I like to tinker and mess around with simple mods like this so if you like to do the same, this DIY project might be something to consider pursuing. If on the other hand you are not that adventurous or skilled, i would recommend getting a professional involved as it is time consuming and you need at least a little bit of patience :)
I did an initial audio recording with the stock sub. I have a video at the end to compare before and after.
************************************************** ****
Items purchased for the install. Rather than online purchase i went to my local audio store to see what they had in stock. I checked online first and had an idea of what i wanted and they had it all in stock and on sale.
1. Kenwood KFC-XW800F
I was looking for an 8" size to replace the stock size. Also wanted a single coil rather than dual coil but either was fine. Simpler the install the better. This one is 4ohm so it matches the amp perfectly. I was also open to a dual 2ohm as well but this was in stock. Additionally, i wanted a low profile sub that would have a shallow mounting depth to fit into this tight oem space. Mounting depth on this one is 2-3/4" and fits well.
2. Alpine MRV-M250 Amp
There are a few important points to consider when choosing the amp.
a. make sure it RMS ratings match up. ie., don't use a 500W RMS amp with a 150W RMS sub, you'll blow it up. Also, consider how much wattage you really need. Do you need 1000W or will 150W suffice?
b. Buy an amplifier that has speaker level inputs. This means you won't need a line output converter because the stock wire for the sub can be connected directly to the amplifier for a signal. Makes life easier and cheaper.
c. Make sure the amp only turns on when a signal is detected. On the Alpine amp, this is called "remote sensing function". Most decent amps will do this, just make sure yours does!
So the reason i chose this amp was for all of the above and it matched the 150W RMS @ 4ohm on my speaker perfectly. I didn't think i would need more power than this for my listening tastes but perhaps if you want a huge amount of bass, you can go higher but remember this is an 8" sub so it's not going to perform as well as a standard 12" sub.
3. A generic 8 gauge amplifier wiring kit. This power cable is beefy enough to run a 500W amp and it was cheap. You can find tons of these online.
4. Polyfil for the sub box.
5. Expanding sealant tape from your home improvement store. See further down for more details.
6. Assorted tools including a heat gun, electrical connectors, wire...
************************************************** ****
Ok, on to the install portion.
Stock view of the trunk with mat and plastic tray removed. To remove the sub, you'll need to remove the foam tray obviously and a socket driver and a 10mm socket attachment to remove 2 screws and one bolt, and then unclip the speaker wire connector. Easy stuff.
Now to remove the sub, you'll need a Torx T20 bit. Sub comes out nicely.
Even the cheap Kenwood sub is miles better quality than stock. What a shame the stock speakers are so brutally cheap and piss poor quality. Almost makes me want to upgrade the whole damn system!
The side profile shows the conical shape of the stock sub and why, at least partly, it fits so easily into the stock sub box. The Kenwood shallow depth sub doesn't go as deep but it is deeper all the way around which is more important when it comes to getting it to fit.
Now here we are getting to the most difficult part of the job. Getting the sub to fit the stock box. Firstly, i had to get rid of all these little plastic bits that were sticking out of the plastic and getting in the way of a flush sub install. They are there to orient the stock sub perfectly with its cutouts. I had to clip some off and then shave some of them down as well, there are a number of them to do.
Next step will be to heat the plastic surrounding the sub opening so you can get it to fit. You'll need a heat gun for this so the plastic becomes moldable but not too hot! Don't melt it and ruin the box. This is going to take you some time and fiddling. If i had to do it again, i would basically head up the surrounding plastic and quite a bit and then drop the sub into the hole and push it around until it sits almost flush. I couldn't get it to be perfectly flush as you can see in this photo, there is a few mm gap that i couldn't get any better unless i spent a lot more time. It was easier to make a seal all around that needed to be done anyways. This solution is in the next step.
I visited my local hardware store and picked this up. Very sticky, can be aligned easily around the circular opening, and expands to exactly what is required to minimize air movement. This is what made a good seal all the way around to even out any imperfections in the plastic sub box.
You can see in this photo after applying the seal, the gap has been closed.
At this point i would recommend drilling some small pilot holes for your metal screws. I used the 6 stock screws and 2 of the ones supplied with the kenwood sub. You'll notice that the kenwood has 8 holes for screws, the stock has 6 so the aftermarket sub won't line up with them all, you'll have to drill. Key here is to make sure you have the sub exactly where you want it to be and then drill the holes and screw down firmly, but not too tight to crack the plastic. The sealant will take care of the rest. I also wrapped the speaker wire going into the box with a bit of the foam seal to make sure there wasn't any air getting through that hole either. Before you get the sub installed, make sure you have filled the box with some polyfill. As mentioned, connect your speaker wire before closing it up. I used a nice 14AWG speaker wire. Most sites recommend 12-16Gauge and my setup is pretty low power so 14gauge should be more than enough.
Here is the sub installed and ready to go back in the vehicle. Looks stock, can't even tell if you didn't know.
Now I wanted to use as much of the stock setup as possible to make my life easier. I unclipped the wires right at the stock sub and used those to make my speaker level input connection. Now you'll extend that wire and fashion some connectors to get that signal all the way to where you want your sub to sit. I have mine sitting right on top of the stock bose amp using a few strips of velcro. Here is the speaker wire in the first picture. Second picture is how it connects to my amp (not in final location, just positioned in the trunk to see clearly).
Ok, time to re-install the sub back into its original location and on to the power. Firstly, unhook the negative terminal of the car battery so we can work in relative safety! I believe it's a 10mm socket for this to loosen the nut and take it off.
Here is the location of the finished power cables for you to peruse. Make sure you run your power cable (blue in my photo) as far away from the speaker/input wire as you can to avoid any interference in the signal.
1. connect the ground cable (brown) to a bolt in the trunk. There is a perfect one left back trunk area for this. Run that cable as you see in the photo to the amp and connect.
2. connect the battery/power(blue) cable to the amp on one end first, and then connect the other end to the battery terminal. you'll have to remove the plastic protector to get access to the connectors. i can't explain how to do it but it's easy, just remove the hinge by prying it sideways on both sides and it'll pop right off without having to remove the metal brace holding the battery in place.
3. once you're done with all the connections to the amp and everything is secure, then lastly, re-attach the negative terminal of the battery.
***********************************
Now, re-install all the stock foam and trunk material. Looks perfectly stock but with a lot more bass. Adjust your bass settings on your amp and enjoy! I hope this helps some people out here planning on doing the same.
Here's a sample of some audio before/after. I think it comes through pretty well. Once YT processes it, should be available in 4K. Suffice to say, there is a SIGNIFICANT difference before vs after.
The Kenwood 150W 4ohm sub seems to be plenty powerful for this scenario. More bass gain than what I have now ends up vibrating the whole back end a bit too much. lol. Cheers.
Reply With Quote
Originally Posted by HeelBuff
.
Bookmarks