An illumination device and a projection system using the same. The illumination device includes two or more color channels each including one or more light sources for generating a color light. At least one of the color channels includes light sources of a first type for generating a first (narrow band) light and light sources of a second type for generating a second light. The dominant wavelengths of the first and second lights are within 50 nm of each other, and the width of the combined spectrum (sum of normalized spectra of the first and second lights) is greater than the width of the spectrum of the first light by at least 10 nm. A wavelength-based light combiner is used to combine the color lights from the color channels into a combined light.