Horn Speaker

This is my first instructable, and I decided to document how i made a small horn for a speaker. The measurements for the horn are based on a air pressure horn i found on the internet, as i had no better reference.
The tools i used are quite basic, only some pliers, a knife and some scissors, a saw, and a soldering iron. The materials were similarly basic, i used some copper and brass sheet metal i had lying around, a bit of wood, some solder and glue. For testing i used a stereo version of osgeld's pocket protest.

To avoid building someting that looks like a horn but is kind of out of shape in the end, i found a picture of an air pressure horn on the internet. it was a nice side view, so it was fairly easy to get some measurements of it.
To get these measurements i printed out the picture, marked the different positions at which i wanted to know the diameter of the horn and took measurements. Based on these measurements i calculated the radii of the cones, their lengths and their circumferences (the formula for the angle is alpha = (circumference from the horn picture * 180) / (radius * pi) ). The result of this whole thing is the horn.dxf, which i also exported as a .png so don't have to get LibreCAD or something else to open it.
I won't explain how to use a CAD program, even if it's only 2D, as it's pretty self-explanatory.

To cut out all the parts, i first printed out the drawing from last step. I roughly cut out the parts, so i could stick them onto the sheet metal with some adhesive tape. I made sure to tape over the lines, otherwise the paper would rip while cutting. To cut out the metal parts, i simply used a knife and for the parts that i didn't cut through i just bent it until it broke out. This works fine with the copper i have as it's only 0.1 mm thick. If it's too thick to break it out, i used scissors to cut the parts. This was the case for the brass ring, as it's 0.3 mm.

To solder everything together, i first coated the edges i wanted to solder, then i bent the rings roughly into shape and soldered them together. After that i used my scissors to get everything nice and round. Then i soldered the rings together. I tried to use as little solder as possible, but i didn't always succeed. It would have made everything look nicer, but this way it holds together. To fix everything to a speaker I made another cone which went onto the thin end of the horn. I have no idea if it's better to use a cone or simply a flat piece of metal, but the cone looks better and is a bit more stable. This cone has approximately the same diameter as the speaker, which i superglued to it. At this point, i also soldered wires to the speaker.

The next step was to make a small housing for the speaker so it looks a bit nicer an the speaker doesn't have to stand on the table. I used some bits of wood which i cut from 9 mm by 9 mm square wood strip. My speaker has a diameter of 45 mm, and i decided to make it in the shape of a hexagon. The inside edge is about 23 mm long, the outer side about 34 mm. This gives it an angle of about 60 °, which results in a hexagon. I made two of these rings, and the bottom is cut from some cherry wood veneer i found in some corner. It's all stuck together with wood glue, and the speaker is stuck to this with superglue. It didn't turn out beautiful, but it works.

To test this thing i used a stereo version of the Pocket Protest, which is basically a LM 386 amp. The sound of the horn is a bit odd, because if you point it at your ear it sounds better than the speaker without the horn, but as soon as you leave this area it sounds a bit tinny. I have no idea why, but that's what it's like.
I like shiny things, so i polished it. Especially the brass ring looks much better this way.