audioXpress March 2017, Focus on Test and Measurement, Now Available!

A long-standing tradition, audioXpress' Focus on Test and Measurement 2017 is now available. Start with a thorough review of Audio Precision’s new APx1701 Transducer Interface; explore the DIM-100 device for interfacing and measuring with sound cards; build an Audio Dummy Load; learn how to measure Harmonic Distortion and discover the effects of Community Noise and their measurements. And just how good TIDAL's streaming quality actually is? All that and more in audioXpress March 2017. Get your copy now.

This article focuses on the Poddwatt Series II stereo integrated valve amplifier, a project with roots that go back several years. The design continues to be relevant and to evolve. I call the basic design an “Oddwatt” because of its “odd” configuration, using two stages. This article was originally published in audioXpress, May 2013.

Recently, I got bitten by the nostalgia bug and picked up a pair of old factory-wired Dynaco ST70s in pretty nice condition. On one of the Dynaco ST70s, I installed a new 6GH8 driver board instead of dealing with the rare 7199 issue, and I designed a small (3” × 3”) PCB to combine the bias supply and added the LED bias-setting circuit. This article was originally published in audioXpress, April 2013.

This Test Bench focuses on a new and extremely clever variable Bl 12″ diameter guitar speaker from Eminence — the 12″ Maverick, from the Eminence Patriot series, which uses their new FDM technology (Flux Density Modulation) to allow some really desirable distortion characteristics that have become the signature of blues and rock guitar playing. This article was originally published in Voice Coil, January 2011.

In this reference article, published by audioXpress in 2008, Joe D’Appolito shares his experiments with loudspeaker evaluation. In the two parts of this article, D’Appolito tries to answer the question: “Of all the measurements available to the designer, which ones are the best predictors of listener preference?" In over 30 years of designing loudspeakers, I have found the following measurements taken as a group provide the strongest predictor of loudspeaker preference available to us today,” he states.

When this great tube amp project was published originally in Glass Audio magazine, Ed Dell wrote “Joseph Norwood Still is pushing the envelope. His most recent triode design, which features the Svetlana 6550s and Hammond transformers, establishes new output limits—up to 100W.” Indeed, this would become a very popular project at the time, and still is, considering the frequent references. This article was originally published in Glass Audio 3, 2000.

This Class A tube headphone amp project, which the author created for Vintage Audio, includes a 6SL7GT for the input stage and a 6AS7G for the driver, and is able to drive headphones with impedance at or above 64Ω. The article provides a full description of design fundamentals and some useful guidance on the construction process. The result, as the author describes, should be “a satisfying headphone amp that will provide years of enjoyment.” This article was originally published in audioXpress, June 2008.

In this show report for audioXpress, Oliver Masciarotte highlights some of new and notable products, from headphones and DACs to amplifiers and (some) speakers that caught his attention. “Held April 15–17, AXPONA 2016 was hopping, with attendance up 16% this year. The count settled at 5,934 attendees through the doors to see 400 exhibitors in Rosemont’s Westin O’Hare,” he starts. Read the full report now available online.

It’s very questionable that anyone would still be on the market for another USB 2.0 compact audio recording interface, given the market saturation and the transition to faster and lower-latency USB 3, Thunderbolt or even Ethernet alternatives already in the market. British company Audient believes there is still a chance and released the iD4, a single-channel unit featuring the company’s Class-A mic pre technology and good quality AD/DA converters for just $199.

In 2008, Nelson Pass submitted an article on its new F5 power amplifier design to audioXpress. At the time, he wrote: “I feel that it’s important to support AudioXpress, a magazine with which I have a 35 year history, and which also serves as a mainstay for the DIY community. Lately they have kindly printed projects that I had already posted on the web, but I decided that they deserve a little better than that.” Effectively, the F5 project was published in May 2008 and had a huge impact on the global DIY community and certainly contributed for the fact that audioXpress is still around today.