Audio Related Things

• Here is a link to Defunct Audio Manufacturers that makes for some interesting reading by those who remember these companies.
• Introduction to Electroacoustics and Audio Amplifier Design, Third Edition, ISBN 0-7575-0375-6. A book which I wrote for my Audio Engineering Class.
• Beranek's Law From the book Acoustics by L. L. Beranek.
• The Class-D Amplifier - Basic theory of operation of the class-D amplifier and the filterless class-D amplifier.
• An Op Amp Tutorial - Derivation of the op amp open-loop transfer function, the gain-bandwidth product, and the slew rate.
• Closed-Box Loudspeaker Design - Design equations for calculating the internal volume of closed-box loudspeaker systems.
• Closed-Box Loudspeaker Design - What value of Q_TC minimizes the lower cutoff frequency of a closed-box loudspeaker system?
• Vented-Box Loudspeaker Design - Design equations and charts for calculating the internal volume of vented-box loudspeaker systems.
• Zobel Network Design - Design equations for Zobel networks for closed-box drivers. The high-frequency compensation network can be used with vented-box drivers, but not the low-frequency compensation network.
• An Electroacoustic Analysis of Transmission Line Loudspeakers - This is Allen Robinson's 2007 thesis on transmission-line loudspeaker systems.
• Head Amps for Moving-Coil Cartridges - Three pre-preamplifier circuits for moving-coil phono cartridges.
• The Leach Amp Plans - The latest version of the Low TIM amplifier that I published long ago in Audio magazine.
• The Leach SuperAmp Plans - Plans for the Double Barrelled Amplifier that I published long ago in Audio magazine.
• A Three-Way Satellite Loudspeaker System
• Georgia Tech Audio Lab Loudspeaker Plans. - The woofer for this system is no longer available. I know of no substitute. We are working on a new system that uses all Vifa drivers. The following link has a brief description of these.
• Georgia Tech Audio Lab Vifa 3 Way Loudspeaker Plans.
• 2-Way Loudspeaker System Plans - A two-way system using Vifa drivers.
• An FET Audio Peak Limiter - A simple audio peak limiter that uses a JFET as a variable resistor.
• "A Four-Stage FM Broadcast Audio Peak Limiter,"
• Construct a Wide Bandwidth Preamp - An article I wrote for the Feb. '77 issue of Audio magazine that many people have asked me to post. I have learned a lot since then, e.g. not to use ceramic capacitors. Versions of the circuits with FET diff amps are also included. This is a PDF document which might take several minutes to download. I recommend right clicking on the link and saving it to your hard disk.
• Build a Low TIM Amplifier - Parts 1 and 2 - Articles I wrote for the Feb. '76 and '77 issues of Audio magazine that many people have asked me to post. Several following versions are included. The Leach Amp plans linked above are for the latest version of this amplifier. This is a PDF document which might take several minutes to download. I recommend right clicking on the link and saving it to your hard disk. The amp pictured in Fig. 1 has been running over 8 hours a day, 5 days a week, in my office since the article was published.
• Build a Stepped Volume Control - An article I wrote for the Feb. '79 issue of Audio magazine that someone has asked me to post. Some students building preamps at that time had problems getting good volume controls. One student bought a 23 position dual switch and asked me if resistors could be added to it to form a volume control. This article came from that project.
• Operational Amplifier Circuit for Hi-Fi - An article by Bart N. Locanthi that was published in the Jan. '67 issue of Electronics World magazine. Mr. Locanthi was vice-president of engineering at James B. Lansing Sound, Inc., (now JBL) when he wrote this article. It describes the T circuit output stage which I used in my Low TIM amplifier circuit. Electronics World, published by Ziff-Davis, was a great magazine, but it went out of print in the mid '70s. The former British "Wireless World" magazine now uses the name "Electronics World." Mr. Locanthi died in '94.
• Tubes Versus Transistors - Ever wonder why tube amps sound different from transistor amps? This paper explains it. It was published in the digest of the 1981 IEEE ICASSP conference held in Atlanta. Author Stephen Bussey graduated from Georgia Tech.
• If you need an audio signal generator and have a sound card in your pc, download and install WinISD.
• The Perception of Pitch - An interesting article from the 1974 issue of American Scientist published by Sigma Xi. It explains some of the mysteries of why the same note played on different instruments sounds different.
• MP3 File Sizes - A comparison of file sizes for variable bit rate and fixed bit rate sampling.
• Transconductance Doubling - Can "transconductance doubling" (also called "gm-doubling") occur in class-AB output stages? Some audio wizards say that the transconductance increases in the crossover region where both transistors are conducting. You can read why this is an "old wives tale" here.

This page is not a publication of the Georgia Institute of Technology and the Georgia Institute of Technology has not edited or examined the content. The author of this page is solely responsible for the content. Copyright 2004. All rights reserved.