Ideas, Focus, and Innovation, Available with audioXpress November 2017

October 10 2017, 05:00
In this November 2017 edition of audioXpress, get an inside perspective of the Speaker Design Competition held during Midwest Audiofest 2017, promoted every year by Parts Express. Representing audioXpress as a jury on the competition, Thomas Perazella shares his impressions of the outstanding speaker designs presented this year and reviews the winners in the different categories. "If anyone thinks that DIY speakers cannot compete with the best commercial designs, I think they are very wrong," says Perazella. "The best entrants at this year’s Midwest Audiofest can hold their own against some of the higher-priced speakers I have heard and actually best many of them."
As another of our highlights for November 2017, we feature one of the most eagerly awaited reviews: the OPPO Digital UDP-205 4K Ultra HD Audiophile Blu-ray Disc Player. Already the author of previous reviews of OPPO Digital's prior generations of Blu-Ray players for audioXpress, Gary Galo explains why this is the 4K Ultra HD Blu-ray Disc player for which audio enthusiasts were waiting. The new UDP-205 features dual ES9038PRO Sabre DAC chips from ESS Technology, an improved HDMI audio clock, an asynchronous USB DAC with coaxial and optical inputs, a headphone amplifier, and a dedicated stereo output with XLR balanced connectors. Read it now!
In another review, Stuart Yaniger measures the new Ultimate Ears Pro Sound Tap Personal Monitoring System, a new device created by the leading in-ear monitor (IEM) brand that enables musicians to plug in their custom or universal IEMs and turn the existing stage monitor mix into an in-ear mix. See how this easy-to-use and extremely useful in-ear DI box behaves when relaying sound.
Focusing on audio processing, we feature a contributed article from Peter McCutcheon (ams AG) on "Considerations for the Optimum Digital ANC." This article discusses the key considerations of digital active noise cancellation for headphones and earphones including how to design a headphone for maximum noise cancellation performance and the design trade-offs involved.
We also address "Measurement of Devices that use AGC." The test and measurement of audio devices that feature built-in automatic gain control, also known as AGC, requires special care and attention. Adam Liberman (Audio Precision), explains why, and offers some advice on optimal test settings for amplifiers, recorders, signal processors, codecs, public address (PA) systems, audio workstations, and hearing aids.
And keeping with audioXpress' promise to bring you the Best in DIY, Dan Joffe (AkitikA) describes a 1 kHz oscillator with less than 2 PPM distortion. With sound reproduction equipment continuing to improve, distortion of less than 0.01% has become commonplace. To test equipment with distortion that low, you need a really low distortion sine wave oscillator. This article describes a DIY 1 kHz oscillator for less than $100.
And don't forget our regular columns. In his Sound Control column, dedicated to practical aspects of acoustics, Richard Honeycutt discusses how to tackle reverberation issues in performance spaces or any other type of room, explaining how to control too much reverberation and even how to add reverberation to specific sound sources. 
In his Hollow State Electronics column, Honeycutt offers the start of an exciting project of a small bass amplifier that he calls "The Bolger." Not only will the article series provide interesting details about tube-based instrument amplification in all its different components, but the articles will offer a complete DIY project that will please any bass player.
Finally, Ron Tipton continues to explore the practical aspects of sound reproduction, now focusing on the differences between vinyl and CD. In this second article of the series, Tipton continues to look at second harmonic to fundamental energy ratios for several different playback setups and doubles on the measurements to verify repeatable procedures.
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