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Detailed entries for one subject from the INDEX TO HOW TO DO IT INFORMATION.
Click on a see also (sa) or tracing (xx) to view detailed entries about a related subject.
The entries are in alphabetical order by magazine name and then in chronological sequence.
To obtain a copy of any magazine article contact your local public library or the publisher.

xx   AUDIO

Operation and uses for the 570/571 IC compander chip.
AUDIO AMATEUR 4/1976 [Dec 1976] (v.7#4) pg. 3

Modifications for the dbx 117 or 119 compressor/expander. (1) Record while listening to expanded program material. (2) Add a tape monitor.
AUDIO AMATEUR 1/1978 [Mar 1978] (v.9#1) pg. 45

Noise reduction systems. An introduction to the techniques of inhibiting unwanted noise in audio signals. Looks at both Dolby and the dbX compandor (compander). Includes construction details for the Compex compander built around the Signetics NE570/571 IC.
AUDIO AMATEUR 3/1979 [Jul 1979] (v.10#3) pg. 12
Correction AUDIO AMATEUR 1/1980 [Jan 1980] (v.11#1) pg. 56

Kit report on building the Integrex Dolby Noise Reducer, a full-function Dolby-B processor able to both encode and decode.
AUDIO AMATEUR 4/1979 [Oct 1979] (v.10#4) pg. 44
Added Info AUDIO AMATEUR 1/1981 [Feb 1981] (v.12#1) pg. 40 (Non-kit decode only version)
Added Info AUDIO AMATEUR 2/1981 [Apr 1981] (v.12#2) pg. 60

Equipment review of the dbx Model 21 decoder for disks and tapes previously encoded with dbx-II characteristics.
AUDIO AMATEUR 5/1983 [Jan 1984] (v.14#5) pg. 44
Added Info AUDIO AMATEUR 1/1988 [Feb 1988] (v.19#1) pg. 54

Report on Sound Concepts Model IR2200 "stereo image expander" kit.
AUDIO AMATEUR 1/1986 [Feb 1986] (v.17#1) pg. 45

A two-channel tube compressor. This project features the superior sound of tubes, with a short signal path and versatile controls.
AUDIOXPRESS Jul 2001 (v.32#7) pg. 32

DASP-2002 digital audio signal processor. Include this circuit in every S/PDIF link between two digital audio devices (CD player, DVD player, CD recorder, or MD recorder). It allows modification (bypassing) of the copybit and serves as a universal processor for digital audio signals.
AUDIOXPRESS Sep 2002 (v.33#9) pg. 4

Programmable audio-level controller keeps a receiver's audio volume constant, regardless of incoming signal strength. Utilizes a compandor IC. Est. cost: $30.

Volume expander circuit will give more impact to recorded music which requires a wide dynamic range. It helps overcome some of the effects of compression (especially in cassette recordings).

VFX (voice effects processor) uses a DSP (digital signal processing) microcomputer. Audio special effects processor accepts microphone input, digitally processes the information in one of three modes (harmonizer, echo, reverb), and amplifies the output for listening with a speaker or headphones. Est. cost: $105 (kit).
ELECTRONICS NOW Sep 1992 (v.63#9) pg. 37

Audio expander. Enhance stereo and mono audio with this one-chip audio processor. Simulates stereo on mono, enhances stereo audio, helps restore old recordings, etc. Est. cost: $20 (kit).
ELECTRONICS NOW Mar 1993 (v.64#3) pg. 71
Added Info ELECTRONICS NOW Jan 1994 (v.65#1) pg. 17

Build this stereo compressor (audio compressor) which limits the dynamic range of an audio signal. It is designed to automatically lower the audio "blasting" that goes with some TV commercials and hi-fi video recordings. Est. cost: $75 (kit).
ELECTRONICS NOW Aug 1996 (v.67#8) pg. 37
Added Info ELECTRONICS NOW Nov 1996 (v.67#11) pg. 11

A universal stereo noise filter and compressor will reduce noise and increase clarity of any audio signal. Est. cost: $95 (kit).
ELECTRONICS NOW Oct 1999 (v.70#10) pg. 27

