Originally Posted by
whiskeysquiker
I'm referring to the OEM 18pin amplifier output connector. There is also the 12pin input, if that has any significance. It's possible I may even use that if the 375watt per channel on the new amp is too much and I can't reduce it properly. The HU as a digital preamp of 50watts per channel, supposedly. I already have the front speakers tapped into the 18pin oem output connector through the new amp which is connected to the headunit via a single pair of RCAs. The HU has only one pair of left right outputs, although it recognizes left, right, front, and rear fading and stereo is in fact stereo. There is also a single RCA for mono sub, two single RCA video inputs, one triggered by the reverse lights, one for dashcam, and one video output I'm guessing for an alternative external recording device, because it has also a USB port on the back, I assume, for expanded storage. Oh and a mic input. I have yet to get to all these features as every spare moment I have for this has gone to the music. And the instruction manual was pitiful. 4 pages of microscopic text in poorly translated English. It's also missing, but was useless for my needs anyway.
OK there is a lot to unpack in the above. While words are great, sometimes it's better to speak in pictures. And, more specifically, when it comes to wiring diagrams. I think it would help me and other who might help on this thread to have a your new AMP and HU wiring diagrams.
The head unit will have several outputs. Typically I have seen the RCA to the power AMP as well as the 4 pairs directly to the speakers giving you stereo and front back fade.
As for the 375 amps, more power is great, but there comes a point you can over drive the speakers. Why you need the amps? It's not to drive the speakers loud, it's to drive the speakers correctly. A lot people think the amps (power) are there to make it loud, yes it's true, but the amps are there to move the speaker cone correctly to follow the music waveform. Music is just an analog signal that moves very quickly. For example middle A is at 400Hz. That means the speaker cone has move back and forth quickly (vibrate) and each stroke of that movement can be measured. Just one vibration at 400Hz is 2.5 milliseconds. So it take power to move the speaker cone from from front to back. Distortion comes from not having enough power to move the speaker when it switches direction. So when you are driving the speaker very loud, that means the cone is moving further and those direction changes are hard. Just imaged hitting the accelerator in your car full on, then hitting the brake right away and putting it reverse at full speed.