question regarding port area.

[tcguy85 10+ year member]

will a sub sound "not as tight" with more port area? does giving a sub more port area change the sound of it? what would be the pros and cons of going from the 7sq inch port i have now to say a box with a slot port with 12sq inches? does it do anything other than reduce the chance of port noise?

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[MyFartsStink 10+ year member]

I was curious about this too

 

[MysticalHippy 10+ year member]

I don't know what difference in sound you'll hear with more or less, but for each sub and box combo, there'll be a port size optimum to that setup. One sub in a box with a 7" sq port may sound great, while another in the same box, same port size, will not. At least, that's what I've come to understand. A program such as WinISD or AJ for a vented box should give you the best tuning freq. to your sub/box.

 

[pr-festiva 10+ year member]

Smaller ports tend to make alot of port noise especially with todays high excursion subs.this can be limited with flared round ports or by rounding over the edges of slot ports.

 

[savagebee 10+ year member]

typically, most folks suggest 10 sq" of port for every cube of box volume

20 seems to be the top end of where most suggest.

Im @ 19, and not having any probems. I have a 10 cube box and 190 sq" of port, but Im only feeding the subs 600wrms each, so that probably makes a big difference

 

[tcguy85 10+ year member]

thanks guys but none of that really answers my question.

 

[pr-festiva 10+ year member]

going from 7 sq. to 12 sq.inch i would hazard a guess that you wont lose any "tightness" if the box is designed right that is.

 

[mokedaddy 5,000+ posts]

Yes changing port area can change the sound. And too much port area can be boomy.

But in your certain circumstances it is very tough to tell since there is no cut/dry answer.

It is pretty install dependent that is why no one can really answer your question.

Does it have port noise now? If so going larger is a good idea. If not what are you seeking out of going to a larger port? Im guessing more output which you will get as well as long as its not too much.

Im not familiar with your sub and these are just guidelines to try.

 

[audioholic 5,000+ posts]

'Tightness' is a product of the enclosure's alignment, not port area. The amount of port area will help dictate 1) air displacement potential of your system, and 2) velocity of the air as it travels through the port. Greater air speeds = more port noise/whistle.

Round ports flow air more efficiently than do square/slot ports. For this reason you can get away with less port are using round ports than you can using square ports.

You say you have a 7 inch port now.... what? 7" diameter (odd)? 3" round port? The answer is, going from 7" sq inches of round port area to 12 sq inches of square port area wont make much difference, if any.

If you'd be more specific, we could answer your questions better. What exactly are you wanting to do, modify an existing box?

 

[BEAVER.989 10+ year member]

I'd like to hear more about this topic.

I think what he's trying to determine is, when does it become beneficial to increase port area? Is there a "rule of thumb" stating how much port area is needed vs. power applied, etc.?

 

[audioholic 5,000+ posts]

Port area needs are dictated by how much air the speaker is capable of displacing. In a ported enclosure, this is dependant on several factors, cone excursion and power applied (plus efficiency) being two of them.

 

[MyFartsStink 10+ year member]

Port area needs are dictated by how much air the speaker is capable of displacing. In a ported enclosure, this is dependant on several factors, cone excursion and power applied (plus efficiency) being two of them.

Yes but if it is played at low volumes the excursion is low. Now what if you have alot of port area that is correct for a high excursion sub, but then its played at low volumes, would that come into play?

 

[audioholic 5,000+ posts]

Yes but if it is played at low volumes the excursion is low. Now what if you have alot of port area that is correct for a high excursion sub, but then its played at low volumes, would that come into play?

Let me complicate it even further... at what frequency are you playing in your example? And whats the tuning frequency of the enclosure? //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif//content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif
At lower volume levels, air velocity within the port is even lower than at maximum output (obviously), so no there is no negative effect. Remember, port tuning frequency is determined by port area and port length... not air velocity within the port.

 

[ALHII303 10+ year member]

Audioholic can you think of a time where the port affected the sound of the system don't count times with port noise

 

[audioholic 5,000+ posts]

Yes, there is such a thing as too much port area. Cone control drops.