audioXpress May 2025 Brings the Best in DIY Audio with Tubes

This year’s special Glass Audio issue of audioXpress includes interesting explorations such as the Ultra-Linear Power Amplifier by Rudolf Moers, Micro Details in Push-Pull Output Transformers by Hans Polak, Getting Less Gain From Tubes by Merlin Blencowe, and the Type 3 Mu Stage Breakthrough by Alan Kimmel. This issue also includes two speaker designs from Ben (Wolf) Shaffer and Ken Bird, an article about the intriguing return of 78 rpm records, and Paul Marchese’s Part 2 of his insightful Primer on Class-D Amplifiers. Richard Honeycutt shares how he learned to DIY with Tubes.

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.

A brand new series of tubes was launched and the first model is now ready to ship worldwide! The new 6L6GCM-STR is the first model from a new high quality premium tube series named REBASE, from Tube Amp Doctor (TAD). As the German company explains, the 6L6GCM-STR REDBASE is an entirely new TAD development, recommended for lively clean sounds as well as powerful broadband multi-channel amps, an ideal upgrade for any guitar or high-end amplifier that uses 6L6GC or 5881 tubes.

In this article, Richard Honeycutt provides a brief description of the main tube types used in audio applications, from triodes to tetrodes and pentodes, describing its uses, features and potential benefits. If you are looking for a quick reference reading about tubes that have been used in audio amplification this article is a great start. This article was originally published in audioXpress, May 2013 as part of the Hollow-State Electronics monthly column by Richard Honeycutt.

Blue announced the Bottle Mic Locker, lauded as “the world’s most versatile tube mic system in one package.” Combining Blue’s flagship Bottle microphone with a variable sensitivity power supply and four of Blue’s interchangeable classic capsules, the Bottle Mic Locker provides access to the highest caliber blend of modern and vintage textures for studio recordings. Available now, for $5,999 (MSRP).

What can you do to ensure the best possible sound from your system? According to Nelson Pass, the “sweet spot” concept is generally regarded as “that happy balance of conditions that elicits the best possible sound,” including the interiors of the components themselves. This article was originally published by audioXpress, January 2010.

Now available, Linear Audio Volume 10 is the 11th issue of Jan Didden’s series of printed bookzines dedicated to technical audio and perception. It features a great team of contributing authors and a strong collection of enjoyable articles, with a diversified and refreshingly divergent collection of personal takes on great audio topics.

Our super-sized September 2015 issue focuses on speaker design, from industrial/commercial to DIY perspectives. If you like speakers and are looking for new project ideas and new areas of product design, this edition of audioXpress is full of insights into how to approach DIY builds from new directions.

audioXpress July 2015 is one of those editions that we’re certain you will read immediately and keep close for a while, since there’s so much reference material included. We bring you the AXPONA 2015 Show Review, a great R&D Story explaining “The Birth of the World’s First True Software Radio,” great reviews, DIY projects and much more…