Stereo compressor for making a cassette copy of a compact disk. Use this device to restrict the dynamic range of compact disks and make cassette recordings that are suitable for use in an automobile or a "Walkman" unit. Basically, it makes the soft passages louder and the loud passages softer.
HANDS-ON ELECTRONICS Jan 1987 (v.4#1) pg. 69

Single-channel sound exploder. Simulates full stereo sound and control capabilities (reverberation enhancement, bass and treble boost and cut, channel balancing, and four-way fading) from a mono source. Can be cascaded to provide a four-channel surround-sound effect.
MODERN ELECTRONICS [2] Oct 1990 (v.7#10) pg. 25
Added Info MODERN ELECTRONICS [2] Dec 1990 (v.7#12) pg. 9

Stereo compressor (audio compressor). Designed to lower the increased loudness of some TV commercials. Will also serve as a studio sound manipulator and to reduce the louder music and sound effects often found in film and TV. Est. cost: $75 (kit).

Hi-fi volume compressor/extender.
POPULAR ELECTRONICS [1] Oct 1964 (v.21#4) pg. 41

Distortionless speech compressor will automatically maintain the correct recording level for a tape recorder. Est. cost: $16.
POPULAR ELECTRONICS [1] Feb 1968 (v.28#2) pg. 47

Distortionless audio compressor has a large range (45 dB or more) and accepts virtually any microphone input. Est. cost: $50.
POPULAR ELECTRONICS [1] Dec 1971 (v.35#6) pg. 25

A simple compressor-expander circuit is a passive circuit which uses an LED to sample the audio output of system. Can be used as the volume control in an audio system or to prevent speaker blowout in musical instrument amplifiers.
POPULAR ELECTRONICS [1] Apr 1973 (v.3#4) pg. 50

Versatile tape recorder control. This accessory unit adds audio compression, squelch-activated start and earphone amplifier to an existing cassette recorder.
POPULAR ELECTRONICS [1] Oct 1973 (v.4#4) pg. 44

Build a "compander" to enhance hi-fi recordings. Provides either expansion or compression of sound. Expansion replaces the missing peaks which may be lost in recording and compression eliminates loud level changes.
POPULAR ELECTRONICS [1] Apr 1975 (v.7#4) pg. 38

Audio signal delay unit is built around a MOS-type shift register. Makes for a livelier sound. Also used to simulate stereo from mono input when making tape recordings. Est. cost: $39 (mono); $59 (stereo).
POPULAR ELECTRONICS [1] Jun 1976 (v.9#6) pg. 33

Special focus on audio. Dynamic noise reduction systems and expanders.
POPULAR ELECTRONICS [1] Sep 1977 (v.12#3) pg. 60

Build an audio compander. A 2:1 and 1:2 compander will allow you to record the 115-dB range of live music on the 65-dB range of most tape recorders, then play it back without losing its original dynamic range. Est. cost: $59.
POPULAR ELECTRONICS [1] Nov 1977 (v.12#5) pg. 43

Audio "listening-room" expanders. How time delay enhances sound reproduction. A buyer's guide to eight models. Performance comparisons.
POPULAR ELECTRONICS [1] Feb 1979 (v.15#2) pg. 41

Audio time delay systems. Part 1. A low-cost analog audio delay line. Part 1. Provides adjustable delays and wide dynamic range. Estimated cost: $250.
POPULAR ELECTRONICS [1] Jul 1980 (v.18#1) pg. 53

Audio time delay systems. Part 2. A low-cost analog audio delay line. Part 2. Power supply and construction information.
POPULAR ELECTRONICS [1] Aug 1980 (v.18#2) pg. 83

Audio time delay systems. Part 3. Build a digital audio delay line. Uses computer-type RAM memory and both A/D and D/A converters.
POPULAR ELECTRONICS [1] Sep 1980 (v.18#3) pg. 68

Peak unlimiter audio dynamic range processor. Increases system gain when passing peaks that may have been limited during the original recording process. Est. cost: $59.
POPULAR ELECTRONICS [1] Sep 1981 (v.19#9) pg. 75
Correction POPULAR ELECTRONICS [1] Jan 1982 (v.20#1) pg. 6

