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How much port space?

 

Bronze Member
Username: J_baby15

Kentucky

Post Number: 30
Registered: Feb-06
I'm hookin the L7 up finally, but im just going to make a temporary box to use for a lil while. If i was to make a 5cu. ft. box, about how many sq. in. of port space would i need and how deep of port? Is 5 cu. ft. too much or should i go bigger? Just leave me sum suggestions of wat will play low but loud.
 

Bronze Member
Username: J_baby15

Kentucky

Post Number: 31
Registered: Feb-06
Anyone?
 

Gold Member
Username: Tdeaton1021

Near Tampa, Florida USA

Post Number: 2317
Registered: Sep-04
is this an L7 15?going for straight SPL (as in competing)? or just a loud daily driver? what amp are you using? oh i just saw you want it to play low. well for an L7 tune probably around 32-34hz. im not at my regular house so i dont have any of my links but answer some of those questions first.
 

Gold Member
Username: Southernrebel

Monroe, Louisiana USA

Post Number: 2409
Registered: Mar-04
for a 5cuft (net) box...50-60sq inches of port is good.

 

Bronze Member
Username: J_baby15

Kentucky

Post Number: 32
Registered: Feb-06
It's going to be in the trunk of my car, but i took out the factory 12 in the back deck to let more sound through. You may remember me askin earlier about 3 L7s, but i sold 2 of them and my amp to a friend to pay off 2 speeding tickets i got. Anyways, i dont plan to compete, but I do want very loud. I've got 2 other boxes im using now, one sealed and a smaller ported, and im wanting this one for SPL. A guy comes around here with 6 15" Alphasonik subs(the cheaper series) and a "5800 watt amp" in a crew cab truck and thinks his system is the Sh!t. But of course he gave no attention to the quality of the box he put them in and just made it to fit in the place of the rear seat of his truck and wired it all up, and it sounds raggedy, and not loud for 6 15s. I'm almost positive my single 15 could outplay that. Sorry for the book tho, im really bored at work and not much else to do.
Oh yea, im not sure on wat amp yet, but i have an old school fosgate amp (rough silver look, with red RF on it, kinda like the bd series) being repaird, but im not sure the wattage. Any suggestions on a descent amp for it would help.
 

Bronze Member
Username: J_baby15

Kentucky

Post Number: 33
Registered: Feb-06
oh yea. and when you said 5 cu. ft. net, is that meaning including the port space and everything, or just the actual chamber? I'm not really set on wat volume yet, just lemme know what you think. And how deep would the slot port be in order to tune it to the 32hz region?
 

Gold Member
Username: Southernrebel

Monroe, Louisiana USA

Post Number: 2414
Registered: Mar-04
5cuft net means air space after acounting for port and sub displacments.

w/ 5 cuft (net)...a 60sq inch port tuned to 32hz would be 25" long
 

Bronze Member
Username: J_baby15

Kentucky

Post Number: 34
Registered: Feb-06
Heres a lil drawing of roughly wat it would look like. Correct me if im wrong on anything. Won't making the port 'L' shaped still keep the same frequency as long as it stays 3.5" wide all the way through? If im way off just make a quick paint shop image like i did to give me a better idea. It will be 16 to 17" tall. All are external deminsions. 3/4" MDF will b used.

image/bmpUpload
boxl7.bmp (86.7 k)
 

Gold Member
Username: Southernrebel

Monroe, Louisiana USA

Post Number: 2416
Registered: Mar-04
the measurements i gave you are for the port size if the chamber is 5cuft.

the box overall would be ~6cuft.
 

Bronze Member
Username: J_baby15

Kentucky

Post Number: 35
Registered: Feb-06
Alright. I'm going to get started on it today then, Thanks for the help. Also, this is a lil off the topic, but i hooked a system up for a friend teh other day(2 JL 10s and a 500watt amp) but now they have a buzzing sound when they play. He said it gets louder when he speeds up, and u can barely hear it when hes sittin still. What is this, and how can i fix it?
 

