Before I explain my question I want to say I know WinISD is not going to accurately represent the output in a car, I am just using it to get a general idea of the frequency response shape of the box itself.

I am trying to help a friend decide on what subs to get for his new setup. I am strongly pushing a pair Fi 12's and he asked me to design a box for him. With most drivers I put into WinISD a get reasonable looking response curves when putting in the recommended enclosure specs, and then I go on and alter designs from that point. With a pair of Fi Q 12's I started with a 4.2 cubic foot box tuned to 32Hz and this is the shape of the response I got...

I suspect it is because of the low Vas that the Fi Q's have. But if the Vas is so low, why can't the box be much smaller? I am just trying to make sense of this graph and the sub-woofers Vas.

On an off-note, how do you think the subs will perform in a 4.2 cubic foot box tuned to 32Hz?

Thanks for any help.

Edited January 3, 201114 yr by alonzoub

It simply doesn't model our subs correctly..

Higher motor force and lower vas just throws it off for some reason.

I highly suggest that you stick within our box guidelines, it really doesn't get much simpler then that. Pay no attention to the "response curve" as you are going to have nothing remotely close to that.

Ok, thats what I expected, so 4.2 cubic feet (2.1 per sub) with a 32Hz tuning is withing the suggested range. So ill stick with that for now. Thanks

Being an owner of the exact setup you're pushing for (pair of 12" Q's in 4.2cuft tuned to 32hz) I can tell you the response is great. The subs can get plenty loud enough and sound amazing with the upper bass notes coming across crisp and tight and the deep notes rumbling through with authority, sometimes violently.

Well thats excellent news, I appreciate the input.

Another thing is you may have the file for the old Q's. it took me ALOT of searching to find the 2010 FI Q file. they are quite different. the old sub modeled terrible in small boxes.