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Subwoofer install on a budget

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125
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26
Location
Seattle
#1
***Update*** Jump to page 3 for detailed revisions.

Ok. Let's face it. The Sony stereo sucks. We all know it. It's poorly thought out and even more poorly executed. The sound is flat, even with the adjustments maxed, your arm blocks the drivers side tweeters if it's up on the window sill, the sound stage is too low and wide because the tweeters are too far back in the door, etc. etc. Most glaring of all is the lack of bass. There are lots of threads on sub upgrades around here but this is mine. A little background on me, I was an IASCA competitor and SQ judge back in the mid 90's with sponsorships from Streetwires and Oz Audio. I used to dump a lot of money and resources into cars to win trophies. This is not one of those systems. I am much older and, currently, much poorer. If money was no object I know all the things I'd do to make the cabina place of sonic euphoria but this is a test to see how much improvement in sound a minimum investment can make. Also, I wanted to have the entire system fit under the rear cover with room still for my road emergency kit, Get Home Bag, and California Car Duster. All this plus a cost of under $100. I knew I'd be sacrificing on some things, which kills my soul after what I'm used to running, but taking a hit on brand snobbery was worth it to improve my daily commute. So here goes...

Sub - Boss Audio CXX8. 8" subwoofer, "600" watts, 4 ohm SVC, seals in .35. cubic feet. $26 on amazon.
Amp - SoundStorm SMCM200. Monoblock, 2 ohm stable, 200 watt class A/B amplifier. $29 on amazon
Wiring - Boss Audio Kit Zero 10 gauge wiring kit. $10 on Amazon
Wood - 2x4' sheet of 1/2" MDF. $10 at Home Depot
Carpeting - Roll of black automotive carpet. $10 at AutoZone.

So, all in all I'm on the hook for about $85 in materials, about half the price of a cheap super shallow powered sub. Granted, I had other things like glue, fasteners, RCA block, etc on hand that would add to others' cost, so YMMV.

I used the calculator at carstereo.com to figure out my box volume. I made it just big enough to tuck in by the passenger side rear tail light. External dimensions were 17" x 10.5" x 5", giving me an internal volume of about .35 cubic feet for a basic rectangular box. I have the ability to upgrade a small volume (~.5 cubic feet) 10" sub down the road if I want to build an L-shaped box to use wasted space around the rear hinges for the cargo floor, but in the interest of simplicity I went basic for now. I constructed the box using Gorilla glue and an 18ga finishing nailer. I figure that this should be adequate for a cheap 8" and would save the risk of splitting the thin MDF with screws. If I move to a 10 I can always go back and pre-drill/screw it together between the nails then.

DSC_15551.jpg

DSC_15561.jpg

Tomorrow I'll wire up the amp and get it installed and we'll see what happens.
 


Last edited:
Messages
103
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23
Location
St. Ann
#2
If it works (and I assume it will), you can't beat that price. I used to dump lots of money into systems as well, so I can appreciate someone taking the budget approach.
 


Messages
98
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26
Location
syracuse
#6
As a former SPL competitor I cringe at that subwoofer. I really want to do something in my car but everytime I do. I can't seem to allow myself to drop the quality that much and don't want to spend what I need to, to make it nice. So I end up doing nothing.
 


OP
Stormy
Messages
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Location
Seattle
Thread Starter #7
I've got everything wired up except for the damn power lead. LOL. Getting into that firewall grommet is a royal pain. I tried going into the symposer outlet and it felt like I was catching on something around the firewall as well. Maybe a mesh plug or something? Anyhow, I'll post again with all the pics and stuff once I clear this hurdle.
 


OP
Stormy
Messages
125
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Location
Seattle
Thread Starter #8
Posting this from my driver's seat with a sh*t eating grin on my face. I am very ecstatic with the end result. I have the little guy at about 2/3 gain and crossed over at around 120hz. It is exactly what I wanted. Great mesh with where the door speakers leave off, with a nice thickness to the sound and a bit of punch. Drum and bass and hip hop now have a warm bottom end and some good rumble, without being boomy. Blues and rock have depth and more clarity since I was able to dial back the bass from the doors.

So in other words, I am very pleased with the end result. The only reason I would jump to a 10" would be for a bit more pronounced punch and depth but I am very happy with my 8 and the neighbors are none the wiser.

I will post pics when I get back to my PC.
 


CanadianGuy

4000 Post Club
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Southern Ontario
#10
Silly question but seeing how much room is below the sub floor would using an MDF subfloor and mounting the sub in the center firing up not work? Loose less space in the boot.
 


OP
Stormy
Messages
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Location
Seattle
Thread Starter #11
If I get what you're asking, I think it'd be too tough to get it to seal well. Even a freeair sub needs a definitive seal between front and rear sections of the speaker.
 


CanadianGuy

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#12
If I get what you're asking, I think it'd be too tough to get it to seal well. Even a freeair sub needs a definitive seat between front and rear sections of the speaker.
hmm. Ya an ending up making a box for the underside of the cargo tray just gets way more complicated. I think I will go your route.
 


OP
Stormy
Messages
125
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26
Location
Seattle
Thread Starter #13
Okay, we are back!

