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Discussion Starter · #1 ·
I recently bought a nice factory head unit from a salvage yard and the donor car happened to have the fosgate sub and amp in the trunk, so I went ahead and bought those too. My 04 spec v has the 7 speaker system with the small sub in the rear deck between the rear speakers. I already installed the factory HU and it works like a charm. Is there a way to hook up the fosgate sub and amp in my car? I also bought the pigtails that connect to the sub and amp, if that helps.


Thanks,
Andrew
 

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Hi Andrew, I'm going to assume that the head unit and power amp are the upgrade units from Nissan at the time the car was sold. I find it odd that your Spec-V has the smaller subwoofer package, because my 04 SE-R has the 10" woofer in its own enclosure, factory mounted behind the passenger-side rear seat, along with the amp mounted in the trunk under the speaker deck.

Anyway, the Fosgate head unit serves as a source and preamplier, leaving the speaker driving duties to the power amplifier that is mounted in the trunk. The head unit has four output channels that connect to the power amplifier, and that power amp adds two subwoofer channels to drive the 10" woofer's dual coils. Those two subwoofer channels appear to be referenced at line level from the four main stereo channels; there is no discrete subwoofer preout and pre in labeled anywhere.

There is an additional connection between the head unit and power amplifier, labeled terminal 12, and on the amp13, and I have not tested it to uncover its purpose. Since it does not have any indicated polarity, nor a return conductor, it doesn't appear to be capable of carrying audio waveforms. However, it may use the other channel's negative lines, and if so, it may be the subwoofer input.

http://www.b15u.com/threads/41891-stock-amp
 
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I was going to ask this same question. My 04 spec-v has the standard 7 speaker stereo. And my 03 SeR has the Rockford head unit, amp, and sub. How hard is it to swap systems?
 

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For the time and effort it truely isn't worth it. My factory radio and speakers were trash from the start. Had the sub go out 3 times, all replaced by nissan. Twice was the amp last time was the sub. If you want a little extra bump aftermarket FTW. Price and performance cannot be matched by 10 to 13 year old factory equipment. If you like the look of the factory headunit you can always get a line adaptor (not sure that's the exact name) thing and install after market sub in the trunk and keep the factory headunit.
 

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I was hoping it would be a simple plug and play. I all ready have after market systems in my other cars. I just kind of want the Rockford bling in my spec-v
 

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^^^But its no good, Im very disappointed with mine Its almost embarrassing to call it a performance sound package or whatever nissan called it

Going Alpine when tax refund comes :)
 

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Maybe I can just install the HU like a_brook86 did, and add a better better Rockford amp and then replace the sub woofer in the Rockford box?

Sorry I didn't mean to thread jack.
 

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^^^Now your talking. This is exactly what i plan on doing.
 

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Trust me I paid the extra $900 from the dealer for the option and I ended up replacing all of it within the year. Line out converter is what it's called to get the signal from of the speakers to run rca's from to the amp.
 

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The premium upgrade audio system has several limitations, making a modest aftermarket system comparatively better sounding. I don't know exactly what your listening needs and expectations are, but I'm confident in writing that a control unit with a decent DAC conversion stage, soft-knee antialiasing fiter or upconversion for CDs, and greater than 320kbps MP3 (even better, FLAC compatibility) and adjustable equalizer points will sound better than the Rockford Fosgate/Clarion premium system. Modern aftermarket integrated control units have at least 25 Watts per channel, providing over 10dB dynamic headroom over average listening levels in excess of 85dB on common sensitivity speakers. Bass enhancement causes most of the headroom issues. Look for a head unit with a highpass filter for the main channels, usually around 40Hz or higher, and rely upon a subwoofer for all bass under that range.

