Mitsubishi Eclipse 3G Club banner
1 - 11 of 11 Posts

·
Registered
2004 Eclipse Spyder GS
Joined
·
10 Posts
Discussion Starter · #1 ·
Everyone told me to replace the stock Infinity sound system in my '04 Spyder with a modern head unit, but I like the stock system. It just needed a bit more bass! So I embarked on the subwoofer install journey. And like the jankster I am, I wanted it to be as low-cost as I could get it. Unfortunately, I didn't think to take pics until the very end, so "wall of text" it is, but I'll start with a pic of the final product for the TL;DR crowd.

Car Automotive parking light Vehicle Automotive tail & brake light Vehicle registration plate


I wanted the whole thing to fit snugly into the trunk of the Spyder, so I started with a JVC 10" and a small amp from Boss Audio. After ordering Amazon's recommended Line Out Converter and install kit, I was ready to start the project.

First, the wiring. Following instructions from another post, I drilled into the rubber grommet behind the driver's side wheel-well cover for the battery power cable. It took a few tries to realize the grommet is double-walled! Once I got the drill through both layers, I ran a coat-hanger fish tape from the cabin out to the wheel-well and used the time-honored electrical-tape-and-pull method to get the wire through the holes. Inside the cabin, I ran it down the driver's side electrical channel under the footboard trim and behind the rear seat trim panel into the trunk. Yeah, it involves pulling a whole lot of bits and pieces off the car, but worth it for an invisible install.

For the remote start, I tapped into the accessory power outlet inside the center console. With the passenger seat removed (I'd pulled it out just to have a look at the stock Infinity amp), it was easy to run from the console to the openings in the carpet for the stock amp, and over to the passenger side electrical channel. From there or was the same run to the trunk.

Since I already had both rear cabin trim panels pulled to run the power and start wires, it was easy to tap into both rear speakers to get both channels for the sub inputs, then run alongside the other wires into the trunk. That's it for the cabin!

Inside the trunk, I started by running the positive speaker outputs through a pair of passive inline low-pass crossovers, because my cheapy amp didn't have a built-in crossover. The amp did have high-level speaker inputs which I tried at first, but the output was weak, so I went from my speaker taps to the LOC and then RCA's into the sub.

I decided to install the sub on the driver's side, so I opened up the trim on that side and was happy to see how much space there actually is in there! After testing the conductivity, I connected the ground wire to the antenna bracket screw. Then I cut a plywood panel to fit across the gap in the body, screwed the amp, crossovers, and LOC to it, then bolted the panel to the body through a couple of the random holes near the antenna bracket.

With the trunk trim back in place, the only evidence of the install was the speaker wire for the sub poking out of the trim. And at that point, I realized I'd completely forgotten about the speaker box!

After some hunting online for about on hour for a box that wouldn't basically take up the entire trunk and discovering that nothing short of blowing my budget entirely would do the job, I pulled out my measuring tape and middle-school birdhouse-building skills and got to work.

The resulting geometry fits perfectly between the trunk trim and the spare tire cover, with a decent resonating chamber and front-ported labyrinth. I did think to snap a picture of it before I installed the sub in it:

Wood Automotive tire Art Font Artifact


I'd picked up some Duck heavy-duty foam weather-stripping (so much cheaper than the stuff from the auto store!) for gap-filling on my convertible top gutters, so I used that for isolation on the sub. I ran a ring of it around the hole and screwed the sub down into it. All connected this thing has a nice, solid bump that rattles the trunk lid. With some more weathering-stripping to stop the rattle, I called the install done for now. Maybe next month I'll wrap the box to finish the look lol!

Automotive tire Automotive lighting Motor vehicle Automotive design Camera lens
 

·
Registered
2004 Eclipse Spyder GS
Joined
·
10 Posts
Discussion Starter · #4 ·
It seemed like nobody in the audio communities could agree on any one material. Some folks swore by MDF, some insisted on fancy hardwood plywood, some even claimed flexible fiberboard was the best. I watched some videos where people tested different materials and they only saw a difference up on the high frequencies. So I went with what I had lying around and just made sure the box was solid 🤷‍♀️
 

·
Super Moderator
2001 Spyder GT
Joined
·
1,262 Posts
I guess we learn some things in life and we go by that. I was told by a well-known stereo shop in my area that MDF board is denser and reflects the sound better . The box you built looks good and I see you also sealed it along the seams... Good job... Now let's get a sound clip of your hard work.
 

·
Registered
2005 Spyder GT
Joined
·
498 Posts
It seemed like nobody in the audio communities could agree on any one material. Some folks swore by MDF, some insisted on fancy hardwood plywood, some even claimed flexible fiberboard was the best. I watched some videos where people tested different materials and they only saw a difference up on the high frequencies. So I went with what I had lying around and just made sure the box was solid 🤷‍♀️
Been thinking of doing something similar, but its low on my list of priorities at the moment. Thanks for the how-to, though.
I would, however, highly recommend a tough grille to protect that exposed woofer.
Perhaps you could give us a parts list with pricing???
 

·
Registered
2004 Eclipse Spyder GS
Joined
·
10 Posts
Discussion Starter · #7 · (Edited)
@Sisyphus58 I had the sub, construction materials, and low-pass crossovers lying around from previous projects, so the only things I bought were:

Boss Audio R1002 amp $40
Leige Audio 8 gauge subwoofer installation kit $20
PAC variable line out converter $10
Package of assorted electrical connectors $10

TBH, if I'd been more certain the whole project wasn't going to be an epic fail, I'd have shelled out more for a higher powered amp. The sub is 400W max at 4ohms, and the amp (200W max at 2 ohms) can barely push it to 50W.
 

·
Registered
2004 Eclipse Spyder GS
Joined
·
10 Posts
Discussion Starter · #8 ·
@Widgmaster your point is solid. MDF has great rigidity and it ages well, while OSB is more flexible and swells and weakens with humidity. But since I live in a desert, our maximum humidity is like 30% and the big issue with everything is sun damage
 

·
Registered
Joined
·
788 Posts
Been thinking of doing something similar, but its low on my list of priorities at the moment. Thanks for the how-to, though.
I would, however, highly recommend a tough grille to protect that exposed woofer.
Perhaps you could give us a parts list with pricing???
I'd look at the infinity basslink, unless you really want to make something yourself.
 

·
Registered
Joined
·
332 Posts
I will make this suggestion. SO my 2008 Dodge Ram had the Infinity system but, the radio was shot. I went with a Pioneer headunit (model NEX-2600 to be exact) with the iDataLink integration into the trucks ecu and I absolutely love this thing! I was able to keep the factory amp so I could keep all 7 of my speakers and now all my gauges can be shown on my head unit and my TPS readings can also be shown. Before I only had a dummy light. The iDataLink also shows any engine codes in the event you check engine light is tripped. The head unit as plenty of apps and Android Auto for Android phone people like myself. I really cant speak highly enough about it. I bought another 3G recently that I am swapping all my new part to from my failed GTS project car and I think I am going to go with the same radio in my 01' GT car. Just a suggestion if you want to keep the factory amp with the 7 speaker system but, have the modern conveniences of the new head unit.
 
1 - 11 of 11 Posts
Top