How to: Install an aftermarket amp and sub in your Gen 1 MS3 with a factory Bose stereo

[abdicus]

Disclaimer:

I am not a car audio professional, the following “how to” (whether technically correct or not) is the method I used to successfully install an aftermarket amp under the passenger seat (this tutorial requires removal of the factory sub) of a 1st generation Mazdaspeed 3 equipped with the factory installed Bose stereo, along with the installation of an aftermarket 12” subwoofer. It is provided only as a rough guide to assist any do-it-your-selfers.

Tools you will need:

10 mm socket wrench
14 mm socket wrench
Standard size flat head screw driver
Jeweler’s/Precision flat head screw driver
Wire cutter/stripper
Needle nose pliers

Suggested tools:

Electric drill driver or electric impact wrench
Soldering iron

Materials:

Amplifier (Used here is an Alpine MRP-M500)
Amp wiring kit (this should include speaker wire for the sub and RCA cables for a high/low converter if you need it depending on the type of amp you have. This “how to” does not include installation of a high/low converter as this amp doesn’t require one.)
Subwoofer w/ enclosure (Used here is an 12” Alpine Type R)
14 to 18 gauge additional wire (basically any kind of wire would work here, I just used some I had from previous projects)
Electrical Tape

Suggested Materials:

Sheet of plastic/plexiglass/metal etc; anything to mount the amp with. There are bolts already in the floor where the factory Bose sub was installed under the passenger seat. These bolts offer a great way to secure your amp in order to prevent it from shifting around while driving. I’m sure many of you clever do-it-yourselfers will figure out ingenious ways to secure your amp, this is just the method I found to be useful. Ultimately, though, this is merely a suggestion because you don’t need to secure the amp, however it is highly recommended.
Wire splices connectors
Wire couplers
Zip ties
Loom tubing

How to:

1) Whenever working on a project that includes the electrical system of your car, it is always advisable to disconnect your battery to prevent shock or unintentional grounding or shorting; use your 10mm socket to disconnect your positive battery terminal (I’ve seen others instruct to disconnect the negative battery terminal, unfortunately this is where my non-professional nature falls short: I disconnect the positive terminal when working on the electrical system, and that works fine [or so it has for me], I don’t know if there is a difference between disconnecting the negative or positive terminal [i.e. if one is better than the other]). This is, of course, done after taking the plastic battery cover off. I don’t have pictures of this because anybody thinking of taking on this project should already know how to do this.

2) a) The next step is to gain access to your factory installed amp (under the driver’s seat) and your factory installed sub (under the passenger’s seat), so you need to remove your front seats. The method to remove both seats is practically the same. If you slide the seat all the way back you will notice at the front of the seat, down where the seat is attached to the floor, two plastic pieces covering the two front bolts (see picture below).



The easiest way to get these plastic pieces off is to slide your flat head screw driver underneath the plastic cover right at the front of it and just turn it a ¼ turn. This will pop the plastic cover right off. (Be warned, however, that whenever working with plastic pieces and moldings like this, it’ll behoove you to be cognizant of how the pieces are attached. If you pull too hard or in the wrong direction on any of these pieces, you may break the fasteners that hold it in place and it will annoy the crap out of you.) After you get the front plastic covers off, if you then slide the seat all the forward, you will find similar plastic pieces covering the rear fastener bolts (be equally aware when removing these pieces).



Once this is done, you can now use your 14mm socket to unscrew all 4 of these bolts and your seat should now be loose enough to move around.

b) After the bolts are taken off, you will now have access to the wiring harness under the seats. Remember that you have side-impact airbags in both seats, so there are wires attached to the seats that need to be unplugged before the seats can be fully removed. To do this, if you approach the seat from the front and lift it a little (now that the seat is unbolted it can be moved around a bit), you will see a black plastic box attached to the underside of the seat on the side closest to the center console (this should be true for both sides).



