Question on my box for 2 15" btl's (HELP!!!)

[blackbonnie 0]

im running 2 fully loaded 15" btl's D2 of of 2 ia 20.1's. each amp is seeing a 1 ohm load and it doesnt seem as loud as it should be or as loud as what i was expecting. my box is 9 cubes after displacement, and is tuned to right about 34 hz. im wondering if my port area is to large, im running right now with 157.5 in^2 of port area and used 12 in^2 per cubic foot when designing it. box is 12.73 cubes before displacement. this is in an extended cab 06 silverado and it pounds the lows dont get me wrong, but i expected it to be louder then what it is. i can always make a port plug but have never done one and am wondering if i do need one, what would would you recommend me to run for port area? any help is greatly appreciated. these are the older model btl's and i am wanting to upgrade to the new ones (D1) after i upgrade my alt and run each amp at .5 daily. right now my electrical consists of a kinetik 1800 under the hood, batcap 2000 in the back, all 1/0 wiring, and the big 3 done. do you guys see any problems or did i just set my expectations to high?

[BKOLFO4 29]

Those amps love low ohm loads. With impedance rise, you would have been better off with dual 1 ohm coils. It was a very noticable difference when I went from dual 2 ohm to dual 1 ohm coils runnning my amps at 0.5.

You are not far off with your port area, so it should not be a problem unless you are not tuned where you think you are. If you make a port plug, it might or might not make it sound louder. the change in tuning frequency would make the difference more than the amount of port area.

You could strap the amps on all 4 coils in parallel just to see how loud it is. That is a 1/4 ohm, but with impedance rise, those 20.1's should handle it just fine for long enough to see if you just want more power to get the output you are looking for.

[blackbonnie 0]

well the only reason i dont have them that low is because of my electrical. im in need of an HO alt but havent got one yet. i plan on running each amp at .5 to each sub when i upgrade. there was just alot of discussion over at CA.com when i was building my box that there was to much port area, i disregarded it because stayed within specs of 12 inched per cubic foot and i felt it was fine. when i installed everything it had me thinking otherwise, but i have also heard that there is alot of imp rise with these but most of what i heard were assumptions and not facts. if thats the case then that makes me feel better about why i feel its not loud enough. with imp rise what would my amps most likely see? 1 ohm if ran at .5? just trying to get a feel because i will be upgrading to the new btl's soon and i wanna run D1's. good choice?

[blackbonnie 0]

anyone else

[BKOLFO4 29]

If it is 9 ft^3 net, then 12*9=108 in^2

If you use 16 inches per cuft, you need 144 in^2.

157 is not far off as long as it is tuned correctly.

I have used 300 inches with 11 ft^3 when I had my pair of 18's.

The impedance rise will definitely vary between setups. You should measure what you have now to get an idea of where you might be. Every sub I have run in my box measures an actual impedance that is pretty much 2X my DCR.

Brian

Edited May 15, 2008 by BKOLFO4

[blackbonnie 0]

yeah im tuned to i believe its 33.68 hz but its right around 33-34. so that should be fine. would my HU putting out 2 volts be a problem, should i switch back to my 5100 at 5v outputs? and would i see a noticeable difference?

[BKOLFO4 29]

Should not be a problem if the gains are set correctly. . .I only run 2 volt out.