I used to work part time as a car audio fitter and auto electrician back when I was studying and needed a part time job. Somehow I ended up with a whole heap of warranty returns and ex demo gear given to me for free or at very low cost which I just couldn’t say no to. I installed most of it into the cars of friends and family, but some of the more impractical things remained in the shed waiting for a use. As you may have guessed, all the horded audio gear got cobbled together to became some sort of Frankenstein’s Monster boom box. The speakers were a set of Clarion 4 way Kevlar-cone splits with silk dome tweeters and running through a rather crude crossover. The sub was a cheap and nasty Chinese 10″ single voicecoil unit with a fictional power rating and a polycarbonate cone. The amps were a Kenwood KAC-9103d monoblock D-clas amp for the sub and a Kenwood KAC-7203 class AB stereo amp for the speakers.
The cabinet was made out of some old plywood packing crates that I picked up, and reinforced with 30mm square sections of pine in the corners and joins. Internally the cabinet was split up into 3 airtight sections so that the massive air pressure from the sub could be isolated from the speakers. The crossovers were mounted behind the sub, and all of the connecting wires run out through holes in the back. I must state that there was absolutely no science behind the construction of this cabinet, all it was designed to do was be loud and fit between the wheel arches of my land rover so that I could listen to podcasts over the whine of the gearbox and transfer case. The speaker placements were purely aesthetic, and the wiring running to the amps were very much on the light side being only 6mm, but I had a spool of the stuff, and I don’t intend to crank it too high anyway as I don’t listen to ‘doof doof’ music.
After giving everything a test I covered the whole thing in some anti-skid foam that I had a heap of offcuts from. I used a two way PA speaker connection terminal and housing at the front of the cabinet to hold the power connectors and RCA inputs, there was a small toggle switch hidden away in there too for turning the whole thing off and on. Before finishing the whole thing I squeezed a Bluetooth audio receiver board and 6 volt power supply behind the sub, this made the whole thing much more practical as most of my music and podcasts are on my phone.
The whole thing fitted rather neatly into position behind the spare tire and looked less outrageous than I had expected. After tuning the amps the whole things sounded rather great for something operating in the open air and I can now listen to my favorite podcasts with ease (as can everyone else within 50 meters).