DE2126432C3 - Arrangement for the transmission of four signals over two channels of a transmission medium - Google Patents

Description

The invention relates to an arrangement for the transmission of four signals over two channels of a transmission medium, in which, with the aid of a coding matrix, both the first aK and the signal components of the third. Ν.;:.] Des lic; th signal with a relatively reduced amplitude are added and the resulting first and second signal signals are inputted into the two channels of a transmission medium, and in which four playback signals are derived from the two signal mixtures removed from the transmission medium with the help of a coding matrix, their first and The second mainly contain the first and second original signal with portions of relatively lower amplitude of both the third and the original signal, and their third and fourth reproduced signals each mainly contain the third and fourth original signal with portions of relatively lower amplitude of both the first and the second original included signal.

It is known that the reproduction quality can be improved by increasing the number of reproduction channels of a sound event, especially music. Compared to the previously exclusively monophonic Transmission and playback, stereophonic playback has already made significant progress brought. For some time there has been a further increase in the fidelity of the reproduction from sound events to four channels, the so-called quadrophonic reproduction, transferred. For example, when a listener is seated in front of a symphony orchestra, they will hear a variety of tones Directions and from a variety of instruments as well as reflections from the walls and from the ceiling, which gives it the usual illusion of a room perspective. However, when playing happens using only two channels, it is difficult, if not impossible, to get in To achieve realism with regard to the spatial perspective. Previous attempts have shown that At least three independent channels are needed to get a satisfactory fidelity when playing orchestral music.

Such a three-channel system is described by JM E arg 1e in "An Audio Engineering Society Preprint", which was published during the 35th meeting of the Audio Engineering Society from October 21 to 24, 1966. According to this system, a center channel is transmitted in addition to the right and left channels by dividing the center signal into two ^{signal components phase-shifted by plus or minus 45 D} , one to the left and the other to the right channel for additional transmission of the right or left signal is fed. During playback, a phase-shifted portion of the center signal that is 3 dB smaller then appears in the left and right channels, while the center signal on the playback side is formed by adding the signals transmitted via the right and left channels, with the sum of the in addition to the full center signal The right and left signals appear.

In the DT-AS 21 24 991 an arrangement for pseudo-quadrophone reproduction is proposed in the case of a two-channel signal source, which only has a right-hand signal and a left-hand signal provides, by combining these signals, four output signalsc are generated by adding or subtracting portions of the left signal * to the right signal and components of the right signal are added or subtracted from the left signal and

Can be phase shifted in directions. To this Way, the impression of the presence of sounds should be compared to normal stereo reproduction be reinforced. Of course, you cannot get more information than originally were contained in the two stereo signals, so that there is no question of a four-channel transmission can be.

With modern stereo recorders, modulations can be recorded in two separate channels, which are geometrically 90 to each other and 45 to the disk surface
are inclined. It is common practice to add a third channel as a phantom channel to the other two channels by "matrixing:": or adding, whereby this channel is recorded as lateral modulation parallel to the disk surface. To achieve special effects, some channels are often recorded in phase in the tracks, as is the case with the test disks with the model designations STR 110, 111 and 120 made by CBS Laboratories, a division of the Anmeklcrin of the present invention , are produced and distributed. During playback, the third (or middle) channel appears in both loudspeakers of the stereo record player in phase and at the same volume, and a listener in the middle between the loudspeakers has the illusion that the third channel lies between the other two. The fourth or vertically modulated channel, when played on a conventional stereo record player with two loudspeakers, creates the illusion of a "re-localized" sound. Although attempts have been made to play the third or center channel on a separate speaker, the results have not been entirely satisfactory and most stereos use only two speakers, although many stereo records have a "center" channel.

In the DT-OS 21 25 952 a system is described in which in a two-channel system per se a third and fourth loudspeaker with the sum signal or the difference signal of the right and left left channel is fed. For example, the left and right speakers can be on opposite sides Sides of a projection room, while the two speakers for the virtual Channels are located at opposite ends of the viewing room. Every speaker gives that special information of its channel at the same time with half the power of the signals from its neighboring Channels again. This system produces an apparent vicar channel effect, but the illusion is that each channel appears independently on its associated loudspeaker, not completely.

On the other hand, an independent reproduction of each of the four channels on a separate loudspeaker can be better pretended with a system as described in the application filed at the same time, DT-OS 21 26 4S0, which contains four amplifiers with controllable gain via which the four individual communication channels are each connected to the associated loudspeakers. Furthermore, a logic control circuit is provided which consists of the output for "left" and the output for "right ·· of the transducer or pickup StCUC" ■ '""'"'C'.'W.inni nnH hirrmil ¹ ^' ¹ * VersiiirUiinc ».- iLii controls the amplifier automatically to reinforce the impression of the presence of four separate communication channels. Although this system represents a considerable improvement in the reproduction technique for sound recordings, it has, however, several disadvantages. First, it contains the signal coming from "behind" which is encoded as a differential signal or as a vertical elliptical modulation. Little or no component in the "side" or "hum" direction, and when the recording is played back on a monophonic turntable or broadcast on monophonic radio, the signal intended for the "rear" is attenuated or disappears fully. Second, in the case of a Stcreo record, it is not desirable to modulate the information from the "rear" channel in a vertical direction, because this makes cutting and pressing the record more difficult. Thirdly, when playing a stereo record with the "rear" information available as vertical modulation via a conventional stereo record player, the "rear" signals in both loudspeakers appear out of phase or in such a way that an unpleasant feeling of "pressure in the ears" arises. Fourth, in conventional stereo systems, the two speakers are usually placed in two adjacent corners of the projection room, and four speakers are usually used in the four corners of the projection room when playing four-channel recordings.

However, the systems described in the two aforementioned disclosure documents are designed in such a way that symmetry is maintained with loudspeakers located in the middle of the four walls of the projection room. If you put the speakers in the corners, move! The image of the originally recorded sound changes by 45 ^C , which creates a disagreement that confuses the listener. In addition, since it is difficult to find suitable places for speakers in the middle of the walls in most homes, a playback system is preferred in which the speakers can be placed in the corners of the projection room.

The present invention relates to a system for transmitting multi-channel information over a different number of channels. The system should be suitable for monophonic. Making stereophonic and quadrophonic devices compatible with each other, the problem occurs to distribute signals from one number of channels to another number of channels. This is the case, for example, when there are only two transmission channels for a four-channel program be available. Initially, it makes no fundamental difference whether the two channels two transmission channels of a radio station or the two audio channels or tracks of a recording medium, like a record. On the other hand, the above problem also arises when several signals issued on two transmission channels% ' to be supplied to a four-channel playback system, for example, for example a quadrophonic playback device. Such a system is proposed in DT-OS 20 14 856, which with real quadrophonic coding in front of four-tone signals into two signal mixtures to be transmitted bcfaRt According to this earlier application, the four Unginalsignals are presented without introduction

Phase shifts in certain proportions additive and subtractive to form two signal mixtures combined with each other.

