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Quarter Wave / T-Line tutorial-UPDATED


Forevrbumpn

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how would you work the equations if you have two subs? would the port length stay the same and area change? I have 2 RE SEX 12D4s Fs: 25.1hz and radius of 4" on one. I got 11.25ft for the port length and 50.27sq.inches for the port area OF ONE of the subs how do I get it to two?

edit: nvm i see add the cone areas, but my Fs is 25hz do I have to tune it that low?

My stuff

'06 Scion xA:

-Alpine iDa-x100

-Alpine KTP-445 Power Pack

-Polk Audio db6501 (front components)

-Polk Audio db651 (back coaxials)

-2 RE Audio SEX12D4s

-Cadence F1200-1D

- Custom box tuned to 33Hz

- Kinetik HC1400

- 50 ft2 of Audio Technix sound deadner

- Big 3

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You pick the FS that you want. You dont have to go by what the subwoofer is rated at.

MickyMcD - "Capable of making some serious trouser flapping volumes at where's-my-testicles frequencies, the Servo-Drives used to be fairly jaw dropping..."

Any time you have have a power wire next to your frame put some rubber hosing (or cut up an innertube) around it. The wire is bound to wiggle (due to driving or flex) and the casing will eventually wear through.

Hammerdown... 1%

no links to outside websites, business related FB/YT pages allowed.

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  • 3 weeks later...

Hey everyone, i'm kind of new to car audio and have never built a box before. Pat showed me this thread and i figured i might as well ask everyone here rather than constantly ask him. So i measured my 02 4runner from the back of the trunk up to close to the front seats (back seats down) did some math and came up with this. I wanna put 4 12" L7s in a T line. outside of the box will measure 51L x 38W x 31 H. leaves me a couple inches to spare up front to squeeze in my second battery and amp. The design is gonna be the same as the one on the first page, two lines/tunnels/thingers. figured i'd take it easy on my first build. i used 550 for the port/cone area, port length 97". Can i get some input? this is my 3rd or 4th month dealing with car audio xD. I'm guessin i'll need an obscene amount of bracing. would 3/4 mdf work for this? thank yooooooo

hiiiiiiii
2002 4runner - buncha speakers n amps n shit (gone)
1994 astro - more stuffz

update: pretty sure all the pic links in the logs are broken lol.

ma slop garb build log
16 12's 4th order

4runner rebuild in progress
clickkk meeeee!!!! 4 18's 6th order

UBL - clicky

http://www.youtube.com/yyj11589

lots of hater kids here. Pay no attention, they just want 89,000 watt subs for 3.50
If you would have put a dc dustcap on it and called it lv your mom, they would all be in love

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So I have a question. Now that we know the basics of the transmission, how do i convert that to a folded horn Ken? I know the folded horn also uses the same quarter wave theory, but i believe its compressed as it enters the line and decompressed as it exits the box, correct? So how do you do the math for that one?

BTW, heres my tline. Single 8" custom built TC1000 powered by a zapco 750.2 for roughly 800w. Tline is tuned to 37hz.

And on the meter it was 145.1 sealed @44hz and 138.2 on music

04 Chrysler Sebring

Stinger

C&D Technologies

Alpine

Infinity/cdt

Zapco

TC Sounds custom subs

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This was a great write up, I learned a lot from this.Here are a few boxes I built Friday.

oct22010002.jpg

oct22010001.jpg

built this one with a 6" sounded so awesome I decided to upgrade to a 10"

oct22010010.jpg

oct22010011.jpg

really hard to make these to fit a regular cab Chevy 1500 but doable here is another I built for a friend with 1 12"

oct22010005.jpg

oct22010008.jpg

oct22010009.jpg

he has a 1000 watt amp on a 12" sony explod 2 hours after we installed it he called me back

crying about his front windshield.With the deck turned up to 30 the windshield was breathing

back and forth and cracked all the way across. These boxes are amazing!

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So I have a question. Now that we know the basics of the transmission, how do i convert that to a folded horn Ken? I know the folded horn also uses the same quarter wave theory, but i believe its compressed as it enters the line and decompressed as it exits the box, correct? So how do you do the math for that one?

