Hey, I have a 2005 F150 Reg Cab. I would like to put a 12" Kicker L5 in it. My box size restrictions are 34X9X20. (W X D X H). I'm trying to get the volume close to 3 cubic feet while still fitting because i love the deep lows. I want to make the box ported but i have no idea where to start to make the box ported. Is it ok if my port is on top of the box pointing up because of how my box is going to sit that is the only side without an ubstruction. Any help is greatly appreciated!! Trent Kammerer
Replies (5)
cplkittle on 03/11/2008 09:07:35
It is acceptable for the port to be on top if there are no other options. The tricky part is designing the port, and getting the right airspace in the box. The port is normally inside the box, and you have to subtract the airspace the port takes up from the overall internal volume of the box.
Your dimensions give me 3.54 cubic ft. You have to subtract for the thickness of the wood. I would recommend 3/4" MDF for 2 reasons. The size of the sub and the large surface area of the single sides. I will do some calculations and let you know what I come up with.
cplkittle on 03/11/2008 09:25:26
If the measurements you gave me are outside dimensions and you use 3/4" MDF, your internal volume will be 2.61cuft. The port is going to take up around .1 cuft. I calculated all of the ports on a basic 2"x 6" opening.
38Hz = 2x6 x 6" long
36Hz = 2x6 x 7" long
34Hz = 2x6 x 8.25" long
32Hz = 2x6 x 9.75" long
For your truck, I recommend 38 or 36 Hz. Not only will it resonate in the cab better than the lower frequencies, but the port will be easier to build. If you stick with the 6 or 7" port length, you can simply run it straight down the back wall of the box without having to snake it around inside the box to get the full length. If your measurements are off a little on the port, the only thing that changes is the tuned frequency, and not by much.. for example, the 6" port is 38Hz, and the 7" port is 36Hz.. if the port ends up being 6 1/2", you get 37Hz.. no big deal. The bottom of the port (the opening on the inside of the box) has to be 2" from the bottom since the port is 2" wide. If you choke off the port it will not sound right. So if you use the 7" port, remember you had 9" to begin with, and you are using 3/4" MDF. That leaves 8 1/4" from the top of the box (port opening) to the bottom piece of MDF. You don't have 2" from the bottom to the beginning of the port, so the port will have to stick up out of the top of the box 3/4" or you will have to put a turn in the port to accomodate for the rest of the length.
You MUST HAVE a subsonic filter for your sub set at 30Hz at a 18 or 24 dB slope.. The box will pound, but the sub excursion level goes off the charts at 25Hz. If you don't use one, the sub will destroy itself in no time.
Hope that helps
DaculabBall50 on 03/11/2008 15:11:53
Ok, First of all thanks alot for the info!!! And yes those are the maximum outside measurements for the box and yes i will be useing 3/4 MDF. But my box depth is going to be 9" and the height is going to be 20" so if my port is on top of my box can't my port be really long because from the top of the box to the bottom is 20". I have heard 33Hz is the "golden number" but i really dont know. If you say 36 or 38 thats what i will do. Maybe i'm not seeing something right or maybe i miswrote my dox dimensions. But since my box is 20" high cant i have a longer port? Thanks!!! Trent Kammerer
cplkittle on 03/11/2008 15:51:02
my mistake.. yes, after you subtract for the bottom piece, you get 19 1/4". You don't have to subtract for the top piece since it comes up flush. You can go up to 17"
I don't know what I was thinking there. You are right.