In contrast, the object of the invention is to further improve the surround sound effect in the sense of a more balanced symmetrical presentation, namely the signals of the two additional (rear) channels with the usual stereo signals comparable signals of the two Front channels are combined in a special way that decodes them into four separate signals which correspond to the four original signals. In the four again separate channels • ought to be one of the four original signals used for recording as the predominant signal be included. Furthermore, with the invention, the signals from four communication channels on a two-lane Stereo record can be recorded without a pronounced vertical modulation must be added, and should continue to be the additional introduction of a common middle Signal are enabled, which is superimposed on the four main signals in the middle.

This object is achieved with the characterizing features of claim 1.

The invention is particularly suitable for systems in which the loudspeakers in are arranged in the four corners of a room. At the same time there is compatibility with two-channel Playback systems ensured, with the help of which the four original signals encoded on two channels can be reproduced in a balanced way, so that, for example, according to the quadrophonic system according to the invention Recorded records can also be listened to using conventional stereo systems with good fidelity can be.

The invention also gives the possibility of creating a system with which the dominant Channel is highlighted under control of the signal currently being transmitted in it, so that at a four-channel.i reproduction still has the pretense of four separate, independent sound sources looks more realistic, as has already been proposed in principle in DT-OS 20 14 856 already mentioned is.

Compared to the method proposed in DT-OS 20 14S56, the coding takes place according to the invention with the additional introduction of phase shifts, whereby the equations for the coding of the four signals front left (L,), front right (Ri), rear left (L ,,) and right behind (Ri) in the two signal mixtures to be transmitted or recorded L ₇ - and R _T can be represented in the following way:

L ₇ = L ₁ -J- 0.707L ₆ + 0.707 R _h R _T = R, + j * 0.707 R _b - 0.707 L _b

Such encoding is effected using a combination of phase shift networks and adding circuits, and the two signals L _7- and R _T can be recorded on a two-track record or two-track magnetic tape in the manner explained below.

The signal, which for the sake of simplicity can be referred to as the "left front" signal.

is recorded on the "right" channel. The recording of the "left rear" speaker assigned signal takes place in the "left" channel with a 90 ° phase shift compared to its recording in the "right" channel, and similarly there is a phase shift of 90 ° at the recording of the right rear speaker assigned signal in the »left« and »right« channel. The recording is done in such a way that ίο that the signal for the left rear loudspeaker precedes the left channel and that the signal for the right rear speaker precilted in the right channel. Thus, the recorded according to the invention contain Stereo records are basically four different Signals: a "left front" signal, which is a modulation of the left wall of the record groove appears, a "right front" signal, which appears as a modulation of the right wall of the groove, a "left rear" signal, which is used as a RiI-lcnmodulaiion appears due to a circular movement of the cutting stylus clockwise, and a "Right rear" signal, which is a groove modulation on the basis of a cutting engraver "against clockwise appears. The circular motion is created by the quadrature modulation of the two Groove walls, and if the cutting stylus moves in the longitudinal direction of the groove, then results from the circular motion a helix.

According to another feature of the invention, a signal which when played back as "Phantom" signal should appear between any two loudspeakers, in the same way each of the both channels or, if desired, all channels can be fed together. So if a -middle " Signal is used, the record produced according to the invention contains five different ones Signals.

The Decodierschalmng for the splitting of the The combined signals into the four playback signals contains two all-pass phase shifters. This Both pure phase shifters are used to change the mutual phase position of the "left:" and the "right" channel their restoration as four separate Sicnalc Allow playback in four separate speakers. TJm the individual signals that are in any of lay speaker circuits prevail, even further To emphasize, the mentioned signer working arrangement can the decoding and control logic part and contain the amplifiers whose gain can be controlled, as described in the patent application already mentioned P 21 26 480 are described.

The foregoing and other details of the invention will be provided in order to understand the invention described in detail below with reference to the drawings.

F i g. Figure 1 shows schematically an arrangement for recording four news channels on one Stereo record;

F i g. 2 shows a vector diagram to explain the movement of the cutting stylus during feeding the left, right, middle and difference signals;

F i g. 3 shows a greatly enlarged in cross section

four grooves containing part of a record to

the movement of the cutting stylus "; at the different

ΐΐιι "Γί> / νΓύιΐΓ

Signal F i g assigned to the “right front” loudspeaker. 4 is a schematic representation of a her-

11 12

Conventional stereophonic playback system can be recorded to the tracked tape, whereupon

Pretend a third channel; the output of the tape player to control

F i g. Figure 5 is a schematic representation of one embodiment of the cutting device. The

Apparatus for recording four channels on in Figs. 1 and 2 shown difference signal D is

a two-track stereo record according to Tech- 5 will be dealt with later,

nik, as described in DT-OS 21 26 480; The type of the process just described

F i g. 6 shows, on a greatly enlarged scale, a groove modulation obtained from a record is grooved in FIG. If only the left signal L is applied, the reference signal to the right and left channels, the groove is modulated according to the arrow L , which is illustrated by means of a phase shift network, essentially on a wall of the groove ; restricts. It is done in a similar way when creating

F i g. 7 is the schematic representation of an er of the signal R a modulation of the opposite

inventive coding matrix for summarizing the groove wall in the direction of the arrow R pointing to

Solution of independent signals, which is vertical above four loudspeakers arrow L. When creating each

rather should be reproduced; »5 equal amounts of the mean signal C to the line

Fi g. 8 is a vector diagram to explain the lines L and R , both groove walls are equal-

Circuit according to FIG. 7; timed and modulated in the same way, with

Fi g. 9 shows schematically an embodiment of the magnitude 0.707 Γ in the direction of the arrow L in each case

decoding circuit according to the invention; and in the direction of arrow R, from which a horizontal

Fig. 10 shows from above a demonstration room with 20 valley or lateral movement resulting from the

the arrangement of the four loudspeakers and phase arrow C is displayed.

