Question about port area

[bass-aholic 10+ year member]

I have a box for my 2 18" BTL's and its 9.5 cubic feet and it has 120^2 inches of port tuned to 35 hz. The port is 24" wide by 5" high. Im just not getting the right sound out of the box that i want. It was built for 2 18" FI Q's but i threw these in there. Should i have more port area? Castereo's port calculator said i should have upwards of 250^2 of port area. With my box dimensions i can only manage to raise the port up to 7" high, and make it 21" long and stay at 24" wide. It would put my tuning in the low 30's with 168^2 of port area. What do you guys think. Will i notice a big difference? I am really lacking the low end and thats what i want to fix.

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[blackbonnie 5,000+ posts]

i think your port area is fine, you right around the 12-14in^2 per 1ft^3. i think your box may not be tuned to 35hz if your lacking low end

 

[bass-aholic 10+ year member]

double post ftl

 

[bass-aholic 10+ year member]

Port is 24" wide by 5" high by 16" long. I was told it was tuned to 35 hz. I t doesn't sound like it. I don't know how accurate carstereo's port calculator is but it says it only needs to be 6" long to be at 35hz and 16" for 30 hz and if it is tuned properly i want to extend my port a few inches to get my tuning down.

 

[blackbonnie 5,000+ posts]

ive me a sec. ill check for you

 

[blackbonnie 5,000+ posts]

well the tuning i got is 36.86873848hz. so roughly 37hz, have you checked to see if your subs are out of phase? and what is your subsonic filter set at?

 

[bass-aholic 10+ year member]

Subsonic is set at 15hz (im careful with what i play) And both subs are in phase. There deafening at the higher notes but they just cant seem to play the lows. If i added 4" to that port what tuning would that bring me to? Also would more port area help lows?

 

[bass-aholic 10+ year member]

any helppp?

 

[bass-aholic 10+ year member]

I have 120^2 of port tuned to 35 hz would upping it to 200^2 of port tuned to 35 hz produce better low end?

 

[TheyDontWant 10+ year member]

I have 120^2 of port tuned to 35 hz would upping it to 200^2 of port tuned to 35 hz produce better low end?

no

 

[SWFL 10+ year member]

tune lower like around 32hz

 

[RAM_Designs 5,000+ posts]

I got a little under 37hz tuning as well. That box is pretty small as well, which could be a big reason why the low end sin't where you're wanting it.

 

[IDSkoT 5,000+ posts]

I have 120^2 of port tuned to 35 hz would upping it to 200^2 of port tuned to 35 hz produce better low end?

Think of the port as a passive radiator (Basically a speaker with out a motor). The more area, the more response. But at a certain point, the area is too big and it no longer creates pressure, and ends up acting like the sub isn't in a box at all. Generally, the bigger the port area, the more of a gain you'll get from the box environment. If the lows aren't hitting properly, first make sure that your amp is set to LPF, and I'd turn your SSF up to 25 or so. If you want to get lower notes, tune it lower. I'd tune it to 30, or 32-33. I personally like a low tune. But, it all depends on the driver. I'll be honest, I didn't read the OP. So, I don't know which driver you're running.

 

[bass-aholic 10+ year member]

I got a little under 37hz tuning as well. That box is pretty small as well, which could be a big reason why the low end sin't where you;re wanting it.

Yea i think that might be it because after sub and bracing i lost well over a cubic foot.

Hey ryan i might PM you about getting a new box designed for these. Im gonna try to figure out if i can squeeze 12-15 cubes back there.

 

[RAM_Designs 5,000+ posts]

Yea i think that might be it because after sub and bracing i lost well over a cubic foot.Hey ryan i might PM you about getting a new box designed for these. Im gonna try to figure out if i can squeeze 12-15 cubes back there.

13-14ft^3 before displacement is a good place to start...15 would be great since the port is going to take up ~2-3ft^3.