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"HE Crate" The Adire HE10.1 In A Crate Type Enclosure

The Adire HE10.1 in a crate type enclosure.

Introduction

I have long wanted a set of "stereo" speakers that would also do light duty PA work. That is, I wanted flat frequency response, high efficiency, and a certain level of electrical and mechanical ruggedness. Such speakers would form the core of my upstairs stereo, and would also be what my SO and I play the keyboards and guitars and such through. Along came the HE10.1 kit from Adire which looks to be just the ticket! It uses a 10" Eminence Beta woofer with a unique coaxial tweeter that mounts through the center of the woofer driver magnet assembly. The HE10.1 routinely ranks at or near the top when compared to other exotic stereo speakers at many times its price. Tube heads like it as a stereo speaker for its efficiency and smooth impedance curve. I'm not a tube head, and so am not very concerned about what particular load impedance the drivers and crossover present to the transistorized 75W Haffler amp that powers them. (As a rule, solid state amps have much lower damping factors than tube amps.)

Never a huge fan of black vinyl either, particularly after some age and abuse (of the vinyl, that is) nor of that ubiquitous nappy fuzz covering PA cabs these days, I decided to build a crate type enclosure for these drivers. It should look good, and should be able to take some abuse without turning instantly ugly. I've built other crate or This-End-Up type furniture in the past, so this isn't a huge stretch for me. In fact, I've built a couple of speaker cabinets from real weathered crate wood, and clothes dressers from entire used crates, which have all turned out well. I wish I had been able to find some actual aged crate wood for this project, but my supply has long since run dry.

The crate construction is good for protecting the speaker, port, and grille, and the terminal cup as well, since these items are mounted on the plywood and therefore recessed. If you want to mount these on pole-type speaker stands, then the mount on the bottom would be recessed as well. And the crating makes for natural hand-holds on the sides! Not to mention all this extra wood reinforces the cabinet and makes it less prone to vibrating and such. It does add some weight, however: these babies are about 40lbs each when finished.

The first part of this article describes how I built the cabinets from lumber and hardware that should be available at your local chain hardware store. The second part covers crossover construction and electrical testing.

Cabinet Construction

I changed the cabinet plans from Adire somewhat in order to make the crate type construction work out better. Since I no longer own a pickup truck, I also wanted to make the raw building materials easy to transport via the family car.

The cabinet wood is 3/4" BC plywood, hand selected for flatness and lack of blemishes. For a pair of speakers, you'll need five pieces measuring 2' x 2' or the equivalent (e.g. two pieces of 2' x 4' plus one piece 2' x 2', etc.). You could use birch plywood, but be aware that this will increase the weight significantly. Pick out two of the best looking 2' x 2' panels for the fronts of the boxes. Four of the panels are cut exactly the same: a front / back and left / right side are cut from each panel. The remaining 2' x 2' panel is used for the tops and bottoms.

Plans 1. The dimensions and cut order for the plywood sections are shown here.

The "crating" consists of 1" x 3" (nominally 0.75" x 2.5") pine, with 1" x 4" (nominally 0.75" x 3.5") pine surrounding the baffle edge. The 1 1/4" wide trim work around the baffle may be ripped from a 1" x 4" which will yield two pieces, or from whatever pine you have left over at the end.

Plans 2. Crating and hole detail.

Yellow carpenter's glue is used throughout. Two lengths of fine-thread drywall screws are used: 2" to hold the plywood box together, and 1 5/8" to attach the crating. Use the black type so that the screws won't be so obvious after staining. Measure all screw locations and pre-drill all holes for the screws. After pre-drilling, remove any wood splinters from the joint side with a file or sandpaper so that the joints will go together as tightly as you can make them. Counter-sink the screw heads that hold the plywood box together. Don't countersink the screws that attach the crating, as the wood is generally soft enough for the head to sink in below the top surface of the wood. Be careful when the driving in the crating screws when the screw heads get near the wood surface. It is all too easy to drive the screw deeply below the surface, which is ugly and should be avoided. Drive the screw heads just slightly below the top surface of the crating, deep enough so that finish sanding won't remove the black coating on the screw head, but not so deep as to tear into the wood. You might want to do the last few turns by hand with an un-powered screwdriver.

