Amplifier Series: Axign of Things to Come

October 10 2018, 14:00
Continuing audioXpress' Amplifier Series, looking at the latest technologies and Class-D amplification platforms, Ward Maas writes about Axign, a new company from The Netherlands, founded by former Philips and NXP employees who worked on the pioneering Class-D efforts. Established in 2014, their efforts have resulted in the development of the AX5689m a Class-D audio amplifier controller chip in a QFN package. The solution uses a digital control loop with feedback behind the output filter, across the loudspeaker terminals. It requires a digital input signal and suppresses all artifacts with a fifth-order digital feedback loop. audioXpress visited the company to find out more and to receive a demo.

On the article introduction, Ward Maas writes: A traditional application area for Class-D amplifiers is high-power amplification for professional use. Efficiency, weight, and reliability are determinant factors for such uses. They might be workhorses, but audio-quality-wise, they have not been good enough to run in the Kentucky Derby. In the past few years, however, the industry has seen the rise of high-quality Class-D amplifiers. Not only did they keep (and reinforce) their traditional strengths, but claims have been made (and confirmed) that they could also play a role in high-end audio applications. From that moment on, the entire game started to change. The combination of high-quality and low cost is, as could be expected, irresistible to audio manufacturers. Most people listening to Class-D amplifiers, do recognize the qualities in the bass area, but doubt the merits in the mid and high regions. Checking a datasheet often reveals some Class-D artifacts in the distortion curves and some load dependent behavior. As we have said in previous articles dedicated to this topology, we saw a dramatic change in performance as more Class-D manufacturers are able to minimize these effects. So, the use of Class-D in the high-end market is now a reality. The new Marantz PM 10 flagship, powered by Hypex Ncore Class-D amplifiers, is one of the obvious examples. And for those who still have doubts, that’s where the efforts of Dutch chip developer Axign can persuade even the most reluctant “traditional” analog diehard. To put it simply, Axign’s new AX5689 chip lays a very high-speed feedback loop around a Class-D amplifier, transforming its performance to almost theoretical levels. Too good to be true? Let’s see.

This article was originally published in audioxpress, December 2017.

Read the complete article here.
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