Quadraphony

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Quadrofonie (also: Quadrophonie or Vierkanalstereophonie ) is a form of multi-channel recording and playback, which was mainly to be found in the late 1960s to early 1980s. It is important as a forerunner of today's Dolby Surround technology and its successors, as well as surround sound with 5.1 channel configuration.

Schematic representation of the Quadrofonie

history

Quadrophonic sign (4.0 sound)

In the mid-1960s, stereo slowly began to prevail over mono . The Philips company developed the first compact cassette devices as dictation machines . The first devices for music were also in mono, and stereo soon became popular on cassette recorders , analogous to records . Many records appeared in parallel in stereo and mono. At the beginning of the 1970s, the era of mono records in the consumer sector was slowly coming to an end. In the radio station sector, the mono page on promo pressings lasted until the mid-1980s.

The market was looking for something new , especially in the hi-fi sector. They were convinced that this was found in quadraphony. The problem was the transferability from the studio to the end consumer. While the multi-channel capability of the tapes could easily be realized by adding more tracks and only found its limits due to the width of the tape, this was difficult with the record with only two flanks of the groove. But even the 4-track tapes for home use could only be played back in one direction with 4-channel recording .

Technical processes and their dissemination

Real quadrophony (system 4-4-4), also called discrete quadrophony

The four audio channels remain separate along the entire signal path. Quadro-capable playback devices are required for every sound carrier format: CD4 method for turntables (see below), 8-track cassette decks, tape recorders with at least four simultaneously usable tracks.

In the early to mid-1970s, the Quadrofonie technology was intensively developed and sold. The company JVC was in this area as a leader. JVC developed a possibility for records to keep the two front channels compatible with the normal stereo channels and to transfer only the two rear channels into the inaudible range with the help of a converter and to bring them back again.

This was achieved through the development of a special diamond cut on the pickup, which was also able to pick up signals in the frequency range inaudible to humans from the record. The two rear channels were transferred from the normal audible range of 20 Hz to 20 kHz to 30–60 kHz before the record was produced,  and after the needle was scanned, they were brought back into the audible range by the converter. This technology was marketed under the name CD4 and was the only true quadraphonic method for records. With its four discrete channels, CD4 is not one of the usual matrix methods with only two transmission channels .

JVC was also the largest supplier of quadruple amplifiers . The introduction of a Quadrofonie Compact Cassette is said to have failed due to the veto of the company Philips, the patent holder , because although the cassette format would have been compatible with the normal cassette, the cassette could only be played and played in one direction with the technology at the time.

For the audio CD , a quadraphonic format was defined in the Red Book standard, but there were never CDs and playback devices for it. Today there are CDs in DTS .

Matrix Quadrofonie (System 4-2-4)

The four channels are coded into two stereo channels with the help of complex mathematical-electronic processes using phase differences and decoded again when played back. Conventional stereophonic playback devices can be retained (the system is therefore downward compatible ), all that is required is a decoder and an associated 4-channel amplifier with loudspeakers. This means that every stereo-compatible sound carrier format can reproduce matrix-coded quadruple recordings; Nothing stands in the way of broadcasting via VHF radio. In some cases, radio stations even “unintentionally” send Quadrofon when they send a matrix-coded record. The disadvantage of these methods is that the front-to-back channel separation does not work as well as with the discrete methods, and that the channels are actually under-defined, which can result in phantom signals. At that time several, mutually incompatible matrix coding processes were created at the same time. These processes competed with one another (similar to the VHS, betamax and Video2000 video sector); many potential buyers did not buy any of the systems because they feared they would choose one that would not prevail and for which it would not be possible to buy phonograms.

The Dolby Surround system, which later became widespread in the film sector, uses the same approach.

Quadrofone recordings for the matrix technology are based on the directional dominance circuit and were recorded on so-called "quadro records" (SQ, QS, RM), tape or 8-track cassettes (Q8).

Due to competing and incompatible technological matrix quadro systems such as SQ, QS, UD4, EV4, QM, UMX , etc. , quadraphony was never able to establish itself on a larger scale.

The problem of dissemination also arose from the fact that in the early 1970s, when Quadrofonie was being promoted by various audio manufacturers, the audio systems were very expensive. For many listeners it was not possible to keep up with the sequence of innovations. Most of the recordings at that time were only mixed in stereo and were therefore not suitable for quadraphony. The stereo recordings could only be played back in pseudo - quadrophony .

Pseudo quadraphony (system 2-2-4)

The reproduction of two-channel stereo recordings via four loudspeakers or loudspeaker groups is referred to as pseudo-quadraphony.

This type of playback was the most common at the time. Many suppliers, for example Dual , Marantz , Pioneer and Scan-Dyna, brought "Quadro adapters" onto the market. Most of them just split the signal to different speakers: the difference between the left and right sound channels was directed to the rear speakers and one of these speakers was rotated in phase.

If the sound recordings were accidentally or deliberately suitable for pseudo quadraphony, only those sound sources were located from behind that can also be heard from behind during a music performance in the concert hall, such as reverberation and applause from the audience. In many cases, pseudo quadraphony significantly worsened the sound, similar to attempts to imitate real stereophony with pseudostereophony .

Marantz even worked with Quadrofonie- tape decks , with a so-called pan control divided the signal and initiated with different strong signals on the main and Rearspeakers. This was also not a “real” quadraphony.

Four-channel in the cinema

Ray Dolby and his company (known for noise suppression processes in magnetic sound recording, namely Dolby B , Dolby C, Dolby S and Dolby HX Pro) introduced Dolby Stereo in 1974 . Dolby Stereo was a multi-channel sound system that could encode four channels (left, center, right, rear) onto a two-channel stereo track. In the cinema, the four channels are decoded again from the two channels of stereo sound with a decoder. This made a cost-effective introduction of surround sound possible. Existing film projection systems could be retrofitted with a Dolby stereo decoder.

Newer procedures

Quadrofonie is a forerunner technology of the Dolby Surround system, which was based on the matrix method of Quadrofonie, and the current digital 5.1 , 6.1 and 7.1 surround sound processes.

However, these processes could only assert themselves when the trend moved away from enjoying music and shifted its focus to home cinema. The reproduction of noises and voices is (subjectively) subject to a different spatial positioning behavior and is therefore easier to divide into several channels.

Well-known quadruple albums

Between 1970 and 1980, complete albums in Quadrofonie appeared again and again, especially re-releases of already successful albums by well-known artists. The following list is not exhaustive, but only shows an excerpt from a narrow program, regardless of the process.

See also

literature

  • Michael Dickreiter: Handbook of the recording studio technology. 6th edition. KG Saur Verlag, Munich 1997, ISBN 3-598-11320-X .
  • Thomas Görne: Microphones in theory and practice. 8th edition. Elektor-Verlag, Aachen 2007, ISBN 978-3-89576-189-8 .
  • Peter M. Pfleiderer: HIFI in a nutshell, playback technology for unadulterated hearing. 1st edition. Richard Pflaum Verlag, Munich 1990, ISBN 3-7905-0571-4 .
  • Thomas Görne: Sound engineering. 1st edition. Carl Hanser Verlag, Leipzig 2006, ISBN 3-446-40198-9 .

Web links

Wiktionary: Quadrofonie  - explanations of meanings, word origins, synonyms, translations