[cburdick1]

Hi Everyone,

New to the page!

I've been interested in an IB system and I've tried modeling an IB with 2 Fi Car Audio IB18 drivers in WinISD, but I think I'm missing something.

It appears that the subs will start dropping off around 40hz. I was under the impression that IB subs would reach way down low, so I wonder if I have dome something wron in modeling them.

Suggestions as to what I might check?

Thanks!

 

[BandY]

Hi Everyone,

New to the page!

I've been interested in an IB system and I've tried modeling an IB with 2 Fi Car Audio IB18 drivers in WinISD, but I think I'm missing something.

It appears that the subs will start dropping off around 40hz. I was under the impression that IB subs would reach way down low, so I wonder if I have dome something wron in modeling them.

Suggestions as to what I might check?

Thanks!

Hi,
sorry, I cant help you with modelling the sub, however, from personal experience, 2 Fi IB18 can get VERY low.

 

[BP1Fanatic]

Use Hornresp.net to model the enclosure.

 

[witwald]

I've been interested in an IB system and I've tried modeling an IB with 2 Fi Car Audio IB18 drivers in WinISD, but I think I'm missing something. It appears that the subs will start dropping off around 40Hz. I was under the impression that IB subs would reach way down low, so I wonder if I have dome something wrong in modeling them.

That definitely looks like something is wrong. Check that the Thiele-Small parameters that you have entered are correct.

The Fi Car Audio IB318 v2 S4 driver has Fs = 24.4Hz and Qts = 0.79. The latter is just a little bit greater than the Qts = 0.71 value needed for a maximally flat second-order Butterworth high-pass response. The driver should show as being –3dB at approximately its free air resonance frequency, Fs = 24.4Hz. The higher Qts value means that you will get a little bit of peaking in the response.