Neurochrome Launches Universal Purifi Input Buffer

Neurochrome, the Canadian audio electronics company created by Tom Christiansen, just announced an interesting new upcoming product for builders and all DIY enthusiasts. A new universal input buffer board, designed to extract the best possible performance from Purifi and Hypex Class-D amplifier modules. Improving on the Purifi EVAL1 and the Hypex NC500 evaluation board, the new universal single-channel (mono) design provides a differential output for the amplifier, even if the input to the buffer is single-ended.

A personal account of a professional journey that led to the creation of Neurochrome, a company successfully serving audio enthusiasts all over the world with a complete range of power amplifiers kits and circuits, all well-engineered, thoroughly tested, and well-documented. Neurochrome is a small, highly dedicated audio company, providing inspiration, or perhaps a forewarning, for those wishing to venture into the audio business.

"Designing a preamp is probably the most challenging engineering task in the audio chain, and many designers have invested a lot of time and effort in it," wrote Erno Borbely in this original 1985 article for the Audio Amateur. "My reason for designing this preamp is quite simple: I wanted to have a top-quality preamp without paying megabucks for a Levinson or Accuphase unit. It is up to you to decide whether or not I have succeeded in achieving the same quality." This article was originally published in The Audio Amateur Issue 4, 1985, and is still frequently referenced.

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.