An LED assembly includes two strings of surface mounted LED devices mounted to a central ceramic plug portion of a PCB substrate. One string has a CCT of 4000 degrees Kelvin. The other has a CCT of 1800 degrees Kelvin. For each LED device in one string there is a corresponding LED device in the other string. The LED devices of each pair are closely spaced with 0.2-0.6 mm between them. A Highly Reflective (HR) layer is disposed on the substrate between the LED devices. The HR layer has a thickness in a range of from 20 to 50 percent H, where H is the height of an LED die. A transparent silicone layer covers the LED devices. A resistor of a warm-dimming circuit is mounted over the ceramic portion of the substrate whereas an integrated circuit portion of the circuit is mounted over the PCB portion of the substrate.