Hi Rob,

For me the ku or kah isn’t a hard breath attack, rather it’s more like the first sound of the word kick or ketchup (same for the ku/kah of the triple tongue — ttk) — so a real tongue attack but, I think, using the middle/back of the tongue against the top of the mouth. I tend to practice exercises that call for double tonguing both single tongued and ku/kah tongued. After that shift to double tongue very slowly with metronome, coordinating fingers and tongue. Then increase tempo as it becomes more controlled/clear/easy.

Nate