Tuning round ports?

[AltarCrystal 10+ year member]

Alright, I've finally got my box all planned out...EXCEPT for the ports.

Due to the boxes shape (5-sided...having some fun with this one //content.invisioncic.com/y282845/emoticons/naughty.gif.94359f346c0f1259df8038d60b41863e.gif) I'm using ruond ports.

I've never done round ports before.

So, I found a port calculator, and it said if I use tubes 3" in diamater, it needs to be 8.39" long to tune the box to 30hz. Would this be good for an Fi Q in a box that's 2 cubes?

Now, do I attach the port so it starts at the hole for the tube, not sticking in the box, and goes out 8.39"? I assume so, or do I have part of that in the box? What if I want 2 tubes? Would PVC with custom made flares be good enough for this? It should I buy aeroports?

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[patrick1202 10+ year member]

lmao no you go inside the box not outside of the box and if you got two then the tuning would be off you probably have to divide the length by two not sure if you can do that

 

[patrick1202 10+ year member]

have you ever seen a box with 8 inch pvc pipes sticking out of it im not sayin it wouldn't work but i dont think so

 

[AltarCrystal 10+ year member]

have you ever seen a box with 8 inch pvc pipes sticking out of it im not sayin it wouldn't work but i dont think so

Well, yeah, I have. Thus, the question.

But alright, cool, thanks.

 

[jaco 10+ year member]

have you ever seen a box with 8 inch pvc pipes sticking out of it im not sayin it wouldn't work but i dont think so

my box has 4-4" ports sticking out of it.

what you act like you've never seen that before

 

[patrick1202 10+ year member]

no i've seen it before just not much around here and somethin like you app not like a box 8 in port sticking out that would probably cause difficultys unless in a suv or somethin no i could see of your box was to small in a certain demension for you to tune it correctly couldn't you change the tuning by just adding piping??

 

[mazdakid 5,000+ posts]

you should have atleast 2 4" ports for that sub and box. a single 3" one isnt going to sound nice

 

[bdawson72 5,000+ posts]

have you ever seen a box with 8 inch pvc pipes sticking out of it im not sayin it wouldn't work but i dont think so

Aren't you just the smart one

 

[AltarCrystal 10+ year member]

you should have atleast 2 4" ports for that sub and box. a single 3" one isnt going to sound nice

Hm, alright. Now, the calculators I found that calculate more than one round port, but when I calculate 2-4" ports to tune a 2 cube box to 30hz, it says the vent length needs to be 34.7". Is that per each tube? Or total, making each tube 17.35"? Also, since that's actually deeper than my box, would I leave lsome room from the back of the box for one end of the tubes, and have ends of it sticking out from the box a few inches?

Sorry for all the questions, like I said, I've never worked with round ports before.

 

[jdawg 5,000+ posts]

is the internal volume of the box 2 cubes minus the displacement of the woofer?

 

[AltarCrystal 10+ year member]

is the internal volume of the box 2 cubes minus the displacement of the woofer?

It's 2 cubes AFTER the displacement of the woofer. I havn't built it yet, so I can easily change it by makign it wider or less wide.

 

[mazdakid 5,000+ posts]

you can have the port inside the box or outside the box, doesnt really matter. just dont put it too close to the back wall. when you get the port length its for each port, not both together

 

[AltarCrystal 10+ year member]

you can have the port inside the box or outside the box, doesnt really matter. just dont put it too close to the back wall. when you get the port length its for each port, not both together

Man, so to 34.7" long tubes that are 4" in diamater? That's kinda...big.

Am I doing something wrong here? I mean, two 34" tubes? That's about as long as the trunk itself.

 

[mazdakid 5,000+ posts]

dont tune it to 30hz and they wont have to be so long, or make a slot port

 

[SSS 18734 5,000+ posts]

Don't forget to account for the airspace of the port inside your box when building it. They can take up quite a bit.

two 34" ports is too much. You can save space my using a single 4" port and raising the tuning to, say... 35hz. That should make the port at least manageable. You might have some port noise at high SPL levels, but for daily driving, and even moderately loud music, you should be alright. I'd say that beats having two 3 foot ports sticking out of the box.