looking at pi's fab horn shootout am sometimes confused with regards to harmonic disortion figures as can only look at one or two tones.

a simple 8cu.ft. Karlson box here will look better below passband (and perhaps inside the band) than my UCS1 or a Z-fold JBL sub.

here's 30vrms/50Hz into a simple karlson w. old Eminence 18 without front shelf which corrects 1st dip (somewhat) guess nominal would be ~150w by z-minimum critera - IIRC fb was around 42hz with two 4"x4.5" pvc ducts

smoke? not in a few seconds!

lower level sine UCS1 vs karlson UCS1 had 15dB more 3rd harmonic than the karlson. UCS1 has a fairly high input Z

one sheet klam w. 3cu.ft. rear chamber is it ~BP4

karlson are odd things with regards to initial slot gap and flare - if gets clogged by an inch then sounds 10X worse run wideband. might be possible to squeak a bit more performance within a givin bulk by going taller and should be looked at by 3rd Z peak to compare to bandpass boxes for similarities.

added some height to a test box but affair was too rickety to judge. crazy part - when running an 18" wideband a very narrow slit in the extension running up to very top allowed it to play better including the sense of HF - doubt if would show on RTA - be like that dumbass show with guy lookin' for ghosts with a $10 multimeter.

k are reasonably simple and light - if using cheap birch - lol -whether have place in pa - dunno - I'd use one but am stubborn.

Freddy