Port opinions

[herbykw 10+ year member]

Soon i should be getting a 18" HDC3-A. I am trying to make a box 6 cubes at about 38 hrtz. The sub has a mounting dept of 9.75". Trying to get a balance of loud/deep.

My trunk opening is kinda small. I can not have the sub face forward/back-due to hight. Right now i have a 6.5 cube 16.5"h x 35"w x 25"d with forward facing ports and my subs firing up.

So i should be able to take it down to 14" tall and make it a lil longer. but heres my question.

When designing a ported enclosure how does the port shape play on the sound?

Skinny long ports vs wide short and straight vs L shaped??

Or does it even make a difference as long as the square inches is the same?

Click to read more...

 

[herbykw 10+ year member]

Here is some pics of my thoughts...let me know which ones might sound good and which are a bad idea--and why please.

NOT DRAWN TO SCALE

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sorry for the bad pics, the original drawings i couldnt get small enough to post, so i had to take pics and post them.. //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

also could just do one sloted port along the bottom of the box.

 

[herbykw 10+ year member]

bump for any opinions

 

[herbykw 10+ year member]

Anyone?

 

[IDSkoT 5,000+ posts]

It's 4 AM here on the east coast. So you might want to relax.

To answer you question, shape does matter. Wider ports allow for more air to be released at a given time. The port acts as a passive radiator (google it, I don't feel like explaining). Bigger the area, more air it can move. That's not to say that just taking out one side is justifiable... after a certain point, it becomes too much. But there's also too less. There's a formula somewhere (I programmed a program (go figure that's what you program) that figures out all of that and gives me a read-out of the minimum for everything is.) that tells you the minimum port cross-section has to be.

Straight vs L vs folded ports is all based on how long your port length needs to be. The most ideal is straight, L after that, and folded coming in last due to the amount of turns and port velocity lost. If you want, I can design a box for you. I understand you want to learn, and I can teach you. But you don't want your box to sound like *** as a learning experience.

 

[herbykw 10+ year member]

Thank you, if you could help me, that would bennifit me more then doing it for me. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif Your right, i dont want to take the time and effort to design and make a box and it sound like crap.

 

[herbykw 10+ year member]

How do you determine the port cross section? Wouldnt it depend on the sub itself? or is it all based around the target tuning frequency?

 

[mlstrass 5,000+ posts]

HDC's like 16^2 per cube, so you'd want 96^2 for a 6cube net box...

 

[herbykw 10+ year member]

HDC's like 16^2 per cube, so you'd want 96^2 for a 6cube net box...

Thank you, but for future reference how do you determine those measurements?