We urge you to download the July 2020 edition of audioXpress because there's a lot to read, enjoy, and build.
audioXpress July 2020 is now available, and there's a quiet revolution happening in audio amplification. On our market update feature about audio amplifiers we cover the latest trends in Class-D solutions from the smallest and lowest-power applications to the latest pro audio amp modules. Essentially it is the direct result of strong innovation in Class-D technology, with incremental improvements introduced on multiple fronts.
In this month's Market Update, we detail a few of the "Class-D Products Getting Smarter" and then Stuart Yaniger discusses Class-D amplifiers from two of those companies: Purifi Audio and Orchard Audio. Also, Ward Maas details his visit to Purifi Audio. Dimitri Danyuk shares his "Fully Balanced Transconductance Preamplifier" project, Roger Russell is "Hunting the Elusive Transient," and Ed Simon concludes his "Powering Your Circuits" series.
There's a quiet revolution happening in audio amplification. Essentially it is the direct result of strong innovation in Class-D technology, with incremental improvements introduced on multiple fronts, together with the demanding requirements of new high-volume applications in mobile and personal audio, wireless speakers, and automotive audio. The reality is, in the consumer space at least, there was never so much activity in the segment. Learn more in our Audio Amplifiers Market Update.
Also in this edition of audioXpress, we discuss two of those disrupting companies: Purifi Audio from Denmark, founded by some of the best minds in audio; and Orchard Audio, a new US brand, the product of the creativity and entrepreneurship of Leonid (Leo) Ayzenshtat, in this case exploring the latest gallium nitride (GaN) semiconductor technology.
And to complement this extended and detailed review, Ward Maas visited the headquarters of Purifi Audio, in the Danish city of Roskilde, half an hour away from Copenhagen.
And for the builders among us, Dimitri Danyuk is back this month with a fully balanced transconductance preamplifier, where he proposes an open loop design with a fully symmetrical topology, built from readily available through-hole parts. And for the preamplifier stage, Danyuk borrowed ideas from the legendary Blowtorch design by Curl-Thompson-Crump (CTC - John Curl, Carl Thompson, and Bob Crump). A really nice project from a top expert in this field.
And for this edition there's much more on the speaker and audio electronics front, including a very interesting article by veteran engineer Roger Russell, on "Hunting the Elusive Transient."
And from cutting-edge signal processing to the latest in audio electronics, Michael Steffes explains how to convert a spectral 1/f noise profile to the industry standard 0.1 Hz to 10 Hz Vpp noise along with a typical measurement preamplifier, used to detect low-frequency or the so-called popcorn (burst) noise.
To contrast with the cutting-edge overview of the modern audio amplifiers, Richard Honeycutt writes this months about The Development of Hollow-State Live Sound Amplifiers, revisiting the origins and the early inventions that formed the foundation of the live sound equipment we have today for our concerts, festivals, and public address systems.
Plus, Ed Simon wraps up the sixth and final article in his "Powering Your Circuits" article series on ways to power circuits, which has covered battery power, AC power supplies, DC power regulation, and diodes. In the conclusion of his series, Ed Simon covers the unavoidable topic of transformers and safety issues.
And there's so much more in this edition. For those audio enthusiasts looking for a good read, which examines how Bill Hanley's contributions to the outdoor live sound helped shape the music production industry, Richard Honeycutt suggests taking a look at John Kane’s book: The Last Seat in the House—The Story of Hanley Sound.
In his Sound Control column, Richard Honeycutt explores the principles that apply at the acoustical-electroacoustical interface between the room and the speakers as they relate to full-range systems.
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