FR2483723A1 - Digital sound distribution controller for cinemas - stores adjustments to be made on incoming analogue signal for each respective output to main amplification system - Google Patents

Abstract

The system includes a number of parallel amplifier channels supplying respective loudspeakers disposed in different locations in the room. A respective regulating unit is coupled to an input of each channel. The regulating unit is digitally controlled and receives a common analogue signal to be amplified in a manner dependent on the respective regulator setting and amplifier channel. Each unit is controlled by a common preprogrammable memory in which variations in the regulating unit values are stored in a preselected manner for providing the necessary sound variations when required. The control information is stored on magnetic tape which can be read by the memory, the tape possibly being part of a film sound track, the film being shown in the room.

Description

ROOM SOUND SYSTEM
The invention relates to a sound system of a room likely to generate acoustic effects, including localization of sounds, but also possibly modification of the tone of these sounds, from any recording, including monophonic and preferably in connection with a pre-recorded show such as including a rope.

 We know that many theaters and especially many cinemas, are equipped with poor sound systems, barely able to restore clean sounds without coloring. That is to say that such equipment, particularly in the specific field of cinema, is incapable of giving full justice to certain large-scale current cinematographic productions where sound effects have been attempted, such as, for example, localized sound effects. space, using stereophonic recordings.

 The invention not only provides a satisfactory solution, in terms of sound, the new necessities of this kind of show (at the cost of a reduced investment), but it also allows to implement a similar treatment of the soundtrack. any movie or video recording that was not originally intended for this purpose and thus give a new recorded show a new appeal.

 For this purpose, the invention relates primarily to a sound system of a room, comprising a plurality of independent amplification channels supplying a plurality of loudspeakers arranged at different locations of said room, characterized in that it comprises a plurality of digitally controlled control units each having an analog signal output connected to an input of one of the aforementioned amplification channels and an analog signal input, at least some of these analog signal inputs being connected together to receive a common signal to be amplified in a different ratio and variable for each channel, determined by the adjustment value of the corresponding adjustment unit, and that each adjustment unit comprises at least one digital control input of level connected to a preprogrammed memory in which are recorded variations of all the adjustment values according to a predetermined sequence.

 In the case of a multi-channel sound system, a preferred embodiment of the invention is such that the signal output of the preprogrammed memory is connected to the digital signal control inputs by means of multiplexing means for scanning. and set in turn and at a fast pace, all the adjustment units again of all channels, to update the setting value, if necessary, according to the orders read on the preprogrammed memory. The latter can be, most of the time, constituted by a magnetic stripe reader; the magnetic strip of this reader carrying coded information representative of at least the level adjustment of each adjustment unit. Conveniently, the addresses of the different adjustment units to be evolved can be coded and recorded on the magnetic tape (of which the length depends on the duration of the show) together with the corresponding adjustment values of these adjustment units to simplify the design of the multiplexing means and synchronize their operation to the unwinding of the magnetic tape.

 Of course, if the film (or video recording) was made according to the equipment of the room, the memory can be made by at least part of the sound track of this film, a reading device associated with the film projector being connected to said multiplexing means.

 On the other hand, a particularly advantageous embodiment of a system according to the invention is provided with an equalizer device inserted upstream of said interconnected signal inputs, said equalizer device delivering said common signal and comprising a series of pass filters. band tuned to adjacent frequency bands of the audible spectrum, each filter being associated with a level adjusting unit, to ensure different amplification ratios of the sound in said frequency bands considered according to the acoustic characteristics of said room.

This equalizer device, when implemented, allows at least to compensate for the acoustic defects of the room and to be cer
This is why the directivity effects of sounds that one wishes to obtain are not partially destroyed by the characteristics of the room. But it also allows, at certain moments of the unfolding of the show, to favor certain frequency bands. of the sound spectrum to modify the actual timbre of the sound emitted at these moments, which opens the way to additional possibilities of special effects and sound effects
The invention will be better understood and other details and advantages of this will appear better in the light of the following description of a presently preferred embodiment of a sound system according to the invention, given solely to by way of example and with reference to the appended schematic drawings, in which ::
FIG. 1 is a block diagram of the sound system,
FIG. 2 is a more detailed part of a part of this sound system and more particularly of the control unit of one of the aforementioned amplification channels,
FIG. 3 is another part of the system and more particularly the specific part of the equalizer which is associated with one of the band filters; and
- Figure 4 is a timing diagram illustrating the operation of a control unit of the sound system.

