Audio Myths: Why Narrow Bandwidth May Be Better also in the Time Domain.

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.

Aviation pilots and professionals working in extremely noisy environments now have access to hearing protection and communication solutions that are able to reduce noise levels by up to 55 decibels. Two Swiss startups, KeepEars and AVAtronics have announced the successful prototype test and launch of the quietest earbuds on earth, able to be used as hearing protection and communications systems in extreme noisy environments, effectively canceling signals in a wide range of frequencies.

CEVA announced Bluebud-HD, a pre-configured software package for its Bluebud wireless audio platform that includes all the audio, voice and context-aware software required in premium TWS earbuds, gaming headsets, hearables, and other smart audio products. The company also updated its SenslinQ software framework and DSP tool kit for Bluebud that streamlines software migration from other processor architectures to the CEVA-BX1 DSP and virtualizes DSP programming for application developers.

AVAtronics SA is developing a patented, True Wideband Active Noise Cancellation technology. The company is headquartered in Lausanne, Switzerland, with a subsidiary based in Sound Hub Denmark, where it has access to world-class acoustic test facilities and audio experts. Being one of the first international start-ups selected for the SoundTech Accelerator Program, one of the first to establish a Danish limited liability (ApS) company, and one of the first to make use of the Sound Hub sound labs, AVAtronics is now also looking to hire employees in Denmark.

Lectrosonics introduced two new transmitters as the latest generation in the award-winning Digital Hybrid Wireless SM Series product line: the “wide band” SMWB (single AA battery) and SMDWB (dual AA battery). The two new wireless audio transmitters have a similar look and feel to previous SM Series units, but with several innovative new features, including the ability to either act as a transmitter or as a body-worn recorder, as well as wideband tuning.

HEAD acoustics announced that its HMS II.3 Artificial Head measurement system is able to transmit real speech equalized up to almost 20 kHz. According to the German company, the HMS II.3 Artificial Head, designed for measurement of close to-the-ear transducers, such as handsets, headsets, headphones, hearing protectors and hearing aids, is perfectly suited for testing the upcoming generation of VoLTE mobile phones, among many other applications that require super-wideband capabilities.