# Slot porting a Fi sub.



## Slick98ta (Jul 24, 2009)

Hello,
I'm wanting to build my own enclosure and had a few questions before a start with this box calculator and hoping I'm on the right track.
Like in the picture below, I'm wanting to tune to 33Hz but when I build my box is that pic it's saying to make my "L" port 21.5" long or is it 8" referring to where its says Physical Port Length? I'm not sure I'm understanding the difference so any help would be appreciated. Thanks!


----------



## Oliver (Jun 25, 2007)

Measured from top -to- bottom = how *high*

Measured from side -to- side = how wide

Measured from the baffle or face of box going into { think vagina } = how deep or *length*


----------



## Slick98ta (Jul 24, 2009)

a$$hole said:


> Measured from top -to- bottom = how *high*
> 
> Measured from side -to- side = how wide
> 
> Measured from the baffle or face of box going into { think vagina } = how deep or *length*


Thanks I got that. So I drew up another little pic. Going off the box calculator are you saying that what I have marked in red would be the 21.5" ?

I just don't get where the 8" is coming from for Physical Port length.Only thing I can think of was it was 8" after the bend going in to the box. So that the first part of the "L" is 13.5 then after the bend would be 8" totaling 21.5" if that makes sense.


----------



## Slick98ta (Jul 24, 2009)

Never mind, after posting my last message it all made sense. I've been trying to figure this out for over a week. I guess drawing myself a pic made it all click.


----------



## Hispls (Mar 12, 2008)

On a slot port with the side of the box as one wall of the port, the port will actually effectively be increased by half a port width (1" in your case) as the wall acts to lengthen the port. ALSO if the port is against the wall/floor of the car add another inch as that'll extend the port as well.

Not like 1" will make a huge difference, but just so you know.


----------



## Slick98ta (Jul 24, 2009)

Thanks for the help. I'm starting to understand this more. Although building a sealed box is pretty much straight forward, ported takes a little more time to figure out.

Could I keep all my dimensions the same and make the "L" more flow friendly or by doing this will screw up my port length and volume for the enclosure? I know it would affect some but by how much. Here's what I'm referring to. 

Going from this..









To this.. marked in green.


----------



## Oliver (Jun 25, 2007)

I'd do it


----------



## Hispls (Mar 12, 2008)

Rounding off the port should be only negligable difference in box volume and would help make it more arodynamic. I'd reccomend it if you have the skills.


----------



## Torquem (Jun 27, 2009)

your sub is crooked


----------



## jsun_g (Jun 12, 2008)

Torquem said:


> your sub is crooked


And it has a really small magnet 

Seriously though, since we are talking about airflow, might as well flange the inner and outer ends of the port to reduce the eddies/turbulence where air enters/exits the port. You can just use a roundover bit on a router or cut at an angle and sand to more of a curve shape.

Just a word of caution, since you are creating an L-shape duct, you might want to take steps while the enclosure is under construction that will allow you to remove/replace the inner part of the "L" with a different length so you can adjust your tuning easily until you are happy with it...and after that go for the final build/glue/etc.


----------

