I decided to design and build a 2x10 bass cab for the fun of it. I have other commerical cabs I can use, so this is not a do or die project. Using the lite version of WinISD (not pro) I plugged in the specs for the following driver: Warrior 10 Problem Question Here are the results for one design I came up with. My question follows the data: Number of drivers : 2 Box type : Vented Box size : 3.700 ft^3 Tuning frequency : 32.00 Hz Vent : 1 vent(s) 2.73 in length for each 3.00 in round Freq Gain SPL [Hz] [dB] [dB] 20.00 -24.13 77.88 25.00 -12.59 89.42 30.00 0.81 102.82 35.00 2.87 104.88 40.00 0.31 102.32 45.00 -0.17 101.84 50.00 0.03 102.04 55.00 0.42 102.43 60.00 0.81 102.82 65.00 1.12 103.13 70.00 1.34 103.35 75.00 1.48 103.49 80.00 1.54 103.55 85.00 1.56 103.57 90.00 1.53 103.54 95.00 1.49 103.50 100.00 1.43 103.44 However, for this result and any other frequency tuning/volume combination I played with, the db/gain curve goes up sharply right before my desired frequency tuning, sort of like a ski jump. Is this a common result or an anomaly? Or is it just a "boom" effect that I can insulate out? I double-checked the speaker specs I typed in, and there doesn't seem to be a problem. I know the design provided is for 32 HZ tuning...The 31HZ results indicated just a little bit more of a negative relative gain/db curve than I wanted in the 50-40 HZ range, but maybe I'm being picky. My priority is to build a midrange bass cab that can at least attempt to handle a low b and not fall out too much on the low notes (60-31HZ), since I will use it mostly standalone for worship music and an occassional rock jam in small venues. It will be a 4ohm cab running through my Peavey Firebass 700 head (475w@4ohm, 700w@2ohm when my 2x12 is added as a "sub"). Any questions, comments, help, etc. is appreciated. Thanks!