Extraudio X250T Integrated Amplifier Lab Report

Lab Report

The features, applications and specifications for the Ncore module at the heart of the X250T (and X250) are available to download here. Extraudio changed its '200W/8ohm' power output rating during the course of our review – this is a 150W/8ohm Class D module with onboard PSU and, as expected, on test it delivered 2x150W/8ohm and 2x280W/4ohm. Also, because this is a PWM/Class D amp, there is no significant headroom under dynamic conditions, and so the X250T offers 151W, 285W, 275W and 195W into 8, 4, 2 and 1ohm loads at 1kHz/10msec at <1% THD [see Graph 1, below]. This is more than sufficient for most 'sane' loudspeakers.

Distortion also shows a distinctive pattern. From 1-10W it bests Extraudio's 0.008%/1W/1kHz specification by a decent margin at ~0.001% but then increases to 0.007%/20W, 0.06%/50W and 0.11%/100W. However, bearing in mind that most hi-fi amp/speaker combinations are running at or below 10W for much of the time, the subjective impact of this is uncertain. On the other hand, the trend of distortion vs. freq. – from a very low 0.0009% through bass and midrange before a sudden rise above 10kHz to 0.03%/20kHz is entirely typical of this Class D module [Graph 2, below]. Output impedance remains a low ~0.019ohm (20Hz-20kHz), as indicated by Hypex, with an ultrasonic peak of 1.01ohm at 93kHz. The frequency response cannot meet Extraudio's claimed 0.5Hz–350kHz/–1dB (this spec may be for the custom preamp section only) but has a –1dB point at 25kHz and –6dB/100kHz. Finally, the 83dB A-wtd S/N ratio (re. 0dBW) is excellent for a Class D amplifier. PM


Dynamic power output versus distortion into 8ohm (black trace), 4ohm (red), 2ohm (blue) and 1ohm (green) speaker loads. Max. current is 14.0A


Distortion versus extended frequency from 5Hz-40kHz at 10W/8ohm (one channel driven)

Power output (<1% THD, 8/4ohm) 150W / 280W
Dynamic power (<1% THD, 8/4/2/1ohm) 151W / 285W / 275W / 195W
Output imp. (20Hz–20kHz/100kHz) 0.020–0.017ohm / 1.01ohm
Freq. resp. (20Hz–20kHz/100kHz) –0.15dB to –0.75dB/–6.1dB
Input sensitivity (for 0dBW/150W) 201mV / 2525mV (balanced)
A-wtd S/N ratio (re. 0dBW/150W) 83.1dB / 104.9dB
Distortion (20Hz-20kHz, 10W/8ohm) 0.00085–0.029%
Power consumption (Idle/Rated o/p) 17W / 175W (3W standby)
Dimensions (WHD) / Weight 445x125x395mm / 18kg
Price £8495

Extraudio BV
The Netherlands
Supplied by: Whole Note Distribution, Scotland
02039 115 549