So i just put in Alpine 10 inch Type E's in a FOXBOX, which is awesome, with an Alpine PDX-1.600 amp. I tried mounting the amp behind the rear seats but i'm retarded and put it where the seat brackets go. I screwed it to a piece of MDF and attached it to the truck using velcro. I have the amp sitting on the floor right now but theres a few things i dont really understand yet. What do the controls on the Amp mean. I did what the instructions told me on the gain control but i dont know if i could turn it up more or if its up to high. I dont even know what that does. It also has a switch on there where i could change it between .1-1.0 and 1.0-8.0. It tells me to switch it to the one that fits my head unit. How do i find out which one it is? I have the Alpine CDA-9884. It also has the LP Filter on it. What does this do? It's the first time i have ever farted around with this kind of stuff and it took me and my friend almost 6 hours to get it all set up. I'm pretty happy with it so far. I just want to know if i could fine tune it even more or if i'm pretty much ready to rock.
I am also getting a security system once my tax refund gets deposited. The Viper 7900. Anyone have experience with this security system?
One thing I would add is that you want to "set" your system NOT using the maximum volume on your head unit. The head unit can introduce an unclear signal at it's max setting. A rule of thumb is around 2/3 to 3/4 of it's max number. If you're introducing distortion at the signal's beginning then everything else is just amplifying distortion.
Also, the general rule on your low pass is to start at 80 hz and blend it with your midbass (or in this case coaxial). 120 hz is the upper end of the bass spectrum, and can cause your soundstage to fall behind you in the lower frequencies. Not always, and sometimes 120 is a compromise you have to be willing to accept (if your frontstage doesn't handle midbass very well, as may be the case without a dedicated amplifier).
About your front speakers and how they relate to your head unit's limitations - If you only have one set of preouts for your front, I'd recommend only amping the front speakers, and let the rears play off head unit power. Most experts will tell you that rear speakers hurt the quality of your soundstage until you really know what you're doing. The goal in car audio is to have your dash become a stage where you can pick out where each instrument or band member is located. If you can make the stage extend beyond the walls of your vehicle, that's even better. Also, you don't lose fade control.
Setting gains is a "set it and forget it" practice. It's not to be used as a volume knob so if you followed the Alpine instructions, you should be fine. It's very likely that your frontstage wont be able to keep up with the substage when you crank up the volume. If that's the case, you'll definitely benefit from amping the front. The .1-1.0 setting is for what are called low level inputs. Basically when you tap a speaker wire to get your signal for the bass. This is common on dodge vehicles that include the infinity package since you'd have to bypass the factory amp otherwise. So you definitely want to be on the 1.0-8.0 setting in your situation, and ideally match your head unit's preout voltage. (ex. 2V, 4v, 5V, 8V preouts). These days, less expensive decks use 2V, mid level decks use 4V, and high end decks use 5V. That's not a guarantee about a certain deck's quality, but among the audio elite, the higher the number, the stronger the performer. It's also become something of a marketing gimmick more recently, so it's no guarantee.
If your head unit has on board filtering, then you can even turn off the amps low pass filter and use the head unit. Later on you'll be able to adjust it on the fly from your head unit, versus digging around behind your back seats to try to tweak things.
If your foxbox starts jumping out of the storage holes, you can drill a hole through the bottom of both sides and bolt it down to the cab. MAKE SURE you know where you're drilling and don't hit a critical component underneath the cab. I've heard Joe say he can get Alpines making the box jump. Mine has a tendency to make the box buzz on the sides from the washers from the seat spacers vibrating toward it over time so I used duct tape to quiet it down.
I've been through my '02 and '04 rams quite extensively with my audio installs, so if you have any questions about the truck or other audio stuff, feel free to private message me. I've done the back wall amp rack, fiberglassed some tweeter pods into the a-pillars, sound deadened nearly the whole thing (pulled everything out of the truck and did a thorough job), and done all my own wiring multiple times.