Different Porting methods

[netzero 10+ year member]

Hey all,

I've got a few quickies. I've seen people do boxes for two subs, one of each side of a common port. Where the port is T shaped, but no separator between the port that comes out of the box. How does this work and is it effective? Also, is it better when you have two subs to have a separator between the two and port them individually? Or have them in one big airspace with one larger port? THanks

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[azimuth 5,000+ posts]

it depends on alot of things. most common, it comes down to space. the box will be larger with 2 ports and 2 chambers. some people like the looks of 2 ports. for a daily driver, it probably won't make much of a difference in sound.

 

[GearGuy2001 10+ year member]

Like this

Yes it works //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[netzero 10+ year member]

Gearguy, yes just like that. Could you explain the tuning of that way? Like, with air moving together and out that port, does it change anything? And like, how is it treated, like two separate ports? I'm considering this setup to keep things looking smooth in my next box. Thanks

ps anyone with info on this type of box, that would be awesome!

 

[tcguy85 10+ year member]

i would think that the back portion where it T's or splits off would be half the width of the longer part of the T.

 

[azimuth 5,000+ posts]

i would think that the back portion where it T's or splits off would be half the width of the longer part of the T.

the back part of the T is a seperate port for each. changing the width would change the tuning.

 

[tcguy85 10+ year member]

the back part of the T is a seperate port for each. changing the width would change the tuning.

yea i know that. i'm not explaining what i am trying to say right i guess.

since the long part is being the port for both subs it needs to be wider than the other part i would imagine. the part where it splits off into two ports would be narrower than the other part.

 

[azimuth 5,000+ posts]

yea i know that. i'm not explaining what i am trying to say right i guess.
since the long part is being the port for both subs it needs to be wider than the other part i would imagine. the part where it splits off into two ports would be narrower than the other part.

you mean splitting the width of the front between the 2 in the rear?

 

[tcguy85 10+ year member]

you mean splitting the width of the front between the 2 in the rear?

yes, the back part that runs parallel to the back wall would be half the width of the main section of port that runs the other way out the front of the box.

 

[azimuth 5,000+ posts]

it's the same concept as with aero's. i can't explain it in a technical sense, in a box tuned for 1 aero, you can't split the length and cut the aero in half and put in 2 ports. the length actually gets longer with 2 aero's instead of 1.

edit: after reading back on my own post, i think i may have succesfully confused myself.

 

[tcguy85 10+ year member]

one part of the port is acting as a port for both subs, the other two parts are acting as a port for each sub. so the part thats acting as a port for both would be twice as wide as the parts that are acting like a port for each sub.

correct?

 

[azimuth 5,000+ posts]

one part of the port is acting as a port for both subs, the other two parts are acting as a port for each sub. so the part thats acting as a port for both would be twice as wide as the parts that are acting like a port for each sub.
correct?

no. in the end, there is just 1 port, but the box doesn't know that. you have to tune the box as if there is 2 slot ports, which, when you tune them with whatever port calculator you use, you would enter 2 ports, each of which is the same height and width. each port has to stay the same width all the way through the length of the port. you're seeing it as a bottleneck, but that's not the way the math works with tuning frequencies. i suppose this design could cause problems with air flow in a high power spl system.

 

[GearGuy2001 10+ year member]

no. in the end, there is just 1 port, but the box doesn't know that. you have to tune the box as if there is 2 slot ports, which, when you tune them with whatever port calculator you use, you would enter 2 ports, each of which is the same height and width. each port has to stay the same width all the way through the length of the port. you're seeing it as a bottleneck, but that's not the way the math works with tuning frequencies. i suppose this design could cause problems with air flow in a high power spl system.

The Back "ports" are 1/2 of the width of the port you see on the front, also some people make a triangle piece to help divide the 2 ports and direct them out the middle port, I didnt and it works fine.

 

[azimuth 5,000+ posts]

The Back "ports" are 1/2 of the width of the port you see on the front, also some people make a triangle piece to help divide the 2 ports and direct them out the middle port, I didnt and it works fine.

so how do you tune a port that is 2 inches halfway and then jumps to 4 the rest of the way?

 

[tcguy85 10+ year member]

The Back "ports" are 1/2 of the width of the port you see on the front, also some people make a triangle piece to help divide the 2 ports and direct them out the middle port, I didnt and it works fine.

thats what i thought.