DSP--best place to tap signal for JL/BSW sub?
 

I plan to decide shortly on one of these subs to add to my factory DSP-equipped system. I read through a bunch of stuff here on this forum, but could not find any clear opinions on where is the best place to tap the signal. Should I tap before the DSP amp or should I just grab it as it enters the factory sub (post-amp)? What are the pros and cons of each method?

Thoughts and opinions appreciated...

you will have a PM shortly

Thanks, Essam...very helpful info.

CORRECTED EDIT: For those wondering about the answer to my question--you tap the signal where it exits the DSP amp (high level signal). The amp does the processing all of the speakers, so tapping the signal here gets you the full range signal that you can then feed to low pass filters in your aftermarket subwoofer amp. The disadvantage is that the DSP processing is still occurring, so as your volume increases, the DSP amp is filtering out low frequencies that the stock sub could not handle.

One method is right on the x5world main webpage here.

I installed the JL stealthbox this weekend--good thump and nice addition for low volumes, especially when stationary. After living with it for a couple days, however, it is my opinion that adding a sub such as this to the factory DSP system is a poor expenditure of a lot of $$$. Whenever you turn it up loud, you pretty much lose the whole purpose of the sub because the factory DSP filters out the lower frequency signals. For just a few more bucks, I will be adding a 4-channel amp shortly to power the satellite speakers as well and bypass the DSP altogether.

Did you tap into the oem sub outputs or the rear speaker channel outputs?

So where can we tap into the OEM DSP setup to power the JL without filtering out signals at high volumes? I ask because I will be adding the JL setup myself soon using my directed D800 amp for power...

Odds are I will find a way... just gotta look through the wiring schematics a bit. This kinda stuff is why I removed the oem amp in my older bmw's and wired in my own, but I don't want to do this as I am pleased enough with the DSP system to keep the amp and just add more precise thump.

There is an OEM sub output, but it is AFTER the DSP amp (i.e. runs from the amp to the sub). Unfortunately, it is a DSP modulated output. I suspect (but cannot confirm) that the low pass filter built into the DSP amp raises the frequency of the filter as volumes increase to protect the cheap factory subwoofer from distorting. If you find a way to tap a sub or full range signal BEFORE the DSP amp, please let us all know!!!

You could download the install guide right off our website. Will show you exactly what you need to do :)

Thanks, Halston. I just checked the instructions but without the schematics it was not clear from the instructions whether the signal being tapped is before or after the DSP amp. Can you confirm that by following these instructions it is grabbing signal with sufficient voltage to power the speaker level inputs on my aftermarket amp or do I need a LOC to use the signal from here?

I replied to your PM.