 Referring to Figure 1, the schematic installation comprises several amplification channels Ai,. .- An ... Am, feeding as many speakers MPi ... HPn ... HPm (or groups of speakers) arranged in different locations of room 50 (these speakers are not represented in place in the schematic representation of the room 50 so as not to impair the clarity of the drawing) so as to generate in said room all the desired effects, including directivity sounds emitted, by any suitable combinations of amplification ratios between these The main purpose of the invention is to automatically adjust these amplification ratios according to a predetermined sequence, in particular as a function of the progress of a visual spectacle and in synchronism at least approximately with this one.

 According to a first characteristic of the invention, the system comprises several digitally controlled control units Ui ... Un. .Um whose signal outputs Si ... Sn ... Sm are respectively connected to the inputs of amplification channels Ai ... An ... Am. The structure of such a control unit will be described in more detail. detail below. The installation also comprises other adjustment units U1. Ui ~ l) substantially similar but used to fulfill another function which will be analyzed below. However, it may be noted that the illustrated installation, in that it thus uses a large number (m) of substantially identical subassemblies, lends itself well to a modular technological embodiment with pluggable and interchangeable cards.

The entries Ei. .In . Em control units associated with the different amplification channels are connected together to receive a common signal to be amplified provided by an amplifier-summator
A + whose output is connected to the common point of all inputs
Ei ... In ... Em via a switch I1 (or any other similar means) whose role will be explained later. The common signal will therefore be amplified in a different ratio by each amplification channel according to the adjustment value of the corresponding adjustment unit.

A setting value is set by the signals arriving at level control means reaching the respective control unit via a wire strand BUS common to all setting units and connected to a preprogrammable memory 60. , (via a microcomputer 1 realizing the electronic interface), in which at least variations of all the above-mentioned adjustment values are recorded and encoded, according to a predetermined sequence of time. In the example represented in FIG. 1, the memory 60 is constituted by a magnetic tape reader. It is of course on this magnetic tape that are recorded in coded form, for example in decimal-coded-binary code, the variations of all the adjustment values of the adjustment units and also, according to a preferred embodiment, their addresses. In this way, the microcomputer I forms multiplexing-type driving means and receives both the addresses and the corresponding adjustment values to control the evolution of the settings of all the adjustment units as and when required. scrolling of the magnetic tape whose length is of course related to the duration of the sound show broadcast simultaneously in the room 50. A particular arrangement of the microcomputer I will be described completely by way of non-limiting example but it should be noted that many variants of multiplexing control means are possible without departing from the scope of the invention, their basic function being simply to ensure correct identification of the adjustment units to pilot their level control means at the desired time, under the control of the scrolling of the magnetic strip. The mode of realization which will be described later however has the advantage of allowing in addition the i in the memory 60 (and in this case the tape drive is a complete recorder-reader) from the control units manually controlled by an operator responsible for developing once and for all the program of sound effects in connection with a pre-recorded show, such as for example a movie film, not originally planned for that.Il also note that, especially when this film is the subject of copies for several rooms equipped similarly, the content of the magnetic tape can be directly transcribed on the soundtrack of the film; the magnetic tape drive 60 then being deleted and replaced by a simple reading device associated with the film projector and connected to the aforementioned multiplexing control means; this reading device can be that of the projector itself if means are provided for separating the analog signal representative of the sound of the film control signals of the control units. Finally, note that the memory 60 can still be made by very different means and in particular a disc intended to be read at the same time as the unfolding of the show. The analog sound signal, intended to be the object of the special effects sought in the context of the invention, is applied to the input E of a control unit
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The adjustment unit Uo thus acts as a general preamplifier by which the average sound level is established in the room, for example by means of two manual actuation keys, respectively one touch
R level lowering and a level increase R key, which also exist on all the adjustment units of this type.

However, it should be noted that once the average sound level has been set manually (or automatically under the control of the memory 60 at the beginning of the scrolling of the magnetic strip), this sound level, therefore the setting value of the Uo unit, may be later modified under control of the memory 60 if it has been programmed for that. The signal output So of the unit Uo is connected to a subassembly 70 mainly constituting an equalizer device, intercalated upstream of the interconnection of the signal inputs (Ei ...

In ... Em). More specifically, the subset 70 is inserted between the output So, via a reversing switch I2 (or any other similar means) and the switch I1 connected to the output of the summing amplifier A. This sub-assembly 70 which produces a common signal modified by frequency bands for all the control units Ui ...

