audioXpress May 2024 Glass Audio Special Issue Now Available

In the 2024 Glass Audio Special issue there’s Menno van der Veen’s TubeSociety TS-2022-OTL hybrid amplifier, and a Low-Feedback Triode Amplifier With Zero Output Impedance (ZOI) as DIY projects, designed by Tim Mellow and Peter Farrow. More great audio electronic articles by Rudolf Moers, Christopher Paul, and Dimitri Danyuk. Read about sustainable acoustical absorption, the Pure Acourate Sound Project, and The Neurochrome Story. And Andrew C. Russell concludes his High-Performance 60-Watt Class A Amplifier project.

We looked at the popular articles of 2021 in audioXpress.com (including selected articles from audioXpress and Voice Coil magazines), and we created this Top 10 list of news stories and online articles. Once again 2022 expanded slightly on the record-breaking year that was 2021 for audioXpress.com, in terms of number of visits and regular users of the website. Visitors from all over the world returned more often to read the more than 8.650 stories available. Which of the topics and stories published online in 2022 were the most popular? Here are the results!

This DIY-focused article introduces the Pentriode, a concept to explore the familiar idea of connecting commonly available pentode tubes as triodes, creating a circuit that excels in linearity. The Pentriode is formed by making one simple change to connect the screen grid to the cathode of a cathode follower. The article proposes different possible approaches, including for a mu stage, a design that the author previously wrote about for audioXpress. This article was originally published in audioXpress, May 2022.

Following the announcement of the new and improved NCOREx Class-D amplifier technology, Hypex has also reserved a surprise for this year's High End Show in Munich. In a completely separate announcement, Hypex will be launching the Nilai500DIY module, which is specified to deliver 500W with 1% THD @4 ohms and will improve output noise and idle losses significantly, compared to the popular NC400 module. This, the Dutch company says, is a completely new unique amplifier module that sets a new benchmark for high-end audio applications.

For those readers following the fascinating article series by Morty Tarr on "Cascodes, Folded Cascodes, and Current Mirrors," this final article in the series contains an additional section with important aspects of amplifier design. In the first two parts of this article series, Tarr discussed the technical merits of cascodes and related circuits. This useful addendum covers a simple test circuit for matching FET devices, the fascinating story of the Blowtorch Line Stage design, and additional notes on inverting and non-inverting amplifier stages and integrators. This article was originally published in audioXpress, December 2021.

In Part 1 of this three-part article about circuit topologies that are used to provide specific functions for an amplifier design, the author discussed cascodes and folded cascodes. In this Part 2, he focuses on current mirrors and line stages. As the author writes, “As designers, we have many devices to choose from. Some devices are ideally suited to certain tasks. Other tasks require performance that is difficult to achieve. While many excellent devices exist today, ideal devices do not exist, except maybe in Spice simulations.” This article was originally published in audioXpress, October 2021.

For this audio electronics article, Morty Tarr wrote a fascinating exploration of circuit topologies that are used to provide specific functions for an amplifier design. Cascodes, folded cascodes, and current mirrors are some of these topologies, intended to improve the performance of the devices, but which also add complications. In the first of a three-part series, the author discusses cascodes and folded cascodes, useful to improve high-frequency response and device linearity.

Hypex Electronics, the specialist supplier in power amplifiers, power supplies and DSP solutions announced a new powerful UcD700 mono kit featuring its UcD technologies marketed under its DIYclassD brand - specifically for the DIY audio market. As the company explains, the Hypex UcD700HG with HxR amplifier module has been around for many years but was never offered as a DIY building kit before. Now, DIYclassD offers an easy to build 700 watts monoblock kit including all the necessary parts that users don't even need to solder.

This reference DIY project details of an upgrade construction for the legendary Hafler DH-220 lateral MOSFET power amplifier, which can also be used to upgrade other Hafler models or even inspire new designs. The design is implemented on two PCBs, one as a drop-in replacement for the original Hafler circuit board and another board that consolidates all of the output stage wiring and components within the heatsink and under the main PCB. After the authors detailed the design and performance of the DH-220C upgrade amplifier, in this second part of the article, Bob Cordell and Rick Savas discuss the construction and testing. This article was originally published in audioXpress, August 2021.

This article offers the first serving of an amazing DIY project from amplifier experts Bob Cordell and Rick Savas with an upgrade for the legendary Hafler DH-220 lateral MOSFET power amplifier. The design is implemented on two PCBs, one as a drop-in replacement for the original Hafler circuit board and the other as a new board that consolidates all of the output stage wiring and components within the heatsink and under the main PCB. This article was originally published in audioXpress, July 2021