Subwoofer amp installation - with pics
First, let me warn you that I'm not a professional car audio installer, so please don't read these as installation instructions. Second, let me offer that this installation was neither quick nor easy (most likely due to the first point made). But if you're like me, where you're willing and confident enough to tackle yourself rather than paying someone else to screw something like this up, read on.
The most difficult step in this process is drilling a hole through the firewall to pass the amplifier's power wire through. Beyond that, get ready to spend some quality time sitting in the trunk and slumped over the engine compartment and driver's side floor board. There was also a problem with the OEM head unit's remote amp signal not working with the amp I chose covered at the end of this post.
Here's the money shot:
I really need to get back in and tidy up the wiring a bit.
I chose to go with a Rockford Fosgate Punch 201S 2-channel amp to drive the 6.5" Punch HE RFP4404 subwoofer I previously installed in the OEM enclosure. The 201S is rated for 200W continuous power to a bridged 4 Ohm load. It takes a 10 gauge power wire fused to 20 amps. To each his or her own on the equipment, just be mindful in selecting the appropriate power wire and fuse for the amp.
You will need about 22 feet of power wire to get from the battery to the location in the trunk I chose to install the amp. A 17 foot kit will leave you stranded under the back seat like I was. Oh well, I have a soldered and insulated pump splice that only we know about. Lesson #1: Order plenty of power wire.
OK, here's the hard part: Drilling a hole in the firewall. There's a large grommet just above and to the right of the gas pedel that what looks like 2 vacuum lines pass through. The problem I had with using it to pull the wire through was I couldn't get to it from the engine compartment due to lack of clearance between the engine and the cowl. I decided not to chance what I couldn't get to for securing the wire and sealing the grommet back up.
Taking a hint from ultravorx's "Some amp install tips" thread, I drilled a hole here:
Cabin side
Engine compartment side
Notice that there's a wire bundle on the engine compartment side just above the spot I chose to drill. I was able to wedge a 1" x 2" down in between the cable bundle and hood release so I would tear up some wood before doing damage to any wiring. I used a right-angle drill to get to the location from inside the cabin. You won't be able to get a straight drill to this location.
I fabbed up a bulkhead fitting with a close nipple just big enough to pass the 10 gauge wire through, two nuts, and a rubber washer instead of using a grommet. I had a grommet pull out on me after installing an amp in a pickup truck a few years back, eventually cutting through the power cable. Not something I want to live through again. The rubber washer on the engine side and silicon caulk on the last few inches of the wire prior to pulling through the firewall bulkhead fitting should ensure a leak-free install.
Here's the installed wire from both sides of the firewall:
cabin side
engine compartment side
Next was running the power wire to the battery. I went straight up and then shot across the cowl to the battery side of the engine, and then followed the wire bundle across the valve cover and around to the battery.
Here's the power wire ran in the engine compartment (I used "Paint" to highlight the route in yellow):
The 20A inline fuse is just to the left of the fuse/relay box.
Running the wire in the cabin was fairly straight forward. Again using ultravorx's install tips, I ran the power wire in the drivers side wire trough. The door sills came off with even upward force, working from one end to the other.
The door sill clips insert into enlongated holes in the sill sheetmetal, which you might be able to see here:
The removal of the back seat has already been covered, so no additional explaination is needed to get to the trunk from here.
While I was at it, I decided to install a Tsumani Silencer trunk kit (similiar to Dynomat). The kit comes with 12 sq ft of the "Silencer One" matrixed mat, which the spare tire shelf took every last bit of:
The kit also comes 8 sq ft of the "Premium Silencer" (foil covered), which I used two 1' x 2' pieces of to stiffen the package shelf inside the cabin. I didn't think to take pics of this, but I covered around the rear speaker and subwoofer holes. I still have to get to the front speakers.
I fabbed up and carpeted an amp shelf out of particle board. Nothing too much to look at, but here it is prior to carpeting:
I attached it to the back of the OEM sub enclosure with two bolts. The vertical fastening along with the horizontal support of the shelf bottom is enough to make it quite solid. I didn't want to even think about drilling through the gas tank.
After everything was wired up and ready to rock, I discovered an issue with remote wire signal mentioned at the top of this post. The OEM head unit puts out a 7.4 VDC signal to turn on the OEM subwoofer amp when the radio is on. The Rockford Fosgate 201S needs to see 12 VDC to switch the amp on. Just connecting the remote signal wire from the original harness didn't do any good.
My solution was to utilize $30 worth of my electronics education and build an analog switch out of the Radio Shack parts bin to make 7.4 VDC magically turn into 12 VDC. If you look close at the first pic, you can see the little project box just to the left of the amp. The switch on the box is so I can defeat the remote signal if I ever wanted to instead of having to pull the fuse. If anyone would like a schematic / pics of this, email me. Of course, they probably make something that does the same thing for $10 somewhere.
The results? Well, for around $350 (amp, subwoofer, amp wiring kit, Tsunami trunk kit, misc Radio Shack parts), I've got much stronger bass and a few more knobs / switches to play around with to tailor the sound to my liking. What would the install at one of the big box electronics stores cost me? Don't know / don't care, it was fun and hopefully now a little more smarter for doing it myself.
Now what did I screw up so I can go fix it?
-JD
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Originally Posted by Marauder57
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