Join Date: May 2007
Location: West Chester, Ohio
I posted up this in another reply, but may be pertanent as people search this thread out in the future:
Maybe I can help a little bit. In my more youthful days, I participated in audio competition.
Subwoofer- What is the depth of the JL? What is the width of the JL magnet and coil assembly? What is the depth and width of the subwoofer housing on the Jeep?
If JL Subwoofer Depth and Width < Subwoofer housing Depth and Width, Subwoofer will fit physically.
Amplifier- What is the load ratings on the stock amplifier? What is the load rating on the new subwoofer? (unless gramps can look it up for you, the best place to check is probably to remove the factory subwoofer, and look at the back. Typically it is printed on the sub). It looks something like a *Number* followed by a *greek omega* (horseshoe looking thing) that represents "Ohms". if this information is not available, get the model number off the sub and look online for information on it regarding load (ohm/omega symbol) and wattage.
If you luck out, and the Ohm rating of the factory sub is the same as the rating on your JL, it will will work in there. * <- see star below. If its not the same, you need to fine what loads the amp can support.
Wattage is potentially a problem as well. What is likely to happen is that your sub could work, but the factory amplifier cannot put out enough power to offer the subwoofers full potential. If this is true, you need to install a new amplifier. If you do not, and run the factory amplifier at above-typical power, then it will introduce distortion, which will blow your subwoofer.
The reverse is also possible. The amplifier COULD output more power than the subwoofer can handle. Turning the amp all the way up could blow the subwoofer.
While I'd say "look at the wattage ratings of your subwoofer and the factory amplifier", this presents a problem. Stock components are typically very conservatively rated, while aftermarket accessories (such as your JL) are typically exaggeratedly rated. Take the ratings with a grain of salt, and look for RMS, not peak power ratings.
*- Some subwoofers are DUAL VOICE COIL. if your subwoofer is DVC, then you need to think of it as TWO SUBWOOFERS. If each coil is 2 ohm, then depending on how you wire it, this subwoofer can be either 1 ohm or 4 ohm... but NEVER 2 ohm. If the factory one is 8 ohm (very typical) and you have a JL DVC at 4 Ohm each, then wire it in series to achieve 8 ohms, and it will drop in. You can post up the actual numbers and I can give you a better explanation on what to do. (the short-
Series will "add the ohm ratings together". Parallel will "divide the ohm ratings in half"
Run from amp<--------RED Black------> Run to amp
Run from amp<------ Red ---Connect----Red
Run back to amp<---Black--Connect----Black
As I'm sure you know, the quality and volume of a subwoofer isn't necessarily the size or quality of the sub, but is the correct matching of subwoofer and box size. This presents a problem. Many of JL audios subwoofers are renown for their quality, but mainly because they are specifically pared with boxes that are the right size for the subwoofer.
to optimize the quality of your subwoofer, your best bet will probably be to use a JL audio box, made for your speaker. If this is not an option, or if you want to do your custom work, then check online for the subwoofer specs, and what type of box it requires.
If Just by chance you luck out, and the subwoofer uses the same amount of backspace as your factory box, and the ported/not ported and sub box material are on par (see below), its near the same wattage with about the same stroke length, then yeah you should be able to drop it in (assuming it fits and the such above). Theres one big problem with this scenario however... Whats the point? You won't see much of a difference from the factory one!
If you choose to take this route, and you need a little more box cu/f, then you can still manage by taking some pillow or blanket stuffing, or "subwoofer" stuffing that has some flashy catchy name, and putting it inside the box. This allows it to "act" like a larger box. You may have to play around with the quanity a little bit to get the right sound quality and quantity.
Two big questions sit in my mind. Is the factory sub ported? Is the factory sub box merely sturdy plastic?
If it's ported or not will really affect the subwoofer your using. If anyone knows this information (I don't have the premium audio) then please post up, as that will help.
Secondly, the sub box. If it's merely sturdy plastic, then I'd be real hesitant to throw in a subwoofer with more power and a longer stroke, as it will either rattle, crack, or flex in a manner that will shorten the life of your subwoofer, and lower the sound quality substantially.
On the amplifier side of things. If the factory amplifier doesn't put out as much power as you want, then an easy fix is to get an amplifier with high inputs.
Note however, that this isn't necessarily the *best* way to do it, as ideally you'd fully rewire a better amp. However, it sounds as if your not interested in spending 2500 on a full new sound system, so this is a good low-cost option. Given that its an 8" and doesnt need that much power, this should be pretty easy and cheap. Put the subwoofer output from the factory amplifier to the high inputs of the new amplifier, and connect this amplifier to the subwoofer.
I tried to simplify this as much as I could. If you have any more questions, just ask. Your best bet may be to hold out for a Q-Logic or other brand factory mount box.
Hope that helps a little!
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