Active and Passive Filters as Loudspeaker Crossover Networks
JAES Volume 19 Issue 6 pp. 494-502; June 1971
Ashley, J. Robert; Kaminsky, Allan L.
This tutorial paper defines the function of a crossover network and then explores methods of meeting this function. For moderately priced two-way loudspeakers, a passive network at about 800-1600 Hz will continue to dominate the designs of the future. However, the use of active filters (electronic crossover networks) and buffer amplifiers offers the most significant means of loudspeaker improvement in the next decade. As one typical factor, crossover frequencies need to be lowered and crossover slopes increased, and the active filter is the only economical method of doing this.
MP3 and AAC Explained
Paper 17-009; AES Conference: 17th International Conference: High-Quality Audio Coding; September 1999
The last few years have shown widespread proliferation of .mp3 files from both legal and illegal sources. Yet most people using these audio files do not know much about audio compression and how to use it. The paper includes an introduction to audio compression for music file exchange. Beyond the basics, the focus is on quality issues and compression ratio/audio bandwidth/artifacts tradeoffs.
A Procedure for Controlling Room-Ring Modes and Feedback Modes in Sound Systems with Narrow-Band Filters
JAES Volume 13 Issue 4 pp. 297-299; October 1965
Boner, C. Paul; Boner, C. R.
In order to control room-ring modes and feedback modes in sound systems, our procedure is to determine the frequency of self-oscillation of a sound system in its acoustical environment, and the frequency of each ring mode of the total system that interferes unduly with the understanding of speech or musical quality. Then, a narrow-band rejection filter, having been tuned to the particular frequency of interest, is introduced into a link circuit of the amplifier. The insertion loss of this filter is adjusted until self-oscillation in the particular frequency ceases or the disturbing effect of the particular ring mode is removed.
Fundamentals of Modern Audio Measurement
JAES Volume 47 Issue 9 pp. 738-744, 746-762; September 1999
Cabot, Richard C.
Fundamental concepts in testing audio equipment are reviewed, beginning with an examination of the various equipment architectures in common use. Several basic analog and digital audio measurements are described. Tradeoffs inherent in the various approaches, the technologies used, and their limitations are discussed. Novel techniques employing multitone signals for fast audio measurements are examined and applications of sampling frequency correction technology to this and conventional FFT measurements are covered. Synchronous averaging of FFTs and the subsequent noise reduction are demonstrated. The need for simultaneity of digital and analog generation is presented using converter measurements as an example.
An Audio Noise Reduction System
JAES Volume 15 Issue 4 pp. 383-388; October 1967
A noise reduction system which is suitable for use with high-quality audio recording or transmission channels is described. A special signal component, derived from four band-splitting filters and low-level compressors, is combined with the incoming signal during recording or sending. During reproduction, the additional component is removed in a complementary way; and noises acquired in the channel are attenuated in the process. Practical features of the system include: 10 dB (unweighted) noise reduction; imperceptibility of signal-modulated noise effects; level frequency response (overall); accuracy of reproduced signal dynamics; low distortion; low internal noise level; and stability of characters.
M-S Stereo: A Powerful Technique for Working in Stereo
Paper 1792; AES Convention 69; May 1981
Dooley, Wesley L.; Streicher, Ronald D.
The practical requirements of broadcast and cinema stereo sound dictate the need for good stereo imaging, as well as full monaural compatibility. Coincident miking fulfills this requirements, and the most versatile of these techniques is the M-5 matrixing of a forward facing directional microphone with a laterally oriented bi-directional microphone. The results offer both good stereo perspective and full (discrete) monaural compatibility. The importance and implementation of this technique to the recording, broadcast, and film media will be discussed.
Automatic Microphone Mixing
Paper 1034; AES Convention 51; May 1975
A method of analysis of sound reinforcement problems by means of active and passive speech zones is outlined. The need for automatic control of multi-mike systems is defined, along with the problems associated with the use of voice-operated switches. Adaptive threshold gating is proposed as the best solution to the problem of active microphone detection. The development and performance of two effective automatic control systems is described.
Adaptive Threshold Automatic Microphone Mixing System Becomes Public Domain
Paper 3050; AES Convention 90; February 1991
Dugan, Daniel W.
