Rough sketchup need to find port length


gen1ms3

CarAudio.com Enthusiast
Feb 20, 2019
37
4
Last post got long & off topic, so starting fresh with a design to run with. Since I value my cargo space, I decided I can come up with the most space if I go with a wide, shallow upfiring design with an aero port facing the rear. This will let me throw a grill over the sub to stack gear on top. I've gone ahead & done a rough design in sketchup, but I still need to figure out port size & its displacement once said & done.

Is there any downfall to having a shallow enclosure ported like this?

Vehicle : 09 mazda 3

Location in the vehicle: behind rear seats, flat on hatch floor

Space available (Length x Width x Height):

  • Length 20
  • width 25
  • height 10


Subwoofer make and model: Alpine SWS-12d4

  • qms - 9.43
  • qes .6
  • qts .57
  • fs 34hz
  • xmax 15mm
Subwoofer Size: 12

Number of Subwoofers: 1

Type of Port (Kerfed, Slot, Aero, etc.): Aero preferred I think, open to suggestion

What type of music do you like?: All styles of electronic - from deep extended low notes, drum & bass, electro/dubstep, & chilled instrunmentals.

Is your goal SPL or Everyday Music?: Everyday music

Tuning Freq (Hz): 32-35? I want to get low but not at the expense of responsiveness & SQ (old pre fab ported sounded muddy)

Volume : Factory recommended is 1.67ft gross 1.4ft^3 net. Proposed design should be around 2.2+ gross

sketchup 12d4-2.JPG

sketchup 12d4-1.JPG

 
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THATpurpleKUSH

Smoke weed everyday
Sep 30, 2009
7,238
438
Banging gears and passing queeers
I would add bracing to that box as well.

Start with 2.26cf minus .11cf (approx) for port disp, .09-.1cf for sub disp and .04-.05cf for bracing, that yields 2cf. A 4x14 port makes a tune of about 32hz. Add more length for a lower tune, subtract length for a higher tune. 32-33hz would be good for your listening perferences.

 
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gen1ms3

gen1ms3

CarAudio.com Enthusiast
Feb 20, 2019
37
4
Awesome I'll go pick up a sheet of wood & figure out exact thickness & cuts. Thank you!

 
OP
gen1ms3

gen1ms3

CarAudio.com Enthusiast
Feb 20, 2019
37
4
Update: I went with different dimensions but ended with 2ft^3 after all displacements & bracing. Will be sub up port back. Just have to add two more pieces & do some sanding on port exit to round things over tomorrow when the glue/adhesives cure

box build 1.jpg

 
OP
gen1ms3

gen1ms3

CarAudio.com Enthusiast
Feb 20, 2019
37
4
Yea had access to a biscuit joiner so figured they'd help out. Spraying the box down with bed liner now will test it out tonight

 

fithwheel

Member
Dec 8, 2017
873
185
indiana
Looks good

Are you joining the panels with biscuits?
What do you think about the sub sitting right over the top of the port opening? He may have enough room to squeeze it in there to the left of the brace idk. Hard to tell from pic..

Yea had access to a biscuit joiner so figured they'd help out. Spraying the box down with bed liner now will test it out tonight
Oh you have it together now I see 

 
OP
gen1ms3

gen1ms3

CarAudio.com Enthusiast
Feb 20, 2019
37
4
What do you think about the sub sitting right over the top of the port opening? He may have enough room to squeeze it in there to the left of the brace idk. Hard to tell from pic..

Oh you have it together now I see 
The hole is cut already. I'll post a pic when it's all put together tonight

 

THATpurpleKUSH

Smoke weed everyday
Sep 30, 2009
7,238
438
Banging gears and passing queeers
What do you think about the sub sitting right over the top of the port opening? He may have enough room to squeeze it in there to the left of the brace idk. Hard to tell from pic..

Oh you have it together now I see 
The sub over the port will be ok, they dont look too close together, what i don't like is that wide brace sitting on top of the port, it will restrict airflow in the box. 

You should prime with a shellac based primer like BIN so the top coat doesn't soak in.

 
OP
gen1ms3

gen1ms3

CarAudio.com Enthusiast
Feb 20, 2019
37
4
The sub over the port will be ok, they dont look too close together, what i don't like is that wide brace sitting on top of the port, it will restrict airflow in the box. 

You should prime with a shellac based primer like BIN so the top coat doesn't soak in.
The brace there is only 3/4 x 1.5" and I did sand over the edges. Didn't think it'd make too much of a difference, though it can be removed & I could pick up a dowel to glue in elsewhere.

I've already started spraying. Going to need another can though which is probably because a bit soaked in like you mentioned... oh well lesson learned. Off to buy another can & finish it up now

 
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THATpurpleKUSH

Smoke weed everyday
Sep 30, 2009
7,238
438
Banging gears and passing queeers
The brace there is only 3/4 x 1.5" and I did sand over the edges. Didn't think it'd make too much of a difference, though it can be removed & I could pick up a dowel to glue in elsewhere.

I've already started spraying. Going to need another can though which is probably because a bit soaked in like you mentioned... oh well lesson learned. Off to buy another can & finish it up now
Whats up with the brace piece I circled?

20190314_171958.png

 
OP
gen1ms3

gen1ms3

CarAudio.com Enthusiast
Feb 20, 2019
37
4
Oh that one... yea that's glued & screwed twice on the bottom & top w/ the pvc fitted through with liquid nails. I suppose I could put a hole saw to it in the largest part there. I didn't want to cut it too short on the sides of the PVC hole in fear of the mdf falling apart

 
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OP
gen1ms3

gen1ms3

CarAudio.com Enthusiast
Feb 20, 2019
37
4
Man that camera angle. It does look pretty damn wide. 
haha yea, after I took the picture & saw it on my computer I was like damn... Just waiting on recommendation on whether to do one big hole or multiple smaller holes in it 🤷‍♂️

 

THATpurpleKUSH

Smoke weed everyday
Sep 30, 2009
7,238
438
Banging gears and passing queeers
Cut off the vertical piece where it meets the horizontal piece. That is too much flow restriction. In the future a better design would be to make a flange out of wood and mount the port tube to that to make an assembly and then mount the assembly to the box. You could even use bolts and wingnuts to make it removable like one of my pics below. 

L13.jpg

N1.jpg

R9.jpg

S2.jpg

 

Boomin_tahoe

Hurtin' feelings errrday.
10+ year member
Jul 24, 2005
15,249
132
WA
I've never in the 25+ years into car audio seen biscuits involved in boxbuilding. Save that shit for making cabinetry or making house doors. It's almost like seeing people taking simple things then overcomplicating it.

Just a few example pics I made a T-line enclosure a few yrs ago. I didn't use any biscuits, once the top panel is on, it's done.

1131.jpg

1128.jpg

 

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