I had shared my rear woofer upgrade on another thread but I figure why dirty up someone else's audio thread with my junk. I went down the road of updating the rear subs mostly from boredom, the 770Watt Meridian system when I first got the car with around 4k miles of use seemed pretty good, lots of headroom and no complaints from me about audio quality. Lately though the low end seemed to be muddy and almost sounded like one of the rear subs was blown/damaged. I saw on one of the speaker upgrade threads @BudgetBiker had replaced his subs with some dual 2 ohm 6.5" subs from Skar Audio. I was interested in getting the subs sounding better but did not want to break the bank, these subs are a steal @ $60 a piece on Amazon! So I ordered up a set as well as some sound deadening as I planned on deadening the doors and the rear of the car (since I was in there and making upgrades).
They went in the original factory frames with some adapter rings I made from 3/8" acrylic sheet.


After applying sound deadening to the rear of the car and around the rear subs (sorry no pics of the first round of sound deadener), I could hear an improvement from the door speakers due to the sound deadener but the the rear subs were just not doing much. I figured the factory amp was just not enough to move these new subs. So I decided to do an amplifier upgrade on a budget. I searched for a simple (small/efficient) mono block amp that I could mount discretely and would do a good job at making these subs move. I found a sub on Amazon made by CT sounds 400w monoblock class D, I watched a video on Youtube where a guys that runs these amps on a dyno and rates them for output and efficiency. The amplifier's performance in testing was impressive so being it ticked all the boxes I ordered one up off Amazon ($109 !!). Only one more issue, the amplifier only accepts low level inputs so I started shopping a line level converter. I settled on a unit made by NVX model XLCA2X ($80 bucks on Amazon), it's a two channel line converter with x-bass enhancer so it is basically made to replace bass on factory systems were the oem amp rolls the base off to save the speakers.
I rewired the subs in a combination of series/parallel between the 4 coils to end up with a 2 ohm load at the amp. One thing that I know is holding back the rear subs of making any good base is the lack of any real cabinet. The area the subs are in is small and irregular with things like the seatbelt reels getting in the way of trying to create any sort of sealed space. I decided I would attempt to seal off the subs with sound deadening mat to try and get some sort of sealed space they could operate. The matting actually did a pretty good job of sealing each of the subs off.


I was able to mount the amp directly to an existing bracket between the seats with a few zip screws, the line level converter is simply velcro'd to the amp with it's adjustments accessible through the removable panel.







Couple of nice things about the NVX unit, it comes with a level controller knob that I mounted in the cubby with the CD player, it allows you so tailor the bass output/response to suite the type of music you are listening to. It also provides a remote turn-on for the amp that is triggered by it detecting that the factory amp is on via the high level speaker inputs.
So now that it's all back together, the verdict is....
Big Success!!!!
After dialing in the input gains and the filters/crossovers on the new equipment the sound is fantastic! I would say they put out slightly more than the doors put out in bass volume and the frequency is lower. No buzzing or rattles, very happy with the end product.
Total spend was $542 with tax and shipping, believe it or not the most expensive thing was the sound deadening.

 

How did you get the sound deadening to stick to the speaker surround? Is it just that sticky? I can see you also trimmed it to not interfere with the speaker itself.

 

I carefully trimmed the factory foam off the perimeter and with a little spray glue reinstalled over the sound mat. The butyl rubber backside is pretty sticky and stuck to the outer acrylic mounting rings no issue.

 

Just had to update on the sound from the powered rear subs. I finally took it for a ride and tried some different tunes that would put the rears to the test. I played some of that "dubstep" music, specifically Skrillex and OMG!! The base response is AMAZING! Super clean and tight, actually messages your back. I didn't mention in the original post but I upgraded the tweeters and mids in the doors with XJ premium units used off Ebay. I also was able to scoop up a B&W co-axial for the center channel for $50 bucks but I'm still waiting for it. I can't believe the presence the system has now, you can literally turn it up to full volume and there is no distortion.
Anyway, highly recommend the upgrade, I feel like I have a new ride, now I have both excellent exhaust AND music soundtracks!!