Audio Precision Expands Electronic Audio Testing with New APx516B Audio Analyzer

Audio Precision announced the new APx516B, a modular and affordable audio analyzer that expands electronic audio testing with even better performance and flexibility. The new Audio Precision APx516B Audio Analyzer is a budget-friendly solution to test both analog and digital audio with two analog generator/analyzer channels with performance suitable for testing consumer and professional audio devices, a digital interface module slot, and seamless integration with APx500 measurement software.

audioXpress December 2023 includes a market overview of multiroom audio, Brent Butterworth writes about new ways to measure ANC earbuds, and Stuart Yaniger measured the new Axign and GaN Systems Class-D audio amplifier board. Richard Honeycutt writes about tubes, BJTs, JFETs, MOSFETs, and ICs, and Dimitri Danyuk, discusses JFETs in audio circuits. Douglas Self explains how to optimize variable-frequency tone controls, and Jan Didden shares his eDD direct-drive amplifier project.

To reproduce an audio signal faithfully over the whole audio band, your circuit needs to have a bandwidth at least as large as the audio band. But that’s not the only requirement: your circuit needs to maintain that bandwidth from the lowest to the highest signal level. That’s where the crux lies: it is relatively easy to get a nice wide bandwidth for small signals, only to have it breakdown with high signal levels due to the dreaded slew rate limiting.

There are many aspects of negative feedback in audio that are the subject of continued discussion. Jan Didden continues to debunk more Audio Myths. This article addresses re-entrant distortion. The idea is that, since negative feedback sends some of the distorted output signal back to the input, this already-distorted signal would only get more distorted by going through the nonlinear amplifier, over and over again.

This article, originally published in The Audio Voice newsletter (#434), explores some practical experiments with Negative Feedback. "If I had a dollar for every time someone mentioned that negative feedback cannot work, because you cannot correct something after it happened, I would be a rich man," says Jan Didden. "Yes, it can be hard to get your head around feedback circuits for audio amplifiers. Yet, all it takes is to look around you," he adds.

The topology and the distribution of the wiring, partitioning between low power and high power circuits, grounding scheme, types of cables, protection techniques, and safety are important factors that must be considered to minimize the interference effects in audio amplifiers. This "tips and tricks" audio electronics article provides several details about inductive coupling effects in audio amplifiers and the simple way to minimize them.

An audio load is an essential piece of test equipment for any audio electronics workshop. Having created the very popular Heathkit ID-5252, more than 35 years ago, Gary Galo decided to design a new option for everyone to build now. The ID-5252 contains four 8Ω, 60W power resistors. The biggest limitation of the Heathkit load is power handling. Series and parallel combinations can be used to produce various resistances and power levels — up to 240W at 8Ω, using all four resistors. But, simultaneously testing both channels of a high-powered amplifier requires two ID-5252 units. Fortunately, the raw parts for building an audio load are easy to find.

Linear Integrated Systems, the world class producer of ultra-low-noise JFETS and other small-signal discrete semiconductors, has announced the re-release of its LSK489 discrete component with specialized parameter grading. The LSK489 is one of the world's premier JFETs optimized for use in high-end sensor front-end amplification designs, and the re-release in 2022 introduces improved manufacturing consistency.

John Melanson, senior technical fellow at Cirrus Logic, has been granted his 500th US patent, an achievement that places him among the world’s most prolific inventors. The Academy Award-winning engineer’s core contributions are within the field of audio and electronics, particularly the analog and mixed-signal technologies that have helped transform the analog world around us into the digital signals at the heart of today’s most advanced products.

Following the launch of three Ferrum products, HEM now announces Serce, a completely new digital audio platform that contains everything needed for a wide range of new hi-fi product developments. HEM is the audio manufacturing company from Poland that recently launched its own brand, Ferrum, with products aimed at high end audio enthusiasts. With Serce, HEM reinforces its position as a one-stop-shop solution for ODM/OEM audio electronics.