Who makes a "true" Transmission Line speaker?...

Buggtussel is out of business. FWIW, I have had the Amygdala's in my house, as Bugtussel was located near me, and while the Amyg's were fun on some rock music I wasn't overall taken with them. IMO, you can do better.

Jean-Marie Reynaud makes TL speakers.

Yes Kinetic is still around. I've had a pair of Labyrinths
since 1996 and I can't imagine ever getting another pair of
speakers. Production is very limited now however. I think
Ted Karson owner/designer is looking towards retirement.
Ted manufactures all of his own drivers. He makes some of
the best 12" woofers on the planet and sells them raw if you
like DIY projects. He's a big fan of Bud Fried dating back
to his original IMF designs.

As far as his speakers are concerned, his larger designs are
what this thread is calling "true TLs." My Labs have a 12"
woofer loaded at the end of a 1.2:1 ratio tapered line
that's 10' long. The terminus is 10" and located near the
top of the rear panel. They're 52" tall and weigh 250lbs
each. F3 is given as 16Hz. I have mine vertically biamped
with a pair of ARC D400mkIIs and I can shake the foundation
if I turn up the volume.

His smaller designs are quasi-TLs with tuned pipe approach.
He prefers simple 1st order crossovers although diverges
from Bud here in that he sticks with parallel crossovers.
He uses L-pads for driver attenuation instead of fixed
value resitors. Common back in the 70s but seems to have
fallen out of favor.

Anyway, check out the web page www.kineticaudio.com. The
pics of the Labyrinths are actually my speakers. I had them
veneered with real pre-quarantine Brazilian rosewood. He had
a small amount left in stock which dates back to the late
70s. It wasn't cheap but man it's gorgeous. Hence the pics.

If you want more in the way of TL design theory, check out
the sites www.t-linespeakers.org and www.quarter-wave.com.

As a side note, some of you may find it interesting to know that there is one bass cabinet manufacturer that makes transmission line cabs (almost exclusively) - Euphonic Audio. I have a number of their bass cabs, and not only are they deep, tight, and very uncolored (for a bass cab, mind you), but they also sound great for PA use. Their older, VL-series cabs are their best, IMHO. If this is of any interest, check out www.euphonicaudio.com.

Their lead designer, John Dong, started out in the high end audio speaker manufacturing business.

I have chanced across a couple of mini-reviews during my outings at the bookstore. General impression was favorable. Have to admit I am out of my depth when it comes to TL etc, so will stop here.

In terms of the sound, what distinguishes a TL from other designs? Do they throw a more halographic soundstage? Are they extremely transparent and open with lots of air around the instruments? Can the listener typically identify instrument positio with TL's? Are the benefits of a TL only realized by a small sweet spot, or do they have a forgiving or roomy sweet spot. Are TL's more dynamic with a heavier bass sound than other designs?