Douglas Self

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Douglas Self
NationalityBritish
Alma mater Cambridge University
Known forAuthor, Electronic Engineer

Douglas Self is a British electronics engineer and author with a particular interest in audio. He received a first class honours degree in engineering from Cambridge University, and then studied psychoacoustics at Sussex University. [1] He is the author of six books on audio electronics, published by Focal Press. [2] He has also contributed many articles to Wireless World magazine, some of which were compiled into a book along with articles by Peter Baxandall. [3] [4] [5]

Contents

He has taken out a number of audio-related patents, including for a "crossover displacement circuit". [1] [6]

He has worked with several major companies, including Cambridge Audio, TAG-McLaren Audio, and Soundcraft Electronics. [7] Circuit Cellar website described him as a 'renowned audio specialist' when discussing a design he created for Elektor magazine. [8] He developed the concept of a "blameless" amplifier in which all the main sources of distortion are reduced to negligible levels. [3]

Self's books have been well received. His Audio Power Amplifier Design Handbook was recommended by Walt Jung and described as "famous" by audio website hifisonix. [9] [10] The second edition of his Small Signal Audio Design received a very positive review in Sound on Sound magazine. [11]

Publications

See also

Related Research Articles

Amplifier Electronic device

An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the power of a signal. It is a two-port electronic circuit that uses electric power from a power supply to increase the amplitude of a signal applied to its input terminals, producing a proportionally greater amplitude signal at its output. The amount of amplification provided by an amplifier is measured by its gain: the ratio of output voltage, current, or power to input. An amplifier is a circuit that has a power gain greater than one.

Distortion is the alteration of the original shape of something. In communications and electronics it means the alteration of the waveform of an information-bearing signal, such as an audio signal representing sound or a video signal representing images, in an electronic device or communication channel.

Audio power amplifier audio amplifier that reaches power output sufficient to control a loudspeaker

An audio power amplifier is an electronic amplifier that amplifies low-power electronic audio signals such as the signal from radio receiver or electric guitar pickup to a level that is high enough for driving loudspeakers or headphones. Audio power amplifiers are found in all manner of sound systems including sound reinforcement, public address and home audio systems and musical instrument amplifiers like guitar amplifiers. It is the final electronic stage in a typical audio playback chain before the signal is sent to the loudspeakers.

Audio crossover type of electronic filter circuitry

Audio crossovers are a type of electronic filter circuitry used in a range of audio applications. They split up an audio signal into two or more frequency ranges, so that the signals can be sent to loudspeaker drivers that are designed for different frequency ranges. Crossovers are often described as "two-way" or "three-way", which indicate, respectively, that the crossover splits a given signal into two frequency ranges or three frequency ranges. Crossovers are used in loudspeaker cabinets, power amplifiers in consumer electronics and pro audio and musical instrument amplifier products. For the latter two markets, crossovers are used in bass amplifiers, keyboard amplifiers, bass and keyboard speaker enclosures and sound reinforcement system equipment.

Woofer loudspeaker driver designed to produce low frequency sounds

A woofer or bass speaker is a technical term for loudspeaker driver designed to produce low frequency sounds, typically from 50 Hz up to 1000 Hz. The name is from the onomatopoeic English word for a dog's bark, "woof". The most common design for a woofer is the electrodynamic driver, which typically uses a stiff paper cone, driven by a voice coil surrounded by a magnetic field.

Audio system measurements are a means of quantifying system performance. These measurements and are made for several purposes. Designers take measurements so that they can specify the performance of a piece of equipment. Maintenance engineers make them to ensure equipment is still working to specification, or to ensure that the cumulative defects of an audio path are within limits considered acceptable. Audio system measurements often accommodate psychoacoustic principles to measure the system in a way that relates to human hearing.

Valve amplifier type of electronic amplifier

A valve amplifier or tube amplifier is a type of electronic amplifier that uses vacuum tubes to increase the amplitude or power of a signal. Low to medium power valve amplifiers for frequencies below the microwaves were largely replaced by solid state amplifiers in the 1960s and 1970s. Valve amplifiers can be used for applications such as guitar amplifiers, satellite transponders such as DirecTV and GPS, high quality stereo amplifiers, military applications and very high power radio and UHF television transmitters.

Limiter electroacustic device

In electronics, a limiter is a circuit that allows signals below a specified input power or level to pass unaffected while attenuating (lowering) the peaks of stronger signals that exceed this threshold. Limiting is a type of dynamic range compression. Clipping is an extreme version of limiting.

Push–pull output

A push–pull amplifier is a type of electronic circuit that uses a pair of active devices that alternately supply current to, or absorb current from, a connected load. This kind of amplifier can enhance both the load capacity and switching speed.

Tone control is a type of equalization used to make specific pitches or "frequencies" in an audio signal softer or louder. It allows a listener to adjust the tone of the sound produced by an audio system to their liking, for example to compensate for inadequate bass response of loudspeakers or earphones, tonal qualities of the room, or hearing impairment. A tone control circuit is an electronic circuit that consists of a network of filters which modify the signal before it is fed to speakers, headphones or recording devices by way of an amplifier. Tone controls are found on many sound systems: radios, portable music players, boomboxes, public address systems, and musical instrument amplifiers.

