Continuing with Speakers, Mike Klasco and Steve Tatarunis start exploring the market for electrostatic and electret speakers. Cone speakers, dome tweeters, compression drivers, even ribbon planars are all electro-dynamic transducers. Just about all use a magnetic structure and some sort of tubular voice coil except the ribbon planar, which uses a flat printed circuit coil. Electrostatic speakers work differently than electro-dynamics and are based on the technology of condenser microphones. Their construction and components are more like a capacitor. The first part of this article series details the technology and construction of electrostatic speakers and discusses their early development.
We also feature a book review, this time about Bob Cordell’s audio reference book “Designing Audio Power Amplifiers”. Peter Delos details Bob Cordell’s thorough, well-rounded tutorial on the intricacies of audio power amplifier design. And since audioXpress has provided two reviews on power amplifier reference books from Douglas Self and Bob Cordell, Gary Galo also discusses a third perspective following a presentation on the subject from John Dawson at the AES convention in New York.
From our Test Bench, this month, Gary Galo reviews the RSX-1 Remote Analog Switch from KAB Electro-Acoustics. This is an effective solution to run multiple different sound sources connected to a single-input preamp or integrated amplifier. Solving a well-known problem, the RSX-1 allows connecting two turntables or different line level sources without compromising our connections.
For our readers devoted to DIY audio, this month we have a very interesting project, from our reputed author Ken Bird: A Bipole Acoustic Labyrinth Enclosure.
Addressing previous acoustic labyrinth speaker designs, and inspired by recent papers and articles by audio engineering veterans like George Augspurger, and Martin J. King, Ken Bird describes a quasi-acoustic labyrinth type line using a chambered two-way bipole speaker arrangement employing the Audience A3S full range, dual voice coil, speaker.
Our DIY section also brings a great project from Shannon Parks, with its Arduino-based real tube preamp. This is a simple 12B4 linestage controlled by a $12 plug-in Arduino Nano board and the tube power supply is probably the simplest in our magazine’s history: it uses a 24V, 1A desktop supply.
Following our June cover article about Psycohacoustics, where Ron Tipton delves on “the application of sound perception to accomplish a useful goal”, the second part in this series is dedicated to noise reduction and sound masking experiments.
This month, Tipton looks at the LM1894, a 14-pin integrated circuit (IC), stereo noise reduction circuit (DNR) for audio playback systems and experiments with sound masking with its own design, TDL model 601 tunable band-pass filter.
In Hollow State Electronics, Richard Honeycutt continuous to address the subject of Tube Preamplifiers and, after discussing the design of a low-distortion audio preamp stage, now looks at the linearity of those designs.
Our column devoted to everything acoustics is dedicated this month the ODEON Room Acoustics Software, from the Danish company with the same name. In Sound Control, Richard Honeycutt looks at the improved calculation methods and analysis capabilities in v.12, the current version, incorporating an impulse response measurement system integrated to the software allowing easy comparison of calculated and measured responses.
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