In this issue

FROM THE EDITOR’S DESK—No Truth. Just Joy, by J. Martins, p. 4
The TubeSociety 2022 OTL Hybrid Tube Amplifier, by Menno van der Veen, p. 8
A Low-Feedback Triode Amplifier with Zero Output Impedance: Part 1—Introduction and Single-Ended Input Amplifier Design, by Tim Mellow and Pater Farrow, p. 16
Tube Output Power: Determining Output Transformer Impedance for Maximum Output Power, by Rudolf Moers, p. 22
Optimizing Single-State Dual-Triode Totem Pole Drivers, by Christopher Paul, p. 20
SOUND CONTROL—Sustainable Acoustical Absorption, by Richard Honeycutt, p. 40
Pure Acourate Sound Project: Greater Than the Sum of Its Parts, by Rens Tellers and Jan Didden, p. 46
The Neurochrome Story, by Tom Christiansen, p. 52
The Open-Loop Complementary Follower and an Amplifying Stage, by Dimitri Danyuk, p. 56
A High-Performance 60-Watt Class A Amplifier: Part 2 —The Power Supply and Measurements, by Andrew C. Russell, p. 60

Perspectives on Automotive Sound Design - In the Era of Electric Vehicles

From combustion engine vehicles to fully electric vehicles, and from sound systems in the car to sound design and synthesis for the car itself, everything is changing in the automotive industry. This conversation with two members of the DSP Concepts automotive team with vast experience in the field, John Whitecar, VP of Product Management, and Steve Ernst, Head of Business Development, offers valuable insights on how things are evolving.

10+ mins

Audioscenic: From Vision to Product

Audioscenic is an innovative 3D audio beamforming technology company spun off from the University of Southampton. It is a remarkable example of perseverance, from early development to the first commercial implementation, which audioXpress considered Best of Show at CES 2023. This article shares the story so far, as Audioscenic continues its groundbreaking journey exploring consumer applications for its forward-thinking approach to spatial audio.

8 mins

The Changing Audio-Ecosystem in Electric Vehicles

The rapid shift to plug-in hybrid and full-battery electric vehicles is having a significant and long-lasting impact on how audio systems are integrated into cars. While some noises are much more prominent due to the absence of the familiar engine noise, the transition offers exciting possibilities for sound systems, passenger entertainment, and enhancing the overall automotive experience.

10+ mins

A (Z)OTL with 300Bs: Part 1-The Makeover

Rebuilding an amplifier for reasons of better reliability, better aesthetics, or bringing it up to the latest standard can be very rewarding. And if it is a classical, technological grandstand, even more so. Thomas Perazella embarked on such an adventure with a famous David Berning ZOTL amplifier. In Part 1 of this article, Tom presents the amplifier and discusses its unique circuitry. In Part 2, he will proceed to dismantle and rebuild the amp for the new owner and place it in a new chassis

10+ mins

The Hypex NCORE NCx500 Amplifier Module

NCORE (NC) amplifier modules are the flagship product from Dutch manufacturer Hypex Electronics and its success among the high-end audio brands is well documented. In 2022, Hypex announced the introduction of its improved NCOREX technology, starting with the NCx500 OEM module, which audioXpress received for review

10+ mins

Monoblock Power Amplifier with Precision Bias Control

In Part 2, Bruce Gillingham discusses the remainder of the MB1's circuitry, its mechanical design, and its performance measurements

10+ mins

A Trip Down Memory Lane

The history of tube application began with radio receivers, the telephone system, and cinema sound systems. Later, tubes began to be used in home stereo systems, and in amplifiers for electric guitars. Today, the primary markets for tubes are high-end stereo and musical instrument amplifiers. In this article Richard Honeycutt remembers his first contact with \"starter\" guitar amps as a teenager, progressing throughout his days as a semi-pro musician

5 mins

The Vanderveen Trans PP80 Valve Amplifier

This new push-pull (PP) valve amplifier, featuring the Trans technique, delivers 80W power, refined resolution, valve-sound envelopment, and low distortion plus good speaker damping. And... the amp is simple to construct

10+ mins

Accuracy in LTspice Modeling

Sometimes we need to consider the human factor when using circuit design simulation tools. In this article, our hollow-state expert details an error that occurred in a past article, which is now being corrected.

4 mins

Transitioning Audio Tests from R&D to the Production Line

Production line audio testing poses many challenges such as noisy environments, harsh operating conditions, high throughput, relative limits, and more. In this article, Steve Temme shares his observations and outlines the main considerations to ensure a successful operation.

