how to build a transmission line

[e-side]

Hello,

i'm going to start with a new diy project. This time i would like to try to build a transmission line. I already searched a lot and i visited martin king's site about TL's, but i still don't understand how to design a TL properly.

Could somebody tell me how to design a Transmission Line?


regards

 

[RJ]

The first thing I do is pick out a speaker or speakers that I would like to be in a TL. I then get the T/S parameters for it. With the FS parameter I then apply this formula to find out how long the pipe is going to be;
(1128/Fs)/4 = 1/4 wave in feet
Feet x 12 = length in inchs.

Let's say the driver has an FS of 40 hz.

1128/40 = 28 28/4 = 7 x12 = 84.6 inches

I then apply this to MJK's worksheet and start entering the numbers.

I massage the numbers until I match the speaker (red line) with the infinite baffle (blue line)...

I then get some chart paper and design the box.

My latest creation;
http://img.photobucket.com/albums/v641/rjakubin/My_Labyrinth.jpg

and the front;
http://img.photobucket.com/albums/v641/rjakubin/DaytonClassic5sSeasH1212.jpg

I haven't charted the frequency response so I can post it yet, but they sound great. Unbelievable bass out of the 2 - 5 " Dayton Classics;
http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=295-300
They sounded so good I removed the 3/4 " Dayton Neo's and gave them a Seas tweeter (H1212) and crossed them over at 1400 hz.

 

[e-side]

thanks, i also tried to use MJK's worksheet, but i don't know how to use it. The graphs are colored red, so there's probably an error or something: qtd can't be measured because it isn't possible to divide by 0 [qed], while qed is 0.44

but even if i change the numbers, there are still no graphs...

 

[RJ]

Have you tried changing the Length (L:=) 60 in
Geometery Section???

 

[e-side]

that var looks OK in my worksheet, i checked everything but the graphs still don't work