Abstract: The present work proposes a method of approximate implementation of constant-power equalization in signal mixing for horizontal Ambisonics with a nonuniform loudspeaker configuration derived from simulation and microphone-array recording. Ambisonics signal mixing with approximately constant-power-equalization is obtained by adding higher-order spatial harmonics in original signal mixing. The power characteristics of the mixed signal is further analyzed, and the appropriate truncation order is selected based on the criterion that the fluctuation of the overall signal power across the target source azimuth is less than 3.0 dB after equalization. Moore’s modified binaural loudness model serves to analyze the proposed method, and a psychoacoustic experiment is conducted to validate it. The results indicate that the proposed method reduces the timbre coloration in the azimuthal range where the power fluctuation is obvious without equalization.