A light source and method for making the same are disclosed. The light source includes a plurality of LEDs mounted on a substrate and a sensor for measuring light from the LEDs. Each LED emits light having a different spectrum from the other LEDs, the average intensity of light from that LED being determined by a drive signal coupled to that LED. The sensor generates a plurality of signals, each signal being characterized by a sensor value that is proportional to the intensity of light emitted by a corresponding one of the LEDs. A controller generates the drive signals and stores a current target value for each LED. The drive signals for each of the LEDs is generated such that the sensor value for that LED matches the stored current target value for that LED.