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where it says front chamber should I put the total cf of air space of my box with the driverand port displacement out. I built a box using this prog the box was 7.2 cf total with port and dirver dis out it workout to 5.020cf. I totaly killed my stroker 12 the spider slpit from the cone the bottom lest weekend I tried to fixed it so I could burp it agian. and the top spider I put a rip in it today at a comp It was at in the edge where the set scerw is.I had left a post about a bandpass box that didnt workout.the ported box that I was using today was 7.2 cf total 118sq inch port 20" long . winisd prog said 47hztunning freq with port dis and driver dis out it was peaking at 60 hz I have a spare 12 but I dont want the same thing to happen to it.do Ineed to cut down the port size? this 12 got to burp about 10 times total between this weekend and last. I had 1 2000x on it off a stock bat and alt so I wouldnt want to see what it would do to my sub if I let it get some real power.oh I hit 145.6 today
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For your confidence, JL Audio tutorial port equation says your box is tuned to 46.8 Hz. So I think it is probably not incorrect.
Hope you didn't try playing much lower frequencies than your box is tuned. Below tuning, driver becomes quickly unloaded, and can suffer mechanical damage. Although port effect reducing excursion at tuning seems to be very small in enclosure you describe.
Regards, Janne
-------------------- For box/port calculations, try these:
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