We report a tunable monochromatic source generation scheme, based on Brillouin filtering of a self-referenced optical frequency comb. The system benefits from the high stability and mode linewidth of the frequency comb,significantly improving the performance of the original laser source used as Brillouin pump. A synthesized frequency with stability under 4×10^-10 and a linewidth under 75kHz was experimentally demonstrated for two separate pump lasers in the C-band.The proposed monochromatic source can be tuned with high precision in a very broad band by combining a coarse control with the pumping source and a fine control with the optical frequency comb references. In our experimental setup, coarse and fine tuning resolutions were 4MHz and twenty Hz, respectively.Influence of Brillouin pump fluctuations in the synthesized signal stability were also analyzed for observation times up 10⁴ s.