check my box build! what do you think? suggestions?

[devin171moto]

Hey guys. first box build i've ever designed myself. 2 sundown sa 12 drivers input to win isd (750wrms ea)
I LOVE my lows (between 28 to 35 hz, I rarely play above 40) so I'm willing to sacrifice some peak spl with the recomended 35hz tuning of these sundowns. i posted transfer magnitude curves for comparison. and i figured it was okay to stretch the 1.5-2.0 cu ft of airspace recommended to 4 cu ft total (2 cu ft per sub)

This will be in a midsize suv hatch( gmc envoy). max dimensions 45W by 18H (to fit beneath back seat line) and 38 deep.

SUB UP PORT BACK CONFIG: subbox will not allow me to switch subs to top mounted, but thats how it will be configured (either diagonally mounted in left corner, box 2. or mounted side by side, box 1. double baffled top) any sound quality advice between the two? any recommendations for software that will give me more freedom in design? (center slot ports etc)

if i love lows. for around this price point, are sa's a good sub choice? any suggestions to comparable subs for this application?

transfer function tuned to 35 hz: (peak; 5.6 db@ 37.3 hz) (0 db line @ 33.3 hz) (-3 db line @ 28.7 hz)
tune to 32hz: ( peak; 4.2 db @ 34.4hz) (0db line @ 28.27 hz) (-3 db line @ 26.34 hz),

sub box does not allow me to design with bracing in mind. but I feel i may need to brace the port or width dimension of box. any revisions or advice is incredibly helpful!
(maybe center slot port is a better option?) (maybe dual slot ports so i can get rid of the L bend in the port?)
notes: there's a 5 hz difference in the 0 db line tuning to 32 hz. can I assume that means I'll be much louder in the high 28's and low 30's?

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[MattinMO]

I would suggest at the very least 45s in the corners and preferably 1 brace somewhere center. I’m not sure what the internal volume that would eat up to make up for

 

[MattinMO]

As @THATpurpleKUSH has stated there is no such thing as too sturdy of a box and vibration and box flex = loss of output

 

[Popwarhomie 5,000+ posts]

I would throw a window brace in that bish.

 

[devin171moto]

I would suggest at the very least 45s in the corners and preferably 1 brace somewhere center. I’m not sure what the internal volume that would eat up to make up for

yeah 45s are part of the plan a well as a port brance, and as popwarhomie suggested. a window brace between the two subs. i just cant find any design software that will let me input those into a computer model and get cut sheets and internal area compensation. will i just have to calculate that by hand and adjust the box accordingly? or do you have any software suggestions? this is my first box. so i want to avoid as many problems as possible during construction

 

[THATpurpleKUSH 5,000+ posts]

Any panel with a dimension greater than 18inches needs to be braced or its going to vibrate (flex) and you will loose output. The enclosure needs to be as rigid as possible- get it as close as you can to the equivalent of concrete.

 

[devin171moto]

Any panel with a dimension greater than 18inches needs to be braced or its going to vibrate (flex) and you will loose output. The enclosure needs to be as rigid as possible- get it as close as you can to the equivalent of concrete.

yeah ive been reading up on this and its helping alot.

Implementing Bracing

UPDATE! - I added a bunch of pictures as examples of bracing Ive done, see page 3. Bracing is a very important part of building a stiff and strong enclosure. There are lots of ways to do it, each with their own advantages and disadvantages. I have developed my own ways for doing bracing and they ...

www.stevemeadedesigns.com

he gives a 10" value for 3/4 in mdf. i thought that was a bit much for 1500wrms'. im just trrying to calculate the brace displacement now (double baffle top for top mounted subs). (1.5 in diameter by 4.15 inch long cylindrical brace between port wall and right panel) (window brace halfway down front panel)

 

[THATpurpleKUSH 5,000+ posts]

I never brace the port itself, just add 45s for airflow, the big panels are what you want to focus on.

Window bracing adds the most rigidity because it ties 4 sides together and is what competitors use.

 

[devin171moto]

I would throw a window brace in that bish.

1 window braces takes up .06 cu ft of airspace. (window brace connecting front panel to back panel, and top to bottom)
i can change box to 4.12 cu ft. and then should i add another kinda half window brace placed horizontally connecting the vertical window brace to the left wall? and then a cylinder brace between port wall and right wall? or just the vertical window brace should be enough?

example: image 1 is side view, image 2 is top view

That left side is 18"

 

[devin171moto]

I never brace the port itself, just add 45s for airflow, the big panels are what you want to focus on.

Window bracing adds the most rigidity because it ties 4 sides together and is what competitors use.

1 window braces takes up .06 cu ft of airspace. (window brace connecting front panel to back panel, and top to bottom)
i can change box to 4.10 cu ft. and then should i add another kinda half window brace placed horizontally connecting the vertical window brace to the left wall? or just the vertical window brace should be enough?

example: image 1 is side view, image 2 is top view

That left side is 18"- 20" depending on the width i choose

 

[THATpurpleKUSH 5,000+ posts]

You need a double thick baffle since you are using SA's. Then use a window brace to front to back between the subs to tie the baffle to the rear panel. Add a 45 in the port bend. You don't need to brace the port, but you should add a vertical brace of material 3/4 thick and about 1-1.5in wide to brace the left wall. You can mount it parallel or perpendicular to the face of the left wall.

 

[devin171moto]

You need a double thick baffle since you are using SA's. Then use a window brace to front to back between the subs to tie the baffle to the rear panel. Add a 45 in the port bend. You don't need to brace the port, but you should add a vertical brace of material 3/4 thick and about 1-1.5in wide to brace the left wall. You can mount it parallel or perpendicular to the face of the left wall.

You need a double thick baffle since you are using SA's. Then use a window brace to front to back between the subs to tie the baffle to the rear panel. Add a 45 in the port bend. You don't need to brace the port, but you should add a vertical brace of material 3/4 thick and about 1-1.5in wide to brace the left wall. You can mount it parallel or perpendicular to the face of the left wall.

im tracking. so just the 45 and the window brace, then cut a piece of 3/4 mdf to the internal heigth of the box and just wood blue and drill it onto the left wall (3/4 inch side glued to left wall, top and floor. )

and yeah subs will be top mounted but subbox wont let me place them there -_-. but the top side will be double baffled

 

[Bobbytwonames 5,000+ posts]

Also, router the end of your port and the square edges on your brace. Basically, don't want any square edges inside of your box. Minimal gain, but it seems like everybody does it these days.

 

[Boomin_tahoe 5,000+ posts]

I never brace the port itself, just add 45s for airflow, the big panels are what you want to focus on.

Window bracing adds the most rigidity because it ties 4 sides together and is what competitors use.

I actually got **** thrown at me for using 45's in my current build enclosure on FB. Said they weren't needed. I've heard they help. So now I'm confused. I'm hoping you can dig into some details for me about weather they're necessary or not.

 

[Boomin_tahoe 5,000+ posts]

@shredder2 has designed a box for those subs.