A ... Um consists mainly of a series of band-pass filters, F1 ... F2 ... F (i (here) tuned to adjacent frequency bands of the audible spectrum each filter being associated with a unit of U1 "U2" "" level adjustment (here) to provide different amplification ratios of the sound in said frequency bands considered, depending mainly on the acoustic characteristics of the room 50. The control units Ut ... U2 ... U (i 1) are substantially identical to the others and can be controlled by the microcomputer 1 via the BUS strand A subset of this type has already been the subject of another request. French Patent No. 80 07198 filed by the inventor and will be described in detail below.At this stage of the description, it should be noted that it can be the subject of a more or less complex realization. first, if we assume the acoustical characteristics of the room are substantially invariable and if we deprive ourselves of special effects on the timbres of the sounds emitted, the subset may be limited to the combination of filters F1 --- F geU1 ... U (i 1) and summing amplifier A with (il) entries connected to the signal outputs S1 ... S (i]) of the control units; the outputs of the filters being respectively connected to the signal inputs (E1 ... E (i 1)) of these same control units. In this very simple case, each adjustment unit acting as a simple pre-amplifier or potentiometer is positioned at a fixed amplification ratio, predetermined from any procedure for studying the acoustic characteristics of the room, frequency band per frequency band, for modifying the spectral characteristics of the analog signal applied to the input Eo so as to correct the defects of the room and be assured that the subsequent effects will not be partly destroyed by the defects or characteristics of the room. On the other hand, if one wishes to extend the possibilities of special effects until modifying during the show the stamps of some sounds, it suffices that the adjustment units U1... (i-1) 'positioned initially at predetermined amplification ratios, have means of adjustment. Level adjustment control, similar to those of the other control units, interconnected to the BUS wire strand, as shown schematically in Figure 1. In this case, the settings of the units U1 ... U (i 1) can evolve during the show under the control of the memory 60. In addition, it can be estimated that the spectral characteristics of the room 60 are not constant and depend in particular on the filling coefficient thereof.

It is therefore necessary to make an analysis of the characteristics of the room with the public, before each show. A very rapid method of analysis of this kind has been described in the aforementioned patent application and, in this case, the installation of the room must be completed by means of initial adjustment of the units U1 ... (here) comprising a pink noise generator 51 (of uniform spectrum) connected to amplification means (not shown) to power one (or more) speaker 52 located in room 50-. The loudspeaker can also be one of the speakers HPi ... HPn ... HPm temporarily disconnected from its control unit Ui group ... A ... Um.This pink noise is captured by a microphone 53 located in the room 50 and whose output 54 is connected, via the inverter-switch I2, to all the inputs of the filters F1 .... F 1) with shifted chords. In this case, and only during the initial setting phase, the outputs S1 ... S2 ... S (il) are looped back to respective electrical control inputs E of level lowering control means of each unit adjustment.

These lowering control means will be described in more detail below. This looping is performed, for each adjustment unit, by cascading a switch I3 (or any other similar means) of a first rectifier Rel (provided with a filtering cell to deliver a representative variable DC voltage filtered signal available at the output of the adjustment unit) and a first threshold detector Se1; this cascade arrangement being interconnected between the signal output considered and the input E of the same control unit. The switch 13 is of course closed only during an initial setting phase of the adjustment units U1 ... U (Il) corresponding to the emission of pink noise in the room 50, the reversing switch I2 being in its position connecting the output 54 of the microphone 53 to the inputs of the filters F1 F (il). Furthermore, each adjustment unit V U U (i-1) also comprises an electrical control input E + level increase control means which will be described later.

Each between E + is coupled to the output 54 of the microphone 53, via respectively another cascade arrangement of a second rectifier Re2 (similar to the rectifier Re1) and a second threshold detector.
Se2 and a single switch 14 (or any other similar means), which is closed only during an initial setting phase of the adjustment units U1 ... U (iî). Re2 rectifiers as described in this embodiment have a very simple structure so advantageous, but they could be replaced by any analog-DC converters, which they fulfill the function. It can thus be seen that, with the exception of the additional inputs E and E, the adjustment units UU (II) are completely analogous to the adjustment units Uo, Ui ...

 One .. Um. All these adjustment units comprise in particular the dull interface interfaces to the microcomputer 1 (the above-mentioned control means level) interconnected to the BUS wire strand. We will now describe the control mode of the control units by the microcomputer 1 and more particularly those associated with the amplification channels, that is to say the units Ui ... A ... Um. Reference is made particularly to FIGS. 1, 2 and 4.

 The microcomputer 1 is connected to a relay memory 2 of direct access coded information, for example in CMOS technology, protected from power cuts by a battery 3 in buffer load.