Vector diagrams of the sound emitted in the four loudspeakers Signals; plate, which the in the manner described above

Fig. Π is a schematic representation of a drawn signal L, R and C contains, schematic-simplified embodiment of the inventive 25 table is shown in FIG. This system contains a Ben decoding circuit; Stereo pickup head 18 with a stylus

12 is a schematic representation of a 20 which runs in the disc groove and is moved through the grooves of another embodiment of the modulation according to the invention, so that decoding circuitry is provided at the outputs; L and R of the pickup output voltages

Fi g. 13 is a schematic representation of a white 30 appear. If only one f. Signal mo-

Another embodiment of the de- dulation according to the invention is present only appears at the output L

coding circuit. an output signal, which after amplification in

For a better understanding of the invention, a power amplifier 22 from a loudspeaker

next, the usual method for recording is reproduced. In a similar way

stereophonic signals with a third or 35 appear to be in the presence of an RS \ -

middle channel and a method for playback gnalmodulation of the groove only at the output R of the

of these signals by means of a streophonic two-tone pickup, an output voltage that

loudspeaker anlace is amplified on the basis of FIGS. 1 to 4 and the associated

very nice. The normally provided signals for the loudspeaker 28 is fed. When the groove

left (L), right (R) and middle (C) are the two 40 if there are the same linings of the left

the inputs of a stereophonic cutting front and the right signal a lateral modulation

direction 10 fed. whose cutting stylus 12 contains, then appear in the left and in the right

is designed that he has a groove in the shellac of a loudspeaker same signals, namely 0.707 Γ, so

Plate matrix 14 cuts, which is on a (not that in the middle between the loudspeakers 24 and 28

shown) the pick-up plate rotates. The C signals 45 an apparent or phantom switching source C (in the

pass through a signal splitter 16 of known type. Drawing surrounded by a dashed circle)

so that each of the lines L and R appears to be more additive. However, this illusion has only one

Assign a part of this signal to the listener immediately in the middle 30. If he is

0.707 C is supplied. As it moves in the plate to one of the sides, he hears the C signal

Cutting technique is known, the tip of the stick can come out of the nearest loudspeaker, if not particularly

chels movements within a unit perpendicular to the other measures are taken in order to

Carry out the directional level of the plate, in a way that depends on the characteristics of the loudspeaker

as indicated by the vector diagram of FIG. 2 to set the position of the listener,

shows is. When a left signal L is supplied. The three-channel recording described is

the cutting stylus moves along the arrow L. of the 55 compatible because the signals L, R and C all one

is inclined by 45 ° to the horizontal, and if have a horizontal modulation component and

i? signal is fed to the cutting moves thus be heard when on a monophonic

stylus along the arrow R, which is displayed opposite the horizontal playback device, which

talen is inclined by -45 °. A feed of only responds to lateral modulation, although the

0.707 Divide the C signal to lines L and R 60 relative signal strengths are not as balanced as

in an additive manner creates a deflection that was originally intended by the production manager,

Cutting stylus in the direction of arrow C and in the because the horizontal modulation components in the

carry 0.707 (Z + ä), which is the amount of deflection for L and J? channels 0.707 C. In reality

L or R corresponds, but in the horizontal direction. gives the system described above despite the input It should be mentioned that instead of the direct supply of a third channel only two independent channels

tion of the signals L, R and C to the cutting device, communication channels again. The third channel is C

as shown in FIG. 1, these signals correspond in both the left and right channels

Chciid of the usual practice ranächsl aiii a two-vmhanuen, and the listener ~ ^- will therefore get used to it

borrowed from the speaker hear the closest to him is. This "middle" channel can be reproduced with a separate speaker system, as shown with dashed lines in FIG. 4 and amplifiers are commercially available for this purpose available. This allows the listener, the "middle" To perceive the news channel without being at the same distance from the left and right Loudspeaker must be located. Such a middle loudspeaker can, however, have the consequence that the sounds from the other two speakers seem to be "drawn in" towards the center.

As shown in Figs. 1 to 3, a fourth channel D can be introduced into the two-channel stereophonic system if this channel is divided into equal parts by a signal splitter 32 and these parts are then fed to the right and left channels in opposite phase. As in Fig. 2, the supply of the D signal in this way causes the cutting stylus to move in the vertical direction along the arrow D by an amount which is determined from the difference between the 0.707-fold D signals that are present in the left and right channels are. The vertical movement of the cutting stylus is therefore 0.707 (L - R). As in Fig. As shown in FIG. 3, this is caused by the mutually phased left and right movements of the cutting stylus, which creates an up and down movement. If the vertical modulation with a system according to FIG. 4 is reproduced, the loudspeaker diaphragms are driven in opposite directions so that the listener's ears receive sound pressures in opposite phase. Since such pressure conditions on the ears never correspond to normal hearing conditions, the listener cannot localize the sound. The difference signal D appears at any indefinable points in space, as indicated in the drawing with D in the dashed circle, and the listener is unable to identify the origin. Some listeners have also complained about a strange feeling of "pressure in the ears" when hearing such a phase-shifted sound. This is partly overcome by the arrangement described in the already mentioned DT-OS 21 25 952, in which the difference signal and also the "average" signal are reproduced via separate loudspeakers.

In order to achieve better compatibility with monophonic and conventional stereophonic turntables and at the same time to complete the pretending of four separate channels during playback, the difference signal D is preferably fed in as the inventor of the present application, Benjamin B. Bauer, wrote in an article with the title "Some Techniques Toward Better Stereophonic Perspective." This article was published in "IEEE Transactions on Audio", Volume AU-11, No. 3, Mpi / June 1963. As in Fig. 5, the difference signal is not in the same and opposite phase to the left and right channels as in the circuit according to FIG. 1, but the D signal is sent through an acoustic phase shift network 32, which _{splits the incoming signal into two signals D 1} and D _{2 of the} same amplitude, each signal containing all frequencies of the D signal, but both signals being phase shifted to one another. A relative phase shift between 110 and 170 ° was successful, a phase angle of 135 ° was particularly favorable. It can easily be shown that with such a mutual phase shift of two signals, the tip of the cutting stylus instead of a pure up and down movement, which is shown in FIG. 3 is shown, one in FIG. 6 performs elliptical movement shown. The limits of the stylus movement are shown by dashed lines, and the direction of the elliptical movement depends on whether the signal D, the signal D ₁ , is leading or vice versa. It is important that the groove has a horizontal modulation component, which is determined by the horizontal width of the ellipse, so that both monophonic and stereophonic record players reproduce all four signals. This means that a record with four separate channels is completely compatible with the older playback devices, although the signal D is attenuated by about 8 db in nonophonic systems.

The fidelity of the reproduction four separate News channels that have been recorded in the manner just described, leaves improve by a control device, as described in the DT-OS 21 26 480 mentioned above is. This device takes signals from the right and left outputs of the converter or Pickup, splits the signal mixture into its respective components, compares the strength of these components and influences the gain of controllable amplifiers in the individual loudspeaker circuits. The amplifiers are controlled in accordance with the loudness of the respective signal components in such a way that an essentially perfect pretense four separate independent sound sources takes place.

