Are you asking if you should use a hu's sub output as a signal for your subwoofer?

 

Yes, this is my issue: jbl has a pink noise cd to adjust the signal input and they want the full signal .
if I use the sub out will not satisfy their requirement.

 

Yes, this is my issue.
jbl has a pink noise cd to adjust the signal input and they want the full signal .

In that case use the sub out and turn off the sub crossover.

 

It sounds like you only have one external amplifer and the deck is powering your mids and tweets?

The DSP features on the JBL are duplicating features you have on the head unit. That head unit can do time alignment, crossovers, and it has a FULLY PARAMETRIC 9 band EQ. You only need a DSP if you are need to time align more than 6 channels of output or if you need to EQ channels separately.

Alpine decks have a crossover on the sub channel. If you set it to flat it should output full range. You also have a sub volume adjust built into the head unit (probably just one click into a menu). If you use the sub out you can use that as a bass knob. If you don't need that feature it does not matter if you use the deck to set up the crossover or the amp.

 

I have a separate amplifier for the front doors speakers. I did not connect the rear speakers.
I am replacing the same alpine amplifier you have in your signature.
it is not loud enough because my sub is a 4 ohms, not 2 ohms to get the full 500Watts.
this JBL is marketed as a digital signal processing amplifier.

 

I am with you there, I am running at 2 ohms and I STILL need more bass. (It's not the amp, it is me).

Back to your question: It is 6 of one, half-dozen of the other. Use the rear channel, use the sub channel. It is all the same. Use the amp DSP, use the head unit DSP, you will get the same result.

I use the sub level adjust on the head unit as a bass knob. It is just one click into the menu so it is very easy to access.