TLwrx v 3.0 Transmission Line Software

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Anyone buy and use this software recently? This is the distillation of G.L. Augspurger's work on modeling the TL...similar to King's work but I guess more of "TL For Dummies" style...I think.

Anyway...not happy with a recent bout with some pseudo-technical offering for TL sub design, I'd like to crunch my own numbers for various drivers and cabinets but I'm not ready to get a Master's in mathematics... :D
To continue my monologue... :D

The program is not currently available in a Windows XP compatible form...bummer...

Email from Audioxpress:

"Hello Carlos,

Mr. Augspurger has indicated the software is not compatible with Windows XP. We have not had any updates since 2004 but I have recently contacted Mr. Augspurger to see if he is planning on any updates any time soon since we have had a number of inquires concerning Windows XP.
Once I hear back from him I will let you know what his plans are.

Best Regards,

< >
Customer Service"
CarlosT said:
And if Martin King's listening...Mr. King have you ever considered selling a "TL For Dummies" program collating all your Mathcad sheets with a nice interface? Thanks!

I considered it for a while. But to do that it would require me to stop moving forward with new models, stop improving the existing models, and invest a lot of time programming. This would have to translate into a higher cost and a lot of dog work I am just not that interested in doing right now. So I guess the short answer is I am happy with the way things are right now with respect to the interface.

The MathCad worksheets are very flexible and not that hard to use. If you download and install the MathCad Explorer 8 program you can try the sample problem worksheet. You cannot change the driver but you can modify the enclosure and try your hand at designing a TL. Reading the tutorial will help you understand how to use the worksheets. MathCad really is very easy to use once you get over the initial intimidation of learning something new and very different from Excel. Most people, not everybody, come up to speed quickly and are designing before they know it. Some people are just never happy with MathCad.
Thanks so much, Bjorn.

Two questions...

1- The link to Martin's alignment tables is dead. These would be helpful.

2- Coming from the point of interest of a DJ, I'm interested in designing a subwoofer with a very narrow band of response...let's say 30 Hz to 200 Hz. What aspects of TL design would not be important? Stuffing of the TL comes to mind. Stuffing is normally presented as a way to "cheat" on the length of the line but also as a damping for higher resonances. Limiting the crossover to 200 Hz one would think this is no longer an issue. Ergo, most commercial DJ subwoofers have no lining at all.
Hi Carlos, Martins alignement tables are found on his site. Sorry my link is broken.

Please note, you can not "cheat" the length of the pipe by stuffing.

Stuffing is improving the response. More stuffing = cleaner sound and less bass. You will always need stuffing, but the distribution and density will vary.

General: More volume = more bass, so it depends on what size you can accept.

Take a look at this example: LAT

This sub would not be invisible, but I would expect a good result.

I hope this has inspired you to try out the Mathcad models by Martin J. King

Hi from
CarlosT said:

......I'm interested in designing a subwoofer with a very narrow band of response...let's say 30 Hz to 200 Hz.

This isn't a narrow enough BW for a TL to either omit or at least use minimal stuffing since the deep 3rd harmonic dip will occur around 120 Hz. By the time you stuff it enough to damp it down, there won't be much gain BW left and why relatively high Qts drivers are preferred.

Because the cabinet design I'm working with only offers a mounting plate for the driver of about 15" x 18", I'm limited to either 10" or 12" drivers. The lore is that cones larger than 12" can get into trouble and are not strong enough (too much cone area...not enough strength in the cone material and surround) for a TL although most commercial offerings from crap like Cerwin Vega's Earthquakes to even decent Yorkville LS808s use 18" drivers.

Also from the sounds of it, a larger cone will require a larger cross area and will lead to an unwieldly cabinet size. The design I'm working with is about 30" H x 30" D x 18" W.
CarlosT said:
When you look at these DJ type folded subwoofers is the entire front open area in effect the port area you guys refer to?

This is a folded compression horn, so yes, that's its 'port' area. Typically when you want small and loud you use multiple small cabs and stack them so their mouth areas combine.


To run my worksheets you will need to install MathCad. There is a free download version that is on my Models page. You will need to download and install this software.

Then you can open the sample problem to make sure it runs correctly on your PC and to try your hand at editting the inputs. If all goes well, you can decide to buy a license at which time I will send a user ID and password so you can access all of the latest worksheets. Pdf files showing the diferent worksheets are on the Models page.
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