May 2017 is a strong edition for all tube and audio electronics aficionados. As our editorial highlights, audioXpress carries on the Glass Audio tradition up to the present day. When Glass Audio was founded in 1989, solid-state equipment was a dominant focus and it was thought the interest in tubes would diminish. Quite the opposite has happened, and one of our cover stories illustrates why.This month we bring an exclusive R&D Story on the revival of the Dynaco brand and the development project of the new Dynaco ST-70 Series 3 stereo tube amplifier. The article is written by Dan Fraser, the Senior Design Engineer responsible for the Radial Engineering team who designed the new generation Dynaco ST-70 Series 3. An historical revival.
Since acquiring the legendary Hafler and Dynaco brands in 2014, Radial Engineering has been carefully working on the Dynaco ST-70 Series 3 tube amplifier. In an effort to create a truly worthy successor of one of the most successful tube amplifiers of all time, its design team has considered all the options needed to meet the expectations that come with David Hafler’s work. As Fraser writes, “Tens of thousands of original Dynaco tube amplifiers are still in use around the world. In fact, more quality music systems have included Dynaco tube preamps and power amplifiers than any other combination. The original Dynaco Stereo 70 is a true classic still regarded with awe by audio enthusiasts worldwide. This “new ST-70 Series 3” reflects the illustrious history of Dynaco’s involvement with vacuum tube designs as well as the latest advances in vacuum tube technology. We like to think of the ST-70 Series 3 as the update that David Hafler would have made if he were alive today.”
Next up, we jump straight into the future of tubes, with an overview of the Korg Nutube 6P1. As Pete Millet writes, the Korg Nutube 6P1 is a new, miniature, low-power dual directly-heated triode device. It was developed by Korg (of musical instrument fame) and Noritake Itron, a manufacturer of vacuum fluorescent displays, in Japan. Although it is a true directly heated triode, it is manufactured differently than traditional vacuum tubes, which gives it some unique attributes.
And for our DIY and audio electronics enthusiasts with an urge for hands-on experiences, this edition includes some really high level projects.
We start with a great tube amplifier project, The Circlotron, by Gerhard Haas. In this exclusive project for audioXpress, he proposes a unique approach to famous 1950s circuit principle for tube power amplifiers. The “Circlotron” was preferably designed for studio applications, but Haas managed to reinvent the topology to create a truly high-end tube marvel that any enthusiast will want to build, using two or four EL 34, KT 88, or KT 120 tubes on the output stage.
Another great DY project, the Kismet 5 - 20th anniversary edition, comes from Fabio Camorani. As Camorani explains, “My first Kismet amplifier project appeared in Glass Audio in 1996. I could never have imagined that 20 years later I would be writing about the fifth generation of the Kismet amplifier!” And it was worth the effort, because the Kismet 5 is another historical amplifier for tube enthusiasts.
Next, Scott Dorsey wrote an article titled, “Inrush Current Protection for Tube Amps,” in which he discusses how to balance transformers, rectifiers, and filter capacitors to increase the lifespan of components, reduce mechanical and thermal stress, and protect older tubes.
Finally, our Glass Audio special concludes with a great project article from tube expert Bruce Brown, sharing his experience with some small but essential projects in “Four Gadgets for Tube Enthusiasts.” The four “gadgets” include: a line voltage monitor, a variable resistance box for setting bias and decoupling resistor values, an inexpensive bias meter, and a simple tool for determining the impedance of unknown transformers.
Focusing on today’s cutting-edge audio technology, following our article about ICEpower, which kick started our Amplifier Series of articles in April 2017, this month we discuss the Swedish brand Anaview, now part of the ETAL Group, and its latest Class D modules. This article from Ward Maas combines an overview of Anaview’s most recent amplifier modules, recaps some of the company’s corporate history and technology, and ends with some hands-on experience with its latest-generation and surprisingly small, ALA0080 Class-D module.
Continuing our series on Streaming Music Experiences, which evaluates the quality of streaming music services, Part 5 explores the powerful combination of Sonos whole-home solutions and Deezer service. Ron Tipton clearly enjoyed this one.
In our Hollow-State column, Richard Honeycutt examines the evolution in Phonograph Recording and Playback Electronics with some truly classic circuits. This is one of those reference articles that we are certain all of our readers will enjoy.audioXpress May 2017 is truly a Glass Audio Special edition for collectors.
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