8:1 port ratio guideline

[Savag3 10+ year member]

is there a construction guideline stating that a port should be divided if width and highth are greater than 8:1 ? or some other ratio ? i thought i remember something about this , i.e. a port that is 3x47" should be divided into 2 or four

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[slam 5,000+ posts]

what size and how many subs

 

[Savag3 10+ year member]

is there a guideline like this is ? or is it just for structural integrity ? like can you run just a 47" wide port without dividing it into seperates ?

 

[basscort2009 5,000+ posts]

its actually 4:1 ratio for spl. daily may be differant though

 

[Savag3 10+ year member]

ok yea , i think the daily is different . . thanx tho

 

[bubbagumper6 5,000+ posts]

Hmm, never heard of that before...

 

[AudioXtremes 10+ year member]

Well the scientific rule is that more than 9 to 1 changes port tuning. Spl is 3 or 4 to 1 IMO for maximum performance.

 

[bubbagumper6 5,000+ posts]

Well the scientific rule is that more than 9 to 1 changes port tuning. Spl is 3 or 4 to 1 IMO for maximum performance.

Why? Is there someplace I could read more about this?

 

[amartin_72]

You get more port wall surface area with skinny ports. Thats why round ports are the best they have the least port wall surface area per port surface area.

 

[AudioXtremes 10+ year member]

Well a very vague description would be that a port slows down the rear wave. A port that is 9x10 will have a different "rear world" tuning than a port that is 3x30 of the same length due to flow diff.

 

[bubbagumper6 5,000+ posts]

Does it raise the tuning or lower it?

 

[AudioXtremes 10+ year member]

The lower the flow the slower the flow and lower the tuning.

 

[bubbagumper6 5,000+ posts]

Well on my build, the box is 6.2 cubes net, tuned to 32hz, with about 86 sqaure inches of port, but the actual port dimensions are 34.5x2.5, any idea how much the tuning will be affected?

 

[Savag3 10+ year member]

Well on my build, the box is 6.2 cubes net, tuned to 32hz, with about 86 sqaure inches of port, but the actual port dimensions are 34.5x2.5, any idea how much the tuning will be affected?

yea see with a port like that it should have been divided into two and maybe raised to 2.75(or other) to compensate ?

 

[bubbagumper6 5,000+ posts]

yea see with a port like that it should have been seperated once and maybe raised to 2.75(or other) to compensate , is what im getting anyway

Haven't built it yet

But why would separating it change anything? Like if I ran a small piece of MDF down the center and turned it into 2 separate ports, it would be better?