It is obvious when looking at it that there is a bundle of wires going into this box and more wires attached to this box at the back. This box can be detached from the seat when you are at the front of the seat by using your precision flathead screw driver and lifting up the little securing clip found on top of the black box, which secures it to the metal overhanging mount, while sliding the black plastic box toward the front of the seat. This should just be common sense. Still, however, the seats are not completely free. Now you have to detach each of the wires from the back of this black box and you can use the precision flathead screwdriver again to do this. Mind you to be careful when pulling these wires out of the back of this black box. If you tug too hard, you may actually pull the wires out of the connecting unit, and this will probably give you a headache to fix. Thankfully, though, once this is done, the seat is ready to be removed. Now, both of the driver’s seat and the passenger’s seat are removed the same way. Take note, however, that the passenger seat’s seatbelt is attached to the seat, so when it is removed it must stay close to the car if you don’t want to bother with detaching the seatbelt as well. But otherwise, if you slide the seat all the way forward, and tilt the seat forward as well, you should be able to lift it up and turn it out through the car door. Be careful not to grab the seat adjustment bar under the seat near the front when lifting it (like I did repeatedly), because the guiding tracks under the seat will move independently of each other and will become misaligned. It’s not hard to straighten out if you do, it’s just extra work.

3) Now that you are staring down at a car with no front seats, both of the factory amp and sub are in full view and easily accessible. First thing will be to pre-wire your speaker wires. To do this you are going to need to access your pre-amp wire bundle which is identified by the blue securing clip (the one on the right when you are standing at the driver’s side door).



The wires leading into the amp are going to be taped together with black electrical tape and coming from a source under the carpet. It may feel like there is not a lot of slack, but you need to remove about 2.5” of this electrical tape in order to have enough room to splice into the speaker wire. Once the electrical tape is removed, you’ll need to locate the following wires:

L-: is yellow w/ a light blue stripe------- R-: is white w/ a light blue stripe
L+: is brown w/ a light blue stripe------ R+: is yellow w/ a green stripe
The remote wire is practically solid light blue with a tiny white/silver color on it.

You can use your wire splicer to attach the wires that will be running to your amp. Now, because the amp will be going under the passenger side seat, what I did was ran the newly extended wires under the center console for concealment. There may be better ways to do this, I just wasn’t prepared to pull up the carpet to run the wires underneath.

4)With the speaker wires done, you’ll want to begin the next step by removing the factory sub enclosure. The enclosure is secured by 3 bolts. Two are immediately noticeable; these are the ones closest to the back seat. The third is located under a flap of carpet at the front of the enclosure. You’ve probably also noticed the wires that are attached to the outside of the enclosure. At each place this wire bundle has been secured to the enclosure, there is a plastic retaining clip holding it. If you look underneath each one of these points, you can see that if you were to squeeze this clip together at the base with needle nose pliers, you can simply pull the wire free from the enclosure. You’ll want to do that at each one of these points until you come to the connecting clip that attaches these wire to the sub wires; you’ll also want to disconnect this clip. The sub enclosure should be free now and it can be removed from the vehicle. (I’m sorry I don’t have pictures to illustrate this step, but if you’ve made it through the seat removal, this shouldn’t be a problem.)

5) Next is the step for wiring the new amp. You should have your amp wiring kit which (at least for my rated amp) comes with, at minimum, an 8 gage power cable. This cable is going to have to run directly from the battery under the hood straight to the amp. To do this, you will need to pass the cable through the firewall in the engine bay. Fortunately, there is a way to do this with our cars that does not require drilling. To start, and this will also help to organize the speaker wires coming from the driver’s side, you’ll want to dismantle your center console. Don’t worry; this is very simple in our car. With the e-brake up, you’ll need to open your center console compartment, and at the front of that compartment you need to just pull the plastic straight up:



After this piece slides off over the e-brake, the next piece (the one that covers the console where the gear shift is) will come off in the same fashion. This will just make it easier to inconspicuously run the power cable to the amp under the seat. After the console is open, you next need to turn your attention to the passenger’s side foot space. If you look up underneath the glove box, you will see a black panel that can be released by two clips. This plastic panel can be put aside.



Uncovered by this panel will be a fuse box of sorts (no, I don’t know what it’s for but I’m sure the operations manual can tell you if you’re interested). This box is also loosed by two retaining screws; these screws can be turned by hand, however, and only need something like 1 rotation.



