TL (Transmission Line) + Fork

[cochleus]

Here is a patent (by Bose) that deals with the dual path length concept. US7426280

 

[Deathsurfer]

... (text removed) ...

Is there a reason you don't want to do a quick and simple sim to find these answers? It took me about 5 minutes to do these sims, it takes longer to create and host the picture than to do the sims.

( ... his answer continues ... )

Short version: "Yes." My application doesn't exactly adhere to the closed box paradigm. It's a new method for a specific setting. (But thank you for your discussions, I enjoy them.)

.Ds.

 

[just a guy]

I'm not going to try to guess what you mean by "new method for a specific setting" that is apparently not open ended but also not a closed box but I can tell you that all the questions you have asked so far can be answered with quick 5 minute simulations or by searching for and reading the theory which takes a bit longer. There isn't much you can dream up that can't be simulated pretty accurately but if you can't come right out and state what you are thinking I don't think anyone can help much.

 

[xrk971]

You need Akabak to model multi fork horns and any geometry beyond a tapped horn. I did something similar with the 5 length pentahorn BLH.

http://www.diyaudio.com/forums/full-range/236779-panpipe-pentahorn-blh-speaker.html

The Cornu BLH has two lengths of horns and they do provide a smoother output. It's a little more complex than just taking the average of the lengths. There are two discrete modes and the solutions are based on discrete resonances.

Also see this thread:
http://www.diyaudio.com/forums/full-range/263354-dual-triple-tuning-tl-horn-bad-idea.html

 

[just a guy]

You need Akabak to model multi fork horns and any geometry beyond a tapped horn. I did something similar with the 5 length pentahorn BLH.

Actually the Leonard Audio software I linked earlier will simulate any number of forks, either open or closed ended, no matter what shape or size. It won't let you reconverge the forks later in the line as Akabak will but it has no problem with divergent forks that stay separate.

For example it could simulate your Pentahorn design just fine. And it wouldn't take more than 10 minutes to do the sim assuming you already have the segment cross sectional areas and lengths figured out. A lot quicker and easier than Akabak.

 

[xrk971]

Thanks for clarifying that Leonard Audio can do forks without recombining. Not sure if it is easier or faster than Akabak (for me) as I have tons of code blocks and snippets that I can copy and paste to model new and more complex speakers.

 

[just a guy]

Copy and paste does make things easier. Fortunately the Leonard Audio software can cut and paste too. IIRC it can cut and paste segments so you can just cut, paste, make small modifications really quickly. If you are really comfortable and fast with Akabak I wouldn't use anything else but if you want something super simple to use and very fast with very little learning curve the other software is quite nice. Completely broken when it comes to simulating a tapped design last time I checked and I don't think it's been fixed, but other than that very nice.

 

[Matthew Morgan J]

I don't know about getting simple forked TL sections to resonate at independent frequencies but i have had some luck adapting the old DCR (Weems/Augsperger style) with parasitic chamber over to a TL design with parasitic chamber/resonator ...

The first one that i made ended up with the parasitic tuning at about FB*Phi which was what i was shooting for (an attempt to control the hump in excursion above fundamental tuning), they were MTM towers loaded with some small drivers that had limited XMAX ....
Fun experiment which worked out well ..