So I am going to build a bandpass substage

[///M5 2,833]

I have modeled the enclosure and everything looks fine, but since modeling doesn

[mrray13 30]

pm 80inches..dude knows his bandpass.

i think once you measure your car though, you'll be better able to plot your response. also, SS subs have never modeled well, lol.

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

[Adrian_D 520]

if you want to try bandpass, there's always the decware deathbox. i really like how mine performs in home. i can only imagine it's going to work even better in a car.

how do you want to do the measurement ?

measure the anecho response of a certain box then measure the in-car response ?

[///M5 2,833]

if you want to try bandpass, there's always the decware deathbox. i really like how mine performs in home. i can only imagine it's going to work even better in a car.

how do you want to do the measurement ?

measure the anecho response of a certain box then measure the in-car response ?

That would be the plan; I will probably use the True sub that sits in my living room and a spectrum analyzer. As for the deathbox, this is more of an exercise to learn than a "for sure" it is staying in my car.

[Adrian_D 520]

aha...i get it.

imo, best way to learn would be to see how the cabin gain of your car. and then build the 4th order.

since both subs will use the cabin diffrently there are going to be some diffrences in cabin gain. i'm curious if the is more cabin gain when firing straight through the ski-port.

[///M5 2,833]

I definitely plan to measure first, adjust the plan and then build. Once built I will measure the box both inside and outside the car and post results.

I actually just put the battery back in the car about an hour ago. Bummed I can't use the snowmobiles anymore, but happy to drive my baby again. I need about 10 more degrees so I can put a fresh coat of wax on her.

[DevilDriver 28]

From my previous experience with bandpass enclosures in a vehicle, it is usually best to have the peak that you're seeing (which is primarily courtesy of the interaction with the front chamber) with a 3dB drop down to the Fc of the rear chamber, then a ~18dB/octave slope at that point so long as your bottom end is sufficiently fat, for lack of a better term. From where you are now, this can be achieved by dropping Fb a little bit and decreasing the rear chamber's size minimally. How much you change these will vary dependent on the efficiency gains you are willing to give up that are inherent with a bandpass enclosure. I highly, highly, highly recommend using a flared port, particularly with a small box driver like an Rl-i 8; doing so will allow you to use a smaller diameter port with shorter length will keeping vent velocity lower.

I don't have any of the 8" RL-i t/s handy right now so I can't model something specific up immediately, but I think you will find your next project to be a very entertaining one. Predicting cabin gain with a sealed enclosure is relatively easy (even in a car, it's not too hard) but predicting cabin gain and modeling any consistency in that regard with a bandpass enclosure is quite challenging. Personally, I have had success in few trunk cars using the suggestions I listed above. My girlfriends Grand Am is seeing a similar treatment right now and everything is sounding good so far.

There is a caveat to the suggestion I made above, and that is simply that if you end up with in vehicle response where the lower end is actually rising, you will probably be very disappointed by the perceived "sloppy" sound that is natural to the human ear at lower frequencies.

[///M5 2,833]

Thanks for the insight Neil. I will gladly fatten up the bottom end which was my concern from the model in the first place.

The port will be external as I have to fit it through the ski hole eventually, by your comments are you saying my port too small? I could use a round flared one, but with the length it is modeling to a labyrinth will be the easiest to implement. On the same note, I could surely use more than 3/4" on the end of the port so that I can round it over more.

As to your caveat, before I build the first attempt I will post measurements of my in vehicle response as well. I will be out of town for the next three weeks, but when I return the project will get put on the fast track.

[Aaron Clinton 2,372]

I am very curious as to how this turns out.

[Mike Troll 0]

Subscribed.....

Ive been considering bandpass in my car for a while now.

[Godsmack 361]

I like this idea man..........all I have to add is pics are a must!!!

J