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Discussion Starter · #1 ·
I'm looking into installing a new head unit in my 2009 Altima. I have done lots of searching around and have found some of the information that I will need in order to install a new deck while maintaining the rest of the bose system however I do still have a few questions. The deck that I will be installing is a Kenwood DDX9902s. From what I have read there are the things that I know that I will need, please correct me if I'm wrong.
1. An iDataLink Maestro ads-mrr to maintain my factory steering wheel controls, bluetooth, and to get diagnostic information to the deck
2. Metra 40-NI12 Nissan 07-Up Antenna Adapter
3. Metra 70-7553 Harness to integrate the audio signals from the head unit into the bose system.

The way that I understand it is that the audio signals from the head unit need to be toned down before they are sent to the stock bose amplifier in the back of the car and this is what the Metra 70-7553 harness will do. The four rca's on the harness connect to the audio outputs on the rear of the deck and each correspond to the front and rear, left and right speakers. So with the harness I will still have control of fade. There are just a few things that I am still wondering about for the install.

1. How will I be able to maintain control over the stock subs that come with the bose system. Being able to control the bass level is something that is pretty important to me so I would definitely like to figure out a way to do this.

2. The bose speakers are 2ohm however most aftermarket decks use 4ohms. Does the Metra harness adjust the impedance so that everything will function properly or is there something else that I will need to add to adjust for this.

Any help would definitely be appreciated and if I can get all of this figured out then I might to a writeup with my install.
 

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09 Altima 3.5SE 6MT Sedan
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Stock BOSE amp is expecting line level inputs, not amplified speaker outputs. If your deck has line outs then the local wisdom is to connect the differntial inputs on the AMP to the single ended line outputs of your deck, positive to positive, negative to ground (BOSE amp to Deck).
 

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Discussion Starter · #3 ·
Okay so basically that is what the Metra wiring harness does. The RCA's on the adapter plug into the preamp outputs on the deck which will then be sent to the stock Bose amp in the back of the car at preamp levels. To get control of the stock subs I'm going to buy a couple of RCA cables, hook them up to the two preamp sub outputs on the back of the deck, cut the cables open and attach the positive and negative wires to the wires for the subs so the audio signals for the subs will also be sent to the stock amplifier at preamp conditions. If I do that everything should work properly correct?
 

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09 Altima 3.5SE 6MT Sedan
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Ok, I haven't looked at the wiring super closely, but the whole point of a BOSE system is it takes those 4 line level inputs (Left, front and rear, Right, front and rear) and internally does some math ie digital crossovers and spits out 5/7/9 or whatever number of drivers your car has, as amplified speaker signals. You won't drive the subs off the line outs (pre amp) outputs from your HU...will need (to add) dedicated amp(s) if you want direct control of subs from your HU.
 

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Discussion Starter · #5 ·
Okay yeah I see what you're saying. I know that I have the 9 speaker system. 3 tweeters up front, two front door speakers, rear door speakers, and two 6x9 "subs" in the rear deck. I guess it all depends on how everything ends up being wired when I take it all apart. I haven't really found any good wiring diagrams for the Bose system in an 09 Altima yet. The reason I think that there might be separate wires coming from the stock head unit for the two rear deck speakers is because you have control over bass with the stock head unit.
 

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09 Altima 3.5SE 6MT Sedan
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If you look at the AV section of the FSM you'll see the BOSE amp sends out a pair of wires to each driver (amplified signal). You'll also see that the HU only sends 4 audio signals in to the amp (as stated above). All else is digital signal processing to generate the spacial and frequency separation.

One thing that you could do, which M-train hinted at in another post would be to add a big audio cap (>1F) under the rear deck spliced into the power feed to the BOSE amp..not the amp_on signal, but the actual main power line. That should provide more available "punch power" for heavy voice coil excursions and so provide a crisper thump to the subs. Haven't tried it but the theory is good.
 

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Discussion Starter · #7 ·
I was looking at the wiring diagrams in the FSM and I've found a way that I think I'm going to make this work. Obviously there are wires coming out of the stock bose amplifier that go to the two rear deck speakers so if I was to add another amplifier solely for the rear deck speakers this should work. All I should have to do is to cut the wires coming out of the stock amp and bypass them with the audio signals from the aftermarket amp. The aftermarket amplifier would then be connected with an RCA to the sub output on the head unit and this should give me full control over the rear deck speakers.
 

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09 Altima 3.5SE 6MT Sedan
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I was looking at the wiring diagrams in the FSM and I've found a way that I think I'm going to make this work. Obviously there are wires coming out of the stock bose amplifier that go to the two rear deck speakers so if I was to add another amplifier solely for the rear deck speakers this should work. All I should have to do is to cut the wires coming out of the stock amp and bypass them with the audio signals from the aftermarket amp. The aftermarket amplifier would then be connected with an RCA to the sub output on the head unit and this should give me full control over the rear deck speakers.
Yup, that's what I was hinting at earlier--take your HU sub pre-amp outs and separately amplify them. I'd still splurge on a capacitor for your new sub amps, and you'll need to wire a new circuit back there for power, and you'll need some new good ground(s). Watch out for the driver impedance...not sure what the Bose 'subs' are...but make sure your amp will handle their impedance.
 
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