The author demonstrated the first effective automatic microphone mixer in 1974 at the 49th AES Convention in New York. A later system, specialized for speech, has been manufactured since 1976. Other manufacturers developed their own systems, and automatic mike mixers have become common in unattended sound reinforcement systems in the U.S.A. The original patent expires in 1991. The author celebrates this anniversary by explaining how to use it.
Attack and Release Time Constants in RMS-Based Feedback Compressors
JAES Volume 47 Issue 10 pp. 788-804; October 1999
Mathematical models for feedback and feedforward compresssors are developed. A couple of possible configurations are explored: linear-output rms detector with linearly controlled VCA (linear-domain compressor) and logarithmic-output rms detector with exponentially controlled VCA (log-domain compressor). It is shown that the transfer functions of both configurations are equivalent. A formula for transforming the compression ratio of a log-domain compressor to that of a linear-domain compressor is derived. The difference between feedforward and feedback compressor configurations, with regard to time constants and performance, are considered.
An Introduction to Electromagnetic Compatibility (EMC) and Electromagnetic Interference (EMI) for Audio System Designers
JAES Volume 37 Issue 7/8 pp. 570-585; July 1989
Electromagnetic compatibility and electromagnetic interference engineering are well-developed fields, and many of the concepts and techniques used by professionals in this discipline are brought forward. This will allow audio system designers to begin to understand why many of the techniques used in audio engineering exist and will put them in a better position to make further use of these techniques in difficult situations and new designs.
Design Aspects of Graphic Equalizers
JAES Volume 31 Issue 6 pp. 394-407; June 1983
Greiner, Richard A.; Schoessow, Michael
The analysis and the design of graphic equalizers are discussed. Useful properties of Hurwitz polynomials and positive real functions are applied to the types of active networks commonly found in graphic equalizers. Questions converning frequency and phase response along with the optimum number of bands and their Q are addressed, and some practical situations are examined. Seven different basic topologies are shown with a discussion of the advantages, disadvantages, and unique features of each. three of the seven, representing the most commonly used topologies, are examined in more detail, and the important design equations for each are given. All three are shown to have minimum phase characteristics for any combination of control settings, although other performance differences exist among them.
Acoustical Measurements by Time Delay Spectrometry
JAES Volume 15 Issue 4 pp. 370-382; October 1967
Heyser, Richard C.
Some New Audio Measurements
Paper 1008; AES Convention 51; May 1975
Heyser, Richard C.
Geometry of Sound Perception
Paper 1009; AES Convention 51; May 1975
Heyser, Richard C.
Paper 1350; AES Convention 60; May 1978
Heyser, Richard C.
A Signal Biasing Output Transformerless Transistor Power Amplifier
Paper 91; AES Convention 11; October 1959
Heyser, Richard C.
Specific Acoustic Wave Admittance
Paper 2400; AES Convention 81; November 1986
Heyser, Richard C.
New Factors in Phonograph Preamplifier Design
JAES Volume 24 Issue 4 pp. 263-270; May 1976
Active Crossover Networks for Noncoincident Drivers
JAES Volume 24 Issue 1 pp. 2-8; February 1976
Linkwitz, Siegfried H.
A Family of Linear-Phase Crossover Networks of High Slope Derived by Time Delay
JAES Volume 31 Issue 1/2 pp. 2-20; February 1983
Lipshitz, Stanley P.; Vanderkooy, John
On the Audibility of Midrange Phase Distortion in Audio Systems
JAES Volume 30 Issue 9 pp. 580-595; September 1982
Lipshitz, Stanley P.; Pocock, Mark; Vanderkooy, John
Noise Susceptibility in Analog and Digital Signal Processing Systems
JAES Volume 43 Issue 6 pp. 435-453; June 1995
Constant-Voltage Crossover Network Design
JAES Volume 19 Issue 1 pp. 12-19; January 1971
Small, Richard H.
Correction Techniques for Sound System Performance Optimization
Paper 2833; AES Convention 87; October 1989
Loudspeakers and Rooms for Stereophonic Sound Reproduction
Paper 8-011; AES Conference: 8th International Conference: The Sound of Audio; May 1990
Toole, Floyd E.
The History of Audio and Sound Measurement
Paper 3598; AES Convention 94; March 1993
Ampel, Frederick J.; Uzzle, Ted
Dither in Digital Audio
JAES Volume 35 Issue 12 pp. 966-975; December 1987
Vanderkooy, John; Lipshitz, Stanley P.