Rotel CD11/A11 CD Player/Amplifier Lab Report

Lab Report

Over the last four decades, Rotel's back-to-basics integrated amplifiers have always comfortably out-punched their basic power specifications, and the A11 is no exception. Rated at 2x50W/8ohm, in practice it delivers 2x78W/8ohm and 2x110W/4ohm with sufficient in reserve to support clean (<1% THD) peaks of 114W and 191W into 8 and 4ohm loads under dynamic conditions. Power into lower 2 and 1ohm loads is limited to 185W and 71W, respectively, as the amplifier switches off by way of protection [see Graph 1, below]. Distortion is held to within 0.004-0.006% over its rated 50W range through the midband, increasing to ~0.02% at high treble frequencies. The A-wtd S/N ratio is a little below average at 80dB (re. 0dBW), but this is caused by an innocuous white noise, not hum, while the treble response is subtly 'shaped', rolling away to –0.3dB/10kHz, –0.6dB/20kHz and –1.0dB/100kHz.

The partnering CD11 player is based around the Burr-Brown PCM5102A DAC and offers a generous 108dB A-wtd S/N from a maximum 2.1V output. The 450ohm source impedance is a little higher than I'd like to see, but distortion is consistently low at ~0.0015-0.003% over the top 30dB of its dynamic range through bass and midrange [black trace, Graph 2], increasing to 0.04% at high (20kHz) frequencies [blue trace]. Digital jitter is at the measurable limit for 16-bit CD at 120psec. The DAC chip offers both FIR and low-latency IIR filters, with Rotel evidently opting for the former with its 64dB stopband rejection and transient pre-ringing. There's a slight ±0.05dB in-band ripple but the response merely dips to –0.20dB/20kHz and stereo separation is held to >100dB across the 20Hz-20kHz span. PM


Dynamic power output versus distortion into 8ohm (black trace), 4ohm (red), 2ohm (blue) and 1ohm (green) speaker loads. Max. current is 9.6A


THD versus 16-bit CD digital signal level over a 120dB range at 1kHz (black) and 20kHz (blue)

Continuous power (<1% THD, 8/4ohm) 78W / 110W
Dynamic power (<1% THD, 8/4/2/1ohm) 114W / 191W / 185W / 71W
Output impedance (20Hz–20kHz) 0.054–0.059ohm (450ohm, CD)
Freq. resp. (20Hz–20kHz/100kHz) +0.0 to –0.6dB/–0.95dB (Amp)
Distortion (20Hz-20kHz, 0dBFs/0dBW) 0.003–0.042% / 0.0028–0.022%
A-wtd S/N ratio (re. 0dBFs/0dBW) 108.1dB (CD) / 80.2dB (Amp)
Digital Jitter 120psec
Power consumption (idle/rated o/p) 20W / 216W (6W, CD)
Dimensions (WHD / Total weight) 430x93x345 (314)mm / 12.7kg
Prices £429/£599

The Rotel Co. Ltd
Supplied by: Rotel Europe/B&W Group, West Sussex
01903 221500