The Many Takes of Audio Amplifiers in audioXpress July 2022

Read audioXpress July 2022 to learn the latest about Audio Amplification technology, an interesting perspective on audio bandwidth measurements, and read the AXPONA 2022 report. On DIY audio, this issue offers a solid-state, modular preamplifier project by Bruce Heran, the Egg Speaker Amp and System by Reinhardt Metz, and how to achieve a triode sound by Richard Honeycutt. And Ethan Winer describes the input stages for his Guitar-Controlled Synthesizer project.

Danish audio powerhouse Purifi Audio is not showing any intention of slowing down its efforts to push innovation further in both audio amplification and speaker transducers. Adding to the original formula - featuring proprietary fiber paper cones - used in the successful PTT4.0X and PTT6.5X midbass drivers, Purifi now announced a new aluminum-cone version of the PTT6.5X, delivering extended frequency range with ultra low distortion for superior midrange performance.

This Test Bench addresses Purifi Audio’s PTT4.0X04-NFA-01 4” midbass, which is very similar to the PTT6.5X reviewed in Voice Coil July 2021, and includes the same constant Sd surround and low magnetic hysteresis motor design. The distinct cone assembly for this driver consists of a flat profile paper cone made with a proprietary fiber mix, a concave dust cap that covers about 90% of the cone surface, plus the addition of a V-shaped edge reinforcing ring glued around the outside rim of the back side of the cone. Compliance is provided by a unique NBR surround, which as in the PTT6.5X surround, deserves to be explored, motivating Vance to discuss it with Purifi’s co-founder Lars Risbo.

NAD Electronics took value and audio performance to a whole new level with the launch of its new M23 Masters Series stereo amplifier featuring once again Purifi Eigentakt amplifier technology. The M23 Hybrid Digital stereo power amplifier (US $3499 MSRP), builds on the design first introduced in the acclaimed M33 BluOS Streaming Amplifier - described by NAD as "a once-in-a-decade amplifier innovation that will define the pinnacle of power and performance in the category for years to come."

We looked at the most-read articles of 2021 in audioXpress.com (including selected articles from Voice Coil magazine), and we created this Top 10 list of news stories and online articles. 2021 expanded slightly on the record-breaking year that was 2020 for audioXpress.com, in terms of number of visits and regular users of the website. Visitors from all over the world returned more often to read the more than 7,700 stories available. Which of the topics and stories published online in 2021 were the most popular? Here are the results!

Sonarworks has announced that its SoundID Reference correction software will now be integrated into the highly acclaimed Jones-Scanlon Studio Monitors. The partnership with Wayne Jones Audio, an Australian manufacturer of bass guitar speaker cabinets and high-end studio monitors, allowed the first direct integration of the calibration software to run straight from the monitor's built-in DSP SHARC processors. SoundID Reference (Reference 4 software), will now be integrated into select Wayne Jones Audio monitors.

This edition celebrates 35 years of Voice Coil, the Periodical for the Loudspeaker Industry. We discuss a new earphone technology for Balanced Frequency Range, Mike Klasco writes about Subwoofers and Bass, and James Croft reviews a new loudspeaker patent from Tymphany. Finally, Vance Dickason places Purifi Audio’s PTT4.0X04-NFA-01 Home Audio Midbass, and Eighteen Sound’s AMT200P AMT driver and XMT200 waveguide on the Test Bench. Now available in print or download.

In this article for Voice Coil, the two co-founders of Purifi Audio share some details about the company's unique research with loudspeakers, and reveal their findings in looking for the roots of speaker nonlinearities and distortion mechanisms. A research effort that the authors believe deserves consideration from the industry, as a new set of standard parameters that should be included in datasheets. This article was originally published in Voice Coil, August 2021.

The Purifi Audio PTT6.5X04-NFA-01 midbass transducer is an over-achiever, and to help understand why, Dickason talks with Lars Risbo about the research and thought process that lead to many of the features found in this woofer. Including the unique cone assembly that consists of a mildly curvilinear paper cone made with a proprietary fiber mix, a 3.13” concave dust cap, and a V-shaped edge reinforcing ring, the NBR surround, and what Dickason calls "probably the most unique surround in the history of Voice Coil’s Test Bench. This article was published in Voice Coil July 2021.

After reviewing the compact but mighty M10 Masters Series streaming amplifier from NAD Electronics, Stuart Yaniger simply had to try the new flagship NAD M33 Masters streaming DAC amplifier. This was the first mainstream product to implement the Purifi Audio Eigentakt (self-clocking) amplifier modules, but there is a whole lot more to make it a very complete package for a musical life. The article, published in audioXpress, July 2021, reviews the experience and performance measurements.