10+ mins

Acoustical Measurement and DSP Application in Automotive Audio

This article offers a primer on how to approach acoustic measurements and the practical application of DSP in car cabins, one of the hardest acoustic environments for quality sound reproduction. The topics addressed in this article will be expanded in future articles.

8 mins

Power Transformer Parameters, Selection, and Testing

The initial group of articles focused on the history of transformer cores, construction methods and materials, and various testing methods. After having discussed the parameters of transformers, this article expands on their losses.

10+ mins

Modern PC Board Design Practices

Tips and Techniques

10+ mins

Lumped Element Modeling of Transducers

Many engineering tasks require a common ground from which discussions among those involved in a project can take place in a structured manner. This will often involve a so-called model of the concept or product, and this article discusses one such model: the lumped element model.

8 mins

Burkhard Vogel's Slopes and Levels

Spice Models to Simulate Vintage Op-Amp Noise

7 mins

Modular Evolution in Audio Testing

The audio industry continues to benefit from significant progress in advanced software as well as modular hardware solutions. This overview of the latest audio and industry-related test and measurement solutions identifies market trends for this critical segment.

10+ mins

Echo AIO

A Cost-Effective Audio Test System

10+ mins

Power Transformer Parameters, Selection, and Testing

Part 6 - Quality, Reliability, and Design

10+ mins

Building a Soundbase

One of the most successful speaker categories today, soundbars were originally intended to compensate for the poor sound quality of thin-display TVs. This project takes the concept up a notch in sound quality and fidelity for any living room application.

8 mins

Monoblock Power Amplifier With Precision Bias Control

Part 1- The Design

10+ mins

Wrong Things "Everybody Knows" About Acoustics

Our acoustic expert sets the record straight about some of the more common misconceptions about acoustics that he has heard over the years.

9 mins

Acoustic Topology Optimization for Vibroacoustics Applications

Acoustic topology optimization is one of the most interesting new technologies in vibroacoustics, and is a powerful tool that enables engineers to find optimal solutions to problems related to their applications. In this article, several acoustic topology optimization examples are shown.

8 mins

Remote Recording in the Rock Era

David Hewitt's On the Road

3 mins

More Choices for Headphones Test and Measurement

This article is a brief update on test and measurement solutions for headphones and earphones that we couldn't fit in our March 2023 issue. An update on solutions that perfectly complement our hearables-focused article.

10+ mins

State of the Hearables Industry

From April 2022 to April 2023, true wireless earbuds and all the efforts to create product concepts in the hearables class have evolved dramatically. That’s why this year’s article focuses on projecting the evolution and the new possibilities.

10+ mins

Power Transformer Parameters, Selection, and Testing

Part 3 Insulation Materials, Winding Bobbins, and Testing Methods, In the previous two articles in this series, Chuck Hansen detailed the history of transformer cores and their various construction methods. This article explores transformer insulation materials and winding bobbins, and testing methods for the insulation system.

10 mins

Loudspeaker Driver Displacement Decomposition

This valuable tutorial offers a unique overview on the possibilities of three-dimensional analysis of loudspeaker driver displacement, using Phase Decomposition and Axial-Symmetrical Decomposition techniques.

6 mins

The Audio Foundry Automotive Audio Development Platform

This article details the possibilities of the Audio Foundry platform for automotive audio prototyping and to support the development of audio experiences in vehicles with powerful design tools and services. The result of a collaboration between Tymphany and DSP Concepts.

10+ mins

OTC Hearing Aids

Is Innovation Leaving the Rule Behind? A wave of new developments promises to solve the most pressing need for people with milder hearing loss, allowing mass-market hearables to supplant over-the-counter hearing aids with less stigma.

9 mins

Acoustical Test Sources

The choice of a sound source for acoustical testing and reporting is decisive and should be determined according to the applications. Let’s explore the characteristics and benefits of available sources for acoustical measurements.

7 mins

Read all stories from audioXpress

audioXpress Magazine Description:

Step into the realm of audio, sound technology, and the latest developments in the field with audioXpress Magazine. We're delighted to introduce you to this publication, your ultimate source for all things related to audio, audio equipment, and the art of sound reproduction.

audioXpress Magazine, published by KCK Media Corp., is not just a magazine; it's your portal to the world of audio and sound technology.

As you explore the pages of audioXpress Magazine, you'll find a world of content that celebrates the magic of sound and audio technology:

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