Gold Member
Username: Southernrebel

Monroe, Louisiana USA

Post Number: 2418
Registered: Mar-04
thats alternator-whine.

make sure all your power and grounds are solid (grind off any paint) and make sure your RCA's are one the opposite side of the car from the power wire.

also, upgrade your big3.


oh yea...in that pic you drew...you dont measure a port by the outside wall...you measure it through the center line of the port.
 

Bronze Member
Username: J_baby15

Kentucky

Post Number: 36
Registered: Feb-06
Can you help me out a little and take the pic i had and change the measurements i put in so that it would sound its best, the max width will be about 30".
 

Gold Member
Username: Southernrebel

Monroe, Louisiana USA

Post Number: 2426
Registered: Mar-04
i'll do ya one better...

for $10 i'll send you cut-by-cut instructions. :-)
 

Bronze Member
Username: J_baby15

Kentucky

Post Number: 37
Registered: Feb-06
Well right now, I'm just needin a quick box that will sound good. It's not permanent because i still have about $200 in fines left to pay or my license are removed...which sucks...I had talkd to Wahl earlier about designing a box, but I may talk to you for a design when i get my trunk completely measured and decide wat my new set up is going to be.
 

Gold Member
Username: Southernrebel

Monroe, Louisiana USA

Post Number: 2427
Registered: Mar-04
thats kool man...tell ya what, just give me the measurments you have to work w/...i'll do it for free. (lol...i'm bored)
 

Bronze Member
Username: J_baby15

Kentucky

Post Number: 38
Registered: Feb-06
18"Hx39"Wx21"D

the depth is variable, but the height and width is the exact amount i have, so thats the max external dimensions. the depth i listed is from the backseat to the hinges of the trunk and about where i would like the box to stop. So u can take those and just have some fun so u arent so bored :P. Anyways, tell me about what the best sound im going to get is. About how many DBs can you estimate this hitting? i have the year deck ported to let more sound through, and assuming im giving around 1100rms
 

Gold Member
Username: Southernrebel

Monroe, Louisiana USA

Post Number: 2431
Registered: Mar-04
how bout this...

16.5" tall, 38" wide, 21" deep...

port boards
15" x 15.5"
15" x 6.5"

the port opening will be 15" x 4"...box tuning will be 32hz, and you will have 5.1cuft (net).
 

Gold Member
Username: Southernrebel

Monroe, Louisiana USA

Post Number: 2432
Registered: Mar-04
make the second port board:
15" x 5.5"


---sorry bout that.
 

Bronze Member
Username: J_baby15

Kentucky

Post Number: 39
Registered: Feb-06
2nd port board? explain please. I know alot about the electrical part of audio and all that, but box building is something im kind of new to. I've built several sealed, but this is the first ported that I'm trying out.
 

Gold Member
Username: Southernrebel

Monroe, Louisiana USA

Post Number: 2435
Registered: Mar-04
the 1st board will be the one that goes from the front of the box to the back...the 2nd board will make the L part that follows the back wall.

here is a pic of a box i built awhile back...maybe it will help ya out.
http://www.sounddomain.com/ride/650399/5
 

Bronze Member
Username: J_baby15

Kentucky

Post Number: 40
Registered: Feb-06
Nice. Thats about how im wanting mine to look. Hopefully I can have a digital camera by then and show yall how good(or bad) i do. Whats a descent amp i could get for this in the $150 range? And im wanting 4 6x9s for the rear deck, any suggestions? I love Ebay so thats an option.
 

Silver Member
Username: Safe_cracker

Chicago, IL US

Post Number: 489
Registered: Jan-06
Who da hell serving up crawdads? :-O
 

Gold Member
Username: Southernrebel

Monroe, Louisiana USA

Post Number: 2436
Registered: Mar-04
that pic is from last summer...wish i had some mud-bugs right about now. but they are ~$1.99/lbs right know :-(

when they get down to about $0.90/lbs latter down in the summer....IT'S ON!!! :-)
 

Gold Member
Username: Southernrebel

Monroe, Louisiana USA

Post Number: 2437
Registered: Mar-04
thats ~$1.99/lbs live.
 

Gold Member
Username: Southernrebel

Monroe, Louisiana USA

Post Number: 2438
Registered: Mar-04
oh yea...one more thing, look close in the pic.

my trunks are on fire, like them mud-bugs :-)
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