DIY Back-Loaded Horn Enclosure

Load horns from the back of the enclosure.

Horn enclosures are part of a three-way sound system. Speakers deliver the mid-range. Woofers deliver the bass. Horns deliver the treble. They can all be in the same box, or they each might have separate boxes. The more expensive the system, the more likely that they will have individual boxes for each component. You can add back-loaded horn enclosures to any system if it has external speaker outputs. It's no different than adding another speaker. Just build a plywood box and install the horn from the back. Horns are narrow. Make your enclosure 12-by-18-by-18-inches.

Things You'll Need

• Table saw
• 2 pieces fir plywood, 3/4-by-18-by-18 inches
• 4 pieces fir plywood, 3/4-by-12-by-18 inches
• Glue
• Nylon strap clamps
• Cordless drill
• 3/8-inch drill bit
• Jigsaw
• Pin nailer
• 1 1/4-inch pin nails
• Magnetic screw tip
• 3/4-inch screws
• 3/4-inch drill bit
• 3/16-inch drill bit
• 1 1/4-inch screws

Instructions

1. Tilt the table saw blade to 45 degrees. Slide the fence over to within 1/32 inch of the blade. Miter three sides of the 18-by-18-inch pieces for the top and bottom. Miter two of the 12-by-18-inch pieces for the sides, and miter all four sides of the other 12-by-18-inch piece for the front. Leave the final 12-by-18-inch piece as it is for the back.

2. Smear glue on the three mitered edges of the sides, the top and bottom pieces. Use your fingertip to get the glue even. Stand all four pieces on the flat edge and bring them together to form a box 12-by-18-by-18-inches. Place two nylon strap clamps around the box and tighten until glue oozes out of the cracks. Let the glue dry for at least one hour.

3. Remove the clamps. Smear glue on the four mitered edges that are facing up. Drop the 12-by-18-inch front on that side that is mitered on four sides. Shoot pin nails spaced 1-inch apart around the perimeter of the front through the mitered edge. Finish by shooting pin nails around the perimeter of all the other dried mitered corners to strengthen the enclosure. Wait at least one hour for the glue to dry on the front.

4. Place the horn upside down on the front of the box and center it. Trace around it with a pencil. Remove the horn and draw another perimeter inside the tracing, 1-inch from the tracing. Drill a hole in the center with a 3/8-inch drill bit and cordless drill. Insert a jig saw blade into the hole and cut along the inside perimeter line. You should now have an opening in the front that is 1 inch smaller than the front of the horn.

5. Stand the enclosure on its front. Insert the horn down into the box from the back. Position it over the opening that you cut with the jigsaw. Place a 3/4-inch screw on the magnetic tip of a cordless screw gun. Reach inside the enclosure with the screw gun and screw. Using the tip of the screw gun, place the screw through one of the holes in the frame around the perimeter of the horn. Screw the screw into the plywood through the frame. Repeat until all of the perimeter holes have screws in them.

6. Drill a 3/4-inch hole through the last 12-by-18-inch piece of plywood. Drill it anywhere you like. Drill holes spaced 4-inches apart, 3/8-inch from the edge, around the perimeter of the piece with a 3/16-inch drill bit. Reach into the enclosure. Grab the wires coming from the end of the enclosure and pull them through the 3/4-inch hole.

7. Place the back on the enclosure. Flushing it with all four sides. Insert 1 1/4-inch screws in all the holes. Finish by tightening all the screws, securing the back on the horn enclosure.

Tips & Warnings

• Paint the enclosure black and staple a piece of wire mesh or screen over the front. The measurements here are for examples. You can build back-loaded enclosures any size, depending on the size of the horn.

• Wear safety goggles when working with wood.