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Okay, it’s a brand new year and time to kick things off with the first full install of the season. This is a pretty unusual vehicle and one that I have never touched before: A 2008 Acura MDX.

After going over things with the customer, we decided that utilizing the Audible Physics XR DUO, with its super wideband 3" driver, will be ideal for this truck like interior.

Let's start with the goals:

1. Achieve a good level of sound quality utilizing the stock signal source

2. Do a simple install in the back and retain as much usability and cargo space as possible

3. Mount the amps within the stock in floor tray and maintain usage of the jacks and tools, along with the 3rd row seats.

Let’s get started...

As it turns out, this generation of Acura MDX utilizes a different stock system than the last gen TL...in that it’s a data link system where the headunit does not control the volume but instructs the stock amplifier via a data link signal chain. The main system amp powers the interior speakers directly while sending a line level signal to a secondary subwoofer amp, mounted within the stock sub enclosure on the passenger side rear panel.

What this means is that we cannot tap the signal before the stock amp and have to utilize the speaker level signal post-amp for front stage and the line level signal for subwoofer. Happily though, there are no separate signal wires for midbass and tweeter so no summing was needed.

In order to flatten out the signal response and provide a master volume control (all OEM processing and level adjustment is within the stock amp thus affected by the stock volume knob), a JL audio Clean Sweep 441DSP unit was used. The master volume knob for the unit was mounted in a blank switch panel to the left of the steering wheel, within easy reach:



As the system uses Zapco DC Reference amplifiers, all tuning is done via a laptop from the front seat:



As mentioned before, the front stage consists of the Audio Physics AR DUO, the 3" XR3M super wide band transducer was molded into the stock A pillars, rewrapped in dash matching vinyl, with a press fit grille over the speaker itself. The XR is designed to work well off axis and they are done around 60 degrees off axis in this case:











 

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Pop off the grilles and the XR3M stares at you with its exotic rosewood phase plug. :)







Some build pics of the pillars, first, the ring baffles with their flush mounting walls made out of low heat plastic was aimed and secured to the stock pillar:



Next, grille cloth was pulled to form the shape; resin applied, allowed to cure and strengthened from the inside via a generous helping of duraglas/resin milkshake:



Then, filler was applied and the entire shape blended together and sanded smooth:



The interior of the pods received a layer of modeling clay to kill resonance:



Supplemented with another layer of deamplifier pro which also aids in holding the clay in place. More damper went onto the back side of the pillar panel:

 

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Then, medium dark pewter vinyl was stretched and wrapped around the pillars, this was quite a difficult job due to the drastic curvature of the pod, but in the end, with enough pulling, I got them done:







Here are the neat little XR3M wideband drivers:





Speaker cables were soldered to the terminals and wrapped in heat shrink:



They were then mounted in the pillars:





Here are the rings that make the press fit grilles:



 

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The midbass drivers went into the stock lower door location, and for the first time, I didn’t have to cut any metal on a Honda/Acura door to properly fit an aftermarket 6.5" speaker!

A combination of Closed Cell Foam and vibration damper sealed the door panel, and new speaker wires were run into the door. Oddly, the driver side door featured a Molex plug connection with a totally empty plug for me to drill and pass wires thru, while the passenger side was a simple plug in rubber boot...not that I am complaining, just find it a bit odd to have different architecture from the factory :)



Here is the XR6 midbass driver, reminds me a little of the Seas Lotus Reference but with a less pronounced phase plug and a more open basket design, wires were soldered in place and heat shrinked once again.





The stock speaker mounting baffle proved to be a near perfect fitment for the XR6, so they were retained, a layer of vibration damper went onto the inside:



And the speaker was mounted in place:





The entire structure was then bolted back into the car with the stock screws:





The bottom portion of the plastic door card received its dose of deamplifier to help kill resonance; there was simply too much electrical component up top for me to lay much damper on.

 

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Moving to the cargo area. As mentioned, the goal was to save as much trunk space as possible. So here is the normal view with the cargo mat in place, the only thing visible is the new sub enclosure on the passenger side, in the same general area as the stock subwoofer, but molded out of course. I had no carpeting that matched the dark titanium color; so instead, I went for a close match to the pewter colored leather/plastic trim. A black breathable carpet grille protects the subwoofer, the black color was chosen for its resistance to dirt and smudges, versus the lighter pewter colored carpet.



Remove the cargo mat and it still looks pretty much stock, with the 3rd row seats folded flat and 95 percent of the cargo space retained:



Flip up the door for the stock storage compartment and here is what you see. Two Zapco DC reference amps sits in the well trimmed on top with a vinyl covered board. A DC 500.1 sends 500 watts to the subwoofer, while a DC 650.6 is run in four channel mode powering the XR6 and XR3M with 180 and 150 watts a piece, respectively. The subwoofer is a Zapco ZSS10 10". Simple and straightforward:











 

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Here is the view with the 3rd row seats flipped up:



Now comes the build pics.

The subwoofer enclosure design posed by far the biggest challenge of this install: How do we obtain the proper amount of air space and mounting depth without having the subbox come past the opening threshold of the storage compartment door? After all, we only had about 5" of usable distance from that point to the side wall.

