What can anyone say about Quarter Wavelength transmission line enclosure design ?

I came across a design for a 10" TL back in 1981 that I built using the 10" woofer from my JBL L-26 speakers. The result was a lot bigger than the JBL speakers, roughly 14" wide, 20" deep and 48" tall and heavy being made of 1" HDF. But they had MUCH better frequency response, not only flatter but a LOT deeper, way more than I ever expected, honestly deeper and flatter than anything I ever heard back then and frankly few I have heard since. Even more surprisingly they seemed to be about as sensitive (efficient) as the original ported JBL factory enclosure.

I forget the details but the folded taper design was not that complicated or hard to build. Basically it tapered from being a little bigger than the driver which was at the top front of the enclosure to maybe about 1/4 where it ended in a rectangular port at the bottom front. The taper went first from the front to the back, then folded down to the bottom, up again then back down and out the front. The whole thing was stuffed full of dacron fluff.

Never got the impression there was anything terribly difficult involved in the design either. In general, starting from about 125% of the driver area you taper down to about 25%, over a length of about 10'. The actual math I think has to do with the wavelength of 20Hz but that's just very old memory this was after all 1981!

Bingo! Exactamundo! Pre-internet days!

I built the electrostatic panels too, rodman. Just the way Sanders described. They sure looked like they would work! But being a starving college student it took me a while figuring out how to find and buy everything for the power supply to make them work. In the meantime I for some unfathomable reason decided to remove the woofers from the TLs.

Now if you ever do this be sure to use a cap or something to cover the speaker mounting bolts. Because the whole thing is stuffed with dacron. If you don't cap the bolts then when you go to remove the bolt the dacron gets wrapped around it so tight you're never getting that bolt out without destroying the cabinet, or the driver, or both.

And that will be the end of your glorious Speaker Builder Electrostatic TL project. Sigh.

Found it! https://sanderssoundsystems.com/downloads/speaker_builder_dec_1980_an_electrostatic_speaker_system_P...

Exactly what I built! Excellent deep bass. Is this the same design you used too Rodman?

That's what I remember. But it was so long ago, conditions so crazy, and other equipment so much different it was hard to be sure. But they were definitely the best bass I ever heard back then, probably ever. A few deeper,  but none of them were as articulate. Even my Talon Roc sub doesn't seem as good as I remember these being.

Which come to think of it the last time I used the 10" woofers from my JBLs. This time I could use the much better drivers from the Talon sub. Already have more than enough MDF just sitting in the shop. And a proven design. Now if someone can just help me find the time... lol!