Long story short, i'm disappointed with my jbl system sound in my DBL cab . I like the headunit thought, the navi and the entune is ok.
So my first step was sound deadening. I just couldn't stand the rattle from the sub area at even half volume .
I sampled GTMAT ( all 4 types) , Fatmat , and milla mat . I chose Fat mat because it was the stickiest out of them all and the easiest to work with and bend . Im really pleased with the fatmat.
I also used thick rubber double sided tape and all of the plastics, and alittle clear RTV on the plastic clips . Even used the double sided tape inbetween the plastics that cover the rear of the back seats. ( I know some remove these but double side tape did the trick )
The jbl amp brackets also rattle, I took it apart and used some high temp RTV. Theres a bracket that attaches at the top of the amp I determined is the cause of most of the rattle. Once you take it apart and see the bracket that attaches to the screws below you'll see what I mean .
I also wrapped the JBL box.
Next came the sub, the oem jbl jub is paper junk, I replaced it with a rockford p3sd4.
Now I tested the sub with the oem JBL amp and it actually surprisingly sounded good. I was impressed, didnt think the jbl amp could do it.
I plan on adding more subs, so I went ahead and wired up my amp and wired it to the sub. My amp is lot larger then ill ever need but I got it for next to nothing so why not.
After some testing. The rockford amp pushing the rockford sub it to much, the bass sounds hallow and the poor plastic box just doesnt sound good. I think Im going to hook it up back up to the stock JBL amp. And use my rockford amp for my future subs.
What I would recommend to someone that is just looking to improve sound quality rather then add bass, Just sound deaden and get a new sub . The JBL amp will push it plenty if you get a average shallow mount. For example a 150watt rms rockford sub like I have , and if you get a 2ohm it would sound even better then mine.
heres my amp ,
-Overall verdict, all rattles and gone and I get nice clean bass. Not much bass though considering all the work. Now this is very involved and time consuming process , But with all the rattles and lose plastics I didn't want to just add subs. That would add bass but Im also looking for quality bass. The other benefit to my setup is I now can turn the bass way down on the headunit and the door speaks sound 10x better, I havent gotten around to upgrading those yet.
My next step is to actually add some bass, nothing crazy . I like the idea of maybe 2- 8" subs under the rear drivers side seat, or a 10 behind the rear drivers side seat.
If anyone wants to share what they have that's similar to my two ideas please share