How to Build a Scoop Bin

How to build a scoop bin comes down to three things: a proven plan, accurate panels and an airtight, rigid box. The plan sets the acoustics. The builder's job is to reproduce it exactly, keep the rear chamber sealed and fit the driver to its own data sheet, not to the drawing.

Start with a proven plan

A scoop is a short front-loaded horn: the cone fires into a curved or angled flare, with a sealed chamber behind the driver. Rear chamber volume, throat area and flare all interact with the driver's T/S parameters, so small dimensional changes shift the response. Use a published design with a full cutting list and drawings. See our designs page.

Check three things in the plan before buying board:

• Driver it was designed for. Horn-loaded designs are modelled around a specific Fs, Qts, Vas and Bl. A different driver means re-modelling (Hornresp is the usual free tool). See choosing an 18" scoop driver.
• Board thickness. Panel sizes assume one thickness. Build an 18 mm plan in 15 mm ply and every internal dimension moves by 3 mm per panel.
• Joint method. Butt joints, rebates or dados change panel sizes. Know which before you cut.

Tools and materials

• 18 mm birch plywood or the board the plan specifies (see best wood for speaker cabinets)
• Track saw or panel saw with a guide; jigsaw or router with a circle jig for the driver cut-out
• Water-resistant PVA (D3 class to EN 204)
• Wood screws, drill/driver, countersink and plenty of clamps
• T-nuts or threaded inserts and machine screws for the driver
• Sealant for internal joints, gasket tape for the driver flange
• Dust mask, eye and ear protection

1. Cut and label every panel

Cut everything before assembly. Measure from one reference edge, check rectangles by comparing diagonals, and mark each part with its cutting-list name and inside face. The internal scoop panels usually meet at angles: cut them to the drawing, not by eye.

2. Driver cut-out and fixings

Cut the driver hole while the baffle is flat and easy to clamp. Take the diameter from the driver's data sheet, because baskets differ: the WM1850/8 needs a 392 mm cut-out, while B&C's 18SW115 needs 425 mm. Check mounting depth against the rear chamber too (WM1850/8: 202 mm). Mark the bolt holes from the frame, then fit T-nuts or threaded inserts from the hidden side so the driver can come out and go back without stripping wood.

3. Dry fit

Clamp the main parts together without glue. Confirm the scoop panels fit, the magnet clears the back wall, and you can reach every joint in your planned order. Mistakes are cheap here and expensive later.

4. Glue and screw in order

Follow the plan's order if it gives one. Otherwise:

1. Fix the internal scoop panels and driver baffle to one side panel.
2. Add top and bottom, keeping everything square.
3. Fit the braces shown. See bracing and sealing cabinets.
4. Seal every internal joint you won't reach later, especially around the rear chamber.
5. Fit the second side or back last.

Glue both faces, clamp, then drive screws through pilot holes so the ply does not split. Let the glue cure fully, normally overnight, before loading the box. A leak in the sealed chamber turns it into an unintended vent and changes the loading.

5. Wire and mount the driver

Fit the input socket and wire positive to the driver's positive terminal. See the Speakon wiring guide. Put gasket tape on the frame, lower the driver in without touching the cone, and tighten the bolts gradually in a cross pattern. The WM1850/8 weighs 20 kg: two people.

6. Finish and test

Paint or cover, then fit grille, handles and corners. Check polarity, sweep at low level for buzzes and air leaks, and only then run it up. See finishing speaker cabinets and testing a new cabinet. Set a high-pass filter below the horn's working band before playing loud: below it the cone is unloaded.

Safety

Wear a dust mask when cutting ply and MDF, use blade guards and keep hands clear. A finished scoop with an 18" driver is heavy: lift with two people using proper handles, and stack only on firm, level ground.

Sources: Wavemark WM1850/8 spec sheet and WM18X451 product data; B&C Speakers published data for the 18SW115 (8 Ω), checked October 2026.