An All-JFET Amplifier: Exploring Modern JFETs Circuits

This article describes the design and performance of a high-quality DC-coupled all-JFET amplifier. The circuit was inspired by John Curl and Erno Borbely designs and was built with readily available junction-gate field-effect transistor (JFETs) from Linear Systems. The input stage is the the complementary JFET differential pair, the second stage is symmetrical differential amplifier with two pairs of opposite polarity JFETs, and the output stage is a complementary source follower. The amplifier can drive loads up to 150Ω. This article was originally published in audioXpress, October 2017.

This Test Bench article examines the CQQ76 ribbon tweeter from BoZhen New Audio Lab. The original device BoZhen sent to Voice Coil in 2013, the CQ76 ribbon tweeter, was portrayed in the company literature as a unique (patent number ZL200820128865.6) ribbon tweeter design. “CQ” is an acronym in Chinese pinyin “Chuan-dao-pian Qu-dong,” which in English means “ribbon loudspeaker based on slice-conducted technology.” This article was originally published in Voice Coil, October 2017.

For this month’s Test Bench article, I examined the 745NEOBe, a pro sound 1.4” beryllium compression driver from Radian Audio Engineering. Radian Audio was founded in 1988 by its president, Dr. Richard Kontrimas, however, Kontrimas has since retired and the company is under new ownership, based in Orange, CA. With more than two decades of success under its belt, Radian Audio is now entering its third decade as a pro sound manufacturer. This article was originally published in Voice Coil, October 2017.

Ethan Winer explains how to "Build the Mojo Maestro," a simple device that allows "subtle distortion" or saturation from any recording or track. Just using two diodes and a few resistors, Winer designed this simple box using the free LTspice simulation software and only half a dozen parts. And the results can be heard on the audioXpress website, with Winer playing multiple instruments, with and without the "Mojo effect." This article was originally published in audioXpress, October 2017.

Getting ready for another edition of the AES Convention in New York City, and many other October shows, this edition of Voice Coil is another one for the records, including an extensive directory of Amplifier and DSP Vendors, and a review of Bose's latest patent of a new bass reflex and tuned pipe enclosure. In Test Bench, Vance Dickason characterizes the 745NEOBe, a pro sound 1.4” beryllium compression driver from Radian Audio, and the updated CQQ76 ribbon tweeter from BoZhen New Audio Lab.

audioXpress October 2017 brings another strong combination of inside perspective, educational value, and practical projects. In this edition, Christopher Paul explains his Denali Voltage Reference low impedance amplifier design, Stuart Yaniger does a full objective review of the surprising Markaudio-Sota Viotti speakers, we explain how Harman is using COMSOL Multiphysics simulation software on car audio, Richard Honeycutt explains the story of the Circlotron amplifiers and so much more...