Update, and a tip for anyone putting bass in their trunk...

My setup still sounds great, but I had a vibration coming from the center pass-through cover when certain frequencies were hit. I picked up some 3/16" foam weatherstrip tape at the hardware store today, and ran it around the inside of the pass-through cover. The cover fits very snug now and no more vibration!

Thanks for the tip!

Where did you draw power from, did you run the power from the battery? Did you tap the rear stock amp for the line in for the Alpine amp?

My last car, vehicle before last, was a 2000 Neon. I put a single 12" sub in a box in it and put a Pioneer 150 watt bridged on the side just as you mounted it on the back. I ran the power from the battery and the line in feed from the head unit. However, before I ran the line in feed from the head unit, I used some speaker level converters and tapped off the rear deck speakers. Of course, the quality wasn't as good as the head unit's line out. That's why I ran the wire, to the head unit in the end.

Does anyone know how much power is going to the rear deck amplifier on the stock Bose system? Also, is the audio feed to this amp a line level or is some digital signal?

I did not run the power wire to the battery- I tapped into the 20a accessory port in the center console. I will likely run it to the battery eventually when I feel like tearing into the right side of the car. My Alpine amp has both line level and speaker level inputs, so I took the easy route and tapped into the rear speaker wires coming out of the amp. If you have to use line-level inputs, there is a thread on the forum with wire color/pinout info for the pre-amp line outs coming from the head unit- shouldn't be hard to find with a quick search.

The sound is incredible- this set-up will hit as loud as you want or as muted as you want- I really had to turn the down the gain and the "Bass EQ" as Alpine calls it.

Edit
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Since this post I have now tapped into the pre-amp line level outputs going from the headunit to the rear amp - pictures and details at the end of this thread....



-Sean

you should be sure that thing is secured to the car well. I had two 12's that flew back and hit the back of my trunk and it ripped the terminals out of the amp. not the terminals on the wires, the terminals on the amp itself. needless to say, my $450 dollar amp was toast after the spark shower.

That's a very good point... one that I ran into myself with this box. When it's pushed all the way towards the rear seats, it's very snug top-to-bottom (I measured it to fix exactly in there), so it's held in place by the rear deck (and 6x9's). I did however slide it out to see what the sound difference would be in the middle of the trunk, and did exactly what you did, but fortunately my ground wire snapped at the ground point when the box rolled backwards, not at the amp. I would still feel better if I had some straps holding it in- something I'll look into.

Update-- pre-amp wiring details:
 

Me again- this weekend I decided to tap into the line-level pre-amp inputs coming from the head-unit instead of the amplified speaker-level inputs I had been using. Part of this was just an experiment to see what the difference was between high and low level inputs as it would relate to a amplified sub box, but I also wanted to use the Bose AudioPilot feature again. When using the speaker level outputs, AudioPilot did some weird stuff with the bass signal- modulating between extreme bass and no bass when below volume level 10.

Anyway, below are some pics that should help anyone tap into the headunit's pre-amp outputs... I took the information from the Mazda wiring diagram as well as eXentric and Rotarygod's post regarding this subject and it did indeed work for the rear line-out. I like this option as you can use the fader if you need to dramatically reduce bass (i.e. kids in the back seat), as well as fine-tune the bass level.

As always, email or PM if you have any questions...

Pre-amp input pics
 

Here are the connectors removed from the rear amplifier:

Pre-amp input pics
 

After cutting back the electrical tape, here are the two wire bundles carrying the rear signals:

Pre-amp input pics
 

More pics of the wires to tap. I use these wiretap connectors since they're easy to use, carry a good signal, and can be removed if necessary and returned to stock with little problem.

oops... here's the pic

The connectors snapped back into the amp and the new wires bundled up with wire ties...

Slightly different topic, but here is my ground point- after removing the spare tire mount, I was left with holes and bolts on the right and left of the speakerbox- this one provided a perfect grounding point for the amp:

Lastly, here is a pic of the speakerbox with cleaned up wiring using the pre-amp inputs...

did you notice and sound difference using the pre's as opposed to speaker level?

Yeah- the bass seems to "blend in" better with the rest of the speakers. With speaker level inputs I had to adjust the bass level more often depending on what kind of song was on- might sound good with rap, but overwhelming with rock... so I was doing more adjusting to keep it optimal. Now with line-level it sounds more natural with all music, and I just crank up the Bass gain for rap/hip-hop if i really want to feel it in my chest. And I can use AudioPilot again, which keeps me from playing with the volume so much.

As an experiment I wired up a line level converter to eXentric's car to see the difference. The line level adapter was actually not as loud as the way I originally did it. Consequently it is back the other way, tapped into before the amp.

Rotarygod- The pre-amp output coming from the head unit is standard impedance and phase wiring, correct? Any idea if the rear Bose amp changes that to something proprietary or non-standard?

After driving around for a couple days now with the line-level inputs driving my sub amp, I'm definitely much happier with the overall sound from the system.

-Sean

Yea buddy that's nice I want to do something similar.

Never worked on a sound system besides the 85 skylark radio I fried that is.
 

That's actualy something I've been wondering too. I've tried a breif forum search to see if anyone else had the answer, but so far found nothing.

I don't yet have an RX-8, but plan to and am wondering if the premium sound system has a different output than the standard level. I want the premium, but I want to be able to throw an amp and subs in the back, however I have a book that states some factory premium level sound systems (like those from Bose in Fords) are designed for a different impedance level, and are resistant to modifications. Is the RX-8's sterio one of these?

Forgive me if my questions seem ignorant or stupid, but I've never actualy modified a sound systme before, so I'm learning here.

Re: Never worked on a sound system besides the 85 skylark radio I fried that is.
 

Well, you can wire it the way I did in this thread and you'll be set. The line-level outputs I'm tapping into before the Bose amp are working great. I wasn't as happy when using the high-level output after the Bose amp because the Bose AudioPilot noise levelling/cancellation feature was do some annoying things a low volume levels. Bose is known for doing non-standard configurations, but as far as I can tell the head unit is the same factory unit as the non-Bose system... it's just the speakers and amps that make it "Bose"... so tap into the wires I diagrammed above and you'll be grabbing the signal "Bose-free" : )

-Sean

hmm.. could ya make me one? what's yer price?:D

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I know this is a stupid question but once you have tapped into the FR FL RR RL , I know how to get power to the app and ground it, but what is the best way to make your app come on when your sound is on and off when you turn it off, automatically...?

I tied my amp's power trigger into a circuit that is only on when the car's ignition is on- which was the cig lighter in the center console- it's easy to wire to from the trunk.

OK, great. I'll be running my Amp powerup wire to there as well. I think others have discussed it in other a couple other messages but does your amp turn off properly when you attach to the cig lighter? Others have reported "popping" sounds due to the initial power surge when you turn things on and off..(?)