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The Zingers, the Zangers, the Zoinkers, and now, the Zonkers! How does that sound? I had to glue up four of the shelves into 2x4 foot handi-panels in order to create the side, top, and bottom panels. This put a glue line horizontally around the cabinet, going directly through the center of the tweeter. To cover this up, I am going to paint a horse-shoe shaped racing stripe around the tweeters. (See pics showing the glue line). It should look interesting when I get it done.
DRIVERS: One RST28F 1" dome tweeter and two SD215A-88 8" subwoofers per side. I bought a pair of SD215A's from Craig last year. Since then, PE put them on sale again, so I picked up another pair. My plan is to build an isobarik, which will cut VAS and box size in half. Should dig really deep in a very small box.
MAIN CABINET: See drawing below. Net internal volume, less the isobarik tunnel, will be approximately 0.8 cu. ft. Effective isobarik volume will be 1.6 cu. ft.
LUMBER & FINISHING: I picked up five pieces of 12" x 48" x 3/4" laminated "value shelving" at Menards for $0.99 each. This should be enough for both boxes and stands. Total lumber cost: 5 bucks!
COMBO PORT/TRAP SPEAKER STAND: To save space, the port will be built into the speaker stand. This allows the port to be 20+" long using 2.5" x 2.5" inside dimensions. This also allows the use of a 1/4 wave stuffed trap at the end of the port, since an external trap/port system will be very easy to fine tune once the boxes and stands are built. Fb tuning will be 31Hz with an F3 of 28Hz.
ISOBARIK LOADING: The isobarik tunnel will act as an internal brace and will also help to break up internal mid-bass cancellation/reinforcement modes. The internal 4" space immediately behind the tweeter will be stuffed with denim and used as a resonant box trap. Also, the sealed off spacing distance of 4" between the two woofers will create a frequency response dip at 1.7kHz, which will help to suppress woofer cone breakup in the 1-2khz area.
TARGET EFFICIENCY: Since I will need to hook the isobarik woofers In series for 8 ohms, there will be an efficiency loss of 3dB. After BSC and tweeter padding, final system efficiency should be in the 84 to 85dB range.
CROSSOVER: Since the rear panel must be removable to install or remove the internal woofer, I plan to put the crossover inside as well. My initial target will be 4th order acoustical at 2kHz.