Fieldcoil + K-tube

Wow really love this I want to make a 1in version and a 2in version of the k tube but don't know how long to have them I got a pair of evdh1a and jbl2410 both go down to 500 hz but I heard some play the evdh1a down to 300hz , what would you guys recommend also I got a crazy idea wondering how would I implement k tube into a car audio build how would one aim and place the k tubes on dash or underdash would love insight on this if anyone is interested in helping me out let me know thanks again
 
regarding damping of an aluminum tube, a set of X15 had tubes with a green coating - I don't know what as those tubes belong to K-builder Carl Neuser. Below is an early interpretation of an X15 with original K-tube. Carl said that using a curved Fig.6 reflector (patent 3540544) improved sound quality.

One thing to try would be to use a strip of self-adhesive led foil down the length of the tube.

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I've been posting about K-tubes for around 23 years but there seems to be very few folks using them. IMO they are a nice option to horns when super high sensitivity isn't needed. Subjectively the Transylvania Power Company's "THE TUBE" kept up with my double JBL 15" woofer cabinet.

It would be nice to see some younger folks try Karlson and K-related stuff. I have a lot of horns yet find K quite enjoyable.

GregB really helped with his "Karlsonator". Suntiger build's K with curved reflectors and employs K-tubes.

I'd like a 2.1 K system with 6 inch fullrange or coax speakers but my new Volt 6 pair got put in a shed and probably will never see them again.