The comparison between observable SEDs obtained in the full hybrid approach (circles) and the universal hybrid method approach (solid curves) for different values of the z_c parameter: black – z_c = 0, red – z_c = 0.02, green – z_c = 0.05, blue – z_c = 0.10, cyan – z_c = 0.15, magenta – z_c = 0.18. Primary proton energy E_p0 = 30 EeV. The universal spectrum for the case of primary γ-rays with energy 1 PeV is shown for comparison (dashed black line). Relative normalization of all spectra is done at E = 10 GeV.