Upgrading the Audio in a 2010 Fit: Subwoofer and a Stock Radio

I decided not to change out the stock radio in my 2010 Honda Fit Sport. So, I’ve been doing upgrades here and there to the audio system. I had previously decided to not add a subwoofer to this car.

But, I had an old 10″ Infinity Subwoofer in a sealed enclosure and an old Phoenix Gold amp with a built in crossover. It’s rated at 300 Watts when bridged to mono. Someone had ordered this one painted white instead of the normal black. It’s pretty old (and dirty), but works well.

Since I was not swapping out the stock radio, I did not have easy access to RCA outputs for a subwoofer. Once in a wile I would miss the low end a subwoofer can bring, but not enough ti change out the radio. Then I basically ended up with a Line Out Converter for free.

A Line Out Converter (LOC) takes high output signals, like from the speaker lines of a stock radio, and converts them to RCA outputs. I had never used them before. The plan was to siphon off the audio from the rear speaker channels. The LOC gives me a remote turn on for the amplifier as well as two RCA outputs. To install the amp I needed a power cable from the battery and a ground.

This was easier said than done. The Fit has a small engine bay, and it seemed to be impossible to find a grommet to pass the wires through the firewall. I ended up, after some Googling, running the power cable through a hole in the fender, and then through a grommet near the door. The cable is covered by the inner fender lining, so you cannot see it, and it should be protected. I wrapped some electrical tape around the cable as well, for an added layer of protection.

I was able to get the power ran around to the battery, through the carpet and under the seat.

The amp fits right up under the seat. I used velcro to secure the amp, so I can remove it if needed. The LOC is supposed to take audio from the left and right speakers. But, I didn’t want to run the audio from two locations. I was curious if this would work. So, I hooked both left and right positive and left and right negative into the LOC inputs. Then I attached the remote turn on, and ground to the remote and ground of the amp. And I ran the RCA cables. And tied into the left rear speaker.

At this point, it should be done. When I turn on the stereo, the signal on the speaker wire should trigger the remote turn on and the amp should fire up. I had no idea if pulling the signal from just one side would give enough power. I know, if the low end is stereo I will miss it on the subwoofer. But I’m willing to try it.

Just a quick test, and I can already see the signal level is plenty high. I had to significantly reduce the sensitivity (Turn down the knob) on the amp. It was way too loud.

So, I still have some tweaking to do, and time will tell if I need to run wires to the right rear speaker or not. But I have enhanced low end in the Fit now. The LOC was very easy to use.