Designing a ported box with George

[IgnoreMe 5,000+ posts]

I'm experiencing deja vu...

i dont get it? what are you tryin to say?

 

[Scarenius 10+ year member]

I've gone over these time and time again. I'd rather just pay Jmac to design one for me, just for the peace of mind. It'd take me days to get the design, and even then I don't know if it'd be right. It's worth the $15, and it's not like you have to get a new one every month.

Of course, it'd better be a helluva box. If it sounds bad, I'll put the thing on JMac's lawn and go for 150db playing polka in the wee hours of the morning.

 

[IgnoreMe 5,000+ posts]

you dont feel good about yourself that you actually learned how to design your own boxes? thats what does it for me. should always try to increase your skills imo

 

[Scarenius 10+ year member]

Math skills have never been a high point for me. I mean, I'm already spending $30 in materials for an enclosure that the nearest shop wants $200 for. Is another $15 going to kill me? Not really. I would naturally do the math myself, give whoever I pay the design so he can check over it and modify it as needed, but in the end, I take enough pride in knowing I built the box myself, I just didn't design it.

Trust me, I am capable of enough trades as it is. I'm typing on a computer I built myself, visiting a site I programmed myself (not caraudio.com, naturally), attached to this PC to a car amp attached to my XBox, with RCA cables I made myself running between. Outside is the car I repair and maintain myself, and inbetween in the house I'm building. If you don't believe me, I can get a digital camera and prove it all.

Penny wise, pound foolish and that, a shitty design will kill a custom built $30 box, wasting materials and lots of time. A $45 box, professionally designed, is significantly less likely to do that. Your instructions are good, no doubt. But in the end I will stick with what I am best at.

 

[IgnoreMe 5,000+ posts]

Math skills have never been a high point for me. I mean, I'm already spending $30 in materials for an enclosure that the nearest shop wants $200 for. Is another $15 going to kill me? Not really. I would naturally do the math myself, give whoever I pay the design so he can check over it and modify it as needed, but in the end, I take enough pride in knowing I built the box myself, I just didn't design it.
Trust me, I am capable of enough trades as it is. I'm typing on a computer I built myself, visiting a site I programmed myself (not caraudio.com, naturally), attached to this PC to a car amp attached to my XBox, with RCA cables I made myself running between. Outside is the car I repair and maintain myself, and inbetween in the house I'm building. If you don't believe me, I can get a digital camera and prove it all.

Penny wise, pound foolish and that, a shitty design will kill a custom built $30 box, wasting materials and lots of time. A $45 box, professionally designed, is significantly less likely to do that. Your instructions are good, no doubt. But in the end I will stick with what I am best at.

whoa whoa whoa. i never called you a liar lol. im just sayin that imo its always good to have an infinate amount of knowledge. im in no way doubting you of your abilities or skills. if you feel that its better to spend the money and get designed by all means go that route. i was just thinkin it would be nicer to add something else to your repitaur (sp?) of skills //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif . maybe ill pick up spelling as my next assignment lol

 

[LBX2G 10+ year member]

audiobahn has a couple of port calculator.

i do not kno if they are right or not so do no credit me on this.

**** i got a headache????????

http://www.audiobahninc.com/tech/Calculators/PortLengthCalc.htm

 

[Jayhawkk 10+ year member]

Might want to brush up on those math skills if you're building a house //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[spr_f150 10+ year member]

Jmac,

YGPM

 

[spr_f150 10+ year member]

^2 ........

 

[Scarenius 10+ year member]

It's $10, I don't have a lawn, and I offer to refund money if not satisfied ... //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

I'll have so many dumb question you'll charge the $5 for me being stupid. That or I'll end up with some really weird request you have to calculate 6 times over. Gotta wait til I buy subs, though. Hooray for the expensive holiday of Christmas.

 

[Goldtaz1 10+ year member]

Step 3: Figure out port length using this formula

Lv = Av*1.84*10^8/[Vb*1728*(Fb/0.159)^2] - 0.823*sqrt(Av)

Lv is port length (what your solving for)

Av is your port area (height x width of the port face)

Vb is the internal volume of your box

Fb is the tuning frequency you want

It should be noted that the formula above is not totally correct.

