Box build advice

[VictorwithAC]

So I asked on reddit and didnt get much input. I just got 2 massive audio hippo84 8's. I plan to build custom ported boxes for the individual speakers, not one enclosure. Ive built boxes before but never tuned or anything special. I want to get the most outta these little 8's. Im gonna push 500 w rms to each. My truck is a 1996 dodge ram single cab. Plan is upward firing subs and upward vent? So with the program I used I have dimensions as follows:

All 3/4" MDF

Height: 15"

Depth: 10"

Width: 20"

Net volume is 1.05cuft

Massive says optimum is 1.1cuft

Vent tuned to 28hz

Height: 4"

Width: 2"

Length: 22"

Port area: 8insq

Massive says optimum is 7.07insq

(I know the vent will have to make a turn in the box and to keep is at least its width away from the back wall)

So to me this sounds like the woofers will be very happy and sound good in their new homes but ive never attempted to put this much thought into a Box before nor have I tried to maximize sound from 8's. Any input or advise is appreciate as I plan to start the build tomorrow.

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[THATpurpleKUSH 5,000+ posts]

28hz is way too low of tuning for those subs. They should be tuned in the 35-40hz region. Those subs have a high fs in the 40s and tuning them nearly a full octave below will make them play like shit.

 

[VictorwithAC]

Ok so how about changing port dimensions to 2x6x20 which tunes it to 35hz. Only thing is that raises port volume to 12in2 which is a bit higher than optimum. Thanks for the input btw.

Edit: if I make the box 22" wide as well that keeps the tuning at 34.58hz but lowers my port volume to 10.6in2. Or should I shoot more for 37hz and port volume closer to the recommended 8in2?

Ok last edit. If i change the box dimensions to W25"H15"D10" and port size W2"H6"L15" that makes the net cuft 1.38 and port volume 8.7in2. With tuning of 35.25hz. Let me know what you think and sorry for all the edits just have noone to bounce ideas off of lol

 

[THATpurpleKUSH 5,000+ posts]

You misunderstood the port sizing, in the manual it says a 3 inch round port that equals 7.07 sq in of port area. Round ports are more efficient than rectangle shaped ports so you would need a larger port opening like 16 sq inches of port area per cubic foot which makes the box a lot bigger because the port is so big. Since you are a beginner and they are already telling you to use a round port, stick with the round port. If you do it right you can tune them to your liking and they are easier to work with and calculate around.

Do something like this:

24 wide 14 tall 15 deep, 3/4 baltic birch or equivalent or mdf

4 inch round port either flared aero or pvc pipe and a 9-11 inch port length. If you use pvc pipe you can mount the port to a piece of wood and use nuts and bolts to make it removable to play with the port length. That will give you about 2cf tuned 35-40hz

Here's an example of what I mean:

 

[kr15 5,000+ posts]

Tune those mid 30s. And if slot, give em about 15^2 depending on how much power you actually have on tap

 

[BOOMINGRANDPA 5,000+ posts]

min 12 sq in port per cf is the norm for slot port, as kr said depending on power.. the sub needs to be modeled in box program to check rear port air velocity to help determine port size.. that said 500rms on 8's i imagine 10-11 sq in per cfad is fine..

 

[THATpurpleKUSH 5,000+ posts]

min 12 sq in port per cf is the norm for slot port, as kr said depending on power.. the sub needs to be modeled in box program to check rear port air velocity to help determine port size.. that said 500rms on 8's i imagine 10-11 sq in per cfad is fine..

Until the day comes when you have real world experience building and designing boxes, you have absolutely NO business trying to give advice, especially to a first time builder. Stick to your prefab ebay bullshit boxes and leave the box building threads to those who have ACTUALLY DESIGNED AND BUILT boxes.

 

[shredder2]

I came up with 2 separate enclosures sub/port up at .89ft3 net, 14.54in2^ft3 tuned to 36hz slotted in your given space OP... but as Kush said the 3" round might be easier. This used .5" and .75" materials.

But as Kush said a round would be easier to build... I don't think tuning much lower ported would be what I'd advise.