Issues with adding subwoofer to Harmon Kardon System

[2009leggy]

Hey guys,

 

I was just curious if anyone here has the factory Harmon Kardon Stereo system on their legacy (05-09 has the same setup I believe, correct me if im wrong) and has ADDED a subwoofer and Amplifier while keeping the factory system in place. I know the H/K system isn't the greatest, but for now I figured it was a good enough system, and just needed a little more bass because the factory 8" Sub sucks.

 

Anyways, I am having issues with my sub randomly tripping the protection circuit.

 

My Current setup:

 

Line out converter from back of factory HU. This is the part that concerns me. All I did was find a wiring diagram for the back of the headunit, and tapped into rear channels to get my RCA outputs for the amplifier. Was I supposed to wire the LOC in after the factory amp that powers the door speakers, or behind the head unit like I did. Another issue might be the fact that I used those stupid insulation displacement connectors (the stupid T-tap connectors where you put the two wires side by side, and the blade pierces through the insulation and makes a connection). I've been told from several audiophiles that those connectors are garbage, but I used them anyways because I had nothing else.

 

Power: Memphis Audio 16-sr1.250 Monoblock Amplifier, 250 Watts at 2ohm, 125 watts at 4 ohm (rated stable 1 ohm). Power wire is 10 awg and comes directly from battery with inline fuse block about 6" from battery through the firewall, and fished back to the amp. Its grounded to the metal trunk floor pan where I have removed all of the paint.

 

Subwoofer: Rockford Fosgate Prime R1L-2X10" Pre-built, sealed subwoofer enclosure, (300W-RMS 600W Peak, 2 Ohms total impedence) with spring post connectors. The wire going from the amp to the spring post is 14 awg.

 

This setup worked perfectly and kicked really hard when I first got it, but now I am running into issues. The protect circuit on the amp keeps randomly kicking on and cutting power to the subs. Sometimes it will make it through a whole song without doing it, sometimes it stays in protect for the majority of an entire car ride. Occasionally, it will go into protect for 30 seconds, kick back on for a second and hit one note, and then go right back into protect. This issue happens at any volume, any gain setting, and at any EQ setting. Some songs its a lot worse, and some songs have no issue at all.

I did some troubleshooting with a Multi-meter and confirmed that my voltage at the positive and ground terminals stays above 12.5 volts when it is kicking the hardest. Voltage at the battery and at the terminals is 14.6 with no music on and car running. The subwoofer box reads 2.7 Ohms at the terminals so I doubt there is an issue with them.

The amp doesn't get hot at all, and none of my wires are getting hot either.

I did all the typical stuff already: Checked my connection at the battery, its fine. My ground is great, all paint is scraped off and its super tight. I replaced the speaker wire going from my amp to the subwoofer, and that made no difference. So I have eliminated those as possible culprits to the problem.

 

I did some reading around on other forums and heard that a clipping signal from the head unit could be causing this issue. OR too much/too little voltage through the RCA's cables.

OR the problem is my stupid T-tap connectors, and I have shorting out somewhere behind my head unit.

 

Regardless, I just want some insight on the issue before I go ripping apart my dash again

 

Any help would be appreciated guys, because I am totally lost