View Full Version : Help before my comp! Fi btl n2

07-13-2013, 08:46 AM
Okay so I had a custom box made that cost me 150 and a crap box that I got with the sub. It's a 15 fi btl n2. The box I got made was supposed to be for burps but I hit a higher number with my smaller one. The nice one is tuned around 45 and I'm not sure the small one but it peaks at 53hz in my cabin. Someone had any experience with this sub during comps? I need a design. My max dimensions are 37w 40h 22d the car in question is a 2000 golf hatch. Power is a hifonics Zeus 3000 big three extra batt. Volts around 13.8

07-13-2013, 10:26 AM
Could be a simple matter of what direction subs and port are aiming! Tuning to @ 45hz should be loud. If you tune even higher you can probably get more out of it... at the expense of not being able to play music at all.

At a glance that's plenty enough space for a 15. I'd be shooting for 5 cube (after all displacement) 100" ^2 port area 17" long. That's the cookie cutter SPL box that DD and a few others would use for a 15. From there you can tune higher, but I'd experiment with that... also experiment with best way to point the sub and port. Once you have that, you really need a meter if getting big numbers is your goal. Moving the box around a few inches, folding seats up or down, lowering visor, opening glove box, turning on defroster vents, etc. etc. can often find you as much as 3dB.

Joseph M
07-13-2013, 11:00 AM
I believe i did 5 cubes on a BTL 18 on a sundown saz 3k at .5 ohm, so im guessing the big box could use more power but like the guy above me said, could be box position, and all other variables. Just by moving my box was, i was able to to get .5 db

07-14-2013, 02:51 PM
Thanks guys! I used your advice and got second:D
147.7 outlaw!

07-14-2013, 02:58 PM
Now the addiction begins. Folding your seats around and all that to squeeze out every tenth. Have to checked to see where your car peaks? With a sealed box..

07-15-2013, 10:46 PM
ya car peaks at 58hz sealed. so i figure i box tuned around 55 would be perfect so i can peak at 58.:veryhapp:

07-17-2013, 12:54 AM
ya car peaks at 58hz sealed. so i figure i box tuned around 55 would be perfect so i can peak at 58.:veryhapp:

although it differs in various setups, 10Hz below the car's resonant frequency would be a good place to start. so if it actually is58Hz, then I'd shoot for 48Hz.