Anyone familiar with TL design requirements? (1 Viewer)

[cayce B]

I'm trying to crunch some numbers to see if I can come up with a reasonable design for a transmission line project. My starting point is the D'Appolito designed Thor project for SEAS. I'd like to change the taper ratio of the line from 3:1 to 4:1, while increasing line length and internal volume.

What I'm coming up with so far looks like this:

Internal dimensions
45.25" H
8.5" W
19.5" D
123.33L/4.35 cu. ft./7526.27 cu. in. V
4:1 taper ratio
roughly 100" line length (?)
extra fold in the line
line ends at bottom rear of enclosure

I'm thinking of eliminating the base, but I'm not sure where I would place the crossover (I do have a few ideas, though). Don't hesitate to tell me if my math stinks, because it's an issue I'm already aware of . Also, this is the first time I've ever tried to do anything like this, so it wouldn't surprise me if I'm way off base in my thinking.

Questions:

Using the same drivers as the Thor, what kind of low frequency performance do you think I can expect? (I've run some numbers using formulas and a calculator, and think I have a general idea. The tentative numbers look pretty good.)

Will I be able to use the same crossover design as the Thor, or will it need to be modified?

Will the line opening up on the bottom rear of the enclosure negatively impact on the sound of the speaker?

To take a look at a breakdown of the original design and its process, click on the audioXpress Thor review (written by the designer) link on the Madisound Thor page.

http://www.madisound.com/thor.html

 

[Pete Mazz]

Check out Martin J. King's site:

Quarter Wave.com

You can D/L a free copy of the MathCAD software and his worksheets to model the line.

Pete

 

[cayce B]

Thanks, Pete. Actually, I've already been there. For some reason, I prefer to work out the design by hand using Augspurger's (and others') work as a basis. I'm usually a very thorough researcher and actually have quite a bit of reference material (though, not everything I'd like just yet) to work with. Just thought I'd ask for a little feedback from others who've had experience with building and listening to a number of designs. This is the only audio board that I'm a member of (so far), so I thought I'd ask here first. I'll check with the members of the Madisound and DIYaudio boards, if I need anymore info.

 

[Pete Mazz]

DIYAudio board is a good one for TLs. MJK and Dave(Planet10) of T-Linespeakers are on it. In fact, I remember reading a thread about redesigning the Thor.

Pete

 

[cayce B]

Thanks for the link, Pete. I had read that thread (been doing a lot of searching around for info). Like those guys, seeing the complaints of others about the bass extension of the Thor had made me want to look at redesigning the Thor according the parameters Mr. D'Appolito had originally put forth. I think he may have made concessions that took style and WAF into account (just a guess).

Luckily, in the article he wrote on the project, he gave just enough information about Augspurger's design parameters to give those of us who wanted to do our own thing a headstart on "optimizing" the performance of the prototype design. Size be darned, I guess. I'm single (no WAF to worry about just yet :b ), and it is turning out to be just as much fun as everyone describes trying my hand at this to see what I can come up with.