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About Jan Didden

Jan Didden has written for audioXpress since the 1970s and he is the magazine’s Technical Editor. He is retired following a career with the Netherlands Air Force and NATO. He worked in logistics, air defense, and information technology. Retirement has provided him with the time to finish all the audio projects that have piled up for decades. He sometimes writes about them on his website linearaudio.nl. Didden is also known as the publisher and managing editor of the twice-yearly bookzine Linear Audio, which he published until 2018. He is currently teaching audio electronics for enthusiast hobbyists and serious amateurs in the Belgian city of Hasselt. More information is available at linearaudio.net

All items written by Jan Didden

Book Review: Bob Cordell’s Designing Audio Circuits and Systems

December 4, 2024 by Jan Didden

Book Review: Bob Cordell’s Designing Audio Circuits and Systems

Designing Audio Circuits and Systems is a surprising effort by the author and one that deserves careful exploration. A true compendium of lessons in audio that reflects Bob Cordell’s long-standing track record of designing audio equipment as well as advanced test equipment. The vast content contained in this book makes it an essential reference for anyone designing audio circuits, including excellent “hands-on” material for anyone starting to experiment in audio electronics.

Ground Rules: How to Mitigate Grounding Issues in Audio Equipment

November 14, 2024 by Jan Didden

Ground Rules: How to Mitigate Grounding Issues in Audio Equipment

Or why not all grounds are created equal. How to mitigate grounding issues in audio equipment, understanding resistance, inductance, and capacitance of ground wiring, and voltage differences between points. Also, how not add to the construction complexity.

Joachim Gerhard on Low Noise Phono Stages: The Discrete INA Design

November 13, 2024 by Jan Didden

Joachim Gerhard on Low Noise Phono Stages: The Discrete INA Design

Ask audio industry insiders and audiophiles alike about Joachim Gerhard, and chances are that they mention the many high performance speakers he designed over the years. But he also has a great track record designing phono preamps and this interview explores that aspect of Joachim’s career. In this second part of the interview, Jan Didden explores Gerhard's design ideas and goes into details on his Discrete INA design, a discrete input stage instrumentation amplifier topology.

Joachim Gerhard on Low Noise Phono Stages: Design Considerations and Circuit Topologies

November 6, 2024 by Jan Didden

Joachim Gerhard on Low Noise Phono Stages: Design Considerations and Circuit Topologies

Ask audio industry insiders and audiophiles alike about Joachim Gerhard, and chances are that they mention the many high performance speakers he designed over the years, initially for Audio Physic, currently for Suesskind Audio. But Gerhard also has a great track record designing phono preamps. This interview explores that aspect of Joachim’s career. In the first part of this interview Joachim discusses the design considerations and circuit topologies for low noise phono stages, culminating in his very low noise and Flexible Phono Stage (FPS) design. This article was originally published in audioXpress, September 2024.

Dissipation, Thermals, and Rds(on)

August 29, 2024 by Jan Didden

Dissipation, Thermals, and Rds(on)

This article explores the significance of the Rds(on) specification of a MOSFET in a linear voltage amplifier and implications on Thermal Design - dissipation, thermal resistances, and heatsinking. It may be of interest to put this in perspective and highlight the connection between these subjects.

ICEpower – An Audio Company That Also Does Amplifiers

August 28, 2024 by Jan Didden

ICEpower – An Audio Company That Also Does Amplifiers

Europe’s Nordic countries have long been the birthplace for high-quality and innovative audio products, particularly excelling at speakers and amplifiers. Located near Copenhagen, ICEpower has traditionally been known as a purveyor of high-performance Class-D amplifiers and associated switch-mode power supplies. The company continues to provide innovative Class-D solutions today, but its scope is now much broader than that, as this report discloses.

Series Versus Shunt Regulators – A Mixed Bag

August 1, 2024 by Jan Didden

Series Versus Shunt Regulators – A Mixed Bag

Series voltage regulators are a great way to provide almost-noise free and rock-stable DC to your audio circuits. But the load current often has distorted signal components that can generate a ‘dirty ground’ across the supply ground wires and tracks. This can introduce distortion components in other circuit sections using this ground. With shunt regulators we can keep the dirty ground localized and largely avoid the problem. Technical Editor Jan Didden explains.

SiliconIntervention: Low-Level Efficiency Improvements in Class-D

July 18, 2024 by Jan Didden

SiliconIntervention: Low-Level Efficiency Improvements in Class-D

Driven by the need to maximize battery life in portable devices, Class-D efficiency at low output levels is receiving greater attention. This is particularly important to achieve longer battery life in designs such as true wireless earbuds. Power optimized amplification is precisely the goal for Multilevel Class-D, and now there's also Fractal Class-D, a new technology developed by SiliconIntervention, a Canadian company formed in 2019 as the result of the pioneering research and development of its founder Martin Mallinson, the former Chief Scientist at ESS Technology.

Interview: An Afternoon with Robert Munnig Schmidt

June 12, 2024 by Jan Didden

Interview: An Afternoon with Robert Munnig Schmidt

Robert Munnig Schmidt is intrinsically connected with advanced motion systems and motional feedback applications. He is now retired from his own consultancy business, following an outstanding career that includes key R&D positions at Philips, being part of the ASML founding team, and teaching Mechatronic System Design at the Delft University of Technology. In this interview, Schmidt revisits the theory and practice of motional feedback, silicon wafer steppers, voice coils, Class-D amplifiers, and much more.

Pure Acourate Sound Project: Greater Than the Sum of Its Parts

May 1, 2024 by Jan Didden

Pure Acourate Sound Project: Greater Than the Sum of Its Parts

audioXpress traveled to Germany to learn about the Pure Acourate Sound Project, which aims to create the lowest distortion sound in a listening room. The initiators of the Pure Acourate Sound project are Ulrich Brüggemann, Markus Grelka, and Ralf Höllmann. The partners involved in this unique system are Purifi Audio, Okto Research, GIK Acoustics, Klippel, Roon, AudioVero, Rose Handwerk, and Joachim Gerhard. Ahead of the presentation at the May 2024 Munich High-End show, audioXpress offers a preview of the project.

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