audioXpress Magazine      December 2021

  audioXpress remains the authority on audio and reproduced sound by connecting manufacturers and distributors with developers, buyers and consultants around the globe! It's readers are the audio product designers, consultants, integrators, DIY enthusiasts, opinion leaders and your best customers. All of them agree that the coverage of trending topics, unique in the audio industry, make audioXpress a must read.

Every month, audioXpress combines the best educational articles on topic such audio electronics, speaker and headphone design, amplifiers (from tube to Class D), acoustics, practical test and measurement, audio engineering praxis, and standards. audioXpress provides inside stories on new audio developments, on R&D Stories, the most complete objective reviews of innovative products and software, and selects some of the best DIY audio projects from worldwide experts.

From The Editor's Desk
4 A New Chapter In Audio Development
We addressed speaker optimizations, room correction,
new sound response emulation concepts, variable acoustics,
and sound calibration for any targeted audio reproduction system. 
Editorial By J. Martins

5 Client Index

Features
24 Dayton Audio DAX88
An Eight-Source, Eight-Zone Distributed Audio Matrix Amplifier
Setting Up a Whole-House Audio System
By Thomas Perazella
In this article, Thomas Perazella explores the
possibilities offered by the Dayton Audio DAX88
Distributed Audio Matrix Amplifier, while setting up a
whole-house audio system in his own home.

30 Directivity Measurement Of In-Wall Loudspeakers
By Christian Bellmann, Ruben Hauschild,
and Mattia Cobianchi
This article details how Kippel's holographic
measurement approach for directivity testing provides
comprehensive, easy-to-interpret data that is relevant
for transducer engineers as well as audio system
designers.

36 Improved Loudspeaker Crossover For the Parts Express "Solstice" Kit
By Richard Modafferi
In this project, the author describes a new crossover
design and build project, originally created as a
retrofit for the already-built Solstice Tower Speaker
Kits sold by Parts Express.

46 Thinking About DC Power Supplies (Part 1)
Circuits Used as Potential Power Sources
By Frans de Wit
This article was written with the ambitious intent to
discuss multiple circuit types for "power supplies" or
better "power sources" for high-end audio systems.

52 Cascodes, Folded Cascodes, And Current Mirrors (Part 3)
Using a Test Circuit
By Morty Tarr
In the first two parts of this article series, Morty Tarr
discussed the technical merits of cascodes and related
circuits. Many of these circuits benefit from matched
(FET) devices. Matching is not hard, but you need to
set up a simple test circuit.

58 Simple Xtal-Based Motor Control For Turntables
By Michel Nieuwenhuizen
The author proposes a special circuit for motor
control using an Arduino microcontroller board that
is likely to appeal to more technical DIYers and vinyl
enthusiasts, as it offers a great way to deal with
issues in mains frequency for critical record listening.

Market Update — Room Correction And
Speaker Calibration Technologies
8 The Self-Calibrating Loudspeaker
By J. Martins
This Market Update explores available technologies and
platforms applied to room response correction and
speaker adjustments, looking at industry efforts toward
configurable audio processing and room compensation approaches
for advanced, adjustable active speakers.

20 The Arrival Of Spatial Room Correction Technology
By Lars-Johan Brännmark, PhD
Dirac Research's Chief Scientist describes an approach
to applying DSP room correction to complex multichannel
setups, intended for immersive audio reproduction.

Columns
Sound Control
43 Miking the Audience
By Richard Honeycutt
Ever since the beginning of modern architectural acoustics,
experts have focused on reverberation time as the most
important parameter in auditorium performance. However,
Richard Honeycutt believes that determining the direction
from which sound arrives at the listeners' ears might be the
real key to great acoustics.

Hollow-State Electronics
62 Subminiature Tubes and Effectrode Pedals
By Richard Honeycutt
Subminiature vacuum tubes have an interesting history that
is directly linked with portable equipment requirements.
Richard Honeycutt talks to Phil Taylor, the founder of Effectrode
Thermionic, a company creatively exploring miniature and
subminiature vacuum tubes for guitar effect pedals.

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