port tuning question

[slc720052 10+ year member]

i can never get those online port calucaltors to work correctly, probably just me.

but any way i have a 9.5cf box that has 2 15 inch kicker l7's (2006 version)

the 9.5cf is before sub and port displacement.

the port i have in there now is 75sq inches (17.5 high and 4.3 wide) this is the most port area that i could posiible fit in my car, i have a 2005 ford focus 4 door ( i know it was amazing i was able to get a 9.5cf box in there at all //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif ) so port area has to stay the same

i am wanting to tune it down to about 30-32hz, my question is with the port area being 75sq how long would the port have to be to be tuned to 32hz?, 30hz?

right now the port is only 9 inches long and it definantly lacks in the low end bass. i had the port tuned higher because i was going to compete but now its just going to be a kick *** streat beater.

heres a pic of the subs in the box with the back seats down, and you will see the port is as big as i can get it.

thanks for your help guys

Click to read more...

 

[Death By Bass 10+ year member]

its currently tuned to like 37Hz...

32Hz would make the port about 15inches long

30Hz and the port would need to be 18inches long

why are people always unable to find winisd?

 

[Pickler 10+ year member]

thats a big *** box

 

[xluben 10+ year member]

if you actually have 9.5ft^3 internal, i come up with a 21" long port.

that would make your actual volume ~8ft^3 and your tuning 30Hz.

right now i get you tuned to just under 40Hz.

 

[slc720052 10+ year member]

if you actually have 9.5ft^3 internal, i come up with a 21" long port.
that would make your actual volume ~8ft^3 and your tuning 30Hz.

right now i get you tuned to just under 40Hz.

the 9.5 is before prt and sub displacement

 

[xluben 10+ year member]

the 9.5 is before prt and sub displacement

yeah, that's what i figured as internal volume before displacement. that's why i guess 8.5ft^3 net (after displacement of a port tuned to 30Hz and drivers).

i used a net volume a bit bigger to guess the tuning of your current box.

i think that's why my numbers were slightly off from the others posted (they didn't account for displacement or used a slightly different approximation).

i'd just extend the port out to about 20" and you should get a tuning right in the 30-32Hz range.

 

[Death By Bass 10+ year member]

yeah, that's what i figured as internal volume before displacement. that's why i guess 8.5ft^3 net (after displacement of a port tuned to 30Hz and drivers).
i used a net volume a bit bigger to guess the tuning of your current box.

i think that's why my numbers were slightly off from the others posted (they didn't account for displacement or used a slightly different approximation).

i'd just extend the port out to about 20" and you should get a tuning right in the 30-32Hz range.

yeah, I guessed 9.0cuft as the volume after displacement, which was probably too small, and didn't bother accounting for the extra port displacement for the longer port...

just make it 20inches long //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

 

[slc720052 10+ year member]

the most i can do is 17 inches because of the way the box front is on an anle and the rear of the box on an angle.

what would tuning be at 17 inches?

or should i make the port a little smaller by putting a piece of 1 inch by 4.3 inch mdf to make the port area a little smaller to 69sq inches.

if the port being 17 inches will tune me to about 33-34hz i should be happy, im looking for a little more lowend from the subs and as you can imagine with it being tuned so high now im loosing quite a bit of lowend roll off

thanks again guys for all your help here

(keep in mind that due to my car's trunk size certain sacrificeies had to be made in box design to get the the box big enough to house the 2 l7's

but on a side note i have been thinking about ditching the 2 15 l7's and getting 1 15 inch something and throwing both of my amps (PG xenon 1200.1) giving them 2500rms to just one sub.

but i dont know what sub could handle that kimd of power daily and hit the low bass notes and still use the same box i have, well with a different face obviously, but i could make the port bigger to take up some extra space.

thanks for your help again guys

 

[nVRuckus 5,000+ posts]

why are people always unable to find winisd?

and the ones who can find it dont realize it doesnt calculate port displacement in its calculations so you have to take that into account when putting the box size to get actual tuning //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[xluben 10+ year member]

the most i can do is 17 inches because of the way the box front is on an anle and the rear of the box on an angle.
what would tuning be at 17 inches?

i estimated the net volume of the box to be around 8.3ft^3 and the tuning will be right at 32Hz!

not sure what i did before, but i think that'd work out great, just make sure there is at least 4.3" between the end of the port and the back wall of the box.

also, if you have box in the trunk of a focus and its

can you draw out a diagram of your box with the dimensions?

 

[xluben 10+ year member]

and the ones who can find it dont realize it doesnt calculate port displacement in its calculations so you have to take that into account when putting the box size to get actual tuning //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

yep, i accounted for that and so did Death By Bass

 

[slc720052 10+ year member]

off the top of my head its something like this

its 38 inches wide by 38 inches long by 20 inches high, then there is a slight angle on the face and the rear and that acoounts for about a 1cf loss innet volume

yes the box was built into the trunk, there was no way of buildoing it out of the car and putting it in, the carners area all braced, here is a pic of the box without subs as you can see in the pic it is a huge box and the holes that are cut out are for the kicker l7 15 so you can usae that for a size reference

 

[xluben 10+ year member]

interesting, looks like you're stuck with that box for as long as you own the car //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

i think you're about right with the volume, so i'd do the 17" port and see how you like it, should be tuned to the low 30's.

 

[slc720052 10+ year member]

interesting, looks like you're stuck with that box for as long as you own the car //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif
i think you're about right with the volume, so i'd do the 17" port and see how you like it, should be tuned to the low 30's.

alot of people dont believe me when i tell them i got 9.5cf out of a ford focus sedan, but it is possible, the box is 20 inches tall, from the top of the sub cut out to the bottom is only 15 inches so the box goes up 5 more inches above the top of the sub cut out.

yea the box is in rough form in this pic as its old, it looks alot better now as i put a fresh smooth layer of fiberglass all over the box so what you ee has saw dust and scraps still in the box, you guys knwo how it is.

yes im stuck with the box for a while, i would have to cut it out if i wanted a new box

yea im going to try the 17inch port this week sometime

thanks for your help guys