Surround-Sound Preamp-Processors

All measurements were made in balanced mode unless noted otherwise.

The Emotiva MPS-1's balanced frequency response was -0.57dB at 10Hz, -0.16dB at 20Hz, -0.46dB at 20kHz, and -2.54dB at 50kHz. Its single-ended frequency response was -0.58dB at 10Hz, -0.16dB at 20Hz, -0.12dB at 20kHz, and -0.71dB at 50kHz. The amplifier's S/N ratio (A-weighted, 10Hz-24kHz, 2.83V@8Ω) measured –86.9dB (single-ended) and -92dB (balanced). Its gain measured 25.9dB (balanced) and 27dB (single-ended).

THD+noise at 2.83V into 8Ω measured 0.016% at 20Hz, 0.015% at 1kHz, and 0.015% at 20kHz. At 2.83V into 4Ω, the corresponding results were 0.015% at 20Hz, 0.016% at 1kHz, and 0.015% at 20kHz.

Driving all seven channels into 8Ω, the MPS-1 delivered 169Wpc at 20Hz and 175Wpc at 1kHz (to the nearest watt) before clipping (1% THD+noise). The channel measured, in position #1, failed during the 20Hz test and did not recover.

Into 4Ω, with the remaining six channels operating, the MPS-1 delivered 215Wpc at 20Hz and 245Wpc at 1kHz.

With only two channels operating, at 1kHz, the Emotiva clipped at 187Wpc into 8Ω and 280Wpc into 4Ω.

Comment: We were surprised to see an amplifier channel fail on the test bench. This is rare, but test-bench procedures do stress an amplifier to the max—a situation rarely encountered in real-world operation at 20Hz with all seven amps operating. But the defective module SS experienced in the same amplifier bay does raise some concern. The replaceable modules in the MPS-1 should make correcting any such problem in the field a relatively simple matter. Our experience with a wide range of electronics suggests that such failures normally happen early in a product's life—or when it's in the hands of a reviewer!—TJN