In Fig. 7 a coding matrix is shown schematically, which are the four independent signals that

are provided for final reproduction with four separate loudspeakers, put together to form two mixed signals in order to record or transmit them on a two-track carrier, such as a stereo record or a two-track tape. The matrixing device contains four inputs 40, 42, 44 and 46 for the four separate signals which, for the sake of simplicity, as left front (Lf), left rear (Lf,), right rear (/?;,) And right front (Ri) Signal.

These designations each indicate the location of the one of the four loudspeakers in a projection room for which the signal in question is intended for its final reproduction. These signals are represented by vertical arrows of equal length, which is intended to mean for the subsequent evaluation that the incoming signals are assumed to be equally strong and related to the same reference phase. The coding matrix contains six all-pass phase shifters 48, 50, 52, 54, 56 and 58 which impart an essentially constant phase shift to the signals fed in over the frequency range of interest without changing their amplitudes. Each phase shifter causes a reference phase shift y that is a function of frequency. The two phase shifters 50 and 56 only effect the reference phase shift. The phase shifters 48 and 58 cause a phase shift of 1 /: 45 °, and the phase shifters 52

and 54 cause a phase shift of ψ + 90 °.

The signals L ₁ and R " u-iii" are assigned to the "left front" and the "right front" loudspeaker are transmitted to the associated summing circuits 60 and 62 via their corresponding connections 40 and 46 and via the associated all-pass phase shifters 48 and 58 fed. The "left rear" signal L _b runs in parallel through the two phase shifters 50 and 52, the output of the phase shifter 50 being applied to the summing circuit 60 with an attenuation corresponding to the factor 0.707 and the output of the phase shifter 52 being applied to the summing circuit with the same attenuation 62 is placed. The “right rear” signal R ₀ is fed in a similar manner in parallel to the phase shifters 54 and 56 , the outputs of which are fed to the summing circuit 60 and 62 respectively with an attenuation of 0.707. Summing circuits 60 and 62, which are conventional and known in the art, produce signal mixes L ₁ and R _T at their outputs 64 and 66. These signals can, for example, be fed to the left and right inputs of a stereo recorder cutting device, or they can be fed to the two pick-up heads of a two-track tape recorder or any other known two-channel carrier in a manner well known to those skilled in the art.

The coding matrix has so far been described in connection with four input signals, but if a signal that appears in the center of the playback channel is desired, a "middle" signal, illustrated by arrow C, can be inputted 40 and 46 or the inputs with the same strength and in phase 42 and 44 or all four inputs are fed simultaneously, as indicated by the curved arrows. The C signal is subjected to the phase shift of those phase shifters to which it is fed, for example according to FIG. 7 the phase shifters 48 to 58, and it becomes part of the signal mixers L ₁ and R ₇ .

The composition of the mixed signals appearing at the connections 64 and 66 can be seen from the vector diagrams drawn next to these connections. It can be seen that each of these signals anterior an overriding signal L ₁ 'or R _1' for a '' Lauisprecher contains, both of which are out of phase with the original input signal L /, and Ri to t, · · 45 ". The L _T - Signal also contains signals L _b ' and R _b , which lead to each other with the /,, ' signal are shifted by 90 ° and compared to the signal L ₁ 'by 45 ° two mixed signals in the same relative phase position as the signals L ₁ ' and R ₁ '.

It is to be pointed out that the signal R _{T is} additionally to the signal R / the two by 90 ^; Contains signals /.// and R _b phase-shifted to one another, but the mutual phase-locking of these two signals is reversed compared to their phase relationship in the /./ signal, ie. R _b is leading and /./ is lagging compared to the corresponding signals at terminal 64. As mentioned earlier, however, signal C ″ again has the same relative phase accuracy as the corresponding signal at terminal 64.

Since the signals L ₁ ' and R ₁ ' are usually not coherent, when they are recorded on a stereo record they appear independently of one another as separate modulations of the right and left channels. The signals C in phase with one another at the two terminals 64 and 66 cause a lateral modulation on the record. The fact that the signal L ₀ ' at terminal 64 leads the signal L ₀ at terminal 66 by 90 ° results in a modulation of the record groove according to a right-hand helical line, similar to a right-hand thread. Because signal R _b at terminal 64 lags signal R _b ' at terminal 66 by 90 °, a counter-rotating helical line is recorded in a similar manner, similar to a left-hand thread. The five of the coding matrix according to FIG. 7 signals thus arrive as five different types of modulation on a stereo record, namely as modulation of the left and right groove wall, as lateral modulation and as clockwise and counterclockwise screw modulation.

In Fig. 8 shows the shape of the modulation on the record as it appears when looking from the tip of the cutting stylus in the direction of the groove. The /., 'signal causes a movement inclined by 45' relative to the horizontal, the / if 'signal causes a movement inclined by -45 ^ relative to the horizontal and the C signal causes a lateral or horizontal modulation. These three modulations are the same as those obtained by cutting a conventional stereo sound board. An essential difference compared to conventional technology is that there is also a clockwise circular modulation L ₁ , which corresponds to the signal for the "left rear" loudspeaker, as well as a counterclockwise circular modulation R ₁ , which corresponds to the signal for the "right rear" loudspeaker rear «loudspeaker. Since the L ₁ , - and R ₁ , - modulations each have a considerable horizontal component (as a projection onto the line C), they both generate equivalent signal components for horizontal operation, so that complete playback is also possible with a monophonic record player. The method just described for combining the input signals to form two signal mixtures has the significant advantage that a stereo record recorded in this way or a tape recorded in this way can be played with all stereophonic or monophonic playback devices with complete reproduction of all recorded sounds.

It should be noted that other modulations can also occur during recording. For example, follow-up components are often distributed out of phase to the input terminals. It It is not intended to limit the signals to the five different types listed above; other forms of modulation in addition to the five basic forms result in double types, do with Have HiHc of the basic forms mentioned analyzed.

In Figures 1 and 9, there is an embodiment of a deodorizing device shown, with which individual signals can again be obtained from the two signal mixtures let that in the manner described above on a stereophonic recorder for

609 64G 121

, Playback via a multi-speaker system, has been added up. D, e be, the signals L _T and Rr are converted by means of a suitable converter (e.g. with a conventional stereo pickup in the case of a

rock of a common stereo pickup in the case of a cne Y

Record) from the record carrier- 5 narrow channels

74 undto _"besc | rubbing is. This

«De ^r » '^ _{106 ennittelt deD} ; _enieen

next all-pass phase shifter erleugt 74 and 76, the latter of which a reference phase shift of _Vl, while the phase shifter 74 causes a phase shift of + 90 ° _Vl. The value of v can be exactly as large as the phase shift ν in the coding matrix according to FIG. 7, but a different value can also be selected, it is only important that the reference _phase Ψι be the same in both phase shifters 74 and 76 The phase shifters 14 and 76 convert the input signals L ₇ - and R ₇ into new signals L ₇ 'and R ₇ -, which _{are almost the same as the signals L 7} - * and R _T , only that they are at 90 ° to- This is shown by the phase vector diagrams in Fig. 9. The individual vectors of the R _r signal lie to one another in the same way as those of the! / Signal, except that the vectors of the L / signal are all 90 ° Since the reference phase shift ν, is the same in both phase shifters, their respective influence was not taken into account in the representation of the vector diagrams.

