How is port length calculated?

[Syphlyn]

Is it calculated down the center line of the port? If that's correct my port below would be 34.5 inches long? (24 3/8 + 10 1/8)

Click to read more...

 

[Kangaroux 5,000+ posts]

Yeah center of the port.

 

[Syphlyn]

Yeah center of the port.

Thanks //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif. Do you have any experience with boxes? I need some quick insight.

 

[Kangaroux 5,000+ posts]

Thanks //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif. Do you have any experience with boxes? I need some quick insight.

Yea what's your question

 

[Syphlyn]

Yea what's your question

Finally got my two box options done with the help of Joe X. The first box is his design and the second just that same box with some small changes I made. The box is going in the rear of my 2000 f150 extended cab truck with the sub/port both firing up. The Zv4 will be running off my SAZ-2000D.

Box 1: http://imgur.com/a/5JNWJ

Box 2: http://imgur.com/a/rsjTk

Box 1 is 2.5 cubic feet tuned to 32hz

Box 2 is 2.8 cubic feet tuned to 30.5hz

Both have very similar port area, within 0.2 sq inches/cubic foot of each other.

 

[Kangaroux 5,000+ posts]

Ok, so what did you need insight on lol. If you wanna know which box to use, honestly either would work fine. Probably would go with the second one out of personal preference (it will be a bit better with lows)

 

[Syphlyn]

Ok, so what did you need insight on lol. If you wanna know which box to use, honestly either would work fine. Probably would go with the second one out of personal preference (it will be a bit better with lows)

Oh **** totally forgot to put the most important part in. Lmao.

Anyways.

The top baffle is 18 inches (shown by the "Width" below) which will have the port and woofer across it. I plan on flush mounting the woofer, so the top layer of the baffle will have a cut out to 12.68 (Outer diameter of the woofer) while the second baffle will be cut to 11.07 which is the cut out. This will let it sit flush.

The baffle sits on top of the sides so if you do the math:

0.75 + 2.75 + 0.75 + 12.68 + 0.75 = 17.68......the 0.75 comes from the baffle sitting on top. So the 0.75 are the sides of the box and inner port wall where they meet the underside of the baffle.

Which leaves me roughly 0.3 inches spare space.

It's a hard question to word properly. I guess I want to know if having such a narrow peice of wood between the woofer and the port/edge of the box is bad and I think it could snap. Maybe I'm completely wrong.

 

[Kangaroux 5,000+ posts]

Oh **** totally forgot to put the most important part in. Lmao.
Anyways.

The top baffle is 18 inches (shown by the "Width" below) which will have the port and woofer across it. I plan on flush mounting the woofer, so the top layer of the baffle will have a cut out to 12.68 (Outer diameter of the woofer) while the second baffle will be cut to 11.07 which is the cut out. This will let it sit flush.

The baffle sits on top of the sides so if you do the math:

0.75 + 2.75 + 0.75 + 12.68 + 0.75 = 17.68......the 0.75 comes from the baffle sitting on top. So the 0.75 are the sides of the box and inner port wall where they meet the underside of the baffle.

Which leaves me roughly 0.3 inches spare space.

It's a hard question to word properly. I guess I want to know if having such a narrow peice of wood between the woofer and the port/edge of the box is bad and I think it could snap. Maybe I'm completely wrong.

I wouldn't worry about it. There will be a lot of glue there since that's where it meets the baffle so it will be really strong. If you really think it will be a problem you can add a third baffle

 

[bubbagumper6 5,000+ posts]

The port extends 1/2 it's length into the enclosure. So if your port is 2 inches wide you would add another inch to your actual length.

 

[Syphlyn]

The port extends 1/2 it's length into the enclosure. So if your port is 2 inches wide you would add another inch to your actual length.

Could you elaborate a bit more? Do you mean if my port is 2.75 wide it automatically adds another 1 3/8 to my port length? So in torres if I have 37 on port length, my actual "effective" port length is 38 3/8?

 

[mlstrass 5,000+ posts]

Mounting sub like that will be fine. I've done several enclosures where I had to grind the port or outer box wall to clear the basket.

If using "end correction factor" you would add 1/2 the width of your port to the overall length. Since you're using one of the walls of the enclosure as a port wall. That's what bubbagumper6 was referring to.

 

[Syphlyn]

Mounting sub like that will be fine. I've done several enclosures where I had to grind the port or outer box wall to clear the basket.
If using "end correction factor" you would add 1/2 the width of your port to the overall length. Since you're using one of the walls of the enclosure as a port wall. That's what bubbagumper6 was referring to.

So I calculated my port length down the center line of the port and get 37 inches so you're saying my actual length is 38 3/8

 

[bubbagumper6 5,000+ posts]

Could you elaborate a bit more? Do you mean if my port is 2.75 wide it automatically adds another 1 3/8 to my port length? So in torres if I have 37 on port length, my actual "effective" port length is 38 3/8?

Exactly. If you want a port length of 37" then your physical port length should be 1 3/8 less to compensate. This is only if you use an enclosure wall as one of the port walls and it extends past the port opening like yours.