After some thought, I decided to utilize the stock subwoofer enclosure to form a two part design.

So here is the stock subbox that resides behind the carpet. It houses an 8" driver in roughly .25 cubic foot of space. The space behind the carpet is odd enough that I felt retaining this enclosure actually offered me the best utilization of air space.



The enclosure is two halves secured by half a dozen or so screws, so I took it apart. Note the subwoofer amp located within:



Next, I removed the amp and dumped a can of spray-on dampening followed by two full cans of rubberized undercoating into the interior of the enclosure to help deaden it against resonance:





The enclosure was then screwed back together with a bead of silicone caulk around the edges to ensure a perfect seal:



Next, a MDF ring was mounted to the front of the enclosure via the stock subwoofer mounting bolts and industrial grade epoxy, while the back and side received a layer of deamplifier and CCF to prevent rattling against metal:



 

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The opening that used to house the wiring plug for the stock sub amp was sealed up and new wires run into the enclosure. The whole structure was then bolted back into the car like before:



The stock side trim panel was then put back into place, minus the stock subwoofer grille. The wooden ring attached to the sub box now peaks through the opening in the carpet:



Next, I taped up the section to be fiberglassed, and secured an identical ring to the front of the sub enclosure’s ring, and made a floor piece out of 3/4" MDF:



So the idea here is there will be a ring attached to the outer portion of the subbox which will mate with the ring on the stock enclosure to form one continuous box. Here is the outer portion pulled out of the car after a dozen or so layer of fiberglass cloth:



This was then trimmed to the desired shape, and an additional 1/8" spacer ring was attached to the back, this will help account for the thickness of the carpet once the enclosure is wrapped:





Test fitment of the mold into the car, note how the two rings match up:



Next, the ring baffle with its flush mounting walls was aimed and secured to the back mold:

 

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Fleece pulled across, resin applied, allowed to cure, and then the entire structure was reinforced from the inside with 6 layers of mat and about a gallons worth of Duraglas/resin mixture, the edges and the opening for the sub sanded smooth, this results in roughly .4 cubic foot of space, making for a total interior volume of .65 or so cubic foot, well suited for the ZSS10.





Carpet was then applied:



Then the enclosure went into the car. Screws were used to bond the two rings together forming a seal, and a later of caulk went onto the mating edge for good measure. The Subwoofer was then wired up:



And done:



Here is the grille before and after carpet:





Here is the JL Cleansweep 441DSP residing under the third row seat:



And the cosmetic top panel for the amps before and after vinyl:



 

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Finally, some wiring pics of the amp rack, note that the jack is still accessible, simply undo the door holding the tools, unscrew the DC500.1 to flip it out of the way, and the jack can be removed by sliding it towards the driver side just as before.











So...that’s it...quite labor intensive but the end result was worth it for me. I will be posting a review of the XR DUO shortly, but to sum it up, they are AWESOME! Having this much of the frequency range (300 Hz and up) above the dash really makes a huge difference in an interior like this. The midbass is excellent, on par with the seas lotus reference I am used to, midrange resolution is SUPERB, and there is absolutely no lack of energy at the top end of the spectrum, in fact, there is a slight bump above 15khz built into the design...in other words, this is a two way system that sounds like a really good 3 way!

Anyway, that’s all for now...cheers! :)
 

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Nice work as usual Bing!!! Do you have plans on a true shop or are u happy with things as is right now?
 

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I was just wondering... Just a heads up, prices are cheaper on the East Coast. You just gave to put up with slightly lesser weather conditions... lol!
 

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Looks great as usual. Thanks for sharing pics and the quick review of the speakers.

Curious to know how you fastened the midbass to the stock baffle. It looks like it only had 3 screw holes?
 

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as the screw went down, the threads bites into the two side walls of that little slot, and torquing it quite well, to the effect that it would engage the clutch on my cordless at setting 5, which is what i use to torque down screws into mdf anyway, add to that i put a bunch down, it should be plenty secure. :)

b
 

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hey, nice install! im a bit curious about that sub. is that their "street" sub, the 10? i have never heard them, and am really curious how they do? i heard that they sound pretty good and take decent power, but in the SQ world its too dirty sounding? any thoughts?
 

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and what tool do you use to trim the sides off of your fiberglass after you lay it down? like when you cut out the shape of the back part of that box? it just looks so clean! i normally use a dremel, and a LOT of the little wheels for it, and im curious what your secret is
 

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hey Steffanan,

1. the zss is the "street" sub...to be honest, its just one of those decent all around subs, very nice output, decent overall performance, good transients...its not a pure sq sub by any means, but its not unlike an IDQ to be honest...a little meatier on the bottom end, but also to me works better in a smaller box like this, we thought about going with an idq, but i prefer that sub in a larger box say around .8 or more. :) in the end, for a car like this with such a large interior and only a single 10, having a bit of extra output is not a bad thing :)

2. i use a jigsaw with a metal cutting blade, slowest setting. followed by fine shaping with a palm sander and 40 grit. if you are asking about around the mdf ring...thats just a lot of sand paper done by hand slowly after rough cut with the jigsaw.


Elmer, yeah you should get to listen to it at sacramento, and perhaps let some of the other guys with better ears help tune it a bit more :)
 
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