Surround-Sound Preamp-Processors

The frequency response of the Primare A30.5 Mk.II measured –0.06dB at 10Hz, –0.01dB at 20Hz, –0.12dB at 20kHz, and –0.74dB at 50kHz. The amplifier's gain measured 29.7dB. The signal/ noise ratio at 1W into 8ohms (10Hz–20kz) was –116.5dB, A-weighted. The THD+noise at 1W into 8ohms measured 0.003% at 20Hz, 0.004% at 1kHz, and 0.002% at 20kHz. Into 4ohms, THD+noise at 2W measured 0.004% at 20Hz and 1kHz, and 0.002% at 20kHz.

Into an 8ohms load with all five channels driven, the A30.5 Mk.II clipped (1% THD+noise) at 92W per channel at 20Hz and 139Wpc at 1kHz (141Wpc with two channels driven at 1kHz into 8ohms). The spread between the output at clipping between 20Hz and 1kHz is larger than we have encountered on most of the amps we have reviewed. And the A30.5 was clearly uncomfortable driving 20Hz at peak output; its internal relays could be heard chattering on this test.

Into a 4ohms load, five channels driven, clipping occurred at 173Wpc at 20Hz and 197Wpc at 1kHz (218Wpc with two channels driven at 1kHz into 4ohms). On the 20Hz test, the relays chattered and the power-supply fuse failed. When the fuse was replaced, however, the amp returned to normal operation. Most typical program sources, as opposed to test tones, should not trigger this problem.—Thomas J. Norton