A mixed-conductivity analysis is used to separate the contributions of n, p. and μn to photoconductivity and photo-Hall spectra in semi-insulating GaAs:Cr. It is shown that the spectral dependence of μn is often important in the interpretation of these data. A room-temperature energy diagram is presented, and includes chromium-related centers at 0.73 and 0.52 eV from the conduction band.