The Definitive NOOB Guide to Building an Amplifier Enclosure out of Wood

Let’s make a gravity mounted enclosure for an amplifier. Usually this is for a tube amplifier, but it’ll work for anything. If you’ve seen a Bottlehead Crack, you know what a gravity mounted enclosure is.

So purty. Let’s make one!

The wood base is called a skirt and the metal sheet that the components ultimately are mounted to simply sits on top of it. Gravity keeps it in place, though taking a bit of time to secure it to the skirt with screws is a good idea. We’ll focus on the wood part – creating a nice top panel by hand is another post entirely.

Before we get any further, we have two important lists to talk about. One makes sure you are not wasting your time and the other is so you can reasonably do this and, thus, not waste your time.

What you should expect:

  1. It will not be perfect. Things will be cut incorrectly, things will be a millimeter or two too long, too short, or of the incorrect slope. You’ll miss a tiny bit of wood glue and it will show through the stain. Accept this will happen.
  2. You have to want imperfection. If you are the person that cannot work with imperfection, you want to just buy something from a company where a machine does it.
  3. It involves time and a lot of waiting. Days worth.
  4. You will make mistakes ranging from “oh, that’s kind cool” to “Eh, I think I can work with this” to “shit, time to go back to the lumber yard”.
  5. You need to have sane tools. You can get away with really basic tooling but the crappier your tools, the crappier your end product and the worse precision you’ll end up with. However, embracing those imperfections will go a long way to a unique and awesome end product. But, no way around shit tools and shit product correlation.

What you need:

  1. A miter saw. A miter box is probably gonna suck, I do not recommend it. I also do not recommend a hand miter saw. I’ve tried that and found it difficult to get accurate angles, especially if trying to put together a skirt requiring angle cuts.
  2. An orbital sander and sanding block. You might be able to get away with only a sanding block, but say good bye to more time and very sore arms/hands.
  3. A quality caliper.
  4. Wood glue, any will do.
  5. Wood screws (optional, dependant on the kind of skirt)
  6. Wood dowels (optional, dependant on the kind of skirt)
  7. Stain, get a few different stains and test them on scrap to see what looks best to you.
  8. Some sort of finish. Shellac or spray-on polyurethane are my go-to. Spray on is going to produce superior results vs. trying to brush it on, unless you’re way more talented than I.
  9. A drill.
  10. An electric screw driver (be nice to your hands/wrists and get an electric one).
  11. Painter’s tape.
  12. Clamps (at least 4 long-ish ones, more the better).
  13. Angle clamps (at least 1 of them, more the better).
  14. A speed square.
  15. A drill press.

That’s the sane list and if you don’t have that stuff already, you’re putting up a decent cost up-front. I consider that list to be the minimum for a decent product. You can get a lot of other things that will help and increase the awesome-ness of the finished product, but are not necessary IMO.

A tale of two skirts

There are two skirt designs I like. The first is a box of 4 equal length pieces of wood with 45 degree angles on each end that fit together to create a box with seams only at the edges. This creates a very clean and classy look. If your metal sheet is 12″ x 12″ and 1/2″ thick, you’re looking at 4 pieces cut to 13″. The downside to building this is that if you’re not able to cut accurate angles, you’ll have issues fitting it together nicely at the end. That is work-around-able depending on how mis-aligned it is, but that’s the biggest risk. We’ll call this the Pretty One™ and is the configuration Bottlehead uses. I’ve used it a number of times and it looks great. It’s probably the most popular skirt DIYer’s make.

A “small” tube preamp using a pretty skirt. Made of oak. This one actually kinda has some flaws, but still looks good to the non-insane.

The other consists of two lengths that are the length of two sides of your top panel and two that are the length of the other two sides, plus the thickness of the wood. So, if your same metal panel is 12″ x 12″ and your wood is 1/2″ thick, you’re looking at two 13″ lengths and two 12″ lengths. Seams on the sides, not the edges. This is easier to put together and will result in much more noticeable lines. There are also ways to incorporate decorative physical seaming or lines with this method. We’ll call this The Rustic™.

A Rustic™ mid-build.

Which method to use? It depends. If I’m looking for a more sleek look, the first option is the best. If I’d like to build something with lines and perhaps a more “worn” or “hand made” look, the latter is best. Both will produce a very sturdy and safe product, which is just as important as beauty.