Building The EZ as Pie Tower Speakers

The speaker is built entirely from 12" mdf boards which lumber sources sell in 16' lengths for 70 cents/ft. You will need two 16' boards which you should have the yard cut into two or more pieces for transporting. I had them cut each board 6-1/2' from one end. What's important is that you have them cut so you can subsequently get five 36" lengths from each 16' board. NOTE: The "12" boards are really 11-1/4" wide.

You can cut out the 36" lengths by measuring with a yard stick, then use a square to draw a perpenducular line across the board.

Then you place the blade of your saw on the line, clamp a carpenters square to the board to guide the saw, and cut. I've shown a skil saw here, which you can use, but a circular saw with a plywood blade would be more precise.

When all the sawdust has cleared you will have eight 36" panels, four 12-3/4" top & bottom panels, plus a number or 1-1/2" pieces to use as braces. The other dimension on every piece is the board's 11-1/4" width.

Next you select two of the 36" panels and draw lines to indicate the center points for the woofer, tweeter, and port. The tweeters should be mounted asymmetrically, 1" off center. Here are the critical dimensions: 1) the tweeter cutout is centered 2-1/2" from the top and is 1" off the center line of the panel (be sure to build mirror image enclosures). The cutout diameter is 3-1/8". 2) The woofer cutout is centered 8-7/8" down from the top of the panel. The cutout diameter is 7-5/16. 3) The port cutout is centered 12" from the bottom of the panel. The cutout diameter is 4-1/4.

After you have located the center points you use a simple compass to draw the correct size circles, which you then cut out using your skil saw.

Now you're ready to test-fit the drivers. Notice you will need to cut a couple of notches to accommodate the tweeter connecting posts.

WOW! It's a perfect fit! The drivers aren't recessed. Not recessing the tweeter will have a measurable and audible effect on the frequency response, but it will not sound objectionable. The effect of not recessing the drivers is less pronounced than the effect of the grill in front of the recessed drivers in most mass market speakers.

Test fit the 4" port too. This is the only part that's different from the Studio One Pi speaker kit. You will need to order two Part #260-411 four inch ports from Parts Express. Port Length: You can cut the port to the desired length with your skil saw. With a 3" length port I find the speakers have a bit of a midbass bloom. They sound best to me with a 4" length, but some might prefer louder midbass, so anywhere between 3" and 4" is ok depending on your taste. The ports are only $1.70 each, so order four and cut a pair of 3" and a pair of 4".

Next you prepare each of the four side panels by marking the locations for four braces. The exact location of each brace isn't critical, but they should be set at unequal distances from each other, and they should be installed perpendicular to the side panel with the ends aligned perfectly with the edges of the panels.

Be sure the install the braces perfectly square with their ends perfectly aligned with the edges of the panel (remember, both the braces and the panels are exactly 11-1/4", so this shouldn't be hard to do). To get it exactly right, clamp each brace in its position, drill two 5/64" holes about 1" into each brace, and drop a #4b finishing nail into each hole. Then you remove the nails and the braces, apply carpenters glue, replace the brace, push in the nail to assure the brace is properly positioned, and clamp. The purpose of the nails is to hold the braces in exactly the right position on the slippery wet glue. After the glue has dried you should pull the nails.

Clamp each brace for about ten minutes. Here you can see all the braces for one side panel have been glued in place.

Here's one enclosure set up on sawhorses for a test fit. The braces inside each side panel add to the stability of the unglued enclsoure during this step. Use the yardstick to make pencil marks along both edges of the front panel at the following distances from the top: 2" 10", 18", 26", and 34". These marks indicate the location of the 1-1/2" #4d finishing nails you will use to align and secure the panels. (OK, I'll admit it - I recessed the drivers because I have a router and it' easy to do, but it isn't necessary).

Click on this picture to display a larger image so you can see the pencil marks.

Align the side panels with the edges of the front panel, clamp, and drill nail holes about 1" deep at the pencil marks using a 5/64 drill bit. (You must use this exact size drill bit so the nails will fit perfectly in the holes yet can be pulled out by hand). The nails will slip easily into their pilot holes and stand about 1/4" to 1/2" proud. Notice now nicely the front and side panels are aligned at the seam, but not the bottom panel which I will do later. Click on the picture to enlarge it to better see the nails in place.

Now remove the nails and the top panel.

Apply a generous bead of carpenters glue along the top of the side panels as shown.

Use your finger to spread the glue to cover all of the edges that will make contact with the front panel.

Place the front panel back in place, insert all the nails, and use a nail set to drive them the rest of the way in so they are slightly recessed within the front panel. The nailheads are larger than the holes you drilled, so they grab the front panel and secure it firmly to the sides. Use a damp rag to wipe the excess glue that seeps out from the seams.

After the glued front panels have dried overnight, turn the attached front and side panels over and use the same technique to attach the back panel. The side panels probably won't line up perfectly with the edges of the back panel, but you can coax them into place to drill the guide holes for the nails.

When the front and side panels are securely glued it's a good time to install the damping material. For these speakers I used some R13 fiberglass insulation from Home Depot. It comes in 16" wide rolls, and you will need to cut across the insulation at about 19" (the 19" provides a snug fit). The insulation is paper backed and about 4" thick - you should peel off the paper backing, then divide the 4" thickness into two 2" thicknesses. It pulls apart easily. Apply some glue to the side braces and back of the enclosure to hold it securely in place, and install it.

Notice I cut out a section of one sheet to provide clearance for the back of the woofer.

The two 2" thick 16" by 19" pieces will cover all but the lowest 6" of the enclosure. Now cut a full thickness 11" by 12" piece from the roll and install it in the bottom of the enclosure.

Then you attach the bottom and the top panels using the same technique you did with the front and side panels.

No matter how carefully you cut all the panels the top and bottom panels may not fit perfectly. Don't worry - you'll use wood putty later to mask over any imperfections.

Two glued enclosures.

A crossover ready for installation. It's a very SET-friendly first order consiting of an inductor in series with the woofer and a capacitor is series with the tweeter. A resistor is placed across the tweeter leads to damp any resonance. I used a copper foil inductor because I had in in the parts bin, but the copper wire inductor supplied with the kit will work just as well.

The installed crossover.

At last! The Theater 3 Pi looks on approvingly as the new kid on the block struts her seductive stuff.

Now I've removed the drivers for final finishing. Here's one speaker after the application of Elmers wood putty. Apply it to all the imperfections, give it a day to dry, then sand it smooth. Be sure to coat the mdf ends so they won't soak up the paint.

The painted speakers waiting for driver reinstallation. The EZ way to paint speakers is to roll it on. I prefer Rustoleum American Accents paint. It's available in a quart size can which is adequate for a pair of speakers. Using a smooth 4" long roller, apply three or four coats about a half hour apart. This vinyl based paint drys quickly, but it remains a bit tacky for a month or more, so don't place any heavy objects on the speakers for a couple of months or they will mar the finish.

A completed speaker

The EZ As Pie pair playing music!