As I said before, I'm really stoked on the final result. I did some driving to test things out at highway speeds and with some more music. When I was test listening in the driveway I started with real bass heavy music and was reveling in the vibes :) but when I got down to brass tacks it was a little boomy so I ended up lowering the crossover a hair to about 100. The end product is still fantastic though. The sound has so much more depth and fullness and the stock speakers are clearer with trying to handle less low end on their own. The little amp gets pretty warm. I may have to find a way to add cooling. We'll see now that I have it turned down. I also get a bit of a turn on pop when I fire up the car. I'll have to sniff that out. Finally, with the carpet, the mounting height of the speaker and all the padding on the underside of the trunk panel, I was resting ever-s0 slightly on the sub. I used a couple of scraps of 3/4" MDF to make small blocks, which I painted black and velcro'd to the underside of the panel. They rest on the two tabs that the panel normally sits on and gives me clearance. If you're going to use my design, knock an extra 1/2" off the height of the box... or just do what I did. You can't even tell.

Anyhow, on with the pictures!

I decided to go the route of using a T-Tap on the Brown and Yellow wire for the remote, simply because I had T-Taps and no mini fuse add-a-circuit things to use in the glove box fuse panel. It seems to work just fine.

IMG_6680.jpg

As previously mentioned, I had a beast of a time trying to get the power wire through the main loom grommet. I ended up using some 9ga utility wire as an electrician's snake. It was stiff enough to push through the grommet, then I taped the power wire to the end and fished it out. Wish I had thought of that in the first place.

DSC_15671.jpg DSC_15681.jpg

I also used T-Taps to splice into the rear speaker wires behind the passenger b-pillar. Just pull off the little panel behind the seat belt to get to a bundle of wires recessed in the pillar, rather than cutting all the tape off of the run that's bundled along the pillar post. The car is a lease and if I decide not to buy I didn't want cut speaker wires. This way was also less hassle. I only used the left side because the amp is a monoblock. I just used a run of 14ga speaker wire off the taps.

DSC_15621.jpg

The power and remote wires were run down between the trim and the weather stripping, just like everyone else.

DSC_15581.jpg

The amp uses these little plug and play quick release harnesses. Kinda janky compared to standard screw down terminals, but at this price point not surprising. They do make it super easy to remove the amp and box if I ever need to. Plug, plug, done. I put heat shrink tubing over all the connections, because electrical tape is ghetto. I did use E-tape for bundling wires, though.

DSC_15651.jpg

And here's the final product. I screwed the amp to the back of the box, because I could. Levels and crossover settings are along the left side for easy adjustment. It fits snugly between the rear of the trunk and the riser for the deck cover.

DSC_15661.jpg

And that's it!
 


Last edited:

CanadianGuy

4000 Post Club
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#14
[MENTION=4755]Stormy[/MENTION] nice job. Are all you sound test with the rear cargo floor back it or simply the way pictured above?
 


Messages
98
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26
Location
syracuse
#16
I feel like my fiesta only having 4000 miles on it rattles enough just driving around. Can't imagine the rattles a sub would bring.
 


MKVIIST

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#17
Nice job on the install.
 


Messages
108
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14
Location
Eastern
#18
I feel like my fiesta only having 4000 miles on it rattles enough just driving around. Can't imagine the rattles a sub would bring.
I've had my 12" RF sub in for about 3500 miles now, and I listen to it pretty damn loud. No rattle. Not even on the outside. Thought it would sound like crap outside the car. All you hear is deep bass.


Sent from my iPhone using Tapatalk
 


LaserWhisperer

Active member
Messages
562
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201
Location
Portland
#19
Okay, we are back!

As I said before, I'm really stoked on the final result. I did some driving to test things out at highway speeds and with some more music. When I was test listening in the driveway I started with real bass heavy music and was reveling in the vibes :) but when I got down to brass tacks it was a little boomy and overpowering for average use. I ended up turning the gain on the sub way down to about 2/5 the max (down from about 2/3) and lowering the crossover a hair to about 110. The end product is still fantastic though. The sound has so much more depth and fullness and the stock speakers are clearer with trying to handle less low end on their own. The little amp gets pretty warm. I may have to find a way to add cooling. We'll see now that I have it turned down. I also get a bit of a turn on pop when I fire up the car. I'll have to sniff that out. Finally, with the carpet, the mounting height of the speaker and all the padding on the underside of the trunk panel, I was resting ever-s0 slightly on the sub. I used a couple of scraps of 3/4" MDF to make small blocks, which I painted black and velcro'd to the underside of the panel. They rest on the two tabs that the panel normally sits on and gives me clearance. If you're going to use my design, knock an extra 1/2" off the height of the box... or just do what I did. You can't even tell.
Hey Stormy, I mirrored your setup, I also have the annoying turn-on pop. Also mine stays powered ON after shutting the car off, does your setup also exhibit this behavior?
Regarding the turn on pop, were you ever able to rectify that?
 


Spaceman_Spiff

Active member
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528
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123
Location
JeffCo
#20
Hey Stormy, I mirrored your setup, I also have the annoying turn-on pop. Also mine stays powered ON after shutting the car off, does your setup also exhibit this behavior?
Regarding the turn on pop, were you ever able to rectify that?
Does it go off after you open the door? Maybe it's related to the power-off delay when the car is turned off...

Sent from my Spaceship
 




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