A friend asked me to build him a manual switch box for MIDI. I had built a similar box for him before, but that was a metal box. This time he brought me four DPDT Center Off toggle switches and some very thin plywood (1/8″). The operation is simple, four each of a toggle switch selecting one of two MIDI connectors or none.

Designing the box

Since the wood was so thin, I cut a matching piece of aluminum to go behind it for support of all the plugging and unplugging. Lots of hole drilling. Fortunately one of my step drills worked well for the connector holes in both materials.

The switches are uniformly spaced across the top of the box. Just rectangular holes in wood into which the switches are press mounted. Lots of drilling and filing. The switches were relocated closer to the back of the box after this drawing was done. Some of the dimensions were changed.

Cutting and building the box

The six wood sides were cut from two pieces of the stock. I narrowed the width of the box in order to get a top and side from one piece and the bottom and the other side from a second piece of stock. I am not much of a wood worker and I don’t have good tools for it. The cuts were done by scoring deeply with an X-ACTO knife and then cutting down the groove with an X-ACTO saw blade. It was not possible to make a perfectly straight cut, and the plywood wanted to splinter.

The first assembly step was making a rectangular shape from the front, back and two end pieces. This was glued together and held with clamps overnight. The next step was gluing the top over this rectangle to make a five-sided box. The box and the bottom were then stained.

Wiring

After mounting the twelve MIDI connectors and the four switches into the finished box, everything was wired together. I used TE Connectivity 5-520263-2 STACON type connectors on the switches to simplify replacing a switch if one failed.

The previous box had wired the DPDT switches shorting pins 1&4 and 3&5. Since that had worked before I just followed it.

Final assembly

I fretted for a while about ways to attach the bottom so that removal would be easy. But it looked too involved, so I decided to glue it at a few spots that could be cut if a repair is ever needed.

Update April 5, 2025

The original switches eventually failed and required replacing. The only switch I found on Mouser.com that matched the size and specification was OTTO K2ABNAAAAA.

My clever plan to simplify switch replacement didn’t work, because the new switches are so deep that with the wired connector attached the cover would no longer fit. So I abandoned that plan and simply soldered the existing wires to the gold-plated tabs.

At least my idea to fasten the bottom panel with just a few spots of wood glue did work as planned and made it easy to open by sliding an X-ACTO knife along the cracks.

My friend had painted the box. Since the new switch profile is a little narrower, he will need to apply a bit of touch-up paint.