I’ve got a AM/FM/Tape/CD boom box (Sony CFD-22) that I got in the early 1990’s. I used it in my office when it was purchased. Eventually it made it’s way into the garage and has been there since (at least 15 years). The garage has not been very hospitable to it over the years. It has finally started to give up with the CD failing, fast forward no longer working, volume either on or off, broken antenna, and only one speaker fully functioning.
I’ve wanted to replace it with a new shelf system with an iPod interface, but I don’t want to spend two or three hundred dollars that most of the better ones demand. It occurred to me I have all the components of a good audio system in boxes. Car audio equipment pulled from systems I built in previous cars. Hrmm! Car audio components are built to handle the extremes of an automotive environment. Good candidates for the harsh garage environment. So, I started thinking about how I can utilize it in the garage.
The first obvious problem is how to power it from house power (110v) since it’s all designed to run off 12v. To this I looked into power inverters. Wow! The ones that can can carry a amperage load of greater than 3 amps start getting very expensive very quickly. I want to use an Alpine V-Drive high power unit which will pull a maximum of 20 amps, but likely between 5 and 10 on average. This price per amp limitation almost stopped this project dead in its tracks.
Then one day while looking at the power options again, I stumbled on the use of PC power supplies to power 12v electronics. A little more research showed car audio equipment being run off a PC ATX power supply unit (PSU). PSU’s supply 12v, 5v, and 3.3v on different rails. They are also reasonably priced. You can’t use just any PSU. You need one that can push enough amperage on the 12v rail. Some have multiple rails, others just one. For an explanation of PSU rails, see this ATX PSU wiki.
PC PSU’s come in many flavors from very cheap, low-wattage, to very expensive, high wattage units and everything in between, some with single rails, and some with dual. The key is finding one that can drive the amperage load needed without taxing the voltage rail or the PSU itself. The ATX 2.3 specification ditches the 20amp (240 VA) limit on a single rail which can be useful if you need to drive high power equipment. Another consideration is the units ability to cool itself without sounding like a jet plane because PC PSU’s can be very noisy, especially at the lower end of the cost spectrum.
So you’ve got power, now what? You need an enclosure of some sort to mount everything in. I’ve seen everything from plastic tool boxes to drink coolers, and I bet they sound like garbage in person. Speakers need a good solid mounting point. Ideally the speakers should be isolated from each other in separate compartments, so you’re looking at a three chambered box with more substance than plastic.
You’ll also need various other items to make it fully operational, such as intake vent(s) for cooling (the PSU draws air internally and pushes it out the back), auxiliary input block-off plates and adapters, and an antenna to name a few. If you build a box you’ll also need wood, nails, wood glue, and something for the finish like box carpet or paint. You could add handles and/or rubber feet as well.
So now your thinking it’s starting to sound expensive and why not just buy a shelf system and call it a day? Because I can, and it will be a fun project.
Below is a list of items pulled out of my inventory for use. I’ve priced out the remaining items I need and it should still save money over a store bought shelf system and will most likely sound a whole lot better.
- Alpine CDA-7893 head unit
- Alpine KCA-121B Ai-Net RCA auxiliary input
- Monster iPod to RCA audio cable
- JBL GTO-605c 6.5″/1″ component speakers
- Fiberfill
I created a CAD conceptual drawing of my vision. I’m going to use spray on truck bed liner to finish it. That finish is not represented in my conceptualization.
In the next few posts I’ll document the build process and final product. Stay tuned (no pun intended). 🙂
Unfinished Bitness 