audioXpress Magazine      July 2020

  audioXpress remains the authority on audio and reproduced sound by connecting manufacturers and distributors with developers, buyers and consultants around the globe! It's readers are the audio product designers, consultants, integrators, DIY enthusiasts, opinion leaders and your best customers. All of them agree that the coverage of trending topics, unique in the audio industry, make audioXpress a must read.

Every month, audioXpress combines the best educational articles on topic such audio electronics, speaker and headphone design, amplifiers (from tube to Class D), acoustics, practical test and measurement, audio engineering praxis, and standards. audioXpress provides inside stories on new audio developments, on R&D Stories, the most complete objective reviews of innovative products and software, and selects some of the best DIY audio projects from worldwide experts.

Comment
4 From the Editor's Desk
Time To Embrace Evolution
Audio amplifiers — from the latest OEM amp modules and topologies to the most advanced and efficient devices and integrated circuits — target different applications, while developers focus on different requirements.
Editorial By J. Martins

8 Amplifiers Market Update
Class-D Products Getting Smarter
By J. Martins
In this Market Update, we discuss the latest trends in new Class-D solutions for audio amplifiers. They are currently at the core of every audio product and system design and they need to be smarter, more integrated, and more efficient than ever.

Features
16 A Look Inside The Last Seat in the House — The Story of Hanley Sound
Review by Richard Honeycutt
Richard Honeycutt reviews John Kane's book, which examines how Bill Hanley's contributions in outdoor live sound helped shape the music production industry.

18 A Tale of Two Class-D Amplifiers
Orchard Audio BOSC and Purifi Audio Eigentakt EVAL1
By Stuart Yaniger
Stuart Yaniger examines two new amplifier solutions from two new disrupting audio companies — Purifi Audio and Orchard Audio.

28 A Visit to Purifi Audio
Where the Magic Happens
By Ward Maas
Ward Maas had the opportunity to visit audio development house Purifi Audio and see where the magic happens.

44 Build a Fully Balanced Transconductance Preamplifier
By Dimitri Danyuk
The author shares details of his transconductance preamplifier design, borrowing inspiration from the legendary Blowtorch design by Curl-Thompson-Crump.

50 Hunting the Elusive
Transient
By Roger Russell
In this article, Roger Russell describes a few different types of drivers, systems, and tests that can help reveal the significance of transients.

56 Powering Your Circuits (Part 6)
Power Transformer Rating, Selection, Fusing, and Safety
By Ed Simon
In his final article on ways to power circuits, Ed Simon covers the unavoidable topic of transformers and safety issues.

Columns
Sound Control
34 Designing Speaker Systems for Live Sound
By Richard Honeycutt

Audio Scope
40 Low Frequency and Popcorn Noise in High-Speed Amplifiers
By Michael Steffes

Hollow-State Electronics
60 The Development of Hollow-State Live Sound Amplifiers
By Richard Honeycutt

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Previous Issues

2020
July