It's Speaker Builder Time! Get Your Copy of audioXpress September 2018 Now!

Once again, audioXpress focuses on loudspeaker building, design, and testing in its September edition. We have three great speaker DIY projects that are certain to inspire our readers, Geoff Hill explains how speaker measurements are evolving under the latest Audio Engineering Society (AES) efforts, and Richard Honeycutt writes about modulation distortion in loudspeakers. We interviewed Crispin Herrod-Taylor, the designer of the amazing SoundBuckets portable speakers, we explain all you need to know about the latest HDMI Enhanced Audio Return Channel (eARC) specification, and Ward Maas tells the story of Infineon's new energy-efficient multi-level amplifiers.

Dayton Audio announced its new MK442 center channel speaker, designed to complement the Dayton Audio MK402 bookshelf speakers in a multi-channel home theater system. The new 80 watts RMS speaker features two 4" treated paper woofers optimized for low-frequency extension, with a centered 3/4" silk dome tweeter, offering a balanced combination for wide dispersion and impressive room-filling sound. The speaker features an attractive textured, black vinyl finish with 5-way binding posts.

Featuring the same build quality and articulation as the original top-rated MK402 speakers, Dayton Audio launched the added convenience of a wireless connection with the new Dayton Audio MK402BT Powered Bluetooth Bookshelf Speakers. The built-in amplifier on the MK402BT is able to provide up to 80 watts of max output power, while a local control panel allows users to change tracks, volume, and even pause/play songs directly from the speaker itself.

Dayton Audio announced the release of the DTA-2.1BT 100W Class D Amplifier with Bluetooth, a discrete whole system amplifier that provides output for two speakers and a passive subwoofer, which allows for a compact 2.1 setup in virtually any room whether it be an office, bedroom, or even a small home theater. The 2 x 50W output power is more than enough for most bookshelf speakers, and the subwoofer output of 100W is ideal for a small scale subwoofer.

Part of audioXpress Speaker Focus edition in September 2017, this article by Don Keele, Jr. reminds us of how things evolved in speaker design, revisiting a subwoofer project that uses an Electro-Voice 30W 30" woofer from 1975! In "True Bass in a Large Space," Keele writes, "Getting true bass in a small place is quite easy and straightforward today, but back in 1975, it was not!"

This year we thought our readers would like to know which of the topics and stories published online in 2017 were the most popular for our community. We looked at the most-read articles of 2017 in audioXpress.com (which also includes selected articles from Voice Coil magazine), and we created this Top 10 list of news stories and online articles. Here are the results!

This month’s Test Bench samples came from US OEM, Dayton Audio. I received a home audio 6.5” woofer, the DSA175, from the brand’s popular Designer Series of aluminum cone woofers. Each product in this line incorporates proprietary stamped steel frame with a thin mounting lip that enables front mounting without insetting the driver (surface mounted), high relative XMAX, with paper cones for the DS series and aluminum cones for the DSA series. This article was originally published in Voice Coil, December 2016.

Published in two separate parts in audioXpress October and November 2007, this hybrid amp design is a detailed and interesting project, frequently referenced by other DIY audio enthusiasts. We thought it was time to make it available online in its entirety, in the best possible quality. The article discusses the unity-gain, single-ended MOSFET output stage, the valve voltage amplification stage and wraps up with the power supplies, printed circuit boards, and construction.

Parts Express will hold its annual Midwest AudioFest from July 14–15, 2017 at Parts Express’ headquarters in Springboro (Dayton), OH. The event includes the Parts Express Warehouse Tent Sale, an Audio Swap Meet, a Mobile Electronics Competition Association (MECA) sponsored Auto Sound Competition, and the highlight of the event — the DIY Speaker Design Competition.

This edition of Test Bench characterizes Dayton Audio’s new 6” diameter ultra-low-profile midwoofer, the LW150-4. This is a new ultrathin profile cone 6” diameter midbass driver featuring a six-spoke cast-aluminum frame with a 1.5” total depth. The depth reduction is significant as the motor assembly is housed inside the frame and uses a neodymium slug and a 1.5” diameter return cup that incorporates a T-pole. This article was originally published in Voice Coil, March 2016.