port area question

[bass-aholic 10+ year member]

When following the rule 12-16 inches of port per cubic foot what is the difference between going on the low side of 12 or the high side of 16. Does more port area mean it will be louder? If i have 15.77cuft for 4 15"s how much port area should i have? Thanks in advance!

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[fasfocus00 5,000+ posts]

When following the rule 12-16 inches of port per cubic foot what is the difference between going on the low side of 12 or the high side of 16. Does more port area mean it will be louder? If i have 15.77cuft for 4 15"s how much port area should i have? Thanks in advance!

do you need a calculator?

 

[Bumpin' Goalie 10+ year member]

i believe OP wants to know the diff between 12-16

 

[bass-aholic 10+ year member]

do you need a calculator?

No fucktard, maybe if you read the question you would understand what i was asking. If i should go with the 12-13 or 15-16 square inches and what the difference was but thanks for another pointless post...anything to kill time with your pathetic life.

 

[bass-aholic 10+ year member]

i believe OP wants to know the diff between 12-16

yes that is correct

 

[SPLluminator 10+ year member]

No fucktard, maybe if you read the question you would understand what i was asking. If i should go with the 12-13 or 15-16 square inches and what the difference was but thanks for another pointless post...anything to kill time with your pathetic life.

The low side tends to be more punchy, the high side tends to be more boomy. As for loudness, it depends on the sub, if its got really loose suspension then typically a smaller port is needed if you throw more than rated at it, and some stiffer subs like huge ports to unload completely it also has a lot to do with your setup tho.

 

[bass-aholic 10+ year member]

The low side tends to be more punchy, the high side tends to be more boomy. As for loudness, it depends on the sub, if its got really loose suspension then typically a smaller port is needed if you throw more than rated at it, and some stiffer subs like huge ports to unload completely it also has a lot to do with your setup tho.

Alright i understand, Thank you!

 

[PV Audio 5,000+ posts]

No fucktard, maybe if you read the question you would understand what i was asking. If i should go with the 12-13 or 15-16 square inches and what the difference was but thanks for another pointless post...anything to kill time with your pathetic life.

Take it easy, you have no business getting upset.

 

[PV Audio 5,000+ posts]

The low side tends to be more punchy, the high side tends to be more boomy. As for loudness, it depends on the sub, if its got really loose suspension then typically a smaller port is needed if you throw more than rated at it, and some stiffer subs like huge ports to unload completely it also has a lot to do with your setup tho.

I don't know where you heard this, but it is not true. The airspace and tuning of the enclosure is going to determine the frequency response, not the variation of the area of the vent all things considered. There are numerous types of vented enclosures out there, none of which I am going to go into, but they are all based on the Vb as a function of the Vas of the speaker, Qts, Sd, Xmax, as well as the Fs. The port area, not so much.

The larger your port, the less its ability to act as a resonator and the more it begins to act like a transmission line. If you have too much port area, you are going to lose output due to cancellation of the backwave. A smaller port won't make anything punchier or a bigger one boomier. That isn't true.

 

[SSS 18734 5,000+ posts]

You're unlikely to hear much, if any, difference between a box that has 12 in^2 of port per cube as opposed to one that has 16 in^2. The internal airspace of your box will have a much greater effect on the response.

If you're not going for competition, just make the port that fits your space requirements and keep it within those "rule of thumb" guidelines.

 

[basscort2009 5,000+ posts]

pretty much should always use 16 for daily and about 20-25 inches of port for competitions and numbers. 12 is just meh...

 

[Boomintempo 10+ year member]

Not to thread-jack here, but I was wondering about port area and a bandpass.

People recommended something crazy like 80 sq in of port area for my bandpass...but I only had room for around 40 sq in of port. The sealed portion is 2 cubic feet while the ported portion is 2.5 cubic feet. The box sounds great, but has me wondering what it would've sounded like if I could've gotten that 80 sq in of port.

 

[thehardknoxlife 10+ year member]

I don't know where you heard this, but it is not true. The airspace and tuning of the enclosure is going to determine the frequency response, not the variation of the area of the vent all things considered. There are numerous types of vented enclosures out there, none of which I am going to go into, but they are all based on the Vb as a function of the Vas of the speaker, Qts, Sd, Xmax, as well as the Fs. The port area, not so much.
The larger your port, the less its ability to act as a resonator and the more it begins to act like a transmission line. If you have too much port area, you are going to lose output due to cancellation of the backwave. A smaller port won't make anything punchier or a bigger one boomier. That isn't true.

A simple "No, stupid" would have sufficed. It's the CA.com way, I think.
Enough of the technical babble. The difference between 12" and 16" of port per cubic ft is not going to be noticed by a human ear. It probably would with a bunch of woofers but I doubt it even then. Only on a meter.

You guys think too much.....

 

[SicAudio 5,000+ posts]

I don't know where you heard this, but it is not true. The airspace and tuning of the enclosure is going to determine the frequency response, not the variation of the area of the vent all things considered. There are numerous types of vented enclosures out there, none of which I am going to go into, but they are all based on the Vb as a function of the Vas of the speaker, Qts, Sd, Xmax, as well as the Fs. The port area, not so much.
The larger your port, the less its ability to act as a resonator and the more it begins to act like a transmission line. If you have too much port area, you are going to lose output due to cancellation of the backwave. A smaller port won't make anything punchier or a bigger one boomier. That isn't true.

so very true PV

pretty much should always use 16 for daily and about 20-25 inches of port for competitions and numbers. 12 is just meh...

you do not know much about box designs or Thiele / Small paremeters i take it?

i have seen and built hundreds of small and large enclosures with less than 8 sqin per cubes that had 0 port noise and played just fine. the "port rule" is more typical to spl anyway not daily. the box is a big resonator the more port you have the less control of the cone you have and lower the mechanical power the sub can handle because it unloads faster. with huge ports like 25 sqin per cube you may as well just do an IB build.

 

[PV Audio 5,000+ posts]

A simple "No, stupid" would have sufficed. It's the CA.com way, I think.
Enough of the technical babble. The difference between 12" and 16" of port per cubic ft is not going to be noticed by a human ear. It probably would with a bunch of woofers but I doubt it even then. Only on a meter.

You guys think too much.....

No, the CA.com way is exactly the problem you're exhibiting. Saying "No, stupid" would have done absolutely nothing besides get someone upset for no reason. By explaining how the enclosure works, you can therefore understand how what he reasoned was false. So it comes down to this: if you don't like "technical babble" which is simply how your box works, then don't read it. For those people who want to know WHY a larger port won't be "boomier", then they're free to read it. Following in ignorance is the worst way to learn new things.

If people didn't think too much, you wouldn't have 100% of the things that you use for granted every day, so think about that before you fire up your amplifier or try to crank your starter motor. Someone had to realize that if you put semiconductor pieces next to one another they'll go nuts and create depletion regions and if you run current through a wire it will create a magnetic field which can be manipulated to be used as a motor. Thinking too much is the solution to the problem on this website: thinking too little. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif