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Port size suggestions?????


Kraken

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Ive got a box designed for my 2002 chevy 1500 ext cab. The box is 9.0ft^3 and im putting 2 sundown x15's in it on 2 sundown 1500D's @1ohm. I have the box designed with 3 4" wide tube ports, and for tuning at 30hz, it was somewhere around 10 inches for each tube. Will this be enough port space for these subs? Im not exactly sure the requirements on the port size or area. I originally had a box designed for 2 DC level 4 15's, but decided I was going to go with sundown instead. The box size was 7.5ft, but now 9ft. Any suggestions on port size, will 3 4" ports be enough?

Thanks for any help guys :)

Alpine cde143bt/ Alpine ktp445u (4x45 amp)

2 Crescendo STS 1 (on alpine 4x45 on 2 channel mode)

4 Crescendo pwx 6.5's in front doors (Skar RP150.4)

1 Sundown zv3 12, SAE1500D.

Box is 2.5 cubes tuned to 30hz.

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doesnt sound like much port area too me. Im no expert. i would do like 2 8" at least if it were me.but then they would have to be 24" long at that size.

 

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Yeah two 8" or a slot port.

91 C350 Centurion conversion ( Four Door One Ton Bronco)

250A Alternator (Second Alternator Coming Soon)

G65 AGM Up Front  / Two G31 AGM in Back

Pioneer 80PRS

CT Sounds AT125.2 / CT Sounds 6.5 Strato Pro component Front Stage

CT Sounds AT125.2 / Lanzar Pro 8" coax w/compression horn tweeter Rear Fill

FSD 5000D 1/2 ohm (SoundQubed 7k Coming Soon)

Two HDS315 Four Qubes Each 34hz (Two HDC3.118 and New Box Coming Soon)

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On 3/3/2017 at 4:20 PM, strangeduck said:

doesnt sound like much port area too me. Im no expert. i would do like 2 8" at least if it were me.but then they would have to be 24" long at that size.

 

I dont have room for 24 inches deep :( . I although do have the room for 2 6 inch ports, is that any better than 3 4 inch ports? Im not exactly sure of the new possible depth of the box, since it was originally designed at 7ft^3 for 2 dc 15's. It will be extruded back to increase the size so maybe I will have room for 2 7 inch ports?? I will play around with it tonight in sketchup and have my drafting teach at school help me out with the volume after all the bracing and the angles (the box has an 80 degree front baffle, and a bunch of 45's inside and a steel tube for support in the middle, its awkward angles).

 

On 3/3/2017 at 4:46 PM, ShadeTreeMechanic said:

Yeah two 8" or a slot port.

I dont have much experience on slot ports, what kind of size/length port would I need to tune at 30hz with 9ft box? The front baffle is at a 80 degree angle and I'd prefer the port to go out of the front baffle in between the subs themselves. If a slot port is possible here, im all for it.

Alpine cde143bt/ Alpine ktp445u (4x45 amp)

2 Crescendo STS 1 (on alpine 4x45 on 2 channel mode)

4 Crescendo pwx 6.5's in front doors (Skar RP150.4)

1 Sundown zv3 12, SAE1500D.

Box is 2.5 cubes tuned to 30hz.

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man, i cant help you much. every time i think i know something i find out it doesnt work in a different situation. if you follow my builds you will see that. im learning just like you. it is expensive and time consuming to build/test/build/test/build/test. some guys gain with less port area, some guys gain with more. Cars are hostile environments for sure. heck, i see guys with those "big ass ports" but its like an 8" port and you find out they are tuned to like 55hz. but it looks cool. 

 

hope you get this sorted out. High power subs are tough to deal with. The bigger the enclosure the more margin of error you have.

 

as far as the math, just use google to tell you the area of a circle and plug in half the port size. so an 8" port you would put in 4 and it will tell you the area of that port.

i like precision ports calc for figuring circle port tuning myself. just keep in mind that the box volume assumes all displacements including the port discplacement so that is something you have to do the math on yourself.

http://www.psp-inc.com/tools2.html 

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Yea that isn't anywhere near enough port area. 3 4" ports only comes to about 37.6 square inches. With that much volume and those subs you're gonna need somewhere between 100 to 130 square inches. To put that in perspective you would need 2 8" ports at 35" long to achieve 30hz. In my opinion you would be much better off with a slot port using 2 or 3 common port walls to keep your volume up.

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With a slot port you can turn it 90 degrees where it meets the back wall and run it along the back to get the length you need. It is hard to design a box and then put some ports in it. You almost need to figure out the port volume based on box volume and power first. Then design a box around it. If the box turns out too big to fit then redesign port to make box fit. There will need to be a compromise somewhere to make it all fit. Either in the box size or volume or port size or all of them.

91 C350 Centurion conversion ( Four Door One Ton Bronco)

250A Alternator (Second Alternator Coming Soon)

G65 AGM Up Front  / Two G31 AGM in Back

Pioneer 80PRS

CT Sounds AT125.2 / CT Sounds 6.5 Strato Pro component Front Stage

CT Sounds AT125.2 / Lanzar Pro 8" coax w/compression horn tweeter Rear Fill

FSD 5000D 1/2 ohm (SoundQubed 7k Coming Soon)

Two HDS315 Four Qubes Each 34hz (Two HDC3.118 and New Box Coming Soon)

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