The composite signal L / passes through an additional A-pass phase shifter 78, which effects a reference phase shift y ₂ without changing the signal amplitude. Subsequently, the composite signal passes through a controllable amplifier 80, DES "s gain is ignals controllable by applying a control", and by a suitable Leittungsverstärker to a speaker 82. In the normal mode, the signal L "prevails in the composite signal L ₇ - ' In a similar way, the composite signal R _T runs through an all-pass phase shifter • 4, which shifts the phase by X ₁ - " · * - 90 °, and then an associated amplifier 86 with controllable gain and a power amplifier. Stronger up to loudspeaker 88. In this signal, the signal R, "predominates. A signal in which the "left rear" signal L ₁ , " predominates, is obtained by summing the signals L ₇ - 'and R _T , in that each of these signals, after multiplication by a factor of 0.707, is fed to a summing circuit 90 of the scanned type The output signal of the summing circuit 90 goes to an all-pass phase shifter 90, which causes a relative phase shift of V ₂ + 90 °, and from there through the controllable amplifier 94 and a power amplifier to the loudspeaker 96. To obtain the fourth signal, in which the »right rear "Sifinal R ₁ ," predominates, the signals L ₇ - 'and R _{T are} summed in a similar summing circuit 98. after the signal L _T 'has been multiplied by the factor 0.707 and the signal R _T by the factor -0.707. The corresponding summing signal (in reality a signal difference) passes through the phase shifter 100, which causes a plug-in splice connection), to controllable amplifier 102 and voii there via a power amplifier to the mirror 104, fis

The amplifiers 80.0- !. 102 and 86 are controlled by the ionic filter circuit 106, depending on the j ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ optimalree signals, so that the amplification of the channel carrying the currently preceding signal is increased! and the gain of the other channels is decreased to improve the illusion of the presence of much separate independent sound sources. If the sound in the first determined channel is weaker and another Γοη appears in a different channel, then the control circuit quickly attenuates the gain of the previous channel and increases the gain in the other channel

It should be noted that the. Circuits according to FIGS. 7 and 9 used all-pass phase shifters can be of any design with which constant phase differences, as indicated in the drawing, can be achieved. The phase angle ψ should be as small as possible without contradicting the creation of the necessary phase differences. The phase shift function should have a smooth course and not allow sudden changes in the phase angle as a function of the frequency, because such sudden changes can cause slight changes in the timbre of the recorded and / or reproduced sound. The direction of rotation of the respective screw modulation during the recording process can also be reversed by reversing the relative phase shifts of the signals L _b and R ₁ in the coding matrix of FIG. The; would have the consequence that the vector R ₁ , ' in the left channel leads the vector R, / in the right channel and that the vector L ,,' in the right channel leads the vector L ₁ , in the left channel. If such a reversal is carried out, the all-pass phase shifters 74 and 76 must be interchanged in order to obtain a correct decoding of the four individual signals.

FIG. 10 illustrates the arrangement of the loudspeakers 82, 96, 104 and 88 in a demonstration room for optimal reproduction of the loudspeakers shown in FIG. 9 decoded signals. The loudspeakers 82, 88, 96 and 10 ^ are located at positions which correspond to the entries "left front", "right front", "left rear" and "right rear". A phase vector diagram of the signals that appear in this loudspeaker is drawn next to each loudspeaker. It can be seen that one of the signals L ₁ ". R ₁ ", L _h " and R ₁ ," prevails in one of the speakers 82, 88, 96 and 104. The signals present in each channel from the respective other channels have a level that is about 3 db lower than the main signal belonging to the respective channel and do not appear to the listener. Rather, it primarily hears the four independent channels that are connected to the four loudspeakers! are presented.

An improved suppression of the sduviidieiei Signals .1,1 ^. ilen other channels for the Fmpfiiniei the listener is heard through the ionic control sound; 106 reached, dutch the a certain L.uitspredie

preferred by its associated controllable amplifier when the predominant signal is in the relevant channel appears. A positive gain control signal is then sent to the amplifier in question placed, while the gain of the controllable amplifier assigned to the other channels is withdrawn or the signals fed to the other loudspeakers are switched off. This further enhances the illusion of four independent channels. But even without that The arrangement is capable of using the controllable amplifier and the logic control circuit 106 according to FIG. 9 four separate signals on four different ones Reproduce loudspeakers with very good fidelity. It was also found that the phase shifters 78, 92, 100 and 84 lead to an audible separation of the channels in the four-speaker system contribute that one still has an acceptable separation without these structural units of the canals.

These findings form the basis for a further simplification of the decoding matrix, as shown schematically in FIG. 11 is shown. In this device, the two composite signals / are., And R _7, which in turn can be present as output signals of a stereophonic pickup or a magnetic tape device, each with an associated allpass Phasenschicber 114 fed through 116 with the previously bcschriebenen properties. The phase shifter 116 provides a phase shift of τ, · ,, and the phase shifter 114 provides a phase shift of y ₃ - 90 °. The output signals of these phase shifters are each passed to an amplifier 118 or 120, which can be the output amplifier of a conventional stereo record player. Instead of the two loudspeakers normally used in the stereo record player, four loudspeakers 154, 156, 158 and 160 are provided.

The loudspeaker 154 is connected directly to the amplifier 118 (with a return line via earth) and therefore carries the signal L ₁ ". In a similar manner, the output of the amplifier 120 drives the loudspeaker 156 directly, which thus reproduces the output signal R ₁ ". These two speakers are usually located in the left and right corners of the screening room. The two connections of the amplifiers 118 and 120 which are not connected to earth are connected via the loudspeaker 158, so that this loudspeaker receives the differential signal from the two amplifiers. The loudspeaker 158 thus corresponds to the loudspeaker 104 in FIG. 9 and is therefore located in the rear right corner of the projection room.