Powered speakers loudspeaker that have built-in amplifiers

Powered speakers, also known as self-powered speakers and active speakers, are loudspeakers that have built-in amplifiers. Powered speakers are used in a range of settings, including in sound reinforcement systems, both for the main speakers facing the audience and the monitor speakers facing the performers; by DJs performing at dance events and raves; in private homes as part of hi-fi or home cinema audio systems and as computer speakers. They can be connected directly to a mixing console or other low-level audio signal source without the need for an external amplifier. Some active speakers designed for sound reinforcement system use have an onboard mixing console and microphone preamplifier, which enables microphones to be connected directly to the speaker.

Clipping (audio) waveform distortion

Clipping is a form of waveform distortion that occurs when an amplifier is overdriven and attempts to deliver an output voltage or current beyond its maximum capability. Driving an amplifier into clipping may cause it to output power in excess of its power rating.

In electronics, motorboating is a type of low frequency parasitic oscillation that sometimes occurs in audio and radio equipment and often manifests itself as a sound similar to an idling motorboat engine, a "put-put-put", in audio output from speakers or earphones. It is a problem encountered particularly in radio transceivers and older vacuum tube audio systems, guitar amplifiers, PA systems and is caused by some type of unwanted feedback in the circuit. The amplifying devices in audio and radio equipment are vulnerable to a variety of feedback problems, which can cause distinctive noise in the output. The term motorboating is applied to oscillations whose frequency is below the range of hearing, from 1 to 10 hertz, so the individual oscillations are heard as pulses. Sometimes the oscillations can even be seen visually as the woofer cones in speakers slowly moving in and out.

A valve audio amplifier (UK) or vacuum tube audio amplifier is a valve amplifier used for sound reinforcement, sound recording and reproduction.

Nelson Pass is a designer of audio amplifiers. Pass is vocal that listening tests remain valuable and that electrical measurements alone do not fully characterize the sound of an amplifier. Pass holds at least seven U.S. patents related to audio circuits.

Peter J. Baxandall was an English audio engineer and electronics engineer and a pioneer of the use of analog electronics in audio. He is probably best known for what is now called the Baxandall tone control circuit, first published in a paper in Wireless World.

Tube sound

Tube sound is the characteristic sound associated with a vacuum tube amplifier, a vacuum tube-based audio amplifier. At first, the concept of tube sound did not exist, because practically all electronic amplification of audio signals was done with vacuum tubes and other comparable methods were not known or used. After introduction of solid state amplifiers, tube sound appeared as the logical complement of transistor sound, which had some negative connotations due to crossover distortion in early transistor amplifiers. The audible significance of tube amplification on audio signals is a subject of continuing debate among audio enthusiasts.

Electronics World is a technical magazine in electronics and RF engineering aimed at professional design engineers. It is produced monthly in print and digital formats.

In electronics, power amplifier classes are letter symbols applied to different power amplifier types. The class gives a broad indication of an amplifier's characteristics and performance. The classes are related to the time period that the active amplifier device is passing current, expressed as a fraction of the period of a signal waveform applied to the input. A class A amplifier is conducting through all the period of the signal; Class B only for one-half the input period, class C for much less than half the input period. A Class D amplifier operates its output device in a switching manner; the fraction of the time that the device is conducting is adjusted so a pulse width modulation output is obtained from the stage.

References

  1. 1 2 "Author - Douglas Self". Linear Audio.
  2. "Amazon.co.uk: Douglas Self". Amazon . Retrieved 21 April 2016.
  3. 1 2 "Ironing Out Distortion" (PDF), Electronics World + Wireless World , pp. 14–20, January 1995, retrieved 21 April 2016, As is often the case with articles on audio subjects, Douglas Self's recent series on amplifier distortion caused a great deal of interest worldwide.
  4. "New Publication: Baxandall and Self on Audio Power", Electronics World , 13 December 2011, retrieved 21 April 2016
  5. Baxandall & Self on Audio Power
  6. "Cambridge Audio 851E and 851W", Australian HiFi, 6 July 2015, retrieved 21 April 2016, Then there’s Douglas Self’s innovative crossover displacement circuit, for which he was awarded British Patent GB2424137.
  7. "Three Simple Rules for Creating an Effective Gain Structure By Douglas Self - Audio Undone". Routledge.
  8. Abate, C. J. "Weekly Elektor Wrap Up: Preamplifier 2012, Pico C, & A Webshop Hunt". Circuit Cellar.
  9. Jung, Walt (May 1997), "Book Reports - High Performance Audio Power Amplifiers" (PDF), Audio Electronics, pp. 50–54, retrieved 21 April 2016, ...I can recommend the book as a general source of audio power amplifier knowledge
  10. "Douglas Self's 8 Distortions (and a Few More)" (PDF), hifisonix.com, Chris Russell, retrieved 21 April 2016, In 1996, Douglas Self published his now famous 'Audio Power Amplifier Design Handbook', in which he described the 8 key distortion mechanisms in audio power amplifiers
  11. "Small Signal Audio Design 2nd Edition". Sound on Sound . SOS Publications Group. excellent technical reference book... if you have the slightest interest in audio circuit design this book has to be considered an essential reference. Very highly recommended.