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Quarter Wave / T-Line tutorial-UPDATED


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hmmm intresting. how long is the vent about? Assuming you got it tuned to a boost of like 45 hz? or you going shorter and stuffing the walls?

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T-Line tuned to 45hz

18"BTL T-line @31Hz (9 weeks pregnant)

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  • 2 weeks later...

wlel i was gonna save up and build a nice t-line when i could afford more powerful subs and amps, but i think im gonna build a tline for my 2 15 inch kicker cvrs, granted i find a way to fit it in my car, lol

heres the t/s of what im working with, found them on some forum, lol

Kicker CVR15 ( 2007 D4 model )

Zn -- 4 ohm

Fs -- 20.8Hz

Pe -- 500W Rms

Xmax -- 0.492 (12.5)

Re (series) -- 6.84

Qms -- 10.81

Qes -- 0.442

Qts -- 0.425

Vas -- 9.23cuft

Net Displacement -- 243.6in3

Outer Frame Diameter -- 15 3/8in

Cut-Out Diameter -- 13 7/8in

Mounting Depth -- 8 1/8in



Here are the specs for the box: I drew it to exact dimensions in Photoshop and used the rulers and guides in photoshop to get the measurements.

Outer Dimensions: 39W x 36D x 20H

Design based on 1 in. MDF board

Port Length: 142.5 in. or 11.875 ft

Port Area: 8 wide by 18 tall = 144sq.in.

Cone Area of Sub: 151.2sq.in.

Fs: 11.875 x 4 = 47.5 - 1130/47.5 = 23.79Hz

Fs of sub: 20.8 (I got it close)

Boxed cubic feet OD: 16.25 cu.ft. - Not sure how to measure inside dimensions for the t-line (forevrbumpn did say a 15 would result in huge box)

Version 1: Sub mounted outside of box firing in (only to try and squeeze out a few more inches of port length)

The white area with red outline just shows the max dimensions for my trunk, this is the box from top view


I have 2 of these 15s and would really love to try and fit both in a T-line in my trunk, but I am not sure how I could get another sub in there and keep proper dimensions, since i believe with another sub you have to double port size and length

I had a sketch where it would have a sort of W or 3 shape where they would have 1 port length of their own and then share the center port that fires out of box, but this would mean they are both sharing the port size for just 1 of them and I am not sure if that would perform any better than just the 1 15 inch sub

please let me know what you think

Edited by kynto
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1 week ago I bought a JL 13w7 and I really like to try a t-line.

Can you help me out with a design?

Some specs of the JL 13w7:

Fs: 23,5Hz

Qms: 7,517

Qts: 0,448

I've already calculated the cone area: 130sq

I will also buy a SAZ-1500D amp soon to power this w7 :)

Thats gonna knock, Ive done a single 10w7 and 12w7s before, and they get rediculess, so a 13w7 on a awesome amp like that should be a killer combo

I will look in to it, but the box will be huge, so I hope you know that

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after a small chat with forevrbumpn, i have come up with 2 other designs to try and get the port close to the sub

i did not bother with measurements, main difference is the port width would be 9 inches instead of 8



for either one, you think i could fit another sub in there, for the second one the sub would be firing directly into the port which i am sure i dotn want, but the first one would have both subs firing same way, maybe i could fit both 15s in that then

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  • 4 weeks later...
  • 2 weeks later...

Yeah, im also having issues with the actual inside box dimensions. If someone could help me out and send a CAD with measurements of a t-line for 2 type r 10's, that would be absolutely AMAZING. OORRR, you can PM and tell me how to find all the things needed to calculate it out myself. IE CAD freeware, and honestly, I don't even know how to find the qt and all those measurements on the sub. Basically, i'm starting from ground zero. :D If someone would help me out, Thatd be absolutely fantastic.

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I would love to have a T-line box for my 2 Sundown sa-10's.... It will be in a trunk car... Can anyone help me design one?

1999 Chevy S102 Sundown Zv3-10's1 Sundown saz-4500d2 sets of Sundown CS6.5 Comps. (Doors)

2 10" Sundown NeoPro 10's (Doors)1/0 KnuKonceptz - Power x2- Ground- Big 3

300 Amp External Regulated Excessive Amperage Alt

147.8 Sealed Mic on Windshiled148 30sec. Average Drivers Door open Mic on Windshield

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Hey Bumpin, I have read this like a hundred times. Lol. I love it. I designed and built a little test box for a 4 inch sub and it turned out awesome so I want to step it up a bit to the full size. I have designed about 10 of these so far for different subs and different set ups so I think I have pretty much got the designing down. I have been trying to come up with a design for a 15 I'm getting (Kole Audio KMX 15) and have come up with a few designs I kind of like. These are the top 3 candidates. Which one do you think would be best? The one on the left is like the one I made for the 4 inch speaker, the middle one I think is a little iffy cuz the walls are barely long enough, and the one farthest right is with the sub mounted inverted.

EDIT: And obviously I would put the 45's in, I just didn't feel like modeling them.

EDIT: Just made another design - added below the first 3



Edited by Coleslaw
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