Need Urgent Amp Install Assistance!

[ALE53]

Hey everybody I have my amp all wired up and ready to go, and am about to tap into the 2 sets of twisted pairs running to the NON DSP radio module/amp. I will be running my amp MONO to a single Infinity Kappa Perfect 10" in a custom box (in need of grey BMW carpet by the way...).

My PPI amp has RCA inputs, and I'm not confident that they just connect to the twisted pairs from the X5. I clipped the ends off a set of RCA cables and stripped them in preparation for tapping the wires from the X5 and hook up to the amp's RCA inputs......

My question is this: do I now need to split apart the two internal wires of each side of the RCA cable and connect them +/- to the pairs from the car? I don't want to be out of phase or F anything up! PPI's website does not instruct you to do this when adding RCA input cables from the headunit wires.

[ALE53]

Got it hooked up.
Sounds OK. Obviously tuning is in order.
Seems like the gain is up high and not enough sound.....

[ALE53]

Got up for some Starbucks this am & no sound. Just alternator whine! It sucked. So, the coffee is next to a Best Buy..............
I went and bought a 4GA Monster install kit. Also picked up a LOC. Removed everything, reinstalled, soldered and shrink tubed every connection. Everything is super tight and looks professionally installed. Tried to tune the amp, to no avail and almost went deaf. Not quite right yet, but I am keeping after it.

[DouglasABaker]

Answer to your original question: Yes. Assuming you have chosen the correct 2 wires from the factory harness you should be holding a + and a - from the same channel (very important!). This is exactly what a single RCA plug represents: + at the tip, - at the surround.

Couple other things:

First, if you tapped into the leads before your existing factory amplifier, then there should be no need for an LOC. Confirm this by checking the voltage in the lines using a digital multimeter at various volume levels and compare to the input voltage listed in your amps owners manual.

Second, alternator whine is almost invariably the result of a bad ground. Make sure you have grounded yourself to bare metal, and ideally in the same spot as the factory amplifier that you are still using for the rest of the speakers.

To properly "tune" your amplifier you need a multimeter and you need to know the frequency at which you want to crossover. Presumably you already know the frequency, so just set that on the amp and let's move on (use an oscilloscope if you want to make sure you get it exactly right!)

Turn the gain all the way down (counterclockwise).

Calculate the proper maximum voltage for your amplifier. Voltage = square root of (wattage * impedance). Take your amp's maximum power output (watts) and multiply it times the resistance of your speaker. then take the square root of that number. This is the maximum voltage you want to see across the speaker outputs of your amp.

Now for the fun part - perform this next step with the speakers disconnected as it will result in rather loud sound levels. Connect a multimeter across the speaker outputs (in other words, touch the red lead to the + terminal and the black lead to the - terminal of your amp. With the head unit at what you would consider "max volume", slowly increase the gain on the amplifier until you get a reading equal to the voltage number you calculated in the last step.

Repeat this for each channel of the amplifier - nothing to it

d-