Crank up the tunes
I’m an old bass head and I love having great tunes in my cars. At a minimum I have added at least a subwoofer to every car that I have ever owned to make up for the lackluster audio system that cars come with. I grew up building massive car stereo systems and traveling around to do SoundQ and DB Drag competitions. Those days are over for me so now I just want to enjoy my music when I cruise around. So for this first version of the stereo I wanted to start with something simple and build off of that.
I first stripped the interior of the car in preparation for some sound deadening. I used Elemental Designs eDead 80 mil. This stuff was about 1/3 the price of the name brand stuff and works just fine. One thing to understand with sound deadening is that slapping sound deadener on every panel on the car is just a waste of money and adding significant weight to the car.
The poly butyl deadener is used to stop panel rattle and noise and nothing more. it’s does this by adding mass to the metal panel to stop the sound and pressure rattling the panel. So basically if you tap a panel and you hear it resonate then you need to add deadener to it. The larger the panel the more it needed, but you only need enough to stop the resonance. Once you can tap the panel and you hear a thud, you’re done!
Next you need to address the outside noise, also known as road noise. Sound Deadener helps prevent this by stopping the vibration noise making it way through the thin sheet metal but it only does so much. You now need to add an acoustic barrier, usually in the form of foam. You’ll see this in everything from fiberglass, butly and eva foam. My fall to stuff is carpet padding, the stuff they lay down in your home before they lay carpet down. It’s cheap, easy to work with and readily available at most home improvement stores. This stuff I use all over the place. I pad the inside of the door panels, the entire floor, the rear quarter panels, and even the trunk floor and sides. The foam muffles if not reduces outside noise. It also keeps the audio inside the car.
Since the subwoofer was going to be in the trunk facing the hatch, I needed to stop any and all rattles and really add mass to the hatch metal to ensure the bass gets reflected into the car and not through the thin sheet metal and out into the world. Due to the structure of the trunks reinforcements you can’t use a normal sound deadener cause you can’t get it in place. Expanding foam handles this issue. Filling in all of the voids and gaps really helps to make things solid. I used Great Stuff Door & Window as this product is more flexible. I was worried using the normal stuff that it would break over time due to the sound waves. The Door & window doesn’t expand as much but still works fine. Once it was set it was trimmed, sound deadener and foam batting added.
I now moved on to building the rear area. Some main things that I had to build around was the fact that I had to keep the spare tire and it could not interfere with the stock mounts for the glass top. Since I was going with a single Sub setup I was able to build the box in the left corner of the hatch which left plenty of room to build a nitged amp rack that would go over the spare. This allows me to use the full area of the trunk, keep the spare and not get in the way of the glass top mounts.
I first built the sealed box to the sub spec, which was a Memphis 10” Street Reference DVC sub. I added rivnuts to the opening of the sub to allow me to bolt the sub in. Screwing subs in/out eventually tears the box up and exposes air leaks. This way I would never worry about that. I then built the metal frame that would be the brace for the amp rack hinge mechanism. I used metal as it would have been too bulky to build out of wood and I needed something really heavy duty considering what the weight of the amp rack would be when done.
Before the carpet was put back in I ran a 2 gauge wire from the front battery to the rear area along the passenger side well. This was good up to 200 amps and more than I needed but better to run over then under. I also ran a 6 way RCA bundle from the front stereo compartment to the rear area. This feeds the sound signal to the rear amp rack area. Lastly power, remote and rca were run from the amp rack to the under the passenger seat where a small Alpine amp was mounted that only ran the tweeters in the dash.
The dash tweeters were a set on Infinity Kappa 10.9T 1” tweeters. I modified the stock tweeter location baskets to mount the kappa tweeters in. They come with their own external crossover blocking anything lower than 3.5k hz to ensure you don’t damage them. I reused the stock wiring and tapped the tweeters into them, in the stereo area I run the stock wiring into the crossovers then run the amp to the crossovers with some short 14 gauge wire. The amp only runs about 25 watts RMS to the tweeters which is right where they should be. This also keeps the amp running very cool since airflow under the passenger seat is very limited.
The 12v power in the rear was interesting to say the least. The main power wire first ran into a main 200 amp fuse, there is one at both ends of the wire, then over to a Kinetic HC1800 1900 amp sealed AGM battery. The purpose of this was as a storage cell to take the stress off of the main battery up front. The wiring in the 3S is already sensitive to demand “IE: lights dimming” so adding this is a buffer of sorts. It also allows direct 12v connection to the fuel pump so the pump never gets starved. The main power then runs over to a 2.0 farad capacitor and fuse blocks. Again the capacitor is used as a buffer. It ended up being overkill for the system with the kinetic battery installed and eventually removed as the LCD display was a power draw that would slowly trickle the batteries down.
Right behind the amp rack was a standing platform which is what I used to mount all of the power blocks, ground distribution, capacitor, etc. There is also a distribution block where all of the speakers terminate at. Since the amp platform hinged all of the cables running into it had to have slack to allow the rack to hinge without causing any issues. So this platform created a channel between where everything could run and be fastened down and out of the way. It’s a mess in the photo but it was all eventually tidied up once all of the wiring runs were finished.
Processing was done via an AudioControl DQS 6 channel digital EQ. This was used to clean up and process the signal coming from the head unit. From there the sub channel went out to a AudioControl EpiCenter which is a bass restoration processor. This really cleans up the low end frequencies. The main amp is a 5 channel Alpine MRV-F353 V-12 which is 50 watts x 4 and 150 watts into the sub channel. Now the amp output was rated at a 1 volt signal input, which means that the more the singla input the more the amp would output. Both AudioControl devices have the capabilities to increase the signal voltage. This allowed me to fine tune the power requirements for the speakers. The rear Memphis 3-way 6×9’s needed a bit more power than the 2-way 6.5” MB-Quart drivers in the doors needed. It also easily allowed fine tuning of the stage in the car to ensure audio came from the front and the rear was just for fill.
The system sounded just as good as it looked. If you just looked inside the car you never would have guessed at the amount of stereo equipment and work that was added which is the exact stealth appearance I was looking for.