Once the fuse box has popped down, you’ll need to give yourself more working space. If you lift the fuse box near the rear of it, you can loosen it from its back hinges to give you some more hand space. Once this is done, (just to orientate yourself, I imagine you should be halfway into the car from the passenger side with your knees on the ground outside of the car) you should be able to see past the fuse box to the internal side of the firewall. Over the top of the fuse box, in the upper left hand corner, there should be some A/C metal tubing (I’m assuming it’s A/C tubing) going into the firewall with insulating material surrounding it. You’ll need to loosen some of this insulation by peeling or scratching it back with your hand (in the picture provided you can see a little bit of the red cable going through, obviously this picture was taken after I had already ran the wire through and your vehicle will not have that wire going through there yet).





If you go around to the front now, and look down into the engine bay from the passenger side, you should be able to see these A/C tubing coming into the engine bay from the car. Because you have already loosened the insulation from the inside, you should be able to take your power cable and push it though the insulation from the engine bay side; it should now be poking through the insulation on the inside; you can grab it from the inside and pull it into the vehicle.



Closer:


From the engine bay side, you’ll want to take note of how you run the cable from this area at the A/C tubing to the battery; in particular, you’ll want to make sure you keep this wire BEHIND the heat shield that surrounds the motor. If not, it will probably melt your power cable and cause you more work in repairs. Of course at this point you’ll want to install the inline fuse that should have come in your amp wiring kit. Keep it close to the battery if you can, and make it easy to access for future work. In my case I actually mounted it on the outside of the battery box and ran the wire into the box with the rest of the wiring bundle.



After the cable is in the car, you can run it down the length of the center console until it gets to the passenger seat. You can also take the time to consolidate the speaker wires coming from the driver’s side, seeing that the center console is already open. This is also a good place to utilize your loom tubing if you have it, just to keep things tidy. After this is done, you can put the fuse box and black panel back, as well as put your center console back together.

6) Now that the power cable is at your passenger seat, you can think about putting the amp in place. Of course, however, you need to pick a spot for your ground cable as well. I chose to put my ground wire between the seat (where it mounts to the frame on the back, passenger side bolt) and the frame. Remember, when choosing a spot for your ground cable, be sure to sand any paint off of the contact so it will have the least amount of resistance possible. If you have any problem with your amp cutting in and out, it will probably be due to a bad ground connection. This is also a good time to connect your speaker wires up to the wire harness that came with the amp. Be sure that you are matching up the wires correctly. This is also the time I chose to mount my amp to the Plexiglas I bought. I couldn’t think of another way to secure the amp, so I bolted it to a piece of Plexiglas and used the two floor bolts from where the factory sub enclosure was fastened too in order to keep the Plexiglas from sliding around.



I don’t think it is necessary for me to go over placing your new sub in its new enclosure, I’m assuming that’s done already. I will note, though, that I ran the speaker wire to the sub by sliding it underneath the rear door runner to the trunk. This kept everything nice and stock looking with the exception of the big sub in the back. You’ll probably want to take this time to reconnect your positive battery cable and test your new sub. If all is well you can go ahead and reinstall your seats while remembering to reconnect the airbag wiring underneath (you’ll have a constant airbag light on if you forget to do this).



I think that’s all! I most likely forgot something seeing as this became a long write up. I probably didn’t need to include everything I did, but hey, it doesn’t hurt. I hope this helps some of you do-it-your-selfers. Just remember that your biggest ally is being alert and paying attention to what you’re doing while you’re working. If you have questions, I’ll try to answer to the best of my knowledge, but I assure you there are more qualified individuals out there. Good Luck!

Quick video of the bass (Please don’t judge this system off of the sound quality from this video, it sounds terrible- this is a not a video recorder it is just a camera with video capabilities, ie. the microphone sucks. The bass creates so much air compression in the cab that it comes off sounding like wind in this video, which overwhelms any music you should be able to hear. The bass is actually really well balanced for the capabilities of the factory Bose speakers. This video is just an attempt to show the amount of bass that can be felt through the car):

YouTube - Visual representation of the bass of this system.

YouTube - Visual representation of the bass of this system.

[ahskeetz]

wow, thanks for the writeup, i'm sure the community will appreciate it!

