Power Amplifier Reviews

Water damage put our audio measurement lab out of commission for nearly two weeks and delayed the measurements on the Rotel RMB-1077 amplifier. But the waters have receded, and here are those test bench results.

All measurements were taken on the left channel except as noted. Measured power outputs are to the nearest Watt.

The Rotel RMB-1077's frequency response driving an 8Ω load measured -0.33dB at 10Hz, -0.10dB at 20Hz, -0.46dB at 20kHz, and +0.69dB at 50kHz.

The Rotel RMB-1077's frequency response driving a 4Ω load measured -0.36dB at 10Hz, -0.11dB at 20Hz, -0.25dB at 20kHz, and -0.73dB at 50kHz.

S/N (A-weighted, 2.83V into 8Ω 1W) from 10Hz-24kHz) measured –106.9dB. The amplifier's gain measured +27.3dB.

THD+noise at 2.83V into 8Ω (1W) measured 0.045% at 20Hz, 0.045% at 1kHz, and 0.052% at 20kHz.

THD+noise at 2.83V into 4%#937; (2W) measured 0.040% at 20Hz, 0.045% at 1kHz, and 0.047% at 20kHz.

Driving seven channels into 8Ω, the Rotel delivered 130Wpc at 20Hz and 118Wpc at 1kHz before clipping (1% THD+noise).

Into 4Ω with seven channels driven, the amp's current protection circuit kicked in before the continuous output reached the 1% THD+noise level. The output just before protection engagement was 73Wpc at 20Hz and 74Wpc at 1kHz. The Rotel's instantaneous power output with real-world program material should be closer to the results obtained with only two channels driven (below).

With just two channels driven into 8Ω, the RMB-1077 delivered 133Wpc at 1kHz at clipping (1% THD+noise). Into 4Ω, two channels driven, it delivered 257Wpc at 1% THD+ noise at 1kHz.