We have utilized an acetylene gas sample to assess the performance of a newly constructed cavity ringdown laser absorption (CRDS) spectrometer at the Arkansas Center for Laser Applications and Science (ArCLAS). During this assessment process, four overtone combination bands were observed for the 13 C 2 H 2 species, three of which have not been previously reported in the literature. For two of these previously unreported bands, a total of 85 rovibrational transitions (over 40 in each band) have been assigned using ground state combination difference theory. The data have been fit to standard energy expressions, and a set of molecular constants for each overtone combination band have been obtained. Here we present a brief description of the ArCLAS CRDS instrument along with the complete rovibrational analysis of these two combination overtone bands.