How much port area?

[jolly_26 10+ year member]

I understand that port area plays a large part in determining the sound and output of your box. I'm building a box for a mate (going to design it myself) and was wondering how much port area it roughly needs. Looking at going for about 2 cubes, maybe slightly less. It's for a Pioneer Champion 12, 400w RMS (ts-w308d4), tuned to around 32Hz hopefully. What he wants is a tight and responsive bass with plenty of volume low down, I guess your typical SQL box. He's doing this on a super tight budget, so no he wont pay for a pro designed box. Once we know the recommended port size I can calculate the port length fairly easily.

Thanks in advance.

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[Qexler 10+ year member]

2 cubes, Port area... 2" width, 12.5" height, 27" length

You can alter that how you need to... I would not adjust the width so much... But as for the length and heights... you may substitute them out and make it how you need it... Just keep it the same Cubic inches.

 

[Moble Enclosurs 10+ year member]

2 cubes, Port area... 2" width, 12.5" height, 27" lengthYou can alter that how you need to... I would not adjust the width so much... But as for the length and heights... you may substitute them out and make it how you need it... Just keep it the same Cubic inches.

You do not keep cubic inches or internal volume the same for constant tuning. Here is why: take a 4" port, that's. 12.58in2. Same as a square port of 2x6.3(rounded). And make it 22"long. For a 2 cubic ft box. Say tuning is 35Hz(theoretical as I am typing on my phone and do not have my formulas in front of me right now). If you keep cubic inches and say you want to make the port smaller by adjusting height to 4" square or equivelant of a 3.19" round port. Keeping internal volume will change the length to 34.6". Now, making the area smaller decreases tuning if other variables are constant. So does increasing length. So, if you do both, you are decreasing tuning majorly just by trying to keep cubic inches the same. Not gonna work that way. Never figure a port based on cubic inches rather than figureing for min port area to reduce noise, then accomodating length afterwards to select tuning based on chamber volume.

 

[skitzafit 10+ year member]

have you looked in the free box plans thread?

Might be something you can use in there

http://www.caraudio.com/forums/enclosure-design-construction-help/137804-free-box-plans.html

 

[jolly_26 10+ year member]

figureing for min port area to reduce noise, then accomodating length afterwards to select tuning based on chamber volume.

basically the plan, i'm assuming a 4 inch round port would do the job, so I'm gonna go slot ported with an area of 16 square inches to be on the safe side.

have you looked in the free box plans thread? Might be something you can use in there

already checked that out, box will be downwards facing, port firing backwards, and none of them are along those lines. Thanks anyway.

 

[THATpurpleKUSH 5,000+ posts]

I wouldnt go any smaller than 12sqin of port area per cubic ft of volume. Ex- 2cubes with 24sq in of port area. It takes a fairly large port to unload the woofer and/or a mounting of the woofer too close to the mouth of the port so just make sure you mount the woofer away from the port opening and you'll be fine.