Isn’t it fun, finding toys you forgot you had?
I totally forgot whether I still owned, sold, or gave away my old amp+sub box. This thing’s been sitting in the attic for, geez, I dunno, ten years? I bought it back when I still had my old square-body Suburban, and would have installed it had I not replaced my ‘Burban with a 1984 Delta 88. Once I got that car, I suddenly wasn’t willing to sacrifice its comparatively puny trunk space just for my tunes.
So it sat in the attic, until I found it again last week. I don’t want to put it in my car, or the truck. Should I sell it? Maybe I should test it out and see if it’s working, first. Besides, my laptop speakers are kinda wimpy, and I have trouble hearing music and podcasts while I’m wrenching away in the garage. It would be nice if I could just hook this thing up to my laptop and be able to hear it all the way out into the driveway...
Fortunately, I had spent Labor Day weekend reorganizing stuff in the garage, and knew exactly where all my wires and terminals were. I grabbed some nice 10AWG wire for the power, and some smaller wire for the rest. I wired it up to my cheap Harbor Freight jump box that I keep charged, and... nothing.
Clearly I don’t even remember how to properly wire this thing. After some quick Googling, I realized that I needed to power the RMT circuit before the thing would turn on. After hooking up another wire to my jump-box, I saw the first sign of progress: a lit LED.
Okay, now to get some signal to the amp to make sure it actually works. Fortunately, a new video on soldering had been posted recently, just in time to serve as a refresher course for my sorely out-of-practice soldering skills.
I soldered some wires onto some RCA terminals I had, and soldered both channels together for mono input. I used butt-connectors and wire-nuts elsewhere, since I’m just trying to see if the amplifier and subwoofer even function. I cut the cable off of an old pair of headphones and attached them to my homemade RCA cables.
The result? Less than spectacular. Sounds muffled and quieter than expected. But after poking around some more, I realized that I still didn’t quite have the hang of wiring this thing down. My RCA cable was plugged into the “low input”, and I needed a six-pin connector to connect to “high input”. Fortunately, I had a spare that came with my last head unit that was easily attached to the existing circuits.
So I wired everything together, both L and R channels going into both high and low input on the amp. I plugged my laptop in and fired up a video to test it out:
HOLY HANNA IT’S SO LOUD.
I have to turn my laptop volume (and the YouTube volume) down almost all the way. Well, for workbench wrenching anyway. I can turn it up a little if I’m elsewhere in the garage, and a little more if I want some tunes in the driveway. It’s still kinda muffled, but tolerable, I guess.
Now that it’s working, I’m not sure I want to sell it after all. Maybe I’ll just keep it around the garage for wrenching. I already took apart some of my test wires and am working on a more permanent solution. I made a run to Radio Shack (still open FTW), and returned with some better parts. I soldered a proper 3.5mm jack so I don’t have to use those puny headphone wires anymore, and installed a switch for the RMT circuit to turn the amp on:
At modest volume, it doesn’t seem to pull a lot of amps (but it could if I wanted it to...)