Walling off blazer, ported or 4th bandpass?

[creyc 1]

I'm going to build my first wall in the back of my 2001 chevy blazer for (4) or (6) 15" AA Havocs.

I'm not looking to burp or compete really, just move a lot of air and sound good doing it. I currently have two Havoc 15's ported in a 9 cube box, tuned to 38Hz and it sounds pretty decent. I'm looking to step it up and I'm already maxed out for box size without a wall, so thats my next move.

I don't know whether to build a bandpass or a large ported wall. I had a 4th order in my old truck (extended cab pickup) and it was one of the best sounding substages I've ever heard, but I don't know how well it would work in an SUV.

[///M5 2,833]

If you are asking the question you probably should be building a ported, it will be louder than a 4th order anyways.

[creyc 1]

I wish it were that simple however I don't think it is.

The relative loudness of one vs. the other is a topic probably better suited for TL numbers and competition discussions, and I am not too interested in either. My criteria is how it sounds to the ear (or feels).

It's difficult to describe exactly what made the sound of a bandpass box a better match in my extended cab pickup than a ported or sealed but two very reputable enclosure designers independently came up with a fairly similar plan based solely on the sound I was after, the punchy, kick-drum in your chest sound. Ultimately one designer concluded that the bandpass enclosure better matched the speakers to the acoustic impedance of the cabin.

On the whole, the alignment is designed so that the state of the wave exiting the enclosure matches the impedance of the cabin air mass...

I think what made the 4th orders sound so good was their relatively flat response, from deep into the subsonics up to around 63Hz where I crossed them over. The ported box I have now is loud, but its peaky nature is less than optimal for serious musical enjoyment. (my purposes) I tried tuning the box to 30Hz, and that helped some but also made sacrifices I didnt have to make in my previous bandpass setup.

Now, going from a pickup to an SUV changes things quite a bit I imagine, but if I wall the back off I'm almost creating something of a pickup truck cabin again, correct? So would I be better off with a 4th order bandpass, since it seemed to work so well in the past?

Edited November 6, 2008 by creyc

[RobClay 20]

offtopic butany pics of your current setup?

[///M5 2,833]

I was after, the punchy, kick-drum in your chest sound.

I think what made the 4th orders sound so good was their relatively flat response, from deep into the subsonics up to around 63Hz

Interesting considering kick drums are in the midbass region and not in the frequency range you just described. I wouldn't expect a 4th order to be flat from subsonics to above 60hz either.

[creyc 1]

Pulled the box back out for some amp work and box finishing but now that I'm planning on doing the wall it might not go back in.

[Duran 387]

Sick lookin' box!

[RobClay 20]

ahh i love havocs nice box and good lookin subs

[creyc 1]

Alright, well supposing it isn't flat in that range then, what would you do?

From Pete K, regarding a previous 4th order I built:

Expect an in-cabin response of 20Hz - 80Hz with less that +/-3dB curve depth, in other words, extremely flat reproduction of virtually the entire bass spectrum.

I'm not too sure about kick drums and exactly what frequencies make up what part of their sound, but I know the subwoofer does play an important part, at least with the sound of recorded kick drums. Rather than try to accentuate any given frequency to enhance this effect I think a flat response will be preferable for a more natural sound.

Granted, I know what you're getting at, and yes for a realistic, somewhat accurate kick drum sound you need a substantial midbass stage to keep up and create a believable effect. Difficult to do with sheet-metal doors and no room for 12" PA basses.

Numbers and drum types aside, I'm still looking for that in-your chest "thump" which is so elusive to me!

Edited November 6, 2008 by creyc

[///M5 2,833]

Got room for 8"+ midbasses?

[creyc 1]

Maybe, with a bit of fiberglass practice and some spare door panels to cut up. I don't really want to tear into the truck too bad, or at least have spare replacement parts in case it doesn't turn out as planned.

How about obtaining a flat-ish response from the substage, any particular direction you would recommend to go with the enclosure?

[///M5 2,833]

Sealed or IB. Neither make a whole lot of sense in a wall though.

[creyc 1]

Bah, not quite efficient enough for me. I have a bit of a pet peeve when it comes to wasting energy unnecessarily.

I would consider a sealed wall if I were trying to stuff 24 15'5 or something crazy like that.

[///M5 2,833]

You get to choose your poison, output or smooth response. You can't maximize both

[creyc 1]

Alright then, worst case how would the output of (4) sealed 15s in a 12 cu ft mini-wall compare to (2) ported 15s 9.5 cu ft @ 38? (current setup)

That might be my route..

[Duran 387]

You do know that vented boxes are more efficient than sealed, right?

[creyc 1]

Yes, but I'm looking to pick up a bit flatter response than my current ported, yet still be loud.

Starting to seem impossible...I wonder how Lil Jons or Gmonks sound.

Edited November 7, 2008 by creyc

[///M5 2,833]

Yes, but I'm looking to pick up a bit flatter response than my current ported, yet still be loud.

Starting to seem impossible...I wonder how Lil Jons or Gmonks sound.

Just port lower, your current box is ported RIDICULOUSLY high.

[creyc 1]

I have interchangeable ports, but the 30Hz port doesn't actually extend the low end by any perceivable amount, nor do I really like the way it sounds on the whole. The 40Hz port is considerably louder, but sounds roughly the same which is confusing. With the 30Hz port the subs move considerably even in the low 30s, which they shouldn't if that's the true tuning frequency. But they seem to just move freely around 30Hz, you can't even feel anything. :\

Thats why i went to the 40Hz port..

[dbjunior 0]

if you can fit a 12 cu keep the 2 15 ported and tune to 24hz that will get you a flat response -3db at 21hz. you will still get a little bump around vehicle freq you can eq that out. and some deadener will help lower the vehicle freq a little. the tight punchy sound i find it more in small high tuned boxes. flat setups usually have a smooth mellow sound. 2 18 bl's in 12 cu tuned to 36hz should be tight and punchy and get decently loud.

[cobracommander 0]

if it wa me, 4th order if you can fit, lots of power, and you are gonna need a strong midbass upfront

[akjay907 0]

maybe the ports are not actually tuned accurately.

[creyc 1]

unlikely.

[Tirefryr 1,742]

How do you know the 30Hz tune is not yielding a flatter response. Surely you don't think your ears will tell you this.

[creyc 1]

Because the 30Hz port peaks in the 40-50 range just like the other port, and is quieter all around to boot.

Albeit, the peak isn't quite as bad as the 40Hz port, but it's still plainly obvious where it wasn't as bad on the bandpass boxes. Even if it were completely flat, the current setup isn't loud enough for me. I'm trying to go louder and with better quality.

Is that a lost cause?