. The DSP is the culprit that makes this factory sound system not only amazing but horrible all at the same time. Now that I have a new subwoofer, I really noticed the bass more which means I noticed my bass frequencies change automatically. This amplifier will actually raise and lower all frequencies to all speakers depending on what it thinks won't hurt the speakers. I will start a song with nice punchy bass, but a few hits later suddenly that punchy bass has been decreased by the amplifier even though the instrument in the song is the same. This double edged sword helps protect the system but ruins some of the sound quality. I did notice though that with rap the DSP did not effect the bass much at all, probably because there is so much bass frequencies in the songs that it can't lower them as much as it wants :p

NO CUTTING OF ANY WIRES OR MODIFYING ANYTHING WAS NEEDED FOR MY PARTICULAR SETUP. I can return it to 100% stock in 15 minutes

***WRITE UP***

Ok, I have been running my new subwoofer in the stock enclosure for a while now and it certainly doesn't make magic but it gave me cleaner and lower bass. I don't remember what my write up was going to have on it. As I re-read what I wrote above I notice that it already covers a lot of information.

Ok this first image is of the aftermarket woofer I installed. It is a Dual 4 ohm subwoofer from RE Audio. I chose it because it almost fit depth wise into the stock enclosure, ALMOST. More on that later. This pic shows it installed and unfortunately, without longer mounting screws, the stock grille will not fit. I dont want to get longer mounting screws so this is where I am at and I am fine with it.
[attachment=14427:IMG_0803.JPG]

Now, on to the next image. See that black ring just chilling there? That ring originally went around the edge of the subwoofer to make it look all cool. What I did is I removed it leaving just the bare metal of the woofer basket showing. It was easy to remove because it is a cheap woofer and the glue peeled right off with no problems. That black ring is what I am using as a temporary spacer to extend the depth of the woofer so it will fit.
[attachment=14428:IMG_0811.JPG]

Now lets move on. See this picture, magic isn't it? That black rubber ring is now my temporary spacer until I can make one out of wood. What I did is I put all of the stock woofer screws into the holes of the new woofer and then took my improvised rubber spacer and fit it on as shown. If you just put the spacer in without putting it on first it makes problems.
[attachment=14429:IMG_0812.JPG]

Now for the wiring. I used the Blue wire as negative and the Red wire as positive. It is crucial that you do it this way or your ohm level wont match and everything will burn like in the great Chicago fire. As I said up top, this is a 2 channel amplifier so you HAVE to take the negative from one channel and the positive from the other channel. In the stock woofer enclosure you will notice the wires are grouped in pairs, each pair is one channel. You could use the Yellow wire and the Black wire instead just dont use all 4 and dont use the positive and negative from the same channel. If you use a Single 2 ohm subwoofer your done, just plug in the pos and neg and install but if your using a Dual 4 Ohm you need to do a bit more wiring. Notice the white and red wire running off into the distance? Yeah I did that myself thank you. You have to run a pos and neg to the other set of terminals on the other side of the subwoofer, this will give power to both coils.
[attachment=14430:IMG_0808.JPG]

In this picture you can see the other terminals that I wired up the pos and neg too. Again, with a single 2 ohm subwoofer you won't have the extra terminals. Now notice the black ring sitting in the enclosure? That is the rubber ring that was originally on the subwoofer. Do as I said before, that when installing put the rubber ring on first. If you make one out of wood you wont even have to bother with a rubber ring. What you may not know is that I also installed Dynamat and stuffed the enclosure with PolyFil to help boost the sound quality even more. If I ever decide to amplifier this woofer with anything but the stock amplifier, adding the poly fiber and Dynamat will really help with the quality.
[attachment=14431:IMG_0809.JPG]

It is very straightforward is you purchase the subwoofer that I purchased. If you use another subwoofer, I have no idea how it will work, depends on depth and stuff. You will most likely need a wooden spacer ring...which again I have but I need to cut it and I dont have the tools so thats why I used the rubber thing on the woofer, creative I know :p
 

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Discussion Starter #2
The way to wire up the FACTORY amplifier with an AFTERMARKET subwoofer is simple. You said you have the wiring in the trunk still? There should be 4 wires total, two positive and two negative. If you do not have the stock subwoofer enclosure then you might have to cut into some wiring.

You need to bridge the amplifier to a Single 2 Ohm subwoofer or a Dual 4 Ohm subwoofer. No other type of woofer will work. The wire inside the stock subwoofer enclosure is in pairs, 2 pairs total. You would take the positive from one pair (which is one channel) and the negative from the other pair (which is the other channel) and connect them to your subwoofer. I dont remember the colors off hand but I can get them for you later.
 

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I used the red wire and the blue wire. The blue one is negative and the red one is positive to wire up my new subwoofer. And I added a write up at the top. I don't know if it covers everything I originally wanted to say all of those months ago but it should be everything to install a new subwoofer.
 
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