Port Questions

[Devil Tiger 10+ year member]

My subs manual says

3 x 12.5” (7.6x31.8cm) port, 20.5” (52.1cm) long

Power Handling = 300W RMS

5 ft^3 + port displacement

for a 12" vented enclosure. The enclosure I'm designing is pictured below for two subs. Do I double the port dimensions? This seems uber small for how big the box is. I used another web sites calculator (PORT Size Calculations and Formulas for WOOFER and Subwoofer BOXES) and it says when I enter my port dimensions "you should use a width:height ratio of less than 1:8" (with dimensions 3"x33.5", volume of 5ft^3, 35hz tuning freq).

If I change the dimensions to 3"x24" it will do the calculating and say the length should be 12.68".

So at this point I'd like to know what is my designs current tuning freq (I'm aiming for 35hz) and if I need to downsize my current port.

My current designs net volume (with port and sub displacement subtracted out) is 4.89 ft^3. The external dimensions are 35"x14"x27".

http://www.kicker.com/sites/default/files/2007CompVR.pdf

http://i.imgur.com/mdb28.jpg

Click to read more...

 

[Devil Tiger 10+ year member]

Really? 40 views and no one can even point me in the right direction?

---------- Post added at 07:01 PM ---------- Previous post was at 07:01 PM ----------

@RAM_Designs

 

[Kangaroux 5,000+ posts]

Aim for port area between like 40-60 in^2 (port width * port height).

 

[Devil Tiger 10+ year member]

So in the current design that would be 33.5"x10"? Which is over 300 in^3...way too big right?

 

[DonH 5,000+ posts]

Before starting a thread about proper port dimensions, use the search feature. I dont care if you said you did, you obviously did not. THOUSANDS of people have commented ont he "golden rule of thumb" for ports. 12-16 in^2 per CUBIC FOOT. take the recomended cubic feet for your subwoofer, lets say 2ft^3. yyou need a minimum of 24in^2 of port area for the box. if you are doing two, you would double the port area. now with the port area in mind factor in the size of the port you can fit into your size restrictions. if you can not fit a proper size port either a) get new smaller speakers or b) go with a sealed box (which i prefer due to personal preference)

So in the current design that would be 33.5"x10"? Which is over 300 in^3...way too big right?

no, you have 33.5"x3"= 100.5" height x width which is still far to big.

 

[Devil Tiger 10+ year member]

I did search ****.

 

[DonH 5,000+ posts]

I did search ****.

vulgar much? done helping you. good luck.

 

[Devil Tiger 10+ year member]

Just calling them like I sees them. How would I have gotten this far without searching? You think I just sketched it all up from mothers intuition?