Ported box for 3 Eclipse 88120.4 Subs

[Drummer65 10+ year member]

Ive got 3 Eclipse 88120.4 subs that I'm putting in my 2001 Honda civic. They will be powered by an Orion 2500d at 1.33 ohms so about 2200 watts rms. I'm only running a front stage setup so i have the two 6" holes open in my rear deck where i plan to put the ports through if i can figure out a design that works.

Here are the specs for the sub:

Fs: 28Hz

Qts: .29

DCR: 3.1 ohm

Vas: 2.68 Cubic ft

Xmax (one way): 1.17"

I just want to roughly get how many cubes the box should be and what frequency to tune them at. I'm looking for a perfect balance of sq and spl. Also should each sub has its own chamber?

Thanks

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[pro-rabbit 5,000+ posts]

The last civic I did here the trunk didnt like the space for 2 12s ported. Not sure, but 3 12s ported would need be built inside the car. Your subs do like sealed though...

 

[RAM_Designs 5,000+ posts]

Your subs do like sealed though...

They work pretty well in both, wouldn't you agree? Guessing that they have a qes around .35, that'll give them an EBP of 80, which is definitely favoring ported boxes. The low fs still allows them to do well in sealed as well...kinda like nearly every TC sub.

 

[Drummer65 10+ year member]

Yeah i definitely want to go ported. I know with all 3 ported i can pretty much kiss my trunk space goodbye. How big should the box be and what frequency would you guys tune it to? I like my sq for daily driving but i also want to be able to turn these up and get decent spl. What db do you guys think i could hit with the 3 12's? im aiming for at least a 148

 

[pro-rabbit 5,000+ posts]

yea, just giving the car I figured the sealed option was best. I don't recall a ported box for all three fitting with out being build in the trunk.

 

[RAM_Designs 5,000+ posts]

Yeah i definitely want to go ported. I know with all 3 ported i can pretty much kiss my trunk space goodbye. How big should the box be and what frequency would you guys tune it to? I like my sq for daily driving but i also want to be able to turn these up and get decent spl. What db do you guys think i could hit with the 3 12's? im aiming for at least a 148

Kinda hard to predict a specific spl level, but it should be decently loud and sound good doing it.

Do you have any other t/s for them besides what you provided already?

 

[Drummer65 10+ year member]

After searching around I'm seeing different specs to what i provided above. I'm not sure which one is correct but i have found these specs below on a couple of different fourms so these might be the correct specs.

>DC-R = 3.1

>FS = 22Hz

>Qts = .35

>Vas = 4.25 cubic ft

>SPL/W/m = 87.1 dB

>Qes = .401

>Qms = 2.9

>Sd = .0511 M squared

 

[pro-rabbit 5,000+ posts]

Yeah i definitely want to go ported. I know with all 3 ported i can pretty much kiss my trunk space goodbye. How big should the box be and what frequency would you guys tune it to? I like my sq for daily driving but i also want to be able to turn these up and get decent spl. What db do you guys think i could hit with the 3 12's? im aiming for at least a 148

148 out of a trunk is a decent sized number out of a trunk. I would say to set a little more reachable goal. Then be happier if you surpass that.

 

[Drummer65 10+ year member]

148 out of a trunk is a decent sized number out of a trunk. I would say to set a little more reachable goal. Then be happier if you surpass that.

Even with my seats folded down?

 

[l7runner 10+ year member]

those alums sound good in 1.25-1.5 cubes a piece tuned low. like 28-33hz

Do a common chamber ~4.5 cubes with (2) 6" areo ports though your rear deck. I would say seal the box off from the trunk, but I doubt the sub baffle can fit within a folded down civic seat.

 

[RAM_Designs 5,000+ posts]

Based on the t/s you just posted, I came up with either 4.5ft^3 sealed for all three, or 6ft^3 tuned to 28hz for all three as good box candidates. That's if those t/s are correct. Normally TC subs like smaller boxes...

 

[Drummer65 10+ year member]

Okay thanks

6 cubic feet seems pretty big, i would have thought a box 4.5 -5 cubic feet ported would have been plenty. For the ports can i use 5" PVC pipe? if i go with a 6" port i will have to cut the holes in the rear deck which i would prefer not to do. If 6" ports over 5" is going to make a noticeable difference then i don't mind cutting the holes bigger.

Thanks for the help

 

[pro-rabbit 5,000+ posts]

I may be able to dig up some T/S on them if I can find the manuals some were. I think we did 1 ft3 after displacement sealed is what we did and 1.5-2 ft3 ported was average tuned low(28-32hz).

Best guesses, it has been several years since I built anything for them though. High possibility I am wrong. However, those numbers seem to match RAM's numbers pretty close.

btw-6ft3 won't just slide in the car I don't think.

 

[Drummer65 10+ year member]

Quick question

I'm building a box that will be 6 cubic feet but i need some help with the tuning.

My choices are between 2 4" ports or 2 6" ports through my rear deck and into the cabin.

Also how long do the ports need to be to get about 28-30hz tuning?

Thanks

 

[Drummer65 10+ year member]

Anyone know how long to cut the ports? And should i go with two 4" or two 6"?

thanks