Kevala kumbhaka

recently I started meditation tummo … I ask if the binding mudra is mandatory to have the experience of samadhi? kevala kumbhaka is it possible to get without kechari mudra?

Not sure about tummo, or the binding mudra you’re using. But I have experienced kevala kumbhaka using a “half-kechari” (where you place the tip of the tongue on the point where your hard and soft palette meet on the roof of your mouth) during my kriya practice. I still work towards full kechari however.