Importance of Port Volume?

[psych0ticnemes1 5,000+ posts]

I am aware that if the port is too small, port noise can occur..

BUT, would making the port wider (more port volume) benefit overall output and performance of the subs?

My two 12"s share a 3" wide port... (42 suare inches of port) tuned to 30htz...

if i made the port 5" wide yet still tuned it to 30htz (74 sq inches) (therefor increasing port volume)

would this improve output and perfmorance??? Positives/ negatives as far as output and sound quality go???

Thanks again...

Edit: By making the port wider i mean, building a new box with a 5" wide port rather then a 3" port... NOT altering the original box

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[SPL140.2 5,000+ posts]

I big fan of huge ports so yeah go with the 5" wide port. Lets more air to travel threw the port and has less turbulance.

egg

 

[nissanrider06 10+ year member]

hey pyschotic havent seen u in a while!

anyways i though u had 1 sx15? what u running now? depending on the subs around 50-60sq inchs of port would probably be good but if u wanted to go bigger im sure u'd be fine if i was u i would keep the box the same height of 16 inches and have it 5 inches wide which would be 70 sqin of port, instead of like 14.25 or watever

 

[psych0ticnemes1 5,000+ posts]

hey man, hit me up via pm's if you want, thanks for the info... more port volume seems to be key

 

[nissanrider06 10+ year member]

yea but there is a such thing as to much, i wouldnt want to get near that i would think 60 inch would be close to optimum but all depends on ur subs! what subs u got mang?

 

[jujumantb 10+ year member]

I believe I once read that any port area bigger than the effective cone area of your subs is pointless, even detrimental to performance. I could be talking out of my ass on this one though, anyone want to confirm this or set me straight? SPL guys should have some insight.

 

[psych0ticnemes1 5,000+ posts]

I believe I once read that any port area bigger than the effective cone area of your subs is pointless, even detrimental to performance. I could be talking out of my ass on this one though, anyone want to confirm this or set me straight? SPL guys should have some insight.

lol i'm waiting for input from the big dogs but doesn't seem to be happening... However i do think you are right.

 

[GreenMachine70 10+ year member]

bigger port can increase box efficiency, and will move more air with less power.

 

[SPL140.2 5,000+ posts]

I believe I once read that any port area bigger than the effective cone area of your subs is pointless, even detrimental to performance. I could be talking out of my ass on this one though, anyone want to confirm this or set me straight? SPL guys should have some insight.

X2 someone told me to not go over the total diameter of the subs or sub 2 12"subs no more than 12 in" port they said at max use 1/2 the of the total diameter, 1-12" no more than 6" but who knows, Ive also heard aeroports work better than slot ports and so on...

 

[psych0ticnemes1 5,000+ posts]

i have a rather small port width for two 12's (3")

should i double it? if i do, will i gain some SQ and Output? still not clear on the magnitude of the change that will occur

Thanks guys

 

[LuNaTiC 10+ year member]

X2 someone told me to not go over the total diameter of the subs or sub 2 12"subs no more than 12 in" port they said at max use 1/2 the of the total diameter, 1-12" no more than 6" but who knows, Ive also heard aeroports work better than slot ports and so on...

I would venture to say there wayyy off, I can't imagine my 15" with 7.5^2 inches of port.....

 

[SPL140.2 5,000+ posts]

I would venture to say there wayyy off, I can't imagine my 15" with 7.5^2 inches of port.....

i heard at the max for a 15" woof have the port be 7.5"w X tall as the enclosure, sorry for the misunderstanding.

 

[SPL140.2 5,000+ posts]

i have a rather small port width for two 12's (3")
should i double it? if i do, will i gain some SQ and Output? still not clear on the magnitude of the change that will occur

Thanks guys

For 2 12" subs Id go has wide as you can without giving up precious internal cub ft!! If your subs need say 4 cubes and you only have 5 cubes, well if you want it ported you only can make the port so wide to cover that 1 cube thats left over. Id go wider but like I said it will decrease the internal cube for the woofers, but if you have the space def go wider.

 

[VereChronicus 10+ year member]

I'm sure that folks that spoke "the rule" of 1/2 the size of the driver for port were talking about area rather than diameter. If not, it would negate what has been common practice in pro audio for over half a century. As stated above, there is a point where it becomes too much....that point is different for every sub out there. The sub is directly attached to the mass of air trapped in the port. It is basically the same as moving mass. The larger the vent, the higher the moving mass is. If you have a really strong motor, it can move a larger ratio of port mass to driver moving mass as compared to weaker motors. Proof of this from back in the days was the Cerwin Vega Stroker over their competitors at the time. The stroker was an extremely powerful sub with a very strong motor and CV sampled many many boxes before they came up with their recommendations for each application. As compared to their other subs as well as their competitors subs, the stroker was able to push a much larger vent and it went down in history as one of the baddest pro audio subs ever built.

This is just history to bring up for some background info on the subject. In car will certainly be "different" because of the confined field infront of the enclosure as compared to an open field application like a football stadium, but it won't negate the way the port is simply driven by the driver. The more air is trapped in a port, the heavier it is and the more HP it takes to move it back and forth. The higher the frequency, the more HP it takes if amplitude remains constant.

Hope some of that info helps.