Audio Myths: Feedback Cannot Fix What Has Already Happened

This article, originally published in The Audio Voice newsletter (#434), explores some practical experiments with Negative Feedback. "If I had a dollar for every time someone mentioned that negative feedback cannot work, because you cannot correct something after it happened, I would be a rich man," says Jan Didden. "Yes, it can be hard to get your head around feedback circuits for audio amplifiers. Yet, all it takes is to look around you," he adds.

AVPro Global, a company that started as a distributor, and evolved to create its own brands of audio/video installation products, display calibration and HMDI cables, has announced the acquisition of the Home Audio division of AudioControl from AAMP Holdings, an aftermarket car audio company from Florida who had acquired the Seattle, WA company in April 2022. AVPro Global says that the AudioControl Home Audio Division makes sense in its strategy to accelerate its business in residential and commercial distributed audio and media rooms.

The new NCx500 amplifier board from Dutch manufacturer Hypex Electronics is the first of a new NCOREx family of modules that evolves from the extremely popular NCORE Class-D amplifier technology, one of the most successful options among high-end audio and studio monitor brands. Stuart Yaniger was able to spend a few weeks with this next flagship for OEM applications. How will this improved NCOREx technology measure up? And will it deliver the "x" times improvements over the proven NCORE? Stuart shares all the juicy details.

This article expands the conversation around feedback theory for electronic circuits and audio amplifiers. Do we "really" need wideband open loop in audio amplifiers? The subject came up at the 154th Audio Engineering Society (AES) convention in Helsinki, Finland. Looking at the frequency domain, not necessarily, Jan Didden argued. In this article he looks at the question in the Time Domain. Narrow Bandwidth, High Open Loop Gain Amplifier versus a Wide Bandwidth, Low Open Loop Gain Amplifier in the Time Domain.

Although feedback theory for electronic circuits has been established for over a century, it is still a subject for discussion. This short essay is an attempt to shed some light on one of those recurring controversies. The subject came up at the 154th Audio Engineering Society (AES) convention in Helsinki, Finland. Audio amplifiers are basically integrators or, if you will, low-pass filters. That means that at some frequency, their open-loop gain starts to fall off. With that, the loop gain available for feedback also starts to fall off, leading to a diminishing of the curative effects of feedback: distortion starts to rise, gain accuracy starts to drop, output impedance starts to go up, etcetera.

The topology and the distribution of the wiring, partitioning between low power and high power circuits, grounding scheme, types of cables, protection techniques, and safety are important factors that must be considered to minimize the interference effects in audio amplifiers. This "tips and tricks" audio electronics article provides several details about inductive coupling effects in audio amplifiers and the simple way to minimize them.

audioXpress July 2023 provides an updated market and technology overview of Audio Amplifiers, includes the review of the Hypex Nilai500DIY 500W Power Amplifier Kits, a visit to Dutch company Grimm Audio, and an interview with Rémi Guastavino to discuss the new GRAS EQset measurement microphone series. Plus a review of the new WiiM Pro Music Streaming System, a new article series about Bass Reflex speaker performance, and a lot more.

ICEpower announced the launch of its new website. Designed to redefine the visitors' experience, the revamped site offers all the information about the cutting-edge capabilities of ICEpower's audio technology in the different fields of application. The website also includes information about ICEpower's turnkey solutions using its Class-D amplifier modules and the company's comprehensive information on R&D capabilities. There's even a shop for those who want to order individual modules and solutions.

Audio amplification solutions company ICEpower announced availability of its latest 1000S power supply, filling a gap in the company's portfolio for high-power amplification equipment. Based on the resonant LLC converter of the tried and tested ICEpower 700AS1 module, the new 1000S offers a stable and consistent power supply solution in a compact format to pair with the company's 300A2 and 400A2 modules for applications in hifi, commercial amps, whole home audio and active speakers.

Infineon Technologies AG and GaN Systems Inc. announced that the companies have signed a definitive agreement under which Infineon will acquire GaN Systems for US$830 million. GaN Systems is a global technology leader in the development of GaN-based solutions for power conversion. The company is headquartered in Ottawa, Canada, and has more than 200 employees. With the acquisition Infineon aims to strengthen its GaN portfolio.