JL 13w7 & 1000/1 Settings
There is no "perfect" setting that can be placed in a manual. It's all done by ear. Your settings will vary depending on the vehicle you are in, the type of enclosure you have, the type of music you listen too, how much voltage your deck put's out. There are many variables, but I can try to give you a basic guide.
First of all you need to know your enclosure. If you have a ported enclosure tuned in the mid to low 30's you may want to set the low pass to around 70-80 hz with your sub sonic set at 30 hz. this will give you the higher bass frequency you need for the loud bass you want, and protect the sub from going too far below the tuned frequency of the enclosure, and losing it's composure.
As far as the gain, and bass boost are concerned, you just have to adjust them by ear. First adjust the radio volume to normal listening levels, by that I mean as loud as it can go without the speakers in the car sounding like ****. Now you adjust the gain first. slow turn the gain control, carefuly watching and listening to the sub.. Adjust the gain to the point of the woofer getting a lil sloppy then back it down a bit until the sound is clean again. Now do the same with the bass boost. if there is a bass boost frequency adjustment, set that as close to the tuned frequency of the box as you can.
If you are in a sealed box the adjustments are a bit easier, and are all about taste. Adjust the radio as described before, and put on your favorite song. Next start udjust thing lowpass frequency to taste, not too high tho, try not us higher than 100 hz in your sub's for better sound. Sub sonic is not quite as important in a sealed box, as there is much less danger of the sub losing control.
Well good luck, and hope this helps!