Practical Test & Measurement - Stop Worrying About Coupling Capacitors!

Another great research article from Ethan Winer, where he designed a simple device that measures capacitor distortion using a USB sound card and free software to try and determine the importance of high-quality capacitors in the signal path. This article details the results of his tests with different capacitor types. This article was originally published in audioXpress, May 2020.

In this edition, audioXpress pays tribute to one of its most esteemed and prolific writers, Ron Tipton (1936–2018). In our cover feature, Scott Dorsey details his fascinating visit to the Library of Congress National Audio-Visual Conservation Center. Tom Perazella concludes the construction of his flagship Egg Speakers, Andy Lewis explains more about Back EMF, Peter Lehmann shares his time-alignment design for a two-way speaker, and Ethan Winer shares his experience with the affordable LabNation SmartScope USB oscilloscope. And that's just the start of another great edition, now available in print and online.

Another edition of audioXpress is now available, and this is another one of those issues you don't want to miss. On our cover, we call your attention to Tom Perazella's amazing Egg Speakers, a project which we continue to detail this month. Next, Stuart Yaniger reviews the latest Phantom Power Microphones from PCB Piezotronics, we discuss advanced test methods for improving Active Noise Cancellation headphone performance, and we interview Michael Goodman, CEntrance Founder and CEO. And there's more speaker projects, and great audio theory articles. Download it now or subscribe!

Peter Delos details how to add tone controls to a three-channel tube-based guitar preamplifier. The circuit is a versatile building block anyone can use for his or her own preamplifier applications. The project is implemented with three 12AX7 gain stages. The tone control at the final output is a standard bass, mid, treble control circuit found in many guitar amplifiers. This article was originally published in audioxpress, October 2014

Linear Audio Vol 12 is the 13th issue of a series of printed bookzines dedicated to technical audio and perception. Published every time Jan Didden things he has good enough content, Linear Audio is a vehicle for publishing technical information, developments and the state of the art of audio from a technical perspective. And this latest edition includes great articles by Chris Paul, Pierre Touzelet, Bill Waslo, Vincent Thiernesse, Hans Polak, Douglas Self and more…

In this often mentioned project published in audioXpress, April 2001, the author explores the advantages of composite amplifiers and provides a detailed description on how he built his 50W per channel unit. A composite amplifier (also called nested-feedback amplifiers) consists of two or more operational amplifiers cascaded together with a negative-feedback loop around the entire network. Read the complete article now available online.

Linear Audio Volume 11 is now available and includes excellent tutorials by Gary Galo, Hans Polak, Giovanni Stochino, Michael Kiwanuka, Guido Tent and Burkhard Vogel; articles on Circuit Design by Dimitri Danyuk and Douglas Self; articles on Room Acoustics by Hannes Allmaier and Bill Waslo, book reviews, and much more.

Linear Audio 9 is the tenth volume in a series of bookzines dedicated to audio technology and perception. Linear Audio offers a variety of articles written by an international team of authors and accredited academics on a plethora of engaging subjects, from tutorials to circuit and system design, test reports and book reviews.

Focal Press released the 2nd edition of Douglas Self’ Small Signal Audio Design originally published in 2010 and a valuable resource on audio circuitry, components and dealing with audio electronics. The second edition is expanded with ADCs and DACs, microcontrollers, more coverage of discrete op amp design, and a completely new chapter on headphone amplifiers.