4th order bandpass enclosure help

[Audiopipe]

I'm trying to design a 4th order bandpass box for two audiopipe 15s but don't know which air space to use the subs I have call for 3cube ft each in a sealed box and 3.5 cubic ft each in a ported box. I have heard people say 2:1 ratio but is it off of total of 13 cubic ft or the seals or ported . I guess what I am asking is what cubic ft should I use for each sub sealed and what total cubic ft for the ported section and what size should the port be for say 32hz please help!!!

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[Jeffdachef 5,000+ posts]

depends if your going for lows or music or spl. Also its 15s man thats always gonna take up room.

 

[Audiopipe]

Spl n I know it's gonna take up room just how much total

 

[Audiopipe]

How much total n how much per sealed sub

 

[Jeffdachef 5,000+ posts]

if its for spl you dont need that much in the sealed area if you plan on giving it a lot of power than recommended probably around 2.25 to 2.5 should be fine, leave more room for the ported section.

 

[Audiopipe]

What should I do for ported area cubic ft wise

 

[Jeffdachef 5,000+ posts]

i've had good luck with the 2:1 ratio and the 2.5:1 ratios

 

[Audiopipe]

So about 8 cubic ft for the port section total or am I totally off? I'm sorry if this sounds dumb but this is why I asked cause I have no clue with bandpass boxes

 

[Beatin' 10+ year member]

from what I've seen, 4th's don't model well on winISD for example, when using a bigger ported chamber to sealed chamber ratio. They become too peaky.

 

[Jeffdachef 5,000+ posts]

i'd suggest sticking with ported or buy a design off of a professional on this site @Buck ; can design you a box that'll get ultra loud.

you dont want to just guestimate with 4th orders you have to make sure a lot of variables are correct first.

 

[Audiopipe]

I just need cubic feet answers for each sub sealed and the total for the ported side with the subs I'm using

 

[Jeffdachef 5,000+ posts]

from what I've seen' date=' 4th's don't model well on winISD for example, when using a bigger ported chamber to sealed chamber ratio. They become too peaky.[/quote']
they dont model well but they do turn out pretty flat in response with a decent bandwidth based on your tuning. It also really depends on how compatable the box works with your vehicle.

 

[Audiopipe]

It's actually going in a trunk of a Benz but has a custom fiberglass rear deck with a big blow threw

 

[Jeffdachef 5,000+ posts]

It's actually going in a trunk of a Benz but has a custom fiberglass rear deck with a big blow threw

even if the trunk is really big, 2 15s 4th order in a trunk is kind of stretching it, unless you build it inside the trunk and take out the spare tire compartment. I wish you the best of luck though.

the 2:1 is a solid choice and gives you a pretty good handling and bandwidth. the 2.5 : 1 has the potential to be a lot more peaky depending on the tuning.

 

[bbeljefe]

If you're going for SPL in a 4th order you don't want tuning that low. In the low to mid 40s would be better for both your goals and your subs, as they will not play well at low frequencies without a shite tone af air behind them.

If you want to do it right, I would recommend downloading WinISD Beta and modeling the subs in a number of different boxes. If you can find a curve you like on that program, then build it.

But just trying different volumes at random or relying on rules of thumb ratios that do not take into account the characteristics of the individual drivers is the reason why 4th and 6th order enclosures have the reputation of being hard to design.