BTW, heres my tline. Single 8" custom built TC1000 powered by a zapco 750.2 for roughly 800w. Tline is tuned to 37hz.

And on the meter it was 145.1 sealed @44hz and 138.2 on music

I think the answer you want is that the point of the mouth of the horn where it is equal to the sd of the cone is where your tuning frequency should be at its mid-point.

This means that if you want to tune to 30hz you want the flare of the mouth roughly half way inside to be equal to the size of your sub and be the point that is 9.417 feet (1130/30 /4) from the driver itself. The flare rate of the mouth (beyond the tune point) and the throat (before the tune point) are up to you somewhat and will basically just roll the tune point in and out flatter the longer and less inclined you make them... I think. I'm no expert on horns though :P

MickyMcD - "Capable of making some serious trouser flapping volumes at where's-my-testicles frequencies, the Servo-Drives used to be fairly jaw dropping..."

Any time you have have a power wire next to your frame put some rubber hosing (or cut up an innertube) around it. The wire is bound to wiggle (due to driving or flex) and the casing will eventually wear through.

Hammerdown... 1%

no links to outside websites, business related FB/YT pages allowed.

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So, a Tline for a 10" with a Fs of 30hz, and a cone area of About 60sq inches, will be about 9.25ft-9.5ft long (rounded) Its okay to be a little off, because this is car audio tlines, the cars accoustics will not notice it, because of cabin gain. But, when building a t-line for a sub based on Fs, you need to keep in mind the speakers Qts, and Qms, they should be low for SQ, Qts of .40 and lower, and Qms of 7 and lower will work great.  Qts is speakers total quality in Ratio to its electrical, and mechanical characteristics, Qms is the Mechanical ratio.

what will be the effects if they are higher. cause i was thinking maybe trying this on my lvl 3 12.

been working the numbers. for my max dimensions i have (32w, 16t,21.5d) looks like i should shoot for the boost freq. the box will be to big to fit in them dimensions with the fs of the sub right. but the other problem im having with that is the boost is 60hz on the amp. any help/suggestions on what to do?

Jacob Sigmund

1 dc level 4 m1 18

1 audiopipe ap1500

2 runs of knu 1/0

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Alex Bennington" <[email protected] ^^^ want one one email this guy he will hook you up!

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Could someone make me a 1/4 T-line for an RE SEX 10" D4? I read the tut, and I'm still kind of confused. I', not sure to get the tuning to 26.6 or something like 32 hz (I want it to sound loud around 32-34hz.)

Would this sub be good for SQ?

FS 26.6

Qms: 4.4

Qts: 0.42

Thanks,

Joe

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Well, I did some math, and a crapy drawing on paper. I can't do graphic design to save my life, just spent two hours trying to get the first straight port wall and couldn't get it the way it needed to be.

But, my math - Box 31.5x31.5 x H 11.5 made out of .75 MDF

Looked up cone area, and tens are roughly 78.54", but Foreverbumpin said 60, so I said ok, 70" of port. Port is 10" tall and 7" wide.I want it tuned to 30hz, so port needs to be 112.92 inches. (I think i ended up a little over or short, by no more than 5 inches I think. Would this work for an Re SEX? I can take a picture of my sketch if someone wants to help :) I'm not sure if I did the calculations correctly or if I did the port right, will the specs fit in a 31.5 X 31.5 X 11.5? On paper I think it looks good but I'm not sure if I did the wood displacements correctly. The way I have it is there is a big space inbetween the ending of the port and the sub, I planned to have the amp here.

Also, in my design I didn't include 45 degree corners, I'm not sure if they are necessary? If so, my design is probably way off, I'm not sure.

Sorry for writing so much.

I could use some help :) I'm a :noob:

Thank you very much,

Joe

Edit: Attached a nice picture to help you help me :)

Edit #2: I just realized that, I think, it's not even close enough to long enough... maybe I'm wrong, Idk. I hope someone chimes in. :pardon:

post-24464-128708166181_thumb.png

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