Planning the enclosure: check the box on paper before you cut (Beginner Guide, Part 4)

Part 4 of 8 of the NB Audio beginner guide to speaker building. Start at Part 1 and the series contents.

Choosing sealed or ported is the easy bit. This is the paper stage after it: turning a cabinet drawing into numbers you can check before a saw touches the board.

Expansion Guide 3 follows one imaginary box the whole way through, so every calculation has real numbers in it.

The volume

Separate the outside size from the inside space, work out the empty volume, then subtract what the drivers, braces and hardware take up. The guide shows each step with the arithmetic laid out, and a second method to check it.

The alignment

Draw the cabinet from three directions so clashes show up on paper, and draw the full port before deciding it fits. If you're developing a new box, it shows how to make a simple model and change one setting at a time.

The drawing

Decide how the six panels meet, then build a cut list that adds back up to the outside size. Plan the braces, lining and access, so the crossover can actually get in. Finally, a revision number before it goes to the workshop.

Who it's for

It's written for a first build. You need the speaker design, the driver drawings, a ruler and a calculator. If you're following a published design, the guide checks it rather than changing it.

What it won't do is let you shorten a port because it hits the back wall, or assume 18 mm board is 18 mm.

Prefer Kindle? It's on Amazon.

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Previous: Part 3: Choosing speaker drivers: from parts list to a checked order (Beginner Guide, Part 3)
Next: Part 5: Building the cabinet: the order of work, from panels to drivers (Beginner Guide, Part 5)