33 Hz would be right at 9" long (2"x6" port)
DaculabBall50 on 03/11/2008 20:09:36
What would be the best frequency in my truck. Like i said its a small regular cab. I have just heard 33 Hz is the best, but i really dont know much about car audio. Now that i have the extra room would you recommend 33 or still 36 or 38? So this 2" x 6" port can be faceing towards the roof of my truck on the other end of the box as the sub and it will still sound good? This box will sound good correct. I can't really screw up a regtangle box and a rectangle port. Also powering this 12" L5 will be a ZX750.1. If i get a DVC 4 ohm L5 then i could get the 2 ohm load from the ZX750.1 and get 750 watts right? That should all be good right? Thanks for all the help!! Trent Kammerer
Replies (5)
cplkittle on 03/11/2008 09:07:35
It is acceptable for the port to be on top if there are no other options. The tricky part is designing the port, and getting the right airspace in the box. The port is normally inside the box, and you have to subtract the airspace the port takes up from the overall internal volume of the box.
Your dimensions give me 3.54 cubic ft. You have to subtract for the thickness of the wood. I would recommend 3/4" MDF for 2 reasons. The size of the sub and the large surface area of the single sides. I will do some calculations and let you know what I come up with.
cplkittle on 03/11/2008 09:25:26
If the measurements you gave me are outside dimensions and you use 3/4" MDF, your internal volume will be 2.61cuft. The port is going to take up around .1 cuft. I calculated all of the ports on a basic 2"x 6" opening.
38Hz = 2x6 x 6" long
36Hz = 2x6 x 7" long
34Hz = 2x6 x 8.25" long
32Hz = 2x6 x 9.75" long
For your truck, I recommend 38 or 36 Hz. Not only will it resonate in the cab better than the lower frequencies, but the port will be easier to build. If you stick with the 6 or 7" port length, you can simply run it straight down the back wall of the box without having to snake it around inside the box to get the full length. If your measurements are off a little on the port, the only thing that changes is the tuned frequency, and not by much.. for example, the 6" port is 38Hz, and the 7" port is 36Hz.. if the port ends up being 6 1/2", you get 37Hz.. no big deal. The bottom of the port (the opening on the inside of the box) has to be 2" from the bottom since the port is 2" wide. If you choke off the port it will not sound right. So if you use the 7" port, remember you had 9" to begin with, and you are using 3/4" MDF. That leaves 8 1/4" from the top of the box (port opening) to the bottom piece of MDF. You don't have 2" from the bottom to the beginning of the port, so the port will have to stick up out of the top of the box 3/4" or you will have to put a turn in the port to accomodate for the rest of the length.
You MUST HAVE a subsonic filter for your sub set at 30Hz at a 18 or 24 dB slope.. The box will pound, but the sub excursion level goes off the charts at 25Hz. If you don't use one, the sub will destroy itself in no time.
Hope that helps
DaculabBall50 on 03/11/2008 15:11:53
Ok, First of all thanks alot for the info!!! And yes those are the maximum outside measurements for the box and yes i will be useing 3/4 MDF. But my box depth is going to be 9" and the height is going to be 20" so if my port is on top of my box can't my port be really long because from the top of the box to the bottom is 20". I have heard 33Hz is the "golden number" but i really dont know. If you say 36 or 38 thats what i will do. Maybe i'm not seeing something right or maybe i miswrote my dox dimensions. But since my box is 20" high cant i have a longer port? Thanks!!! Trent Kammerer
cplkittle on 03/11/2008 15:51:02
my mistake.. yes, after you subtract for the bottom piece, you get 19 1/4". You don't have to subtract for the top piece since it comes up flush. You can go up to 17"
I don't know what I was thinking there. You are right.
33 Hz would be right at 9" long (2"x6" port)
DaculabBall50 on 03/11/2008 20:09:36
What would be the best frequency in my truck. Like i said its a small regular cab. I have just heard 33 Hz is the best, but i really dont know much about car audio. Now that i have the extra room would you recommend 33 or still 36 or 38? So this 2" x 6" port can be faceing towards the roof of my truck on the other end of the box as the sub and it will still sound good? This box will sound good correct. I can't really screw up a regtangle box and a rectangle port. Also powering this 12" L5 will be a ZX750.1. If i get a DVC 4 ohm L5 then i could get the 2 ohm load from the ZX750.1 and get 750 watts right? That should all be good right? Thanks for all the help!! Trent Kammerer
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