4 FI X12"

[B-Rich 0]

Hello, I am new to the forum. I just purchased 4 Fi X12's on sale from Fi. I was wondering what kind of box I should use with them. I would like ported for more air movement. The Fi website does not have any recommendations for the sub besides the size of the box. "sealed= 0.9-1.3 Ported=1.6-2.2" cubic ft. I was looking for some kind of calculator for port size and what frequency would be good with these subs. They are going in a 1990 GMC Sierra ext cab w/removed back seat. they will be in a straight line. Should I enclose each separately or all in one enclosure with one port? Any help would be greatly appreciated. Thanks.

[SpeakerBoy 64]

More details. We don't know your music preferences, max dimensions to work with, electrical/charging, or amplfier(s).

[B-Rich 0]

Oh, sorry. I'll be using a Power Acoustiks BAMF "4000watt" amp. The speakers are 300 RMS each making 1200RMS together. The amp pushes "1700 watts" at 2ohm but I think they are being over confident with there specs. The amount of spce I have is 60"LX13"DX25"H.

I listen to just about every thing, rap, rock, classic rock, country (yes, country), just about anything.

[mjmarovi 8]

I just purchased 4 of them myself. Mine will be in an enclosure that will come out to ~7.2 cuft after port and displacement giving them 1.75 cuft each. chamber is shared, I have always seen better output in shared chambers. Enclosure is tuned to 31hz.

It is same box I used for 2 15" Q's, and specs happen to come out to be good for 4 12's as well. I plan on using BTL's in the future, just slowly saving for the upgrade. Going beyond recommended size of enclosure will lower the power handling but increase the output. since you listen to a variety of music a tune ~33hz would probably suit you quite nicely. No need to do anything way low since none of those genres listed above have anything truly "low" in them.

[B-Rich 0]

Thanks for the info mjmarovi.

[B-Rich 0]

I have one more question about tuning the box I plan to build. I have been using this calculator. http://www.carstereo.com/help/Articles.cfm?id=31

I type in the amount of subs (4), the Xmax (16mm), and the freq (33hertz). It tells me I need 115.7 sq inches of port.

The box I have designed using Google Sketch up (nice program) only has 31.25 sq inches of port at 32.08 hertz. Will this hinder the performance of the subs or make alot of port noise???

Is it all together a bad idea to have a quarter of the recommended port area???

The port I created is 12.5" X 2.5" and 6.5" deep into the box. The box volume is 6.62 cu ft. One port, making 32.08 hertz.

Any info and comments would be great, thanks.

[mjmarovi 8]

need to build a way bigger port, that's only ~4.7 inches of port per cubic foot of box area, 12-16 sq. in. is a generally a good range, 11 is the minimum and as long as you shave down sharp edges and round all the corners on the port, suits just fine. but your port def. needs to be larger, and a larger port needs to be longer as well to get same tuning, which in turn takes up more volume and more air space inside the box, taking away from actual box volume. You need to re-calculate.....

If you'd like, give me your dimensions and I'll design a box for you, or one of us will.

and I mean dimensions you actually want to use, I'm assuming you don't want to use all 60" of length...

[B-Rich 0]

Thanks for the info, I don't think I'll need anyone to design a box for me, that's half the fun. I've built a lot of sealed boxes for myself and friends, just never got into the dark art of tuning a box. I redesigned a box if you would like to look at it. The new port is 16.5 X 7 X 19.5". The box volume is 8.22 cu ft after port and sub displacement. I will most likely add reinforcements to get the Vb down to 8 cu ft even. Here is a google sketch up I made.

http://sketchup.google.com/3dwarehouse/details?mid=41992ace70283e3a52821eea365695fe

[BKOLFO4 29]

Looks good.1700 watts will kill these drivers, so be carefull.

[B-Rich 0]

Looks good.1700 watts will kill these drivers, so be carefull.

I think the Power Acoustik team is a little over confident in thier ratings. The BAMF 4000.1 has three 40 amp fuses, 120 X 14.4 volts = 1728 watts. That is 100% efficiency, highly improbable. 75% efficiency would be 1296 watts, that sounds more like it. I weighed the odds before I bought the amp, even for a 1300 watt amp it was cheap compared to Kicker, Rockford or any other "big" brand car audio. I just hope it performs well and sounds good.

Edited December 4, 2009 by B-Rich

[mjmarovi 8]

just be sure to set gain correctly and not clip the woofers.

1700 watts will kill these? I plan on powering 4 x 12's with a 1500d at .5 ohm.....not a good idea eh? I have no experience with the X line, this is really an experiment and just to use till I save for BTL's or Nightshade V2's, whichever is readily available when I have the cash. I don't plan on ragging on the x12's that much, will probably get beat on the hardest during bassrace, 139.9 class though, so shouldn't have to come close to full board.