PS Audio GCA MC-250 Three-Channel Power Amplifier Measurements
All measurements were taken on the left channel except as noted. Measured power outputs are to the nearest Watt.
The PS Audio GCA MC-250's frequency response from its single-ended input to the speaker out measured +0.04dB at 10Hz, +0.02dB at 20Hz, -0.34dB at 20kHz, and +0.66dB at 50kHz.
From its balanced input, the amplifier measured +0.04dB at 10Hz, +0.02dB at 20Hz, -0.40dB at 20kHz, and +0.73dB at 50kHz.
The S/N (A-weighted, 2.83V into 8Ω (1W) from 10Hz-24kHz) measured –101.3dB, single-ended, and -101.5dB, balanced. The single-ended gain measured +27.9dB. With a balanced input the gain measured +27.9dB with the gain switch set to "0dB" and 23.8dB with the gain switch set to "-6dB."
THD+noise at 2.83V into 8Ω (1W) measured 0.055% at 20Hz, 0.054% at 1kHz, and 0.065% at 20kHz using the balanced input.
THD+noise at 2.83V into 4%#937; (2W) measured 0.033% at 20Hz, 0.036% at 1kHz, and 0.056% at 20kHz using the balanced input.
Driving all three channels into 8Ω, the PS Audio delivered 350Wpc at 20Hz and 1kHz before clipping (1% THD+noise). Into 4Ω, all three channels driven, the amp clipped at 629Wpc at 20Hz and 660Wpc at 1kHz. The amplifier went into protection at 4Ω and shut down at this maximum power, but not before we were able to obtain a reading. After we reset the power switch, the amp resumed normal operation.—TJN