The subwoofer level is non-adjustable, as it is references off the other channel's lines. The turnover frequency is a bit high and there doesn't appear to be any low frquency equalization to compensate for the sealed subwoofer's inherent roll off, leading to bass that can be weak or boomy. The tone control provides the listener with control over two fixed ranges; bass and treble, +/-10dB. The problem is that the bass center frequency is too high and can sound muddy. That is common among low cost all in one tone IC chipsets. Common among mobile audio AM/FM receivers, the radio sound compressed, irritating, and needs alot of tone adjustment to flatten its response, compared to CD. The signal-to-noise ratio is quite poor and it's easy to tell when it has been turned on. Finally, the subwoofer power follows a non-linear gain curve. When the preamp volume is increased past setting 13, the subwoofer does not increase as much as much as the main speakers. This is done using a variable attenuation control circuit, possibly via terminals 12 to 13, although I haven't taken the time to put an oscilloscope on it.

While it says Rockford Fosgate on the front, it's actually Clarion. Like most mobile audio manufacturers, the products are made in the same factory as many others. Many control units and amplifiers feature the same circuitry, with more powerful amplifiers making use of a greater number of output Mosfets and higher gain structuring. I would not spend too much, as any mobile audio amplifier I've seen has fallen short of a good home audio one in several regards. Too much marketing, not enough engineering.

I would advise against spending alot on a speaker-to-line level converter, as a two pole stereo 5k Ohms potentiometer serves the same purpose. The converter is simply a voltage divider network that functions in the same manner using series-parallel resistance.
 

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Discussion Starter · #11 ·
Thanks guys for the information and advice. I think I've decided that I'm just going to sell the sub, amp, and pigtails. There are too many other things that need fixed on my car that should take a higher priority, so I guess I won't mess with a sound system. I'll make a post in the correct forum when I get time to take pics and whatnot.

Andrew
 

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The amp on the RF package is located in on the roof of the trunk. You could even test fit it and see where the slots fit in and bolt holes are. But, you have to take off that pillar cover or whatever its called that sits under the rear window. It bolts in from there.

Does your car have the pigtail for the RF amp that comes from the radio? It might be too much trouble if not because you will need to run wires from the HU for a factory system. Might as well go aftermarket unless you want to keep it original.
 

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Discussion Starter · #13 ·
I figured I'd give up on it. I don't have all the necessary wires ran from the hu to the rear to hook up the factory amp. Thanks for the advice
 

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Oddly this question is asked good day to you all readers...

non R/F audio is a 7spkr setup with a RADIO INTERNALLY AMPLIFIED SYSTEM the wiring is slightly different because of this.

R/F stereos have an externally amplified audio system which is the grey box under the rear deck.

How do you adapt Rockford to a non Rockford car?

1) First you must have the Rockford radio as you cannot use a pre-amplified radio sending signal to a amplifier!

2) Second you will need the Rockford amplifier and hopefully 🙏 8” of pig 🐖 tail.

3) Third you will need the Rockford subwoofer complete with brackets AND THE 🐷 PIG TAIL PLUG WITH SOME LENGTH TO IT, IMPORTANT!!!

4) Fourth you will need to be handy with stereo because it gets like into your MECP caraudio install skills. You’ll need a Metra harness, some extension of 18-22g wire multiple colors, as you’ll have to fab to take non amplifier signals from your dash to your R/F amp, and then take amplified signals from your amp back to your dash and from there to your patch in Metra harness and then the rest works like OEM.

5) Fifth as for the sub because you’ve obviously removed your deck sub and mounted the R/F amp there cut the four wires to your stock sub and that pigtail that feeds the Rockford sub you get the idea cut strip heat shrink that together know your polarity know left voice coil from right.

Easier done than said I’ve done it a thousand times CrickiKaze may suspect I’m a gremlin when it comes to wiring SCHIDT up I have installed Clarion, BOSE, R/F in cars that it did not come OEM into PHUK dudes I’ve got a 1987 Sentra with a BOSE Nissan stereo in it I know my stuff...
 

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This could make things simpler, we used to have to fabricate things like this THE HARD WAY but again LMK what you want to do and check this out...
 
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