audioXpress Magazine May 2025

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audioXpress Magazine May 2025

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: Learn About The Music You Like
I have been using other higher-quality services to explore and compare
Editorial By J. Martins
On arrival in Shanghai, China, to attend a conference of the local audio industry association, I was promptly reminded of how powerful the digital curtain is in the region, being unable to use most of the online services that we rely upon for work. But in this geopolitically divided world, this also reminded me about the dangers of relying too much on the online music streaming services provided by a limited number of companies. In particular about Spotify, the largely dominant service currently blocked in China and which is today the TikTok of music services. It creates an addictive bubble for each individual based on their unfettered predilections, resulting in a vicious cycle from which it's very difficult to escape. For the musically enlightened, Spotify recommendations might seem relatively anodyne since we all know what we like, correct? We all have our list of favorite albums, and the artists we want to listen to most often, and obviously we want to listen to new music from those artists, and we want eventually to discover similar music, and similar artists to the albums and artists we like. That's precisely how Apple Music works, and that's why every time I go there, I have a feeling of going nowhere.
---> Learn About The Music You Like.

5 Supporting Companies

Features
8 78 RPM Returns
By Michael Harkins
Some things never die. We still relish vinyl disc
recordings at the end of the first quarter of the 21st
century. But now, 78 rpm re-emerges! A label from
Virginia is releasing original music in 78 rpm 12" vinyl
records. Find out if it is worth the effort.

44 Anomalies V2
Leaving the Trodden Speaker Path
By Ben (Wolf) Shaffer
This speaker DIY project uses an appealing
combination of Wavecor and SB Acoustics drivers in a
very unusual cabinet design and method, aptly named
the Anomalies V2. This version, a two-way with a
Double Bass Reflex cabinet alignment using passive
radiators, was presented at the annual InDIYana
event and this article offers the first complete
description of the concept.

50 Coffee Can Towers
By Ken Bird
Building a successful 2.1 speaker system using coffee
cans (audioXpress, October 2020) has inspired the
creation of a more ambitious follow-up project.
Consisting of five individual can enclosures per tower,
this three-way design was an interesting challenge,
even for an experienced speaker builder.

57 A Primer On Class-D Amplifiers
Part 2 — Practical Implementations
By Paul Marchese
The successful design of high-performance Class-D
amplifiers requires a sound understanding of the
basic concepts. In Part 1 of this article, we provided
a theoretical review of the Class-D concept. In
this second part, the author discusses a practical
implementation based on a TPA3255 Class-D
integrated amplifier.

Columns
Hollow-State Electronics
62 Do It Yourself With Tubes
By Richard Honeycutt
Ed Dell, founder of The Audio Amateur publications,
believed that combining professional expertise with
hobbyist interests in audio electronics could lead to
success. Reflecting on his own journey, Richard
Honeycutt emphasizes the importance of practical
experience and accessible resources for aspiring audio
electronics enthusiasts.

Glass Audio
16 The Ultra-Linear Power Amplifier
An Adventure Between Triode And Pentode
By Rudolf Moers
In 1951, David Hafler and Herbert Keroes introduced
a pentode power amplifier, in which a tap of the
primary transformer winding was connected to the screen
grid of the power pentode. (Alan Blumlein was the inventor.)
Fascinated by the far-ranging effects of such a seemingly
simple change, author Rudolf Moers decided to investigate.

28 Getting Less Gain From Tubes
By Merlin Blencowe
Getting small amounts of voltage gain in tube circuits is
rarely discussed in design books. Yet, reducing tube gain
is worth exploring and doesn't compromise the sound signature.

30 Micro Details In Push-Pull Output Transformers
By Hans Polak
Stumbling upon reports about the loss of micro details
due to a collapse of permeability in output transformers
at low levels, driven by his inquisitive nature, Hans Polak decided
to delve into the matter in detail. This article presents his findings.

37 Type 3 Mu Stage Breakthrough
By Alan Kimmel
The original Mu Stage project, published in Glass Audio in
1993, remains a popular build, recognized in its purpose to
combat listener fatigue. The Type 2 Mu Stage, offered
a streamlined version with enhanced capabilities.
Reflecting a three-decade process, the Type 3 Mu Stage,
represents a breakthrough in music reproduction.

41 Prototyping Alan Kimmel's Mu3 Stage
By Kim Bond
An experienced DIYer familiar with Alan Kimmel's work
puts his latest version to the test.

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