How I made

My Mobile Mp3 Box

I have a pile of spare parts lying around from various upgrades for myself and friends, so I dug out an integrated motherboard with built in sound, video, and disc controllers. I could have bought a more modern MB with NIC (network interface card) included, but this one was free. It had a Pentium 90 installed, and 36 meg of ram. Looked like a good place to start.

Around here power supplies cost more than a case with a power supply in it, so I bought a new case. I picked up a case and  NIC, tab so far - $50. I wavered for a while on the power supply, was going to order one from the www that runs on 12v., but thought that a standard one would be cheaper and more readily available for possible replacement. I got a modified sine wave (cheapie) 110v. 300w. inverter at Wally World (there's one in YOUR town!) for $30. Tab's up to $80.

I found a 2.5 gig hard drive in the junk pile, thought about putting Linux on it, but had driver problems with the legacy stuff. I stuck in a 98SE CD and in a while installed Winamp and a couple gig of mp3 files through the NIC. Test run in the house showed that the P90 handled Winamp fine as long as that's all it had to do. No visualizations, but there is not going to be a monitor in the van anyway until I can find/afford one of those cute little back lit LCD panels. 

Having read about vibration problems in vehicles, I decided to combat this two ways:

1. Mount the HD with the spin axis horizontal, cutting down on head crash. 

2. Cushion the HD with foam to absorb road vibrations and shocks.

Here's the test box I used to make sure everything would work together in the van.

This worked well, and I drove it around for a few days to see how reliable it was. I learned to turn off anything that takes processor time, like the playlist updating itself during random play. With a faster processor this probably would not be a problem, but the price for this one was right. I plugged a cassette adapter into the line out connector of the sound board, and played through the factory stereo. The sound was acceptable, and the systems proved to be reliable. Back in the house I ran the system through my stereo for a couple of days nonstop without any problems. 

After the system proved itself, I wanted two things - more storage and a smaller box. Storage was easy, just throw money at it. I paid $160 for a 40 gig drive which was the best deal between three computer stores in town. Next month there'll be a better deal, but that's life.

That'll give me approximately 10,000 songs, or about 28 days of nonstop music. That will hold all of my CD collection and many months of downloads. Tab is now up to $240 American. 

Now for the smaller box. I took the system apart and laid it out on the floor, discarding non-essentials like  floppy and CD drives. The NIC was on a standard PCI card, so I removed the bracket by taking out two screws and ended up with a card only 2" above the motherboard. It will be secured with straps. I tried various arrangements and decided on one that would fit in a 9x17 inch footprint. 15x11 would have worked almost as well but was 8 square inches larger, or 40 more cubic inches. You would need to adjust to fit your components.. 

The HD standing on edge was 4" tall, so I decided to make the box 5" deep to allow for foam.  That's about .44 cubic feet total volume for the box. I drove to a small sheet metal shop not far from home, and found it locked up, with a beeper number posted. I called and when the owner returned my call he said a 9x17x5 box would cost about $25 to fabricate. He said he would be back in the shop later in the afternoon. As I was driving back home, I spotted a piece of sheet metal blowing down the ditch a couple of miles from the shop, obviously scrap off some truck as it was cut in an irregular shape. I stopped and picked it up, noting that it was probably large enough for the box I needed. When I got home and measured I found that I could cut the box complete with a top from the metal if I laid it out right. 

If you haven't worked with sheet metal you probably will be better off having a box made, or maybe find some other suitable enclosure. It took me a couple of hours to make my box, and without the right tools for sheet metal work it turned out a little rough in the bends, but it's going to be hidden under a seat so nobody will ever see it. If you attempt to make your own box, you will need tin snips and pliers to bend the metal, rulers, markers, etc. Instructions in sheet metal fabrication are beyond the scope of this web site so if you don't know how to do this, go buy a box.

 Sheet metal is dangerous with sharp edges, and I can't be responsible for anything that happens to you. Use common sense and care, wear leather work gloves, and you should be all right. Watch your eyes! I only bled a little bit while making my box.


Here is a view of the box with everything installed and running. I had to make a suitable hole to accommodate the power supply fan and cables on one end. The hard drive is packed in foam, the motherboard is bolted in place with standard standoffs and spacers. I made a hole for the NIC Cat5 cable and LEDs. I made holes for the monitor connector, RS232 mouse connector, and audio connectors. I also mounted the reset switch and power and HD LEDs in the front panel. To avoid messing with the power supply wiring I removed the switch from the mini tower case and left it in the "on" position, bundled in the case with the extra power supply cables. Power will be controlled by switching the external inverter on and off.

Here is the power supply end, with the foam packed HD visible. You can see Winamp running on the monitor that will not be used in the van.


Here is a view of the completed system. When in the van it will not have the monitor, mouse, or Cat5 cable. (Or the sofa and refrigerator.) The keyboard will be used to control Winamp until I get a keypad. 98SE will ignore the absent mouse if you tell it to. The power inverter is not shown in this picture. I was not impressed with the sound of the cassette adapter so I decided to add an amplifier and speaker system that I already had. If you already have a sound system with audio line inputs, this extra equipment would not be necessary. 

I spent $240 by scrounging parts and making the box myself. Be creative and you can put together a cheap but good sounding MP3 system for less.





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