Originally Posted by geox19
One more question Why did you take signal after the factory amp and not before it I see in the install manual it says after oem amp then to lc7i then to aftermarket amp but why not just take the signals before the oem amp wouldn't you get a cleaner signl? I haven't started my install yet so i have no clue just trying to get some info.
Hello. I'm an electrical engineer in the Detroit automotive sector. I have also been a car audio buff for 25+ years. I have won sound quality competitions via IASCA, MECA, SMWTMS, and such. I won't reveal my credentials, but, I can shed some light on the subject
The reason you can't take full range signal before the factory amp vs. tapping off the factory amp outputs is: volume, tone, balance, and fade control. The signal coming from the head unit is straight line level out. This is similar to what we used to have with a CD player or tape deck going to a home receiver. To make a long story short. This is done to ensure the amp receives a strong "fixed" line level signal with maximum possible S/N ratio.
All volume, tone, balance, and fade control is done inside the factory amp via digital signal processing. Adjustments to your controls / knobs on your head unit are translated to CAN-BUS network messages and sent to your factory amp. The amp decodes these signals and processes them accordingly. The DSP then adds in crossover filters before sending signal to the discrete amplifier outputs.
The factory amp does nothing but receive / process signal, amplify it, then distribute output to the systems speakers. The factory amp is not required if you use something like the PAC C2A-CHY to intercept signal and process the control / knob adjustments. Output of the PAC C2A-CHY is 4 RCA full range outputs controlled by the factory head unit. Add whatever external aftermarket amps you want.
For more info read here:
2004 Dodge Durango - simple system - Car Audio | DiyMobileAudio.com | Car Stereo Forum
Mind you, all this work was done on a Dodge Durango. However, it directly translates to any vehicle. Including my 2012 Overland Summit (WIP).