How To Build A Quarter Wave Transmission Enclosure:
Quarter wave is all based on speed of sound, & length of the sound wave.
Sound travels at 1130ft/sec.
To calculate length of frequency, divide 1130/ (Fs freq)
My speaker has an Fs of 53.8 Hz. Rounded down, that's 53 Hz.
1130/53 = 21.32 ft long full wave length.
Since this is a QUARTER wave length enclosure, 21.32 ft will need to be divided by 4.
So, the total is 5.33'
In order to have a true T-line enclosure, one must keep the port/tune/tunnel/line - a Line, that equals Cone area (SD/Cone)
My speaker has an SD of 12.56sq"
12.56sq" is your Port Area.
So a T-Line for a 4" speaker with an Fs of 53 Hz, and a cone area of about 12.56sq" will be 5.33' in length.
If I were to use two speakers, my SD/Cone would double (giving me 25.12sq"). What else would double?
5.33' is unreasonable in a sedan. I plan on doing a U-Turn enclosure.
Building a TL transmission line Design enclosure Box for 8'' drivers for my home audio system part 2 - YouTube
^Now that looks like a real T line.
The link below is where I learned most about t-lines or at least his interpreation on "t-lines."
It seems like everyone is rippin' on the guy for posting ^ cuz that's not a true T-line. I clicked on the Transmission Line Theory that KoreyHoffer posted & read through it. To be honest, reading that tutorial was like listening to some guy ramble on about nothing. I didn't get the point. There was no "these are the driver specs you need to focus on. Here is how you build an enclosure according to those specs. Now build accordingly."
"Check over at Dogma.com"
Edit: I mean Diyma!