inside and out of the coupler, the open end waveguide is part of "some" modern K-systems
Zintz's Transylvania Power is easy to listen to (bye bye some small horn) I lilke its sound very much.
Karlson's X15 tube as I have it has a diameter transition notch and meant to mount to an internal panel of the coupler tilted down ~30 degrees -- theres a large component if radiation from the slot ~perpendicular to the tube's long axis so a lot of that was mixing in the front chamber (don'f forget the shellaK!)
wonder if Mr. K was trying to get some reverb from that tube? - whatever its firing into the aperture does 120 degrees vertical and about 180 horizontal at 10Khz -- not possible - see below
slot on a tube seems somewhat critical and a straight 1" ID tube ~5.3-5.5" with about 1/8" starting gap and half-ellipse pattern will make a nice DIY tweeter waveguide for a few cents worth of pipe
about to say the tube doesn't work well for larger tube but IIRC Robert Reams "clothepin" for 12" might have worked OK and Dave Young reported using a 2" ID tube for outdoors PA.
FWIW threw in K-bass guitar, horn on top + little coaxial Koaxial have been built with K-tubes mounted coaxially into wideband woofer
CN Test X15A
on't forget the "Mighty Midget" - Karlson Open End Waveguide tweeter lens
unKnown K-team Khyboe + The Tube in Khrome and very lovely little Altec system
