TEST BENCH
DOLBY DIGITAL PERFORMANCE
All data were obtained from various test DVDs using 16-bit dithered test signals, which set 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 57. All level trims were at zero. Except for subwoofer-related tests, all speakers were set to “large,” subwoofer on. All are worst-case figures where applicable.
Output at clipping (1 kHz into 8/4 ohms)
1 channel driven: 88/112 W* (19.4/20.5 dBW)
5 channels driven (8 ohms): 28 W* (14.8 dBW)
* The Onkyo produced up to about 120 W mono, and 50 W for 5 channels into 8 ohms, but current-limiting protection dropped output more than 20 dB following periods ranging from a few seconds (levels just over those listed) to a few hundred milliseconds.
Distortion at 1 watt (THD+N, 1 kHz) 8/4 ohms: 0.02/0.04%
Noise level (A-wtd): –75.8 dB
Excess noise (with sine tone) 16-bit (EN16): 0.4 dB
Frequency response: 20 Hz to 20 kHz +0, –0.3 dB
STEREO PERFORMANCE, AUX INPUT
Reference input and output level is 200 mV; volume setting for reference output level was –59.
Distortion (THD+N, 1 kHz, 8 ohms): 0.02%
Noise level (A-wtd): –85.8
Frequency response: <10 Hz to 21 kHz +0, –0.2 dB (–10 dB @ 200 kHz)
STEREO PERFORMANCE, DIGITAL INPUT
Reference level is –20 dBFS; all level trims at zero. Volume setting for reference level was 58.
Output at clipping (1 kHz, 8/4 ohms, both channels driven): 82/104 W** (19.1/20.2 dBW)
** Sustained full-power tests into 4-ohm loads induced current-limiting protection, dropping output approximately 20 dB following a period of a few seconds.
Distortion at reference level: 0.02%
Linearity error (at –90 dBFS): –0.1 dB (see notes)
Noise level (A-wtd): –75.4 dB (see notes)
● with 96-kHz/24-bit signals: –86.8 dB
Excess noise (with/without sine tone)
● 16-bit (EN16): 0.6/0.5 dB
● quasi-20-bit (EN20): 10.8/10.6 dB
Noise modulation: 0.2 dB
Frequency response: <10 Hz to 20 kHz +0, –0.2 dB
● with 96-kHz/24-bit signals: +0, –1.2 dB at 44.5 kHz
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 80 Hz
High-pass-filter frequency response (crossover set to 80 Hz): 12 dB/octave below –3-dB rolloff point of 94 Hz
Maximum unclipped subwoofer output (trim at 0): 11.7v
Subwoofer distortion (from 6-channel, 30-Hz, 0-dBFS signal; subwoofer trim set to 0): 0.02%
Crossover consistency: bass-crossover frequency and slope were consistent for all sources and formats.
Speaker size selection: all channels can be set to “small.”
Speaker-distance compensation: available for all main channels.
Onkyo’s aggressively priced new A/V receiver produced stunningly good bench results on all the low-level tests: Noise, distortion, and frequency response were all excellent, and digital-to-analog performance — as shown by linearity, excess noise, and more — were simply superb. The Onkyo also had plenty of clean, multichannel-mix subwoofer output, something that even expensive receivers don’t necessarily manage.
The TX-NR509’s power output was relatively modest, but it showed thoughtful use of available resources. It had no trouble meeting its single-channel specs and could produce a good deal more for short bursts (fractions of a second) before entering protection mode. When asked to produce more power for longer intervals, it dropped output by about 6 dB. This is the classic solution for a power-supply-limited audio amplifier, where considerable dynamic power remains on tap beyond the steady-state (RMS) measured power, as my listening tests amply confirmed. — D.K.
