PE Trapezoid kit with DE250 and QSX waveguide
In discussions with Zilch via PM's, it was obvious that the next step up from the basic EconoWave was going to be with a better HF driver, and the B & C DE250-8 seemed to be drawing most of the attention. Also much discussion was being spent on which woofer would work well with an EconoWave approach. The apparent winner seemed to be the Dayton 12 inch Classic, model number DC-300-8. Then came the announcement of the QSC waveguide, which was a bolt on device, while the standard E"wave waveguides are screw on. The QSC is physically larger, but opens up lots of possibilities being a bolt on. Finally Parts Express offered an affordable cabinet kit which seemed ideal for building a complete system. Wow, the die was cast.
I ordered a set of cabinets, waveguides and both DE250's and DC300's to build a complete set of speakers. The original EconoWave was just the Hi end. This will be a new approach to build the entire speaker, not just a sub system. And what works here will be easily adapted to the older original EconoWave, if you don't want to spend near 3 to 4 times the price for HF drivers.
The cabinet was spec'ed as being 2 cubic feet internal volume, but built as supplied is actually 1.6 cubic feet. That is OK, as lot's of nice woofers will work in that volume, including the DC300 chosen. I opted to move the baffle out 3/4 inch to raise volume to 1.72 cubic feet. The difference in performance is not that big, but internal volume is more important to me than having 1 1/8 inch behind the baffle, which is doing nothing. The build can be done either way.
Pic's are shown detailing how I moved the baffle out. The upper and lower panel mounting blocks were installed as per stock. Then two spacers were cut from 3/4 fiber board which are one inch high. This allows the side blocking parts to fill the entire 22.75 inch height, instead of leaving large gaps in the corners as built stock. The side blocking strips are aligned with the spacers, and mounted as per instructions in the kit.
This left a gap along each side of the baffle of roughly 1/8 inch inch, which can be filled with virtually anything. I cut strips of fiber board the proper width, and glued them to the baffle edges. Before receiving the waveguides, I figured the 12 inch woofers would be front panel mounted, and the baffle glued into the cabinet. But the physical size of the waveguide is 10 inches high, and the space between the top of the woofer cutout and the cabinet top is exactly 10 inches. That simply means the woofer will be back ,mounted (which will probably be best for time alignment), and the baffle mounted to the cabinet. Then the waveguide will be screwed to the baffle. Not the way I would have designed it, but perfectly functional, and once the recipe is written, users building their own should have no problems.
Since my original thought was front mounted woofers, I routed out an area about the proper width for the DC 300, and it was roughly .15 inches deep. Whooops!! Now it will need to be filled, since the woofers will be rear mounted. Another lesson learned. Don't rush! Measure twice, cut once! ETC.
Drivers will be here in about another two or three days, which will give me time to fill my mistake. I plan to veneer the baffle front anyway, so the fill will not show. In the last two pics, wax paper shows around the edges of the baffle, which is to keep the glue from the spacers joints from sticking the baffle into the cabinet.
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