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

These ARE, by definition, "transmission lines" and have been found wonderful designs for bass reproduction, by the experienced and dedicated. http://diyaudioprojects.com/Technical/Papers/Non-resonant-Loudspeaker-Enclosure-Design.pdf Good stuff, regarding why they work so well, for the knowledge seekers: http://www.quarter-wave.com/TLs/TL_Anatomy.pdf

@millercarbon- Affirmative. Built three pair of those. Excellent, extended, authoritative, articulate and tuneful bass. The system did a good job of extending the dynamic range of the electrostatics too, relieving them of the longer excursions, demanded by the bottom freqs.

Fried, and his IMF(Irving M Fried) designs, got me interested in TLs.  Man; that's been awhile(I'm dating myself).

I built a pair (in 1981), per Roger’s design, to go with a customer’s Acoustat Model IIIs. He wanted something that could match the speed and definition, of his electrostatics. They worked so well, powered by a Halfer DH-500 and crossed over via a Dahlquist DQ-LP1, I duplicated the system for myself(and my Acoustats) and another customer. Back then, I used a 10" woofer that Milo Nestorovic employed in his woofer systems. In answer to the OP’s original query; TLs(at that time), were the only woofers systems around, that many of us had experienced, able to blend well with electrostatics. I used bi-amped TLs, in concert with various planars, for 36 years. Now, with an Emerald Physics system. The trusty DQ-LP1 was replaced by a modded TacT RCS 2.2X(and Hafler Trans-Nova 9505), about 12 years ago. The TacT’s DSP(time-alignment/room correction/EQ) was the finishing touch, to an already stellar bottom end. Guess I’m a TL believer!

That, Glass Audio and Audio Amateur, were my favorite rags(back in the day).   Inspiring!

@millercarbon- Did you happen to find that design in the Speaker Builder Magazine articles(circa- early 1980’s), written by Roger Sanders? In them, he outlined building a 10", TL woofer system, closely matching your description, to compliment his(then home-built) electrostatic panels.

@erik_squires - Experimentation(a lot), back in the early Eighties and DSP, now. Wasn’t all that hard!

Of course, those are being actively bi-amped.  Only producing between 80 and 20Hz(60dB/Oct cutoff).   

Too bad you can't hear my pair, regardless of what I type(8', tapered, folded, w/10" Seas L26RO4Y D1004) .   Are you ever around the Indianapolis, IN area?