[H2O_Doc]

I added an amp and sub to the stock HK system and while it's a significant of at improvement, I'm sort of surprised the sub doesn't perform better.

I have a JLamp that is putting out 1000 wattsRMS at 2 ohms. I have a 15" Rockford Fosgate P3D2 in a sealed enclosure. It thumps OK, but I expected more. What I'm wondering is if the underperformance has to do with the signal coming out of the HU or if the JL amp is the culprit (or is it something else)? I'll freely admit, I don't know much about car electronics and I had the install done by another party. Anyway, if there is a relatively easy solution, I welcome it. I had this sub in another car and it hit much harder (different amp at almost the same power).

[Encanto]

Originally Posted by H2O_Doc

I added an amp and sub to the stock HK system and while it's a significant of at improvement, I'm sort of surprised the sub doesn't perform better.

I have a JLamp that is putting out 1000 wattsRMS at 2 ohms. I have a 15" Rockford Fosgate P3D2 in a sealed enclosure. It thumps OK, but I expected more. What I'm wondering is if the underperformance has to do with the signal coming out of the HU or if the JL amp is the culprit (or is it something else)? I'll freely admit, I don't know much about car electronics and I had the install done by another party. Anyway, if there is a relatively easy solution, I welcome it. I had this sub in another car and it hit much harder (different amp at almost the same power).

I bet $1 that the "other party" tapped the rear speakers for the sub. There is no bass in the rear speakers.

[H2O_Doc]

Originally Posted by Encanto

I bet $1 that the "other party" tapped the rear speakers for the sub. There is no bass in the rear speakers.

That's correct. Can it be re-done?

[Encanto]

Originally Posted by H2O_Doc

That's correct. Can it be re-done?

Tap the woofers.

[H2O_Doc]

Originally Posted by Encanto

Tap the woofers.

It dawned on me that it might be that stupidly simple.

Will do.

[mikeyymonster]

Any pics of the setup?

[H2O_Doc]

Originally Posted by mikeyymonster

Any pics of the setup?

Nothing that shows where the wiring went. Just the amp stuck to the back of the seat.

[BEM-S4]

You're best off using Technic's add an amp harness, no need to tap anything.

[TropikThunder]

Originally Posted by H2O_Doc

I'll freely admit, I don't know much about car electronics and I had the install done by another party. Anyway, if there is a relatively easy solution, I welcome it. I had this sub in another car and it hit much harder (different amp at almost the same power).

The signal coming from a stereo head unit is full range, 20-20,000 Hz or so, covering low bass all the way to high treble. The amplifier/signal processor (even the non-HK audio system has one) does two things: it increases power to make it listenable and also routes different parts of the frequency range to the correct speakers (lows to the subs under the seats, highs to the tweeters in the door sail panel, everything in between to the mid ranges in the doors.

By design, the signal arriving at the rear deck/door speakers is not full range, it's cut off by the amp to not send anything below 150Hz. If that's the starting point for the sub amp, then there's no way the sub will hit hard since it's not being "fed" anything below 150Hz (hard punchy bass is well below 100Hz).

If the installer didn't know the car has a processor, they may have assumed the signal they were tapping in to was full range when it's not.

Originally Posted by BEM-S4

You're best off using Technic's add an amp harness, no need to tap anything.

+1. It doesn't get much simpler than that.

[H2O_Doc]

Originally Posted by TropikThunder

The signal coming from a stereo head unit is full range, 20-20,000 Hz or so, covering low bass all the way to high treble. The amplifier/signal processor (even the non-HK audio system has one) does two things: it increases power to make it listenable and also routes different parts of the frequency range to the correct speakers (lows to the subs under the seats, highs to the tweeters in the door sail panel, everything in between to the mid ranges in the doors.

By design, the signal arriving at the rear deck/door speakers is not full range, it's cut off by the amp to not send anything below 150Hz. If that's the starting point for the sub amp, then there's no way the sub will hit hard since it's not being "fed" anything below 150Hz (hard punchy bass is well below 100Hz).

If the installer didn't know the car has a processor, they may have assumed the signal they were tapping in to was full range when it's not.

+1. It doesn't get much simpler than that.

Well I do get some signal. I assume the frequency drops off as a slope and not immediately to zero, correct so that might account for the bass I am getting. Again, I am getting some bass, just not what I should (in my opinion) from a 15" fed 1000 watts rms and that only requires 600.

I want to make sure I'm chasing a real and the right problem.

And, yes, I know a 15" sub in a 2 series is a bit ridiculous : )

[H2O_Doc]

Originally Posted by BEM-S4

You're best off using Technic's add an amp harness, no need to tap anything.

Looking into this. Considering options for doors and rear deck.

Thanks much for the suggestion