The correct formula is Lv = Av*1.84*10^8/[Vb*(Fb/0.159)^2] - 0.823*sqrt(Av). Do you see where George multiplied by 1728? Do not do that, this formula is for the port length, not cubic inches of port. Other than that step there is nothing else I can see that is wrong.

P.S. It is also noted that even if you used the 1728 in the formula above, you will not receive the cubic inches of port.

 

[IgnoreMe 5,000+ posts]

bump for any new guys willing to give a shot at designing their own box

 

[mrray13 10+ year member]

tune low + big port area + big box = loud as hell

real quick here...

all that adds up to less power handling as well. well,the big box does. just because the box is bigger isn't necessarly going to make it louder, more efficifient yes, louder no, as power handling goes down the drain.

now for all u guys that are foing to ramble on about this big box being this loud and this big box being this loud.....i know of three small boxes that are world champions this year, two of those in two different organizations (these are people i know personally) and they tell me that more and more are going the small box, big power route.

also, the big port area equates to a longer port for a specific frequency. but it does lower the probablity of port noise.

my advice? read the owners manual on ur sub, if it doesn't have one, go to their website or call them...get the recommended volume and port size and tuning. basicly, ur box is designed ie: they recommend a 1.75ft^3 box for their 12 with 20in^3 of port tuned to 38hz. all u have to do is measure ur vehicle and do the math to see if u can squeeze 1.75ft^3 in there.......that's overly simple, but it's the basic idea.

oh yeah...the vodka and sprite are workin on me..lol //content.invisioncic.com/y282845/emoticons/silly.gif.3549b64aaa5b6729eb8e865319a3234f.gif//content.invisioncic.com/y282845/emoticons/sick.gif.b1847c8dabbfeeddbcf1a78052249e10.gif

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee //content.invisioncic.com/y282845/emoticons/peace.gif.2db28b618ed8d1964ebbe2f5021d2c39.gif

 

[LBX2G 10+ year member]

real quick here...

all that adds up to less power handling as well. well,the big box does. just because the box is bigger isn't necessarly going to make it louder, more efficifient yes, louder no, as power handling goes down the drain.

now for all u guys that are foing to ramble on about this big box being this loud and this big box being this loud.....i know of three small boxes that are world champions this year, two of those in two different organizations (these are people i know personally) and they tell me that more and more are going the small box, big power route.

also, the big port area equates to a longer port for a specific frequency. but it does lower the probablity of port noise.

my advice? read the owners manual on ur sub, if it doesn't have one, go to their website or call them...get the recommended volume and port size and tuning. basicly, ur box is designed ie: they recommend a 1.75ft^3 box for their 12 with 20in^3 of port tuned to 38hz. all u have to do is measure ur vehicle and do the math to see if u can squeeze 1.75ft^3 in there.......that's overly simple, but it's the basic idea.

oh yeah...the vodka and sprite are workin on me..lol //content.invisioncic.com/y282845/emoticons/silly.gif.3549b64aaa5b6729eb8e865319a3234f.gif//content.invisioncic.com/y282845/emoticons/sick.gif.b1847c8dabbfeeddbcf1a78052249e10.gif

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee //content.invisioncic.com/y282845/emoticons/peace.gif.2db28b618ed8d1964ebbe2f5021d2c39.gif

well i totally get what u are saying, But those guys compete. Most of the kids here just get daily setups. Soooo 2 2,000 watt amps will not do very well. I mean alternator upgrades are not fun, when i could have used the money for spinners. Like i said before i am not disageering just supporting george.

 

[reed8857 10+ year member]

well i totally get what u are saying, But those guys compete. Most of the kids here just get daily setups. Soooo 2 2,000 watt amps will not do very well. I mean alternator upgrades are not fun, when i could have used the money for spinners. Like i said before i am not disageering just supporting george.

Did not mean to qoute you but what part of Warner Robins are you from as I am form there my self or are you AF