The Hafler circuit is a passive electronics circuit with the aim of getting derived surround sound or ambiophony from regular stereo recordings without using costly electronics. Such circuits are generally known as matrix decoders. The Dynaquad system works using similar principles.[1]
Named after its early proponent audio engineer David Hafler, the circuit exploits the high amount of stereo separation between Left and Right channels and sound phase.[2]
This type of system is called 2:2:4, since the rear channels are simulated from a two-channel stereo track, with no actual extra tracks encoded. The rear channels will playback out of phase sounds, while the forward channels are unaffected. Using the circuit typically reduces stereo separation by only about 2 dB and the rear speakers are only required to reproduce a limited frequency range (allowing them to be smaller and cheaper).
^Berry, Ray (February 1975). "Four Channel Sound". The Michigan Technic. 93 (4). University of Michigan, College of Engineering: 6–10.
^Elliott, Rod (1999). "Simple Surround Sound Decoder". Elliott Sound Products. Archived from the original on 28 November 2016. Retrieved 13 December 2016.
The Haflercircuit is a passive electronics circuit with the aim of getting derived surround sound or ambiophony from regular stereo recordings without...
have been developed: The earliest and simpler form of decoding is the Haflercircuit, deriving back channels out of normal stereo recording (2:2:4). It was...
version of the Williamson amplifier using the ultra-linear circuit of Alan Blumlein. In 1950, Hafler founded Acrosound with his colleague Herbert Keroes. This...
of individual instruments in the rear channels. DY / Dynaquad (1969) Haflercircuit (1969) системы ABC (Quadra ABC – briefly used only in the Soviet Union)...
introduced as a derived (2:2:4) four channel "decoding" system based on the Haflercircuit, where the back channels played ambient sounds recovered from standard...
channels, the records may also give pleasing results when played on Haflercircuit systems or other simulated four channel systems. Approximately two hundred...
circuit was later used in many home-built and commercial hi-fi amplifiers in the early 1950s. In order to appeal to a wider consumer market, Hafler decided...
The electronics behind Ambiophony was based on, or similar to, the Haflercircuit. "Ambiophony, Beoworld". Retrieved 2016-05-22. "Philips Ambio 4". Retrieved...
Heathkit, and McIntosh, as well as solid state (transistor) kits from Hafler allowed for consumers to build their own hi fidelity systems. Books and...
1937 in the UK, but popularised following publication of a paper by David Hafler and Keroes in the USA in 1951, and became the dominant topology during the...
and later such companies as Southwest Technical Products and the David Hafler Company. Before entering the burgeoning home computer market, Heathkit marketed...
traits of both extremes. In a 1951 engineering paper published by David Hafler and Herbert Keroes, they determined that when the screen tap was set to...
Richard D. James – experimental, ambient, electronic music, techno The Hafler Trio Lou Harrison – (USA) gamelan influenced Carl Michael von Hausswolff...
Ultra-linear topology has mostly been associated with amplifier circuits based on research by D. Hafler and H. Keroes of Dynaco fame. Distributed loading (in general...
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