Day One

Figure 1. The plywood boxes assembled. Sides are rabbeted to accept the top and bottom (with oversize). Note that the front and back panels are not dadoed at the joints, but are simply glued on (butt joint). All joints had oversize which was later trimmed off with a laminate trimming router bit when the glue was dry. All screws heads will later be concealed by the crating and trim.

Day Two

Figure 2. The holes for the driver, port, and terminal cup are cut. Driver and port holes cut with a router circle cutter jig, terminal cup hole is first drilled at corners, then cut out with a hand-held power jig saw. I had to enlarge the 4" nominal port holes a bit with a drum sander mounted on a hand drill until the plastic ports from the kit fit snugly. This final port fit only took a couple of minutes per hole.

Figure 3. Installation of the T-Nuts with a C-clamp after the driver mounting holes are drilled. Protect the speaker baffle with a block of wood, and make sure you aren't crushing wood bits into it during the clamping. The holes locations are marked with a pencil using the driver itself as the template.

Figure 4. The back 1" x 3"s are installed, with ~1/16" overhang all around. This picture was taken after the crating was routed flush to the top, bottom, and sides with a laminate trimming bit. Sand the back before you install the crating. After routing flush, this is your last chance to easliy sand the sides!

Figure 5. Internal bracing installed, also 1" x 3" crating installed on the left and right sides. Side crating will conceal the screws used to secure the side-to-side brace.

Day Three

Figure 6. Big "E" (that's me!) formed by the 1" x 3" side crating. Pieces are cut oversize so as to overhang the sides, then trimmed with the router. This is your last chance to easily sand the baffle!

Figure 7. The front two 1" x 4" crating installed on the left and right. Lengths of these parts are cut finished! The 1" x 4"s overhang the baffle front by 1 1/4". This picture was taken after the other side crating was routed flush to the top, bottom, and back. This is your last chance to easily sand the top and bottom!

Figure 8. Calling all clamps! Top and bottom crating installed, and front trim pieces glued in place. A powered nail gun would have been welcome here, as I only had enough clamps to do one speaker at a time. Creep up on the final dimensions of the trim parts, as you want a snug fit all the way around. Cut the vertical trim parts first, then the horizontal trim members.

Day Four

Figure 9. Trim all overhanging wood with the laminate trimmer bit. Then finish sand all of the crating. Finish sanding at this point will make the radius cutting go much smoother. Otherwise, any imperfections will be picked up by the bit and transferred to the wood, requiring extra sanding afterward. Round the corners using a 1/4" radius carbide bit with a ball bearing guide. Note the use of a scrap piece of trim which made holding the routing level infintely easier (don't want to slip at this point!). Two or three passes of the router makes for a smooth radius. Sand the radii with fine sand paper after routing is complete. Watch that the router doesn't start putting a corner at the end of the radius, my router tends to make the bit extend slightly more as it heats up with use, so I have to adjust it after a couple of cuts.

Figure 10. Enclosure is complete and ready for staining!

I used one coat of Minwax 211 Provincial stain applied with a foam brush and wiped off approximately 15 minutes later with a clean lint-free rag. Note that contrary to the brand name, this is a stain only and not a wax!

Day Five

After allowing the stain to dry for at least a day, the enclosures are then given a coat of oil. I used Minwax "Antique Oil Finish", one coat applied with a clean foam brush, wipe off after allowed to sit 5 - 10 minutes with a clean lint-free rag.

Day Six

After the oil has dried for at least 24 hours the hardware can be mounted. The feet are added to the bottom and one side of each enclosure. These are brown hard plastic types from Home Despot, dia 7/8" or 22mm. To affix the feet, simply remove the corner 1 5/8" drywall screws and replace them with 2" types, with the foot on the screw. This keeps you from having to drill more holes and works very well.

I found that the black screws provided with the HE10.1 kit were too large to use with the terminal cups, and so just used 3/4" black drywall screws instead here. You can use longer screws as well, since the tips inside will never be seen. Just be careful when installing the carpet felt, or when generally rummaging around inside the enclosure with your hand - those screws can be sharp!

Figure 11. Stained and oiled enclosures, feet and terminal cups installed.

Next: Crossover and Testing

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