Box Porting - is location important?

[frikk 10+ year member]

Hey everyone,

I am building a custom box at 3.5 ft^3 as per the manufacturers specs on my sub (Audiobahn Natural Sound 12").

I am building a box that is probably only 16" deep total, but the last 8" is a ramped surface (so the port wall will not go that far..) - See Diagram 3. This means that my port wall will probably be 8" or so (see diagram) if I make it right next to the subwoofer, going from the front of the box to the start of the ramp. The manufacturer recommends 12". So, do I keep it at 8" parallel to the sub (Diagram 1) or do I make it 12" but perpendicular to the sub install? Does this location of the port or length matter?

I've read somewhere that you want the enclosure to start behind the sub magnet. Has anyone heard this?

Any comments are welcome, please hurry since I'd like to buy the wood tomorrow!

Thanks,

Blaine

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[SSS 18734 5,000+ posts]

You should be safe either way. If you're worried about it, go with Diagram 1 - most boxes are designed that way.

EDIT: your wording is a little confusing but I think I got it - if the only way the port will fit is diagram two - go that route. If you cut down on the port length, your box will be tuned higher - a lot higher if you cut 4" off. Although you could just put the port near the bottom of the box and go with fig. 1.

 

[frikk 10+ year member]

Thanks for your quick response!

You're correct - I'd be cutting 4" off of the port. Hmm, that makese sense that I'd be making it a higher frequency...

You're right, I could make it lower. Or I could extend the port out into the ramp and try to make it flush.

Would the location of the port make the tuning frequency change?

 

[frikk 10+ year member]

I've learned a lot.

First - I'm going with a circular port on the side. No more slotted ports.

Second - no, position does not matter

Third - yes length DOES matter //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif