This work reports a combined theoretical and experimental study on large phenol-acetylene clusters, Ph(Ac)n, 8≤ n ≤12, extending our earlier work on the smaller clusters [Singh, G.; Nandi, A.; Gadre, S. R.; Chiba, T.; Fujii, A. J. Chem. Phys. 2017, 146, 154303]. Several trial cluster geometries are generated using the molecular electrostatic potential (MESP) for placing additional acetylene moieties, followed by geometry optimization at B97D/aug-cc-pVDZ level theory. The infrared spectra of energetically low-lying (within 0.5 mH window) isomers of the clusters are calculated and averaged. The O-H stretching band shows two peaks due to the presence of energetically close isomers differing in the arrangement of acetylenes around the O-H group. The acetylenic C-H stretching band appears around 3260 cm-1. The C-H band shows a red shift of about 3 cm-1 on going from n = 8 to 12. Moderately size-selected IR spectra of Ph(Ac)n (n = ∼10 and ∼13) prepared by a supersonic jet expansion are measured for the acetylenic C?H region by infrared-ultraviolet double resonance spectroscopy combined with time-of-flight mass spectrometry. The observed spectral features are in agreement with the trends of the frequency shift and asymmetric line shape of the C-H stretch band predicted by the theoretical calculations. -Close-