TEST BENCH
By Daniel Kumin
DOLBY DIGITAL PERFORMANCE
All data were obtained from test DVDs using 16-bit test signals containing dither, which sets limits on measured distortion and noise performance. Reference input level is -20 dBFS, and reference output is 1 watt into 8 ohms. Volume setting for reference level was -7.5. All level trims at 0 except for subwoofer-related tests, all speakers set to "large," subwoofer on. All are worst-case figures where applicable.
Output at clipping (1 kHz into 8/4 ohms)
1 channel driven: 181/278 W (22.6/24.4 dBW)
5 channels driven (8 ohms): 67 W (18.3 dBW)
Distortion at 1 watt (THD+N, 1 kHz)
8/4 ohms: 0.02/0.03%
Noise level (A-wtd): -76.2 dB
Excess noise (with sine tone)
16-bit (EN16): +2.75 dB
Frequency response: 20 Hz to 20 kHz +0, -0.4 dB
MULTICHANNEL PERFORMANCE, ANALOG INPUT
Reference input and output level is 200 mV; volume setting for reference output level was -3.
Distortion (THD+N, 1 kHz, 8 ohms): 0.01/0.01%
Noise level (A-wtd): -92.7 dB
Frequency response: <10 Hz to 104 kHz +0, -3 dB
STEREO PERFORMANCE, DIGITAL INPUT
All signals were PCM and 16-bit except where noted otherwise. Reference level is -20 dBFS; all level trims at 0. Volume setting for reference level was -3.5.
Output at clipping (1 kHz, 8/4 ohms)
both channels driven: 129/188 W (21.1/22.7 dBW)
Distortion at reference level: 0.02%
Linearity error (at -90 dBFS): 5.6 dB
Noise level (A-wtd): -78.8 dB
(with 96-kHz/24-bit signals: -81.7 dB)
Excess noise (with/without sine tone)
16-bit (EN16): 0.8/3.0 dB
quasi-20-bit (EN20): 11.3/13.1 dB
Noise modulation: 4.2 dB
Frequency response: 20 Hz to 20 kHz +0, -0.1 dB
(96-kHz/24-bit signals: 5 Hz to 42 kHz +0, -1.9 dB)
BASS-MANAGEMENT PERFORMANCE
Measured results obtained with Dolby Digital test signals.
Subwoofer-output frequency response (crossover set to 80 Hz): 24 dB/octave above -6-dB rolloff point of 85 Hz
High-pass-filter frequency response (crossover set to 80 Hz): 12 dB/octave below -3-dB rolloff point of 80 Hz
Maximum unclipped subwoofer output (trim at 0): 7.5 volts
Subwoofer distortion (from 6-channel, 30-Hz, 0-dBFS signal; subwoofer trim set to 0): 12.0%
Crossover consistency: bass crossover frequency and slope same for all signal formats that receive bass management
Signal-format consistency: consistent for all applicable formats (two-channel stereo must be set to Straight); bass management not available for multichannel analog signals
Speaker size selection: all channels can be set to "small"
Speaker-distance compensation: available for all main channels
The Yamaha RX-V657 produced good numbers, but a couple of notes are required. A switch sets the receiver for minimum speaker impedances of 8 or 4 ohms. The 4-ohm position current-limits its outputs to approximately one-half of their potential power. All numbers here were taken with the receiver set to the 8-ohm position, which was contrary to Yamaha's recommendation, because some of my speakers present real-world loads well below 8 ohms. But there were no ill effects as a result either on the test bench or in my listening tests.
Second note: The RX-V657 appeared to exhibit a least-significant-bit (LSB) error of a few decibels in digital-input performance, yielding errors in minimum-signal levels. The result: noise-level measurements that were better than theoretical perfection for CD signals, substantial linearity errors below -80 dB or so, and a large noise-modulation figure. I didn't find these errors more than barely audible using our specialized noise-modulation test tracks and listening on headphones at very high volumes. I never heard any evidence of them with music or movie sound.
