For this July 2023 issue, we have compiled another extensive Market Update on audio amplification, at a time when Class-D is not only dominating but improving exponentially. 2023 is revealing important announcements and product launches and there's a lot to discuss. With the supply chain disruptions extending into 2023, causing delays and even forcing redesigns, in this update we have fewer but very relevant new products, together with important technology updates, including GaN-based Class-D amplifiers. Overall, a broad overview of the market evolution in this core segment of the audio industry, covering all markets and application segments.And on this topic, we feature the highly anticipated review of the Hypex Nilai500DIY 500W Mono Power Amplifier Kit, which Stuart Yaniger found to be a new DIY benchmark. The Nilai500DIY mono amplifier kit is specified to deliver 500W with 1% THD at 4 ohms, improves output noise and idle losses significantly, and comes with a discrete buffer stage and voltage regulators, just like the venerable Hypex NC400 module it will be replacing. This issue offers an extensive review with measurements of the full kit, including the PS500 DIY power supply and DIYClassD preamplifier kit.
In this issue, audioXpress also visited Grimm Audio in The Netherlands to learn more about the people behind the company, its products, and philosophy. Because there's nothing better to learn about product development than to visit an audio company and learn from its history and business journey. As a relatively young company, Grimm Audio has consistently put its mark on both the pro audio and hi-fi scene and Jan Didden shares what he learned about its unique in-house development philosophy.
Next up, Rens Tellers interviews Rémi Guastavino at GRAS Sound & Vibration, to uncover the details of the new EQset measurement microphone series. This important innovation in measurement microphones is directly targeted at production lines and allows users to reduce spread in specifications compared to what's possible with more traditional microphones. GRAS EQset microphones are powered either by phantom or CCP, manufactured in Denmark, and designed to reduce the risk of measurement errors. We hear directly from GRAS' Director of Product Management about the story of the development and the series' first product on the market.
The second Fresh From the Bench article in this issue reviews the WiiM Pro Music Streamer. This is the latest in Linkplay's WiiM home ecosystem, which also includes the WiiM Mini streamer. Linkplay Technology is recognized for its widely adopted wireless audio streaming modules, smart home, and connected AI products. The new WiiM Pro is a versatile music streamer that combines all the latest technologies and protocols, making it the ultimate (and most affordable) home audio hub available. audioXpress received a pre-launch unit to review subjectively and objectively. Oliver Masciarotte shares his experience and Stuart Yaniger does the measurements.
In Simulation Techniques, we have another article from René Christensen about Room Gain - a term not used in acoustics textbooks as such. Room acoustics is naturally often discussed in the hi-fi community, since the room you put your loudspeakers in will heavily influence the sound that reaches your ears, both at low and high frequencies. In these discussions the term "room gain" sometimes comes up. This article was inspired by Erik Wiederholtz (CTO of Perlisten Audio) and his interest in the topic, and he was kind enough to provide measurements and photos from his own listening room for a sealed subwoofer as well as for a vented subwoofer.
From room acoustics to car acoustics, Philipp Paul Klose shares his experience of Acoustical Measurement and DSP Application in Automotive Audio. In this issue, he addresses challenging frequency bands, sound philosophy, fine tuning of the parameters, and NVH (noise, vibration, harshness) issues in car cabins. This is a continuation of his previous articles on measuring audio signals in the cabin and the basic setup of the DSP modules in the processing pipeline. Lessons that can even be applied to other challenging acoustic applications.
And for our speaker designer/builder audience, the July 2023 issue of audioXpress offers the first article by Gary Gesellchen (Vanatoo) in a sequence of articles discussing Bass Reflex Performance. Essentially, this series takes a novel approach to estimating the performance envelope available from ported loudspeakers, considering port and driver sizes and multiple applicable parameters, and comparison with the performance from a passive radiator. This article discusses the basic relationships and response types, the analysis approach, and the assumptions, before expanding to system analysis and a design example in subsequent articles. A series of Excel spreadsheets will be included later to allow the reader to experiment with different designs.
For those following the ongoing Power Transformer article series, this month Chuck Hansen writes about testing and the results that are obtained when looking at no-load excitation, designed to explore concerns whether the metal chassis on which a transformer is mounted will adversely affect its core losses. Another test compares a commercial 60Hz and a MIL-PRF-27 400Hz transformer with 115V AC VA ratings to measure the losses of each type at 400Hz. And finally, a third test compares different 60Hz transformers to measure electromagnetic field (EMF) exposures and the relative leakage flux.
In his Hollow State Electronics column, Richard Honeycutt shares a few chapters of his personal family history in Ten Decades of Home Music Systems, directly intertwined with the use of tube electronics and how these devices were crucial to the development of radio, television, sound recording, and reproduction. A fascinating journey through some early North American product examples and the evolution of home entertainment and amplification of musical instruments.
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