Page description

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

The Internal Life of Vacuum Tubes

September 16, 2020 by Jan Didden

The Internal Life of Vacuum Tubes

A few years ago, Jan Didden designed a high-voltage delay unit and shared its details in a 2019 audioXpress article. Many people built it and like it, but others said that it would be totally unnecessary. As so often happens in audio, arguments pro and con raged without a clear resolution. So Didden thought this was something he needed to get his head around. He found several sources, which he thought were credible, and this article is the result of his investigations, fed by those sources. This article was originally published in audioXpress, August 2020.

Book Review: Getting the Most Out of Vacuum Tubes

August 20, 2020 by Jan Didden

Book Review: Getting the Most Out of Vacuum Tubes

I ordered this book, Getting the Most Out of Vaccum Tubes, from KCK Media Corp. while I was researching tube service life issues. It is an unusual book, not discussing what you can do with tubes, how to use them in circuits, operating parameter calculations, or that sort of thing. Instead, it is solely devoted to factors that decrease useful service life or cause catastrophic failures.

Purifi Audio Unveils Investigation About Hysteresis Distortion

April 30, 2020 by Jan Didden

Purifi Audio Unveils Investigation About Hysteresis Distortion

Purifi Audio, the Danish company founded by Bruno Putzeys, Lars Risbo, and Peter Lyngdorf together with a remarkable engineering team, promises Class D amplifiers with record-breaking performance (as well as speakers). Now, Bruno Putzeys made available a detailed report of his investigation on hysteresis distortion, which motivated the development of the company's products. As Putzeys describes, hysteresis in the ferromagnetic material of the amplifier output filter coil is what causes "a recognizable grainy texture in the sound."

Book Review: A Look Inside Bob Cordell’s Designing Audio Power Amplifiers, 2nd Edition

December 18, 2019 by Jan Didden

Book Review: A Look Inside Bob Cordell’s Designing Audio Power Amplifiers, 2nd Edition

We know many of our readers will enjoy this extended book review by our technical editor, Jan Didden, about Bob Cordell’s Designing Audio Power Amplifiers, 2nd Edition. When Cordell published his long-awaited first edition of Audio Power Amplifier Design, it was hailed as a significant addition on the subject. Reactions of readers made it clear that Cordell hit his mark, and in this article, Didden explains why the long-awaited second edition is an essential buy. This review was originally published in audioXpress, October 2019.

Purifi Audio - A Straight Wire to the Soul of Music

October 23, 2019 by Jan Didden

Purifi Audio - A Straight Wire to the Soul of Music

audioXpress' Technical Editor Jan Didden met with Bruno Putzeys and Lars Risbo, the founders of Purifi Audio, the new Danish company that the entire audio industry is talking about. The Netherlands Audio Engineering Society (AES) section invited the duo for a technical update on their plans, and they gracefully agreed to a presentation on June 13 at the Royal Conservatory of Music in The Hague, which Didden attended and reports here. This article was originally published in audioXpress, September 2019.

You Can DIY! A High-Voltage Delay for Tube Amplifiers - The Sequel

October 9, 2019 by Jan Didden

You Can DIY! A High-Voltage Delay for Tube Amplifiers - The Sequel

In this project for audioXpress magazine, Jan Didden offers a modern update on his original 2014 high-voltage delay design, which he built to complement tube amplifiers. The new unit needs no additional outside power, and allows setting the delay between 20 seconds and 254 seconds, which should cover all requirements. The article describes the complete project, and there's a DIY kit available at diyaudio.com. This article was originally published in audioXpress, November 2019.

FREE DOWNLOAD

T-reg: A High-Voltage Regulator for Tube Amps

November 1, 2017 by Jan Didden

T-reg: A High-Voltage Regulator for Tube Amps

Tube amplifiers can benefit from regulated and stabilized power supplies, especially sensitive preamplifier stages, but also (single-ended) power amps. But traditional high-voltage regulators add several extra tubes, complexity, and power losses, while good performance is not easy to obtain. This article, published in audioXpress, April 2009, describes a novel design that is very simple yet offers excellent performance. Output voltage is fully adjustable with a single resistor without any compromises in performance.

Kii Audio's Three: The Next Step in Loudspeaker Evolution

January 16, 2017 by Jan Didden

Kii Audio's Three: The Next Step in Loudspeaker Evolution

audioXpress January 2017 featured the much-anticipated review of the brand new Kii Three speakers from the company everyone’s watching, Kii Audio. “The Next Step in Loudspeaker Evolution,” as Jan Didden and Paul Wilke titled their review, examines whether the Kii Threes are effectively “the most advanced loudspeaker on the market today,” as is claimed by Kii Audio. Learn what they discovered in this definitive review, now available online here.

FREE DOWNLOAD

Interview with Nelson Pass

March 31, 2015 by Jan Didden

Interview with Nelson Pass

Over the years, some of the best Nelson Pass projects have been featured by Audio Amateur and audioXpress magazines. The A40 power amp article was published in The Audio Amateur, 4/78, and the A75 power amplifier appears in The Audio Amateur 4/92 and 1/93. His other works are posted at passdiy.com. Originally published by audioXpress on May 2010.

Extend the useful life of those precious tubes: use a Tube Amplifier High-Voltage Delay

February 25, 2015 by Jan Didden

Extend the useful life of those precious tubes: use a Tube Amplifier High-Voltage Delay

Tube life can be extended if you delay the application of high voltage until after the heaters have warmed up and current can flow. This little module does just that: depending on the setting of a jumper, it delays the high-voltage for 40 or 60 seconds after the amplifier is switched on. And the module is available as a kit. This article was originally published in audioXpress, February 2014.

FREE DOWNLOAD

«
1
2
3
4
»