Building the JoyAMP

Making a DIY Build look a bit more like a real product..

When I wrote about building my table speakers, I didn’t include a final image showing it all nicely built into an enclosure. That’s because there was no nice enclosure:

The poor thing was placed in a taped-closed Ferrero Rocher Gift box and left to collect dust behind my desk.

I needed to remedy this with a nice enclosure so I bought a small MDF box and some parts and started building.

Parts List

Note: This is in addition to the list here.

Build Process

I wanted a nice drilled pattern in the top and bottom of the box for airflow and aesthetics so I stuck on some masking tape, measured:

Drew some lines and drilled a grid of holes with a handy drill press:

But how would one drill a perfectly spaced arrangement of holes?

A brief digression into mathematics

The question I’ve heard a million times while tutoring maths, “When will I ever use this?”. Well, dear student, your knowledge of geometry and equations will be very useful right now.

I wanted to drill a specific pattern, where the gap between holes was the radius of the hole. To drill this grid of holes into a rectangle of dimensions l & w:

(1) defines the relationship between w, r and the number of holes in w (a).

(2) defines the relationship between l, r and the number of holes in l (b).

However, since our unknowns have annoying constraints, it’s easier to let a spreadsheet substitute values for us.

First, we set up a few more equations:

(3) is a rewrite of (1) with r as the subject of the formula.

(4) is a rewrite of (2) with b as the subject of the formula.

And then porting them over to a spreadsheet:

This sheet shows (with the darkest green) that for a 44 x 86mm rectangle, the perfect solution (zero error) is a 7 x 14 hole grid with r = 2mm and I’ll need a 4mm bit to drill the holes. However, I want to use a 5mm bit so I’ll choose the less optimal 5 x 10 hole grid pattern and take a bit of error.

Build Process continued

With the mathematics explanation over, more ruling and drilling:

After painting came assembly:

With heatsinks placed on the amp and Pi, it was time to mount the last components:

Closing the box, adding some feet and a laser-cut Joy attached:

Ooh, nice


The JoyAMP is complete! It’s nice to have it be pretty, neat and user-friendly with a proper power jack and nice speaker posts. Making all my builds be finished to a level that they need not be hidden is something I hope to continue in future.

The Future

I’d have saved myself from a lot of mathematics and drilling if I had a laser cutter and some software…

If you have any questions/would like to share your experience with making enclosures for your projects, leave a reply below. To receive an email when I publish a post, subscribe here.

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