All items tagged with March 2025 (10)

Audio THD with QSPICE: An Interview with Mike Engelhardt

July 23, 2025 by Tim McCune

Audio THD with QSPICE: An Interview with Mike Engelhardt

The creator of LTspice has designed a new and much improved simulation tool suite called QSPICE (the Q is for Qorvo, the company that supported the new effort). Mike Engelhardt, physicist, analog engineer, and entrepreneur talked to Tim McCune, former president of Linear Systems, to discuss how QSPICE can help solve many issues that audio designers simulating their circuits might confront.

You Can DIY: A New Op-Amp for Phono Preamps - Part 2 - Development and Measurements

July 9, 2025 by Brian Lowe

You Can DIY: A New Op-Amp for Phono Preamps - Part 2 - Development and Measurements

Brian Lowe (Belleson) developed a unique custom-designed transconductance amplifier (Bel Amp) with fully differential (balanced) low-noise JFET inputs and current output. it offers 50dB of current gain prior to any voltage excursion, virtually eliminating distortion caused by voltage-dependent node capacitance exhibited by more conventional approaches. This is the second article detailing the op-amp design, containing simulations and measurements.

Test Bench: GAIT BGD-D72-64-4-0A1 Glass Diaphragm 1" Dome Tweeter

July 2, 2025 by Vance Dickason

Test Bench: GAIT BGD-D72-64-4-0A1 Glass Diaphragm 1" Dome Tweeter

Glass Acoustic Innovations Technologies (GAIT) is a company from Taiwan and a renowned specialist in Ultra-Thin Glass (UTG) diaphragm technology, quickly gaining recognition in hifi and high-end audio circles. This 1" dome super tweeter uses a unique glass diaphragm formed using a chemical strengthening process, and includes a 1” voice coil and neodymium magnet motor, assembled with an injection-molded plastic faceplate, a phase plug, and a damped rear chamber.

Test Bench: Dayton Audio’s Ultimax II 8-22 8” Subwoofer

June 24, 2025 by Vance Dickason

Test Bench: Dayton Audio’s Ultimax II 8-22 8” Subwoofer

This powerful Dayton Audio Ultimax II 8-22 8" subwoofer from the company's recently upgraded series maintains many common features with the original Ultimax drivers. After having examined the Ultimax II 10" version in January 2025, this Test Bench looks at the new 8" version where the very stiff and thick carbon fiber cone stands out with the NBR surround, assisted by the two flat 6" diameter cloth spiders.

Practical Test & Measurement Testing Power Amplifiers

June 17, 2025 by Adam Liberman

Practical Test & Measurement Testing Power Amplifiers

Power amplifiers present a unique set of testing challenges that are usually not encountered with digital or low-level analog circuits, as they must supply significant current as well as voltage to their loads. This comprehensive checklist on what is needed for testing power amplifiers covers the fundamental measurements, with specifics on how to best accomplish the tests using Audio Precision's APx series audio analyzers and APx500 measurement software.

Practical Test & Measurement: Measuring HDMI Audio

June 11, 2025 by Steve Temme

Practical Test & Measurement: Measuring HDMI Audio

From its origins in 2002 as a new, smaller connector for HDTV, improving upon DVI and adding audio capability and consumer electronics control functions, High-Definition Multimedia Interface (HDMI) continuously evolved over the years to become one of the most widely adopted interfaces. Not surprisingly, testing audio over HDMI, given its multiple options and configurations, still induces many questions when it comes to measurements. This article provides practical answers to those questions.

Enhancing Loudspeaker Efficiency and Bl(x) Symmetry with Virtual Voice Coil, Part 2

June 11, 2025 by Dario Cinanni

Enhancing Loudspeaker Efficiency and Bl(x) Symmetry with Virtual Voice Coil, Part 2

This is the second article detailing the design and simulation possibilities of the SpeakerLAB software and its Virtual Voice Coil (VVC) module for speaker designers. This simulation includes complete temperature management involved in loudspeaker calculus. The article also expands on audio transducer parameter prediction such as maximum SPL, analyzes key design components such as the magnetic circuit, and analyses the resulting simulated metrics that could help determine the highest efficiency.

Book Review: Zoran M. Dukic’s High End Tube Amplifiers Designer Tool Box

May 7, 2025 by Jan Didden

Book Review: Zoran M. Dukic’s High End Tube Amplifiers Designer Tool Box

This extensive, 428-page, self-published hardcover book, is much more than another publication on tube amplifiers. As Jan Didden discovered, this book contains all the knowledge needed to check how an input low-pass filter must be dimensioned, how to investigate the different resistor types and their properties, capacitor types, which tubes to use, how to bias them, and construct the load lines, and even how to design low-noise power supplies. A one-stop resource for tube-based audio power amplifiers, and clearly a work of love!

Loudspeaker Enclosures and Technologies. Voice Coil March 2025 is Now Available

February 28, 2025 by audioXpress Staff

Loudspeaker Enclosures and Technologies. Voice Coil March 2025 is Now Available

in this issue, Mike Klasco offers a renewed perspective about speaker cabinets and enclosures. Nora Wong compiled a highly sought-after Speaker Enclosure Vendors Directory for 2025. In Part 2 of his article, Dario Cinanni concludes his exploration of the SpeakerLAB software to simulate and predict speaker efficiency. In Test Bench, Vance Dickason characterizes the Dayton Audio Ultimax II 8-22 8" subwoofer and the very unique GAIT BGD-D72-64-4-0A1 glass diaphragm super tweeter.

Expand Your Audio Development Skills with audioXpress March 2025

February 12, 2025 by audioXpress Staff

Expand Your Audio Development Skills with audioXpress March 2025

audioXpress March 2025, focused on Test and Measurement and audio electronics, explains how to test Power Amplifiers, and how to measure HDMI Audio. Explore the possibilities of George Ntanavaras' SL-100 Sound Level Adjuster and Tom Perazella's Reinforced Speaker Protection solution. Read the interview with Mike Engelhardt, explaining everything about audio THD with QPSICE circuit simulation. Brian Lowe concludes its article on Op-Amp for Phono Preamps, and much more.