A sum signal which represents the signal L ₁ , " is expediently obtained by means of the transformer 130, the primary winding of which is connected between the output terminal of the amplifier 118 and earth, so that the full output voltage of the amplifier is applied to it. The secondary winding of the transformer is between the output terminal of the amplifier 120 and one terminal of the loudspeaker 160, the second terminal of which is connected to earth. With this type of connection, the output voltages of the two amplifiers are added. The loudspeaker 161t ei therefore holds the sum signal and thus corresponds to the loudspeaker edier% in Fig. 9 and is arranged in the left corner of the projection room in a row. The coil input jars of loudspeakers 158 and 160 are approximately twice as large as those of loudspeakers 154 and 156, so that their output powers are reduced so that the The sound power emanating from the four loudspeakers is roughly the same rt not all the subtleties like the system according to F ^; G. 9, but it represents a simplified, inexpensive system with which a very good prerequisite for a four-channel

I can achieve stereophonic reproduction.

In Fig. 12 there is another decoding circuit for reproducing four as shown in Fig. 7 coded signals. The L ₇ - and /? _r signals are applied to terminals 132 and 134 and thence to all-pass phase shifters 136 and 138. As in the embodiment according to FIG. 11, the all-pass phase shifter 136 generates a phase shift of V ₃ + 90 °, and the phase shifter 138 generates the reference phase shift y _v so that there is a phase shift of 90 ° cn '- between the two signals . The output signals of the two phase shifters L ₇ and R ₇ are, if necessary, amplified in the amplifiers 140 and 142, the output signals of which are mixed in a resistor network consisting of the three resistors 144, 146 and 148. Each of the resistors 144 and 146 has a value ^v on ¹ ^ ₃ A, and the resistor 148 has a value of - ₃ R, wherein R is any value to match the impedance of the amplifier 140 and the 142nd

For example, if these amplifiers have a low impedance on the order of 1 Ω or less, then R is 100 Ω or more. If, for example, 1000 Ω is selected for the value R , then the two resistors 144 and 146 each have 333 Ω, and the value of the resistor 148 is 666 Ω. In addition, the value of resistor R should be chosen so that the impedance is low compared to the input impedance of amplifiers 150 and 152.

The resistor network to a voltage applied to the terminal 132 signal L ₇ 150, a signal L ₇ at the input of the amplifier "form and can appear simultaneously at the input of amplifier 152 a signal that with respect to the L signal ₇ 'has a level of -9.5 db . On the other hand, when a signal R _{7 is applied} to terminal 134 at the input of amplifier 152, a corresponding? Signal R ₇ ", while due to the action of the resistance network at the input of the amplifier 15 (1 another signal appears which, with respect to the signal R ₇ ", has a level of -9.5 db.

The output terminals of the amplifiers 150 and 152 are in the manner shown with the viei Speakers 154, 156, 158 and 160 connected

The loudspeaker 158 is located directly between the output terminals of the amplifiers 150 and 152 unc thus generates the difference signal of these two Ver stronger. The speaker 154 is one of its Terminals connected to the output terminal of the amplifier 150, and the loudspeaker 156 lies with its corresponding terminal on the output terminal of the amplifier 152. The remaining Klcnvnci iler loudspeakers 154 and 156 are un <with each other connected to one terminal of the speaker IM)

^fi f> its other terminal to earth and -mim to the return line to the amplifiers 150 mu! 152 \ a ../. It is known that the loudspeaker is i! Ml di .: summ of the two amplifiers) 150 and! 52 ei / ei!; ·

th currents and therefore the sum of the two signals /., "and R ₁ " reproduces. Each of the loudspeakers 154 and 156 mainly carries that current which corresponds to the channel L _T or R _{1 assigned} to it. The loudspeaker 160, however, forms an additional shunt impedance, as a result of which a small amount of signals from each of the channels Lj and Zf ₇ with a negative sign can act on the loudspeaker of the respective other channel. The network consisting of the resistors 144, 146 and 148 has the effect that a small part of the voltage from one channel is applied to the amplifier of the other channel, whereby the undesired effect of the opposing current is switched off and only the desired one in the loudspeaker 154 Signal L ₇ and in loudspeaker 156 only signal R ₁ appears.

For correct operation of the circuit it is necessary that the impedances of the voice coils of the four loudspeakers are correctly matched to one another. If the loudspeakers 154 and 156 each have an impedance of Z ₁ , which can expediently have a value of 80, then the impedance of the loudspeaker 160 should have a value of 1/1, Z ₁ or 4 Ω, while the impedance of the sound Speaker 158 should be at 2 Z ₁ or 16 Ώ . While these impedance values can be corrected in a known manner in order to achieve an optimal power matching, the values given have the advantage that they make the powers of all channels for the mixed signals L ₁ and R _T equal.

The embodiments according to FIGS. 9, 11 and 12 are set up for operation with four loudspeakers, each reflect the entire frequency range of interest. Because of Due to its size and economy, it is sometimes desirable to keep the low-frequency tones (below about 200 Hz) of all channels with a single woofer, while for the maintains separate and independent loudspeakers for higher-frequency sounds. From this principle makes the decoder shown in Fig. 13 is used. It is assumed. that the low frequency signals (below about 200 Hz) to induce of the directional effect contribute significantly less than signals above this frequency. Hence will be the low frequencies from all channels mixed together and fed to a single loudspeaker, while the higher-frequency signals are reproduced on four additional loudspeakers, each of which represents the predominant signal of a given channel.

For this purpose, the signals L ₇ - and R _T are fed to the input connections 132 and 134 and, as in the previously described embodiment, each run through a separate all-pass phase shifter 136 or 138, which has a phase shift of v'3 + 90 ° or cause v'3. In the present embodiment, however, it is different in that one of the signals, for example R ₇ , is inverted (that is to say phase shifted by 180 °). This can be, for example, by reversing the polarity of one of the elements of the pickup reached, so that the composite signal R _T is the terminal 134 supplied with a negative sign, or by using an inverting element in the decoder circuit itself. For example, the amplifier may be constructed 142 'so that he reverses the phase of the signal supplied to him. As in the arrangement according to FIG. 12, the outputs of amplifiers 140 and 142 'are connected to one another by a mixer circuit consisting of resistors 144, 148 and 146, which in turn is connected to the input terminals of amplifiers 150 and 152.

As a result of the inversion of one of the input signals, for example the signal R ₁ , a sum signal which contains the low frequencies of all channels appears at the outputs of the amplifiers 150 and 152 instead of the difference signal present in the embodiment according to FIG. These low-frequency signals are separated and reproduced by a special woofer 162 which is located between the output terminals of amplifiers 150 and 152, preferably in series with an inductance 164, which has a value such that all higher-frequency signals are above a certain limit value, e.g. 100 Hz. be kept away from speaker 132. The loudspeakers 154, 156, 15 * and 160 for reproducing the direction signals are done in a manner similar to that shown in FIG 168 of the same capacity, which keep frequencies below the limit value away from the tweeters.

