DIY - Increasing / Improving the output of the Bose Murano Subwoofer
I bought a '10 LE Murano for my wife in early December of last year. I was very pleased with the purchase, but I was surprised by the minimal amount of bass that the Bose 7.1 system produced. At first I thought I had a defective unit; but when I went to my dealer, he opened up another '10 LE and the sub sounded exactly the same. The bass just didn't want to hit, there was very little punch.
To preface things, I know very, very little about car audio. I do know a good deal about electronics, and I had my oscilloscope, my multimeter, and my engineering degree to fall back on so I couldn't screw things up that bad. Let me just say, at the conclusion of this DIY, I had to turn the bass down to keep the drinks from shaking, so it works.
The goal of this project was to use the OEM sub and be able to return the sub back to its stock form without anyone noticing. That is why all the wiring changes have been done inside the subwoofer.
- External Amplifier (preferrably one with a gain setting)
- 20' of wire for the Amp Power supply
I used 12 gauge wire since my sub really isn't going to be drawing a whole lot of current. Read the minimum requirements specified in your Amp manual.
- ~10-15' length of wire for extensions and the ground (different colors help!)
- Terminal connectors
Please don't cheap out and just wrap bare wire around the battery bolts and ground bolts. It looks ugly and you will regret it later when it comes loose and shorts out.
- Soldering Iron / Solder
- Phillips / Blade screwdriver
- Wire stripper
- Wire cutter
- Electrical Tape
- 10mm socket / ratchet
1) Start by opening the trunk. Remove the carpet cover, lift up the access panel, and remove any storage trays or flat boards you encounter. I used a piece of wood placed against the access panel and the spare tire to hold the access panel open so I could work.
2) You should be able to see the subwoofer. Remove the retaining bracket (red arrow) by pulling straight out on it. It may take some force, but eventually it will come out. Then, remove the OEM connector from the subwoofer by pushing down on the tab (blue arrow) and pulling straight out.
3) Unscrew the large, plastic star shaped piece (red arrow) by turning it counter clockwise. Eventually, it will pull straight out.
4) Remove the subwoofer from the trunk and set it on your work table. Notice the small screws (10) on the cover. Remove these with a phillips or blade screwdriver.
5) Lift the cover away. You should see the internals of the subwoofer.
6) Notice the cast aluminum rectangle with the "Bose" stamped on it. This is the tiny, tiny internal amplifier used by Bose to power this subwoofer. Remove the four screws around the amp.
7) Gently pry up both sides of the amp with a blade screwdriver. It should be able to be removed from the subwoofer.
8) Turn the amp over, and notice the small tab on the connector (red arrow). Press this tab, and then pull on the connector to remove it from the amp.
9) Remove the insulation covering the wires. You will need about 2" to make your connections. This stuff is sticky, so rub it or peel it off the wires.
10) Cut the green and red wires (both sets) half-way between the connector and where the insulation ends. These are the wires that go to the 2 speakers in the subwoofer. Remember, one set of wires goes to one speaker, and the other set goes to the other speaker, so make sure you keep them seperated. Once cut, remove a bit of insulation from the end of each of the four wires.
11) Now, you will need to figure out how to connect the speakers. The speakers inside the Bose Subwoofer are 2 Ohm speakers. Using the instructions from your aftermarket subwoofer as a guide, you need to check the Ohm requirements for the amp.
Some things to note:
- The wires you will be tapping into from the headunit are High Level connections (~6 volts)
- The signal going to these wires is *already* filtered for Low Band Pass. This means that only those low bass hits are going to played by the subwoofer.
- The speakers inside the Bose Subwoofer are TWO OHM SPEAKERS!!!
My Sony Xplod Amp required a minimum of 4 Ohm speakers, as you can see in the picture below:
12) Therefore, in order to make the Bose Sub work with my Sony Amplifier, I had to connect both of the speakers together in series. Since resistances add in series, I had a total of 4 Ohms in my Subwoofer. I then soldered extension wires to the speaker package and wrapped the solder joints in electrical tape.
13) Now to the other wires on the connector.
- Blue wire: the "Turn On" signal that comes from the head unit. This tells the amplifier to turn on when the radio is on.
- Brown Wire: +12 Volts to the internal amplifier
- Black wire: Ground to the internal amplifier
- Red wire: + signal input to the internal amplifier
- Yellow wire: - signal input to the internal amplifier
- Pink wire: not used in my vehicle
14) Cut all the wires going to the connector. This may seem like a point of no return, but the wires are all color coded so it will not be difficult to reconnect the wires when you are going back to stock.
15) Solder extension wires for the blue "Turn on" wire, and for the + and - signal input wires. Make sure you remember which wire is which. In my case the + signal wire is the black extension wire, and the - signal wire is the brown extension wire. Once soldered, wrap electrical tape around the solder joints to prevent shorting. Also, cover the ends of the three unused wires with electrical tape.
16) Route the original cable and the 5 new wires around the path that is laid out for them. If you have it, a little cable wrap will keep the wires together.
17) Install the connector back into the Bose amplifier. Then, reinstall the amplifier into the subwoofer using the 4 phillips head screws.
18) Reinstall the cover on the subwoofer using the 10 phillips head screws.
NOTE: Do NOT hook the wire to the battery UNTIL you are directed to do so. Otherwise, you may short out the wire and blow some fuses in the car.
19) Now we need to get some power to the amp. Starting from the engine bay, open up the hood and look for the firewall grommet. The next three pictures will show you where it is.