Enhancing stereo sound with signal processors. How to eliminate hiss and other noises, increase dynamic range, remove annoying frequency peaks, etc. A introduction to the techniques and equipment.
POPULAR ELECTRONICS [1] Mar 1982 (v.20#3) pg. 49

Audio gate expands dynamic range and obtains effective noise reduction. Use to strip background noise, mute PA microphones, dup "clean" movie soundtracks, etc. Est. cost: $30.
POPULAR ELECTRONICS [1] Jul 1982 (v.20#7) pg. 49
Correction COMPUTERS & ELECTRONICS Nov 1982 (v.20#11) pg. 6
Added Info COMPUTERS & ELECTRONICS Dec 1982 (v.20#12) pg. 9

Signal conditioner circuit is ideal for cleaning up weak and noisy audio or Morse-code signals. May also be used to clean up digital tone signals in a remote-control extender circuit.
POPULAR ELECTRONICS [2] Nov 1989 (v.6#11) pg. 85

Simple diode circuits. (1) Bridge rectifier. (2) Sound-level (audio signal) limiter circuit never exceeds 1.5-volts peak-to-peak. (3) DC polarity or AC indicator circuit. (4) Kick-back voltage limiter for inductive loads. (5) Steering circuit controls relays based on voltage polarity. (6) Simple temperature sensor. (7) Circuit for selecting matching diodes.
POPULAR ELECTRONICS [2] May 1996 (v.13#5) pg. 64

Compression-type amplifier circuit that can be used to keep the volume level of an electronic organ constant.
POPULAR ELECTRONICS [2] Apr 1997 (v.14#4) pg. 58

Special microphone incorporates an audio compressor and VOX circuit. It will turn on your recorder at the sound of a voice and keep the recording level automatically adjusted.
POPULAR SCIENCE Oct 1973 (v.203#4) pg. 134

Signal processors (audio time delay, dolby decoder, transient eliminator, etc.). How to connect them to your hi-fi system by using the tape monitor circuit.
RADIO-ELECTRONICS Dec 1980 (v.51#12) pg. 71

Build this combination hi-fi noise filter and dynamic range extender. Part 1.
RADIO-ELECTRONICS Mar 1981 (v.52#3) pg. 41

Build this combination hi-fi noise filter and dynamic range expander. Part 2.
RADIO-ELECTRONICS Apr 1981 (v.52#4) pg. 70
Correction RADIO-ELECTRONICS Jun 1981 (v.52#6) pg. 24
Added Info RADIO-ELECTRONICS Sep 1981 (v.52#9) pg. 26

Build this stereo image expander. Part 1. The theory.
RADIO-ELECTRONICS Jun 1982 (v.53#6) pg. 45

Build this stereo image expander. Part 2. Construction. Est. cost: $95.
RADIO-ELECTRONICS Sep 1982 (v.53#9) pg. 63

Audio companding. You can build a professional-quality compander for your hi-fi system using circuits designed around Signetics' NE570 compander IC. A compander is used to reduce noise from your tape recordings and to bring back the dynamic range that is lost when recording and broadcast engineers compress their audio signals.
RADIO-ELECTRONICS Nov 1985 (v.56#11) pg. 67, 77

Analog delay lines. Find out how to use analog delay lines to produce special audio effects such as echo, reverb, room expansion, etc.
RADIO-ELECTRONICS Oct 1986 (v.57#10) pg. 67

Signal processors. Part 1. Beginning a discussion on the relative roles and goals of various types of audio signal processors.
RADIO-ELECTRONICS Jan 1987 (v.58#1) pg. 72

Signal processors. Part 2. Equalizers.
RADIO-ELECTRONICS Feb 1987 (v.58#2) pg. 85

Signal processors. Part 3. Theory of stereo perception and the way that certain products can affect and enhance the stereo illusion.
RADIO-ELECTRONICS Mar 1987 (v.58#3) pg. 80

Four-transistor audio compressor boosts modulation. Est. cost: $10.
RADIO-TV EXPERIMENTER #789 Jun-Jul 1966 (v.20#3) pg. 33