Using a Computer Box for a Guitar Amp!

By John Fisher

In the event of the new ATX computer boxes, the former boxes for PC will become and are becoming obsolete. It is almost unimaginable how many unused computer boxes will be unused or trashed very shortly in history. That's a lot of metal. They will be and are already common articles in junk shops, flee markets and garage sales.

For the rare person who does DIY projects such as power amps or guitar amps this is at least an intriguing idea to recycle that junk into something useful.

Here is the top of an old (becoming) obsolete computer box. There is quite a bit of metal here. It is about 7" wide and about 15" long. The length and width is sufficient for a small guitar amp.

Part of My Delema

I was faced with a problem. We had a gig that we were going to do within a week and I didn't have a guitar amp. I decided that I would build something real simple in time to do the gig and then later elaborate on it and use it as a continual project to experiment with. I would start with a Fender Deluxe circuit and then work up to something else that would have more tone controls and possibly later build an extra channel with a totally different sound that would be switchable between channels. Click here for the basic circuit that I used.



The fact that the top of the computer box already has 2 folds in it makes it easy to just cut the 2 sides down to about 2 1/2 inches. This gives you a ready made U shape with just 2 cuts. I then folded a half inch lip on each side of the U which will be screwed to the wooden box of the guitar amp.

I do not have a metal shop or a sheet metal folding machine so I bent the metal by using pieces of wood cut just right and then clamped it in place to hold the metal ready for bending.

Here I am using a block of wood and a hammer to bend the metal making a fold. In this case this is a 1/2" lip on the top of the box that will later be screwed to the wooden guitar amp box.

Here is the finished U shape for my Fender Deluxe guitar amp that I am going to build. The whole ordeal took me about 1 hour. When the whole amp was put together it looked pretty good. One advantage of using the computer box is that it is already primed and painted. You can still paint over it with another color if desired.

After the U shaped box was finished I started to make the necessary holes for the tube sockets and so forth. I do not have very many tools and I do not have any hole punches but when I got into it , it wasn't so hard to do. If you build 1 or 2 amps a year it's not so bad if you don't have the hole punches. I drilled out the big holes by making many small holes and then getting a large round file to smooth and round out the hole. It took me about 10 to 15 minutes to do each hole. It was a bit of work but it turned out OK.

Here is the amp when it is roughly wired up. I used a lot of junk parts. You will notice that there are extra tube socket holes drilled for future additions and experimenting.

Here is a photo of the front of the amp. The wide angle lens that I used for this picture kind of distorts the shape but you can at least get an idea what I did. You will notice that there are only a couple of knobs on the front, kind of scrunched to the side. This is to make room for the future knobs of the second channel. I made the box out of scrap pieces of plywood laying around. I then covered it with a very fine felt type carpet. The front grill is a piece of perforated sheet metal that used to be an iron table. This amp is by no means "State of the Art" but it worked very well. In spite of the simplicity of the circuit, it had a beautiful sound that was very nice to play and the 15 watts of power was just big enough or small enough that I could crank it a little to get a nice tone without it being too loud. I played in a club with a bass player and drummer and a couple of other rhythm players and they were complaining that I was too loud. Ha!

Here's the back of my junk parts amp quickie.

Well I got the amp done just in time for the show. I am the dude on the right with the gray hair and you can see the amp behind me.

Now, to build the amp into something else.


Update on the Computer Box Amp Idea



After Michael Rogers saw my article on building a guitar amp out of a computer box, he sent me this picture of one that he made out of an old 486 box. Now that's cool!


Here is the inside of his handy work!