Wall or rear port for a 4th order bandpass

[rambronco]

So I was getting ready to start my cuts for my 4th order in a 1999 Tahoe, was going to do a C-pillar box and retain the rear seats, but then......Go big or go home right? So now I have plenty of room to play with. The box will be for 2 18" Sundown Zv.4's. I have heard a few walls in my day but it has been some years now, over the years I seemed to prefer the sound of rear firing boxes in large vehicles and I cant tell you if thats because those boxes were designed better than the walls I heard or if there is an actual change in sound with a large cabin area of a rear firing box. Now that the seats are getting tossed i'll probably be looking for something in the range of 3:1 - 4:1 for the box and would like to hear what you guys think?

Thanks

RB

[Raptorman]

ZV4's are great bandpass subs.

The more ported volume you can fit the better.


Everyone here will tell you to stick to 2:1 because they're afraid of higher ratios. Your enclosure will still be very musical even up to 3.5:1 and possibly higher.

And typically for trunk cars, sub/port rear is going to sound best. In SUV's sub up/port back is going to sound best.

For two zv4 18's you're looking at 15-20 total cubes net that you'll need.

[rambronco]

Thanks for the reply Raptor. Nothing final yet but looking at approx 6- 7 sealed, 24ish ported tuned at 39 ish. I am leaning toward port back.

[Raptorman]

How much power?

Don't do port back. Wall it off and seal it off completely and do port forward.

[rambronco]

Max power avail as far as I can tell (I have the subs but not the amp yet, but think I know what im going with) will be in the neighborhood of 7K, part of the reason im keeping the sealed side on the smallish side.

Port forward huh? Driver side port? why do you say wall vs. back?

[ToNasty]

yes dont do port back unless just ported under window line, were in the bay area are you, id like to come take a look

[Raptorman]

Max power avail as far as I can tell (I have the subs but not the amp yet, but think I know what im going with) will be in the neighborhood of 7K, part of the reason im keeping the sealed side on the smallish side.

Port forward huh? Driver side port? why do you say wall vs. back?

Your sealed size is actually pretty big for two zv4 18's. For 7k i'd put them in 2.75 sealed net per.

Driver side port if you want it to meter well. Do center port if you want it to sound good for both people and not have any wonky loading/unloading problems with certain window/door configurations.

Wall is going to be better than having it back. Less cabin to pressurize, less stuff rattling/shaking/dissipating energy, etc.

[rambronco]

Rarely is there have your cake and Eat it too but may just have happened. I gave up the notion of keeping rear seats all in the name of" bass" but with captains chairs it was difficult thinking about turning a 5 seater to a 2. With your suggestions I may do a C-pillar wall, with the added height should still have the room without issue, now.......what to do with the port? Port high to allow playing with the back seats up or port low and have the seats down for listening? Thanks for the input guys

[ToNasty]

Is center the port if you could

[rambronco]

Raptor, you talked about staying musical up beyond 3.5:1, for me the box would probably stay musical well past that. Now maybe with the Zv.4 might change my thoughts on the upper frequencies but I doubt it, I don't care for the higher stuff, my x-over is set at 50Hz and even though I don't have enough mid-bass for a good transition I prefer that sound as opposed to setting the x-over higher and hearing higher Hz through my subs.