BassJunkie Posted July 8, 2011 Report Posted July 8, 2011 I just got the ported portion of my bandpass on last night. The thing really moves some air on lows now. But when it goes up to lets say 40+ hz it sounds like the subs are going to tear themselves apart. Ive turned my lpf all the way down on the head unit to 50hz but that is still too high. This has left me scratching my head....any suggestions? Quote 1986 C20 Suburban 9 American Bass XFL 15's B2 M1MKII 14v XS Power Batteries Maxwell Caps Acoustical energy is free. Electrical energy is not you havent lived until you've hit a screw with a router.
97maxima Posted July 8, 2011 Report Posted July 8, 2011 I just got the ported portion of my bandpass on last night. The thing really moves some air on lows now. But when it goes up to lets say 40+ hz it sounds like the subs are going to tear themselves apart. Ive turned my lpf all the way down on the head unit to 50hz but that is still too high. This has left me scratching my head....any suggestions? More info Quote American Bass*DC Power
BassJunkie Posted July 8, 2011 Author Report Posted July 8, 2011 (edited) the port is 4.5 x 25.25 Ported is around 9 cubes, sealed is 5-6 cubes. Which I know everyone swears by a 3 to 1 ratio but I simply don't have the power or subs for that. RD audio alphas don't have alot of motor force hence the large sealed side. Edit: forgot to mention its a 4th order wall Edited July 8, 2011 by BassJunkie Quote 1986 C20 Suburban 9 American Bass XFL 15's B2 M1MKII 14v XS Power Batteries Maxwell Caps Acoustical energy is free. Electrical energy is not you havent lived until you've hit a screw with a router.
97maxima Posted July 8, 2011 Report Posted July 8, 2011 the port is 4.5 x 25.25 Ported is around 9 cubes, sealed is 5-6 cubes. Which I know everyone swears by a 3 to 1 ratio but I simply don't have the power or subs for that. RD audio alphas don't have alot of motor force hence the large sealed side. Edit: forgot to mention its a 4th order wall port length? Quote American Bass*DC Power
BassJunkie Posted July 8, 2011 Author Report Posted July 8, 2011 I think its like 3.25, i'll have to double check tho Quote 1986 C20 Suburban 9 American Bass XFL 15's B2 M1MKII 14v XS Power Batteries Maxwell Caps Acoustical energy is free. Electrical energy is not you havent lived until you've hit a screw with a router.
97maxima Posted July 8, 2011 Report Posted July 8, 2011 (edited) You dont always need a 3 to 1 ratio.sealed seems like its way too big. even if you shrink it efficiency should remain almost the same. Most 12s ive seen in bps are around 1-1.5 sealed. You could increase port area but id drop tuning to the 45hz range Edited July 8, 2011 by 97maxima Quote American Bass*DC Power
BassJunkie Posted July 8, 2011 Author Report Posted July 8, 2011 (edited) 45hz is what im aiming for. I may need to shrink the sealed portion, I just feel like the smaller the sealed side the more rise i'll have and the less efficiency i'll have. The sealed portion sounded fine anywhere from 38hz+. but now with the baffle on making it the 4th order it has low end output now but struggles with the highs. these are 18s btw Edited July 8, 2011 by BassJunkie Quote 1986 C20 Suburban 9 American Bass XFL 15's B2 M1MKII 14v XS Power Batteries Maxwell Caps Acoustical energy is free. Electrical energy is not you havent lived until you've hit a screw with a router.
97maxima Posted July 8, 2011 Report Posted July 8, 2011 (edited) Well start with adding port length and see how it does. then move on to shrinking the sealed side. If you shrink too much stuff it with some poly fill. I dont think your rise will increase dramatically why did i think these were 12s? Edited July 8, 2011 by 97maxima Quote American Bass*DC Power
97maxima Posted July 8, 2011 Report Posted July 8, 2011 (edited) 3 cubes per 18 sealed is a little much id shrink to 2-2.5max per subs. But besides all that increase your port to say 150sq in to 200. you can always go back and shrink that if necessary Edited July 8, 2011 by 97maxima Quote American Bass*DC Power
BassJunkie Posted July 8, 2011 Author Report Posted July 8, 2011 (edited) 3 cubes per 18 sealed is a little much id shrink to 2-2.5max per subs. But besides all that increase your port to say 150sq in to 200. you can always go back and shrink that if necessary Absolutely, I built the front baffle to be removable and I didn't glue any of the port except the first piece so I could rip them all off the front baffle to adjust port size as needed. Thanks for the input! Edited July 8, 2011 by BassJunkie Quote 1986 C20 Suburban 9 American Bass XFL 15's B2 M1MKII 14v XS Power Batteries Maxwell Caps Acoustical energy is free. Electrical energy is not you havent lived until you've hit a screw with a router.
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