Extraudio X250T Integrated Amplifier Mod'ing The Module

Mod'ing The Module

Hypex offers a series of 'High Efficiency Self Contained Amplifier Modules' to hi-fi and pro audio companies. The NC252MP – used by Extraudio here – is one of six Ncore 'plug-and-play' solutions that also incorporate a switch mode PSU. They feature the brand's compact Class D technology first seen in its popular UcD modules, but now with improved load-independence, lower distortion and lower output impedance.


Hypex's 'special sauce' lies in the 'phase shift controlled self-oscillating loop' that takes feedback right at the speaker output rather than before the filter network. So, unlike many other competing Class D offerings, the Hypex modules offer a more reliably flat and uniform response regardless of the swings in impedance of the attached loudspeaker.

The Ncore modules are designed so that OEM brands can drive straight into the control circuit giving them a chance, it was suggested to me, 'of adding their own fairy dust'. However, the control circuit must be driven by a voltage source if the transfer functions of the various circuit blocks are not to wander. So any modification to the Ncore module that alters the response of the local feedback loop around the PWM stage can impact on the cancellation network. This may explain the 40dB notch in response at 62kHz which should, if I read Hypex's data sheet correctly, be a few dB only [inset Graph: unloaded/8/4/2/1ohm = black/grey/red/blue/green traces]. How this influences sound quality is not clear, but it shows Extraudio has stirred its own ingredient into the Hypex brew! PM

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