Dodge Ram Alpine Harman Kardon System Amp Interface – AmpPRO Sub-CH41

If you have done any research on adding a subwoofer to your new Ram truck, then you have surely run across the AmpPro from PAC. That is an awesome piece and does a ton of great stuff. But, for a lot of our customers, they are happy with how their Alpine or Harman Kardon system sounds, they just wish that it had a little more bass. And for just adding a subwoofer, the AmpPro is a bit overkill. So, they came out with a baby version that is just for adding a subwoofer, the AmpPro Sub.

This harness works with the 13-18 Rams with Alpine and the new body 5th Gen 19-up Rams with Alpine and Harman Kardon.

This interface takes the crazy signal out of the factory radio, and uses the data coming out of the radio to control the amp, to give us a usable subwoofer RCA output. It even has a subwoofer knob and creates a remote turn-on signal for you. Wiring wise, it is a plug-n-play T-harness. You pull the radio, unplug the factory harness, plug this in between the two, and put it all back together. Easier than installing an aftermarket radio. This system even comes with a bypass harness for the 19-up Alpine and Harman Kardon ANC system. Super simple.

This is the geeky part about how the system works if you are interested.

The way these systems are designed is way different from your base audio systems. Your regular radio has 8 speaker wires, 4 pairs; Front Left, Front Right, Rear Left, Rear Right. These wires vary in volume as you turn the volume knob, adjust fade/balance, EQ, everything. Normal type of radio. With the Alpine System, there are only 4 wire, Left and Right. They are also a fixed volume, meaning if you hooked a speaker up to them they would just play loud, no matter what you did to the volume knob. That fixed level audio signal then goes to the amplifier and the amp is told to do volume, fade/balance, EQ, everything, through a data signal from your radio.

Then, the amp does it’s thing. Instead of just power, the amplifier heavily processes the signals going to the speakers. It limits the audio range of each speaker, through crossovers, so the tweeters only play the highs, the woofers play the mids, and the sub just plays the deep bass. There are no full range signals going to or coming out of the amplifier that you can tap into for an amplifier.

So, in the past, the best way to do this was to use a signal summing device, we like the ones from AudioControl, ARC Audio and DD Audio, but there are many other good ones on the market. The signal summing combines the signals and creates a full range signal that you can send an amp. But, if the wires aren’t correct or on pair is out of phase, then it can create a whole new mess for you.

Then, the next problem is that once you cut the speaker wires from the factory amp or disconnect a speaker, the amp stops putting out audio. So if you have it all wires up but the factory amplifier does not see a load, or thinks that it sees a speaker, it will turn off that channel. Well now you have to install load resistors to keep the audio signal working, and there is no real way to install load resistors and have them look good, or factory.

This is how the system works and what is in the way. By using the PAC AP4-CH41 harness, you eliminate the need for signal summing, load resistors, all sorts of issues. This is a plug-n-play kit that goes behind the radio and does all of the hard work for you.

PAC Audio APSUB-CH41