Ortho Acoustic WAW Part 5.
I constructed a set of boxes out of 16 mm MDF I had laying around (after giving up on concrete). I decided to not make space for the plate amps because I am planning to drive these speakers with something else in the future. I therefor made two separate boxes for the plate amps.
I prepped and painted all boxes like described in this blog post. I then spray painted the boxes in a semi-flat NCS S 0502-Y (the same color as the original white Carlsson OA-50 speakers, a.k.a. Stockholm white, Eggshell white or Antique white). I also applied a layer of wax on top of the paint (for some extra protection).
Making theswe boxes was quick and easy. 45 degree mitered corners to eliminate end grain and rabbets top and bottom for the bottom and the baffle. The real challenge was the baffles. A lot of angles and limited estate. I therefor started out making 3D models in a CAD program to figure out how to maintain the basic properties of the OA-50. A 37 degrees angle in the horizontal plane and a 54 degree angle in the vertical plane of the upright baffle. Putting an eight inch sub-woofer element on the horizontal baffle forced me to put the upright baffle further to the back. It made it impossible to fit the W5-2143 in a shaft like on the original OA-50. I was considering using a piece of sonotube like on the OA-58 and many Larsen speakers but it didn't work out. I finally had to construct a pair of what I call "dog houses". The picture below is of the prototype in chipboard (to make sure I got all the miter angles right and that the element actually fitted like planned) and the pair that I used (in black Valchromat).
The dog houses was a bit of extra work but they provide enough space and a significant improvement of flow and access to the chamber below through the hole in the baffle (if I ever need to add stuffings or a x-over etc.).
The next picture is from try fitting the dog house to a mock-up of the baffle (once again to make sure everything fits before cutting more Valchromat.
And this is what it looks like after the dog houses been glued to the horizontal baffle with holes routed down to the underlying box.
The underlying box has been separated into two different compartments. One 6 liters for the W5-2143 and the rest (almost 15 liters) for the sub-woofer element.
The box was sealed with acrylic caulk (cheap, easy to work with and even to remove if needed). Even the Neutrik SpeakON connectors where sealed (the picture is before the caulk was smoothed out).
Pretty much everything was glued with PVA except the baffles. I use Casco SuperFix to make sure I get a strong and airtight bond between dog house, baffles and box.
Next up is application of hardwax oil on all Valchromat pieces before finally mounting the horizontal baffle to the box (I also need to do some wiring before I mount the speaker elements).
