4th order gurus needed

[rocking.that.eclipse]

Well long story short I'm trying to gain on my low end in my 4th.

Right now I have 4 15 inch n2s on a populous 6500. Sealed section is 7.2 cubes and ported is 19 cubes. Should be right around a 2.5 to 1 ratio.

I can play the lows they just dont have the same presence as the highs do. Right now I would say that my peak is somewhere in the low 40s and the roll off pressure wise probably starts around 34.

And the last thing that is weird to me is that I actually seem to gain when I am totally sealed up.

Any suggestions you guys may have would be awesome

[ToNasty]

I think you need to make the sealed section bigger. Don't quote me on that but that's my unferstanding

[rocking.that.eclipse]

Ive got a suggestion of trying polly fill to to make it seem larger.

I have barely any excursion on my subs right now. 30 hz has got maybe a half inch of movement.

My other suggestion that someone gave me was to let the subs break in more. They are fresh recones from FI and may take a while longer because they are 5 stiff spiders on them

[rocking.that.eclipse]

how the port looks now

[ToNasty]

Seems kinda small for 4 15s. The port for my 2 15 4th order box looks bigger than that

[dolarbilz]

Port area looks smmmmmmmaaalllllll.but I don't know shit.

[sencheezy]

A few things to "try"

Poly Fill

More port area, less port area (testing) - in my explorer, seemed to lose low end with smaller port. My 6 15s have just about 900cuin of port area.

Break in time - if you want to speed this process, try playing test tone of 20hz for 30 mins to 2 hours constant at low volume, maybe 200 watts per sub.

Try to invert

More sealed space.

Bigger ration, anything below 3:1 is a waste in my opinion.

As far as what "sound" louder when sealed up, that is all testing, and even with a meter, it will tell you different. My passenger side sounds like no pressure when sealed up, but db IS higher than when rolled down, but for demo, sounds better with window rolled down. This will all be time and error.

And that's all I can think of right now.

[ToNasty]

Agreed. Invert subs to add some net area and add more port. For sure add more port

[rocking.that.eclipse]

subs are inverted right now.

So more port is more lows? in therory

[sencheezy]

subs are inverted right now.

So more port is more lows? in therory

Didn't say that. I again, emphasize the word TESTING haha. Because, you gotta remember what hobby we're in. EVERYTHING comes with a cost. You're asking the subs a big job here. You don't know how making more port area will effect the rest of the system. But let's play this game. Let's say more port area does gain you more low end. Well how does that effect your top end? How does that effect your cone control? How does that effect your mechanical handling of each sub? It's much harder to hear any mechanical noise in a 4th order design. Etc Etc Etc. Just know, for every cause, there is an effect. Or is it every change? Hell IDK lmao. But I hope you get what I'm trying to convey.