Some Pictures of Farm's Line Arrays:
These 20-driver arrays are built from 3/4 inch oak plywood (Home Depot) externally and 5/8 inch mdf for horizontal walls and shelves.  The shape is trapezoidal and each speaker is divided into 4 acoustically isolated compartments by solid mdf.  Each compartment contains a 3 hole shelf brace.  The mdf/plywood joints are all tongue & groove (1/4 inch wide and deep) except the front baffle is simply butt jointed.  Yellow carpenter's Elmer's carpenter glue binds the joints and additional silicone rubber seals them.  The drivers are Parts Express #269-469, 4 inch full-range, shielded by a bucking magnet and are flush mounted on the baffle with a driver to driver spacing of 1/4 inch.  The drivers are mounted using silicone rubber.  They are wired in parallel sets of 5 (per acoustic compartment) and the 4 groups are then wired in series for a nominal impedance load of 7 ohms (the drivers are about 9 ohms each).  For help on wiring a line array click here. Each compartment is vented using a rectangular port of dimensions 4 x 6 inches and a length of 1.75 inches.  Each array stands 7 feet 7.25 inches in height (0.75 inches due to stabilizing base).  The other external dimensions are: baffle width = 6.125 inches;  rear wall width = 14 inches;  side walls width = 15.25 inches.  The angle cuts on the baffle, sides and rear walls are 15 degrees.  Finally, the inside surfaces are all lined with heavy carpet pad (mix of fiber and foam) except the baffle.  Each speaker weighs about 90 lb. 
Some construction pics are shown below:
Kin and Farm assemble the router table in order to route tongues in the trapezoidal horizontal mdf pieces shown behind Farm.
Kin helps Farm by marking the positions of all horizontal mdf elements on the plywood. (left photo)
Farm routes the grooves in the plywood following Kin's expert markings.
Farm builds the ports.  They are just 1 inch high.   The remaining 0.75 inch comes from the rear wall thickness, as shown below.
At left, a quick assembly is made to check fit.  Notice that the shelf braces do not yet have their holes cut out.  Also, though not easy to see, the top trapezoids are doubled (it's really going to become the bottom of the speaker).  Also, small pilot holes remain to be drilled in the 3 otherwise solid mdf pieces which separate the chambers.  These tiny holes allow the wiring network to run from top to bottom.
Clamping with glue and strap clamps.  Notice that the shelf brace visible in the nearest vent now has its holes cut and the carpet pad is already attached to the walls.  It would be difficult to do this after attaching plywood to mdf (small opening at baffle and long reach).  The baffle isn't attached yet.  That's next.  (No picture, but about 200 books used to apply pressure to glue the baffle snugly.
After two coats of stain/sealer, Farm attaches drivers to the wiring network.  A 5 Hz sine wave is applied briefly when completely wired to confirm the in phase movement of all drivers prior to sealing them with silicone rubber.
Deservedly proud Farm is finished with speaker number 2.
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