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Quiet Loud CB - Randy’s Electrical Corner

Posted in How To: Electrical on May 22, 2014
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Photographers: Pete Trasborg

Now, you might have read the title and thought I’ve finally lost whatever little mind I had left. But you’d be wrong. I might not be the brightest candle in the box (isn’t burning candles in boxes dangerous?), but I haven’t lost it all yet. Sure, I might not be able to find my yearbook, and I have no idea where I put my other pair of underwear, but I did finally get the other sock back from the drier.

Oh right, the whole “loud quiet CB” thing. Well, I ran across this kit that was designed for JKs as a plug-and-play CB interrupt. Instead of installing one of those ugly and often crappy external speakers in the Jeep, this system plays the CB over your Jeep’s speakers. And when people aren’t yammering over the CB, the kit automatically cuts back over to your stereo. The name of it is Audio Interrupt System (makes sense, right?) and it’s from Rogus Innovations.

Here’s the brain box of the system. Check it out! It is fully sealed! So even you guys with no tops don’t have to worry about killing this thing. It has short speaker leads and is intended to install behind the head unit. The short wires are a good idea because it will keep interference down. Even though the kit can go through all four speakers, I only used the front two in this install because the rear speakers are behind the seats and kind of crappy. Of course, I soldered the connections and I then stuffed everything back into the dash. The box measures 2x3x7⁄8 inches, so it fit even in this cramped dash.

As I said before, the kit I originally found was a plug-and-play for JKs, but since none of the Jp guys have a CB in a JK, I couldn’t use that kit. I got lucky (not that kind of lucky), and the company has a universal kit that works with any two- or four-speaker stereo system. It works with any CB that has a 1/8-inch mono output, or what you and I would call an external speaker plug.

Once I dug the CB brain box of Trasborg’s Cobra 75 WT ST out from under the console, I found it did have an external speaker plug -- so I knew this whole thing would work. The pickup wire is about 6 feet long, so it was no problem getting from the behind the dash to under the console where the CB brain box was installed. Even though it plugged in pretty tightly, I wrapped the plug with some electrical tape to make sure it wouldn’t vibrate loose.

You guys know better than I do how loud Jeeps can be with tops-a-flapping and mud tires-a-slapping. But those little black box Charlie Angels speakers don’t sound that great when they are new, and they get worse over time. So, I really liked this idea, but like the time I put the peanut butter and jelly sandwich in the pop-up toaster, I like to find things out for myself. That’s why I ordered a kit and went ahead and stole Trasborg’s ’91 Comanche for the installation.

Here’s a shot of the wiring diagram from the instructions. For once, I wired the power wires up like they told me to. The red power wire had a connector on it to plug into a switched spot in the fuse block and the black wire had a “fork” on it for ground. It didn’t quite reach the factory ground point under the dash, so I just zipped it in with a self-tapping screw. I didn’t use the brown wire, which is an auxiliary negative to trigger a mute on an aftermarket radio or subwoofer. If you have one of those fancy Jeeps with an amplifier, you might have to install the brain of the interrupt near the amplifier. Because the audio-interrupt interrupts the speaker-level wires, it will work even with those fancy stereos.

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