Exposure XM CD/XM5 CD Player/Amplifier Lab Report

Lab Report

Conservatively rated at 60W/8ohm, Exposure's XM5 amplifier achieves closer to 2x75W/8ohm and 2x115W/4ohm, increasing still further to 98W/8ohm and 174W/4ohm under dynamic conditions [see Graph 1, below]. Power is limited by electronic protection to 160W and 86W into 2/1ohm loads, so you'll still get the biggest blast from 6-8ohm nominal loudspeakers with the XM5. Otherwise its low output impedance delivers a consistent –0.13 to –1.0dB response (20Hz-20kHz, down to –13.4dB/100kHz) almost regardless of load impedance while the A-wtd S/N is 'average' for the breed at 87dB (re. 0dBW). If you use the XM5 as a DAC/amp then it reaches out to –0.7dB/20kHz but falls more rapidly to –3dB/36kHz and –10dB/47kHz (192kHz media). Digital jitter is a low 75psec – and this is principally PSU-related – while distortion mirrors that of the analogue amp, increasing from typically 0.002% through bass and midrange to 0.10% at 20kHz (re. 0dBFs).

The partnering XM CD player offers a modest 99dB A-wtd S/N from a maximum 2.2V output, while the 97ohm source impedance (rising to 295ohm/20Hz) shows the effect of the cap-coupled output. The response is necessarily limited, although at –0.2dB/20kHz is 'flatter' in the audioband than the XM5 amplifier. Jitter follows the same pattern as that observed with the XM5's DAC but the trend of low bass/mid distortion (0.001% at 0dBFs) increasing at HF (0.02%/20kHz) is milder through the XM CD [black and blue infills, Graph 2]. The linear-phase digital filter option of TI's PCM1716 DAC is used here so there's some limited pre/post ringing on impulses, traded for a useful (but not extreme) 79dB suppression of digital alias distortions. PM


Dynamic power output versus distortion into 8ohm (black trace), 4ohm (red), 2ohm (blue) and 1ohm (green) speaker loads. Max. current is 9.3A


THD vs. digital level over a 120dB range at 1kHz (XM5 DAC, red; CD, black) and 20kHz (CD, blue)

Continuous power (<1% THD, 8/4ohm) 75W / 115W
Dynamic power (<1% THD, 8/4/2/1ohm) 98W / 174W / 160W / 86W
Output imp. (20Hz–20kHz, Amp/CD) 0.011–0.021ohm / 98-295ohm
Freq. resp. (20Hz–20kHz/100kHz) –0.13 to –1.0dB/–13.4dB (Amp)
Distortion (20Hz-20kHz, CD/Amp) 0.0010–0.018%/0.0019–0.085%
A-wtd S/N ratio (CD/Amp) 99.3dB (0dBFs) / 86.9dB (0dBW)
Digital jitter (CD / LPCM, amp) 160psec / 75psec
Power consumption (idle/rated o/p) 14W / 212W (9W, CD)
Dimensions (WHD / Total weight) 218x94(89)x348(363)mm / 9kg
Price £1200/£1260 (CD/Amp)

Exposure Electronics
Lancing, UK
Supplied by: Exposure Electronics
01273 423877