Because of the reversal of one of the loudspeakers 158, which is connected between the output terminals of the two amplifiers, the buzzing signal again and should therefore be placed in the rear left corner of the projection room. Accordingly, the loudspeaker 160 now carries the difference signal and should therefore be set up in the right rear corner of the room. As in the embodiment according to V ig. 12, speaker 154 carries the left front signal and speaker 156 carries the right front signal. These loudspeakers can therefore be arranged in the left front or right front corner of the room as before. In addition, because of the inversion of the signal R _{T of} the loudspeaker 156 must be reversed as in the case of FIG. 12, as indicated by the black point on the right-hand side of this loudspeaker in the drawing z.

The values of the capacitors 166 and 168 and the inductance 164 for frequency separation can be chosen within fairly wide limits, but the capacitors 166 and 168 preferably have a reactance which is the same at the cutoff frequency of the impedance Z ₁ , and the inductance 164 becomes so chosen that their reactance is twice as large as the impedance Z ₁ at the same frequency. Of course, other suitable means for separating the low and high frequencies can also be used for their reproduction on the associated loudspeakers. The resistors 144, 146 and 148 can also be selected with their respective values V ₃ A, V ₃ A and V ₃ R within very wide limits; this choice depends on the impedance values of speakers 154, 156, 158 and 160 .

The with the arrangement according to F i g. 7 coded signals can also be reproduced with an even simpler decoding circuit in that the all-pass phase shifters 136 and 138 are omitted and the signals I ₁ and R _T di ^ -'-. T ^ to the Eir: uzr.2S-

terminals 170 and 172 of amplifiers 140 and 142 'are applied. Then, however, it is expedient to arrange the loudspeaker 158 carrying the sum signal in the front part of the projection room and the loudspeaker 160 / It carrying the difference signal

in the back of the projection room. The speaker 154 carrying the left front signal should be in the front left of the projection room and the loudspeaker 156 carrying the right front signal should be placed at the front right.

For this purpose 4 sheets of drawings

Claims (22)

