You Can DIY! X-Altra MC-MM RIAA EQ Preamp - Part 2

For all our readers who started following the X-Altra Moving Coil/Moving Magnet RIAA EQ Preamplifier DIY project publish in the February 2021 edition of audioXpress, we have the final pieces. In this second article, Andrew C. Russell details the Moving Magnet EQ stage, system gain amplifier and filters, along with the system’s power supply unit. The article concludes with some measurements.

In this DIY project, Andrew C. Russell proposes the X-Altra, a highly refined Moving Coil/Moving Magnet RIAA EQ Preamplifier. This high-performance phono equalizer features an ultra-low noise LSK389B JFET from Linear Systems in the MM front end with switchable gain and resistive loading. This article was originally published in audioXpress, February 2021.

Our May 2021 Glass Audio Special edition is certain to inform and inspire you. We reveal what is happening at Western Electric's new Rossville Works in Georgia, where production of 300B tubes is ongoing, we explain how to draw tube load lines, and we offer a valuable preamplifier design that enables you to compare the sound of tube and solid-state circuits from the same audio source. There's also a versatile stereo tube amplifier design to build, and plenty more audio electronics theory and practice in this edition. Now available online and in print.

audioXpress February 2021 explains why Microphones have gained Essential Status, and how microphones have a foundational contribution to voice front-ends. Erica Yorga details how Thousands of Virtual Microphones can solve audio conferencing challenges, and Mike Meechan explains how to design high-performance microphone preamplifiers. Brent Butterworth reviews the Widex Moment mRIC RD hearing aids to understand the differences and similarities in the critical sound experience. Michael Steffes explains how to increase the output current for an audio op-amp, and Andrew C. Russell details the X-Altra, a high-performance MC/MM phono equalizer DIY project. Now available in print and digital.

Ending the year with great content, as we do 12 times per year, audioXpress December 2020 is now available in print and online. In this edition, we pay tribute to Jeff Bagby, explore the QuantAsylum QA401 audio analyzer combined with the new QA451 programmable load, and explain the process of measuring wireless audio products using multi-tone testing. Plus, Brewster LaMacchia expands on A2B designs, Gary Galo details how to improve low-output moving-coil cartridges with his Jensen-based step-up transformer, and Mike Harkins reviews the versatile Puffin Phono DSP by Parks Audio. And much more, now available!

4OurEars.com, an authorized seller of Grado products based in Staten Island, New York, launched a new look online store following a surge in demand for key Grado headphones and turntable cartridges in 2020. Following the launch of the brand's first true wireless headphone GT220 in October 2020, and The Hemp Headphone, back in June, this new official Grado online store will make products more easily available to everyone during challenging times.

A renowned manufacturer of phono cartridges and tonearms since the company's foundation in Japan, Audio-Technica announced the introduction of its AT-PEQ30 phono equalizer, designed to add a phono stage to a turntable setup or to serve as an upgrade from a turntable's built-in phono preamp. The AT-PEQ30 accommodates MM (moving magnet) and MC (moving coil) phono cartridges and according to the company, its circuits were designed for "superlative sound quality."

It must be tough to have a product ready, a Kickstarter campaign planned, and then being faced with a global shutdown. That is what happened with Canadian company, Six Acoustic, who recently launched the York, an "ultra" high fidelity phono preamplifier targeting new generations of vinyl enthusiasts looking for an extra level of audio performance that doesn't cost a fortune. And what is “ultra” high fidelity you might ask? According to Steve Meszlenyi, the company founder, it's a level of transparency where noise and distortion are “undetectable to the human ear and nearly impossible to measure with the most sophisticated instrumentation.”

In this final article of the four-part series, Andy Lewis expands upon the Back EMF concepts hinted at in the previous three articles in this series. This article explores the Electrical and Newtonian filters and their intersections, observations on reactive parallel filters as pertains to Back EMF and energy losses. The theories can be applied to virtually all areas of loudspeaker design. This article was originally published in audioXpress, November 2018.

In the third article of the four-part series, Andy Lewis continues his fascinating exploration of Back EMF Phase Relationships in Moving-Coil Loudspeakers. The author discusses what causes Back EMF to simulate inductor, capacitor, or resistor (LCR) components, and explores the concept of slip, in order to explain how and why it causes the impedance to be inductive, resistive, or capacitive, depending on frequency. This article was originally published in audioXpress, July 2018