[emag remrofni]

That was one hell of a write up. Well done.

[bnoon]

Hell of a lot of writing man! I prefer to enter the cabin for power wire/etc. at the grommet behind the battery box on the driver's side as it keeps it a bit more hidden. For all of the effort you went through, why didn't you tuck the wires under the carpet???

[abdicus]

Haha, honestly... Because i'm a noob and it was the first time I've ever installed any type of car audio equipment. The only reason I did the write up was because I had done about a week and a half of homework before buying the equipment and attempting an install. I had found various things to help me online, like what wires to splice and where to enter the cabin, but I didn't find it consolidated like this. I'm sure it exists, I was just trying to help others like me who would have felt intimidated by a project like this. Surely not the best install ever, but it works and I'm enjoying my bass.

[spekkio]

Just wanted to say thanks for this writeup. I recently got an amp, cap and box from a friend of mine and wanted to install it myself but really didn't know what I was doing. This post gave me the info I needed to do it myself and I'm happy I did as I learned a lot in the process. Only thing I did differently was route the power through the grommet behind the glove box. I don't know how you actually managed to get it through the way you did lol. Thanks again!

*edit* Funny story my factory bose sub somehow ended up with a bunch of change in it and I managed to find about a dollars worth of change in there.

[vr4_3000]

Yes thank you for the write up. Very nice. Did this today finally. The only 2 things I changed was. Ran the power wire in from the main grommet behind glove box. actually took glove box out and didnt have to mess with fuse box at all. ran wires down pass side. And the other is that i put the amp in the trunk.

[getoutandlive]

Originally Posted by spekkio Just wanted to say thanks for this writeup. I recently got an amp, cap and box from a friend of mine and wanted to install it myself but really didn't know what I was doing. This post gave me the info I needed to do it myself and I'm happy I did as I learned a lot in the process. Only thing I did differently was route the power through the grommet behind the glove box. I don't know how you actually managed to get it through the way you did lol. Thanks again! *edit* Funny story my factory bose sub somehow ended up with a bunch of change in it and I managed to find about a dollars worth of change in there.

I've taken my factory bose sub out twice now to get change out, its a bitch. the last time i took it out i out a screen over the opening so change coudn't get into it again, that helped major. Now i'm pulling the sub out compeltely to put in a 12 in the back

[AndyMS3]

It looks like some old lady is glaring in your back window dude.

TURN YO BASS OF HOOLIGAN.

[kgb]

LOLOLLOLOLOLOL at that old lady looking in...you should have been like, yo nigga, we gotta problem hur!!??

[BOTTLEFED08]

its a little late on this topic here.. but I was cleaning out my 09' ms3 gt, and I found a white two pin plug, unplugged with two tee-taps on it.. its a white and a silver wire. just kinda wondering whats supposed to be underneath my seat on the passenger front side??? I noticed the airbag box thing, but I couldnt find anything else under there where it could plug into, or why the previous owner taped into those wires. I did also find that the two bronze screws on the bolts under the seats that stick up where very loose, finger loose. any help would be appreciated.

[surfwagon]

FWIW. I did that mod in '08. My install was not as complicated. Very happy after adding a sub to the Bose system

[baseballa1433]

Completly ripped my 08' speed 3 apart trying to wire the remote to my head unit. This just made my life a lot easier.

[TheSki1974]

I followed these steps except I only tapped in and ran the wires from under the driver's seat, back to my amp in the rear. I left the sub under the passenger seat alone and it worked great for about 2 months.

Last Friday, I noticed that there was no power to my amp and no boom. Pissed me off because I like boom. I performed minor troubleshooting (fuses and connections) but couldn't find a problem. I noticed that the amp powers up and I get sound from my subs with the ignition on but not with the engine running. I tried to do it in reverse by intentionally stalling my car to see if the amp would kick on... the amp is smarter than me. Any ideas as to why this is happening? I'm sure it has to do with a signal spike or something caused by the ignition turning over or some weird load placed on the alternator when the engine's running but I'm not patient and I'm hoping that someone has run into it and has a simple fix.

[Mazd1222]

Great write up just need to know if this also applies to the speed 6 with bose as well