Aug 5, 2008 - Page 2
Remeasure With Bass Bins
I decided to go with the RS225-8 for the woofer. I chose to undersize the box a bit. Net volume is roughly 40 liters (1" baffle). The box is 25" high, 10.5" wide and 13.25" deep. The woofer center is 8.25" from the bottom edge. With this placement, I could flip the bass bin, putting the woofer nearer the mid -- if that turned out to be a better alignment for a higher crossover point. (If I couldn't make it work, I could always use it with another mid/tweet combo) The bass bin is tuned to 34Hz using a PE 260-478 2.5" Port cut to 6.25".
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I took the rectangular baffle and added some struts to allow it to sit vertical on the bass bin. I added a solid top as this would be my preferred aesthetic in final form. I took a variety of measurements with
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Wings Comparison and Initial Crossover
As you can see, the wings did little to alter the response above 500 hz. This actually surprised me. I expected more differences to show up in the measurements.
I played with a variety of measurements but I decided a "down" placement with the 225 made the most sense initially (with open baffle). I surpressed the woofer's breakup as best I could, and spent a bit of time coming up with my best crossover. The "busy-ness" in the 800-1500 range could not be completely surpressed. While I hoped it might disappear off axis, alas it doesn't. Crossing at 500 required some really steep slopes on both sides. In listening, the setup is pretty good. Those peaks though will REALLY set my teeth on edge.
The dimensions of the box and of the baffles correspond with anomalies in the frequency response curves -- even after my best crossover efforts. Next steps to be considered,- dampen the bass bin some more;
- try a trapezoidal shape for the neo baffle; and
- bigger rear chamber;
- inclined baffle.
