New Projects, Reviews, and Glass Audio Special Articles Available with audioXpress May 2020

audioXpress May 2020 Glass Audio/Tube Focus edition is now available. Tubes continue to rule, and no other magazine has carried the tube flag higher, starting in 1989 with the foundation of Glass Audio magazine, later merged with audioXpress. For the May 2020 edition, we combined classic tube projects and cutting-edge technology and many audio electronics focused articles.

Highlighted on this month's cover is a review of the RødeTest FuzzMeasure Audio and Acoustic Measurement Software by Luke McCready. For quite some time we have been planning to do this review, which we postponed several times thinking that a new major upgrade would be introduced. After all, this creation of Canadian software designer Chris Liscio was sold to Røde in 2018. The software is now the very first product of the new RødeTest division of Røde Microphones, a subsidiary of Freedman Electronics, also the owner of Aphex, Event Electronics, and SoundField brands and a global pro audio powerhouse. We are glad we did the review, because the available version of the FuzzMeasure acoustic measurement software is a solid tool and deserves to be recognized. It is a unique and useful tool for many applications, as McCready was able to experiment. "FuzzMeasure is known for its high-quality graphs and for tucking an immense amount of control into a sleek, minimal interface," McCready writes, before finding how useful FuzzMeasure could be in setting up his home studio space.

"Stop Worrying About Coupling Capacitors!" is another great research article from Ethan Winer, where he designed a simple device that measures capacitor distortion using a USB sound card and free software to try and determine the importance of high-quality capacitors in the signal path. This article details the results of his tests with different capacitor types.

Among the practical projects we scheduled for this May 2020 edition, we had to include a project that, although not tube-based, deserved to be published in this edition of audioXpress for its tube-like sound properties. The article describes a simple but extremely interesting amplifier project by Mike Rothacher. The MoFo is an inexpensive, single-stage, single-ended, Class A amplifier using a MOSFET Follower (MoFo), powered by a simple laptop adaptor. Rothacher built it and shares all the details.

As part of our Glass Audio Special, we have two great practical projects for our readers and tube-enthusiasts. "Repurposing an Old Preamp for Line-Level Duty" by Bill Reeve is a great modification and restoration article that shows how to preserve the best features of unused tube equipment. The article describes a tube preamplifier that the author wanted to position at the input to his home power amplifier, eliminating the need to adjust his 1972 McIntosh MX10 tuner and 240 power amplifier’s volume high when he wants to fill his home with music. In this case, an old Shure Model 65 stereo conversion preamplifier using two dual-triode 12AX7 tubes provided an excellent platform for the project.

Next for our Glass Audio Special, Bruce Heran details his Mini Blocks, two small mono block tube amplifiers, which derived from a tube-based power amplifier he built for his office. That project was an EL84 stereo amplifier design and for the latest incarnation, 11 years later, he decided to build a pair of mini blocks as they better suited his current needs, supporting also a number of modifications that enhance the performance. We invite our readers to follow the author's detailed and inspiring voyage building these two beautiful units.

And of course, there's our Hollow-State Electronics column, where Richard Honeycutt shares lessons learned after many years of repairing guitar amplifiers. In the more than 50 years that Honeycutt has been repairing these unique tube amplifiers, he has learned that certain models exhibit certain specific failure modes, and if you get to know these modes, you can dramatically cut troubleshooting time.

In our Audio Scope column, Michael Steffes explores Noise Analysis for FDA-Based Audio ADC Drivers. His article discusses the total output spot noise equation for the fully differential amplifier (FDA), which is an extension of the common op-amp noise expression. He also provides relative contributions to the total output noise power for the different terms, including 1/f noise effects to adjust the device noise for a wideband SNR calculation.

And, of course, our readers will not want to miss Part 4 of the "Powering Your Circuits" article series, where this month Ed Simon continues to explore AC waveforms and looks at full wave bridge (FWB) circuits and other forms of DC power regulation.

On the cover of our May 2020 edition some of our readers will recognize the beautiful Experience series tube amplifier designed by audioXpress contributor and renowned tube expert, Gerhard Haas. We received the sad news of his passing while preparing this annual Glass/Tube edition, where many of his articles have been featured in the past. This edition includes a modest tribute to his life and work.

The May 2020 edition of audioXpress is now available online, and on its way to those who subscribe to the print edition. To read it now, you will need to subscribe to audioXpress.

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