The hlg320-c2100 puts out 76-152vdc. One single cob wouldnt be a good to hook up to that driver. Even if they are 72v cobs 76v at 2.1A is kinda high for a single cob. Not all cobs. But most. And not knowing what cob it is. Makes it tricky. Can you take any pics of the light.
One single cob hook...