21 432 claims: 1. Arrangement for the transmission of four signals over two channels of a transmission medium, in which with the help of a coding matrix both the first and the second signal portions of the third and fourth signal with relatively reduced amplitude are added and the resulting first and second signal mixture in the two channels of a transmission medium are entered, and in which four playback signals are derived from the two signal tables removed from the transmission medium with the aid of a decoding matrix, the first and second mainly the first and second original signal with proportions of both the third and the second original signal of the fourth original signal and whose third and fourth playback signal each mainly contain the third and fourth original signal with proportions of relatively smaller amplitude both of the first and the second original signal n shows that the third and fourth original signals (L / ,, R _h ) are contained _{in the first and second composite signals (L 7} -, R ₇ ) with a mutual phase shift of 90 ° in such a way that their phase sequence is contained in the first composite signal ( L ₇ ) beziig-Hch the first original signal (L ₁ ) {, independently of their phase sequence in the second signal mixture (Rt) with respect to the second original signal (R,) and that for the first and the second playback signal (from loudspeaker 82 and 88) the same phase relationship of the third and fourth original signal applies as for the binding signal mixtures (Lf, R _r ), while for the third and fourth playback signal (from loudspeaker 96 and 104) the corresponding relationship for the phasers follows the first and second original signal (Lf, R,) with respect to the third and fourth original signal (Z. _h , Rh) applies- 2. Arrangement according to claim 1, characterized in that in the first signal mixture (L ₇ ) the first signal (L,) in phase or in antiphase to the fourth signal (R ₁ ,) and in the second signal _{mixture (R r} ) the second signal ( R ₁ ) is in phase or in phase opposition to the third signal (L ,,). 3. Arrangement according to claim 1 or 2, characterized in that the with four inputs (40, 42, 44, 46) for the four original signals (L ,, R ₁ , L, "R _h ) and with two outputs (64 , 66) for the two _{mixed signals: (L 7.} R ₁ ) provided coding matrix contains circuit elements (48, 58, 60, 62) in first signal paths, which the first input (40) with the first output (64) and the second input (46) with the second output (66) in such a way that the same amplitude components of the first and second original signals (L ,, R ₁ ) are present at the first and second output (64, 66), as well as circuit elements (50, 52, 54, 56, 60, 62) in second signal paths, which connect the third and fourth inputs (42, 44) to both the first and the second output in such a way that equally reduced amplitude components of the third and fourth signals ( L ₀ , R _1. ) With a mutual phase shift angle vo that is constant in the frequency range of interest n 90 ° to reach the two outputs (64,66). 4. Arrangement according to claim 3, characterized in that the circuit elements (48, 58, 60, 62) of the first signal paths the mutual phase position of the first and second original signals (L ,, R,) during their transmission from the first or second input (40, 46) to the first and second output (64,66), respectively. 5. Arrangement according to claim 3, characterized in that the circuit elements (48 to 62) of the first and second signal paths as the first Signalgcmisch (L _T ) the sum of the first original signal (L,) with a reduced proportion of the third original signal (L ,,) and a reduced proportion of the fourth original signal (R ₁ ) phase-shifted by 90 ° and, as the second composite signal (R ₇ ), the sum of the second original signal (R,) with a reduced proportion of the fourth original signal (R ,,) and a reduced proportion of the 90 ° phase shifted third original signal (L ,,). 6. Arrangement according to claim 3, characterized in that the amplitude components of the third and fourth original signals (L ,,, R “) arriving at the two outputs (64, 66) are 3 dB compared to the amphtuity components of the first and the outputs reaching the outputs second original signal (L _1. R,) are lower. 7. Arrangement according to claim 3, characterized in that the first or second input (40, 46) of the coding matrix via a first and second all-pass phase shifter (48, 58), which the signals fed to them by a phase angle that differs from a reference phase angle by 45 ° Shift phase angle, each with a first input of a first or second Summing circuit (60, 62) is connected that the third or fourth input (42, 44) of the coding matrix via a third or fourth all-pass phase shifter (50, 56), which the supplied to them Shift signals by the reference phase angle, each with a second input of the first and second summing circuit (60, 62) are connected that the third and fourth input (42, 44) of the coding matrix furthermore via a fifth or sixth all-pass phase shifter (52, 54), which changes the signals fed to them by a phase angle that differs from the reference phase angle by 90 ° shift the different phase angle, each with a third input of the second or the first summing circuit (62, 60) are connected, and that the summing circuits (60,62) the add signals fed to them in predetermined ratios and the output of the first Summing circuit (60) with the first output (64) of the coding matrix, the output of the second In contrast, summing circuit (62) is connected to the second output (66) of the coding matrix. S. Arrangement according to claim 7, characterized in that the Siimmierungsvcrhähnis in the output signals of the summing circuits (60, 62) is such that their second and third input zjführlen signals opposite the signals fed to the first input at the output with a 0.707-fold amplitude appear. 9. Arrangement according to claim 1 or 2, characterized in that the decoding matrix circuit elements (74, 78, 76, 84) provided with two inputs (70, 72) and four outputs (82, 88, 96, 104) between their first input (70 ) and its first output (82) or between its second input (72) and its second output (88) contains "which contains the first or second signal mixture (L ₇ , R ₁ ) without mutual phase shift as a first or second playback signal, in which the first or second original signal (L ₁ , R 1) prevails, to the first or second output (82, 88) that further connected to the two inputs (70, 72) phase shifter (74, 76) which shift the two signal mixtures (L _r , R _T ) against each other by such a phase angle that the component of the third original signal (L 1) in a signal mixture (L ₇ ) is in phase with the component of the third original signal (L,.,) In the other Signalgcmischi / ?,) comes and the An part of the fourth original signal (R _h ) in a _{signal mixture (L 7} -) comes in opposite phase to the portion of the fourth original signal (R _h ) in the other signal mixture (R _T ) and that these two mutually phase-shifted signal mixtures (L /, R _T ) two combination circuits (90. 92; 98, 100), the first (90, 92) of which delivers the third playback signal to the third output (96) of the decoding matrix, in which the third original signal (L 1) predominates, and the second (98, 100) of which the fourth output (102) of the decoding matrix supplies the fourth reproduction signal in which the fourth original signal (R ₁ ,) predominates. 10. Arrangement according to claim 9, characterized in that the ratio of the predominant signal components to the non-predominant 1: 0.707 and that the signal combination circuits (90, 98) each 0.707 times the two mutually phase-shifted signal mixtures (L / ', R _r ) combine with each other. 11. The arrangement according to claim 9, characterized in that a first phase shifter (74) shifts the phase position of the signal (L ₇ ) fed to it by a phase angle which differs from a predetermined reference ^{phase angle ι / 1} by 90 ° and a second phase shifter (76) shifts the phase position of the signal (R ₇ -) supplied to it by the reference phase angle ν. 12. The arrangement according to claim 11, characterized in that the phase shifter (74, 76) Are all-pass phase shifters. 13. Arrangement according to claim 9 to ti, characterized in that the signal combination circuits (90, 98) contain a summing circuit (90) which is 0.707 times the output signal of the second phase shifter (76) to 0.707 times the output signal of the first phase shifter (74 ) is added to form an output signal in which the third original signal (L, prevails ₆₎ and a Subt ^r ahierschaltung (98) containing the 0.707 £ surface of the second phase shifter (76) from the 0,707fachen the output of the first phase shifter (74) subtracted to form an output signal in which the fourth original signal (R _b ) predominates. 14. Arrangement according to claim 9 and 11, characterized in that the phase-shifted first composite signal (L ₇ - ') a first amplifier (150) and the second composite signal (A ₇ -') is fed to a second amplifier (152) and that between the outputs of the two amplifiers (150, 152) the series connection of a first loudspeaker (154) and a second loudspeaker (156) for emitting the first and the second playback signal is connected, that furthermore between the connection point of the two loudspeakers (154, 156) and a reference potential a third loudspeaker (160) for emitting the third playback _{signal as a signal proportional to the sum of the two mutually phase-shifted signal mixtures (L 7} - ', R /) in which the third original signal (L ,,) predominates, is connected, and that between the outputs of the amplifiers (150, 152) a fourth loudspeaker (158) for radiating the fourth reproduction signal than the difference between the two r phase-shifted mixed signal (L ₇ - ', /? /) proportional signal in which the fourth original signal (/? ,,) predominates, is switched (F i g. 12). 15. The arrangement according to claim 14, characterized in that instead of the series connection of the first and second loudspeakers (154, 156) have the connections facing away from the amplifiers (118, 120) this loudspeaker is connected to a reference potential and the third loudspeaker (160) with its connection not at the reference potential via a first winding of a transformer (130) at the output of the second amplifier (120), and a second winding of the transformer between the output of the first amplifier (118) and the reference potential connected and magnetically connected to the first winding is coupled in such a way that the output voltages of the two amplifiers (118, 120) add (Fig. 11). 16. The arrangement according to claim 14, characterized in that an inverter circuit (142 ') is provided for reversing the non-phase-shifted second signal mixture (Rt) before it is fed to the input of the second amplifier (152), that between the outputs of the first and second amplifier (150, 152) a fifth loudspeaker (162) is connected in series with an inductance (164) and this series connection has such a reactance that the fifth loudspeaker (162) only contains the low-frequency components of the first and second signal mixture (L ₇ -, R ₁ ) reproduces together and that the first and second loudspeakers (154, 156) are connected to one terminal each via a capacitor (166, 168) to the first or second amplifier (150 or 152) and to their other amplifiers connected together Connections are connected via a third loudspeaker (160) to the reference potential and that the fourth loudspeaker (158) between the kondcnsalorscitigen connections of the first and second loudspeakers (154, 156) is switched (Fig. 13). 17. The arrangement according to claim 14 or 16, characterized in that a resistor network (144, 146, 148) is connected between the inputs of the first and second amplifier (150, 152), which components of the phase-shifted signal mixture (L /) to the input of the second amplifier (152) and portions of the non-phase-shifted other signal mixture (R /) can reach the input of the first amplifier (150). " 18. The arrangement according to claim 14 or 16, characterized in that the first and the second loudspeakers (154, 156) have the same impedances of the value Z that the fourth and the fifth loudspeakers (158, 162) also have the same impedances of the value 2 Z and that the The impedance of the third speaker (160) has a value of approximately Z / 2. 19. Arrangement according to one of claims 9 to 13, characterized in that controllable amplifiers (80, 86, 94, 102) are provided in the four output channels, the gain of which can be changed to increase the directional effect by means of control voltages which are controlled with the aid of a control device ( 106) are derived from the mixed signals (line ₇ , R ₁ ) . 20. The arrangement according to claim 1, wherein the transmission medium is a plate with a single V-shaped spiral groove, the Scitcnwandungen form an angle of 90 "and in which a stylus can slide, characterized in that the walls of the groove in the recording areas of the third and fourth original signal (L _b and R ₁ , respectively) are modulated in such a way that the stylus has a circular movement during scanning in one or in the opposite direction of rotation in a plane perpendicular to the scanning direction between the stylus and the plate. 21. Arrangement according to claim 20, characterized in that the walls of the groove in the recording areas of the first or second original signal (L ₁ or R,) are modulated in such a way that the stylus moves perpendicular to one or the other when scanning Wall of the spiral groove executes. 22. The arrangement according spoke 20 and 21, characterized in that the first and second original signal (L ,, R ₁ ) the two front corner signals and the third and fourth original signal (Lj ,, R _b ) the two rear corner signals of a quadrophone transmitted sound event.