audioXpress Magazine      September 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.

Comment
4 From The Editor's Desk
Beyond Stereo, Speakers, And Reproduced Sound Should the ultimate goal of a loudspeaker be to faithfully reproduce sound as it was originated at the source.
Editorial By J. Martins

Features
8 Parasound Halo JC 5 Stereo Power Amplifier
Traditional Goodness
By Oliver A. Masciarotte and Stuart Yaniger
Oliver A. Masciarotte was looking for an amplifier that he could
respect without emptying his bank account. Richard Schram
offered to send the Parasound JC 5, his company's largest
stereo power amplifier for evaluation. Anticipating the fun of enjoying
the pleasures of this John Curl design, Oliver accepted the
challenge, and Stuart Yaniger tested the JC 5 to confirm the
amplifier's merits with actual measurements.

Market Update — Speaker Technology
18 New Ways To Formulate Speakers
By Mike Klasco
This article looks at new companies, products, and inventions
that are pushing speaker design to new levels. From innovative
speaker designs and new transducer topologies to feed-forward
protection circuits, this is an overview of innovation happening
right in front of us.

Speaker Special Features
26 The Tetrahedral Test Chamber Story (Part 1)
Recognizing the Need for Consistent Measurements
By Geoff Hill
Geoff Hill revisits the development of the Tetrahedral
Test Chamber (TTC). This innovative loudspeaker test
chamber, scalable to any size of loudspeaker driver,
is now defined in international standards and in use
throughout the world.

34 Parameter Estimation And Box Simulation With Speakerbench (Part 2)
Introducing Speakerbench
By Claus Futtrup and Jeff Candy
In Part 1 of this article, the authors discussed the
difficulties in estimating cabinet losses using the
classical Thiele-Small framework, and a solution using
an advanced transducer model. In this second article,
the authors present the online speaker design tool
Speakerbench as an accurate and practical approach to
this problem.

40 Roger Russell (1935—2021)
A Lifetime of Passion for Sound

44 The Sound Of A Column
By Roger Russell
Signaling Roger's passing, we revisit his work, and
hear about his impact on the lives of those who
knew him, and his contributions to the loudspeaker
industry. As part of the tribute, we are also publishing
the last article that he submitted to audioXpress prior
to his death, "The Sound of a Column."

50 Dual Speaker Columns
By Ken Bird
In this simple speaker project, our veteran speaker
builder and longtime contributor to audioXpress
proposes a versatile dual speaker column design.
These affordable speakers are a functional choice
for home listening and matching with home
entertainment systems and can be easily modified
with different driver choices.

54 Central-Channel Upmixer Delivers Stereo Nirvana
By Peter H. Lehmann
The signal processing unit described in this article
derives a center channel from standard stereo music
recordings. Output of the unit is fed to a loudspeaker
positioned laterally in the middle between left and
right loudspeakers of a stereo system. Reproduction
by this center loudspeaker supplements the quality
and localization of the phantom center image.

Hollow-State Electronics
62 The Development Of Hollow-State Home Music Systems
By Richard Honeycutt
An enjoyable journey back in time to revisit the early sound and music reproduction systems
for home listening.

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