We spent the better part of yesterday putting Trevor’s bumps back in his vehicle. His first vehicle was a 1985 Ford F-150, which was severely lacking in the “tunes” department, so he put in some cheap Xplod head unit, and then later a 12″ sub in some tiny choked out box he and his friends built.
After it didn’t perform so great, he commissioned me to build a new enclosure, which can be seen to the left. Sitting directly behind the single bench seat in the tiny cab of an F-150, this thing would shake your teeth out – not bad for a sealed enclosure!
Fast forward about 9 months or so, and he wound up getting a much better job and trading the F-150 in for a 1998 S-10 Blazer. The factory stereo was “acceptable”, so all the stereo equipment lay in his room unused until yesterday. Our initial plan was to use a speaker level to line level converter to steal RCA outputs from the factory head unit. I thought it’d make a really good Hungry Hacker article, so I took photos and documented everything.
I’d spent about two days doing research beforehand, so I thought I knew everything going in… apparently my research wasn’t quite good enough, because it turns out despite what it says on the box about “adding a subwoofer to a factory stereo system” the line level convertor (Scosche FAI-3A, for what it’s worth) wouldn’t exactly do what we wanted. No, as near as I can tell, it’s only any use for adding an aftermarket head unit to a vehicle with the “monsoon” style audio – where each speaker had it’s own mini amp and the “speaker” wires from the head unit carried line-level audio.
The reason being that the FAI-3A, when placed between the head unit and the speakers, reduces the speaker output to line-level as well. The signal still comes out, just really quiet. Aside from the above scenario I can’t really see what use it is for adding a sub to a factory audio system.
So we wound up tearing the factory head unit out, I busted out the soldering iron and we put the Xplod head unit in. A quick trip out to Bluffton to pick up an enclosure for the head-unit and we were putting things back together in short order.
The other trivial mistake I made was reversing the “battery” and “accessory” wires – I’m not entirely sure how I did that, but his head unit won’t hold memory for more than a few seconds of ignition-off… I’ll probably wind up fixing that on Thursday – hopefully this mistake doesn’t drain his battery, because he doesn’t have roadside assistance, he gets off work at about midnight and we have to be up for a doctors appointment at 6 tomorrow. 
On Thursday the subwoofer should go in as well, assuming we can find a suitable place in the incredibly cramped firewall to safely run some 2ga cable through. Anyone who’s ever done a clean installation of a subwoofer in a second generation S-10 is welcome to email me with their ideas!
