I’m about to start an install on my g70 for subs and an amp. Going to try and use what you have shown in the pics but just to be clear, you didn’t lose your factory subs since you only tapped into the wires right? Like the new subs don’t pull too much power that you need a capacitor? Which RCA adaptor did you use to go to the amp? Also the red plug with the wires you used, is that plug, the wires going into the amp? Or coming out? New to stereos but i am a mechanic so i understand wiring just don’t understand it fully…
Factory subs are still functional as I didn’t cut their signal lines, I only stripped the plastic shielding back to wrap & solder in my additional wires for my RCA feeds. You could cut them if you wanted to kill off the OEM subs, but I figured may as well keep them in use despite them not having too much effect.
My amp and sub are rated for 600w at 2ohms peak but would never actually get that high. Capacitor isn’t required in my case but it does help lighten the load from the alternator/battery for quick spikes in draw. Say if you have the music very loud and there’s a heavy kick drum hit, the capacitor helps you in that scenario but overall if you’re not cranking it/drawing heavy all the time, likely can do without. If you went any bigger and were playing it loud often, may want to get a cap. And/or upgrade your alternator haha. Some even go as far as installing additional batteries.
Also, since the voltage tested very strong on those oem sub signal lines, a powered line-out converter was not required to raise the signal strength before it reached the sub amp thankfully. Easier and slightly cheaper without that powered PAC module.
The RCA adapter I used was a generic off the shelf one from my local car audio store. One end has 2 RCA jacks, the other end is raw wires. In theory, you could probably use any old RCA cable and just cut the ends off one side.
The RCA jacks plug into the sub amp’s “Line In” inputs, while the raw wire ends tap into the oem sub signal lines.
My amp has an auto on/off function by sending signal coming in or not, however I found that it always sensed a signal and never shut off, eventually ruining my battery after a couple years. The winter didn’t help I’m sure.
Shut it off for now but will need to install a remote turn-on wire in the summer from my sub amp up to the fuse panel and tap into one of the fuses so that the amp only turns on if the car is running or in ACC mode.