The layout of the memory and its subdivision can be provided by a keyboard 4 which can also provide other specific functions. This keyboard is connected to the microcomputer 1. The latter is also connected to the adjustment units U1, U1, U2, U3, etc. by the BUS strand which comprises ten wires. The control units are also interconnected in cascade by a link 5 of validation step by step which will be described later. Each adjustment unit, in the case where it behaves like an attenuator, can have the equivalent structure of a series connection of several resistors such as R1, R2 ... R15 ... forming a potentiometric circuit with an electronic switch. 16.The encoded information relay memory 2 comprises, as is conventional, a number of elementary memories B. (having two possible states) grouped into storage units. A storage unit is assigned to a setting unit (eg U1). Depending on the capacity of the memory, there will be a number (p) of storage units for each setting unit, that is, ultimately the ability to store as many (p) different combinations of settings or sets of settings. It is understood that with 16 possible positions for the attenuator it is enough for four memories in a storage unit to memorize the 16 positions, in decimal-coded-binary system.

Five basic memories would make it possible to memorize 32 attenuation positions and to obtain a more precise setting. The keyboard can for example comprise p control keys making it possible to choose, via the microcomputer 1, one of the p combinations and It is important to note that this microcomputer is a commercially available set, which does not need to be described in detail. By way of example, it is possible to use the assembly marketed under the reference 8748 by the firm INTEL. However, to facilitate understanding of the invention, the main subsets carrying out the essential functions which are required for this purpose have been indicated. computer, the materialization of these subsets within the computer being performed by a program cable, by means of a read-only memory, possibly re-programmable. This programming leading to the realization of subassemblies that will be described later is within the reach of a technician with medium expertise in this field of technology and is also taught by the manufacturer of the microcomputer.This microcomputer includes therefore in fact mainly a selector means 10 associated with the keyboard 4, interconnected between said memory 2 and said adjustment units for selecting a group of storage units one unit of storage per unit of adjustment, each group constituting a set settings generally selectable by said selector means; and control means 11 interconnected between the selector means 10 and the control means of all the adjustment units U0, U1, U2, etc. via the strand of BUS wires. Only one globally selectable group is required for the implementation of the invention.

 Each adjustment unit U 0, U 1 ... Um (FIG 2) comprises a device for displaying its own state, ie with light-emitting diodes D 1 ... D 16, a diode corresponding to a state of the electronic switch. The manual control means of each adjustment unit comprise the two buttons R +, R allowing, as will be seen below, both to modify in relay memory 2 the state of a selected storage unit and the state of the corresponding adjustment unit, by successive increments or decrements in the memory, through and under the management of the microcomputer 1.

We will now describe one of the adjustment units One in
n connection with the BUS strand. The information of the storage units of a group representing one of the sets of settings, selected via the keyboard 4, are cyclically and sequentially transmitted on the four wires A, B, C, D of the BUS strand by 1 through the control means 11 and at the rate of a clock ADR included in the microcomputer and whose pulses (Figure 4) are transmitted on one of the son of the strand. A cycle start signal generator (RAZ) is also provided in the microcomputer and its frequency pulses (m +)) times lower than those of the clock pulses are transmitted on another wire of the BUS strand. The four wires A, B, C, D are connected to four inputs Ea, Eb, Ec, Ed of a controlled door system having an equivalent number of outputs
Sa, Sb, Sc, Sd connected to the inputs of the "Decimal-Encoded-Binary" type of the electronic switch 16 via buffers Ct.

Specifically, the gate system 15 is a tri-state CMOS adapter having a transfer input T (or third state control) connected to cyclic scanning means which will be described later. A suitable type of CMOS adapter is marketed by National Semiconductors under the reference MM 80 C 98 N. Its operation is as follows. When a pulse is applied to its input T, the adapter 15 transmits the value displayed at each input to its corresponding output. In the absence of a transfer pulse at the input T, the circuit is disconnected and has a very large input impedance and a very large output impedance. This high output impedance is used to store the information. transmitted in the parasitic input capacitances of the switch 16 which thus directly form the buffers Ct> without adding additional components. Since the input impedance of the switch 16 is also very high, the information does not have time to deteriorate between two cycles, that is to say between two transfer pulses applied to the input T.

The switch 16 is also of the CMOS type and is interconnected with the resistors R1-R15 in potentiometric mounting. One type of switch
Usable CMOS is marketed under the reference DG 506 by the firm
Siliconix.

The display device consists of a Digital-Analog converter 17 with decimal-coded-binary inputs whose four input terminals are connected to the four corresponding outputs of the adapter 15 and whose analog output 18 is connected to an analog input. al of a switch 19 with analog inputs, CMOS type. The other input a2 is connected to the output S of the unit of
n setting one or possibly at its signal input E if it is expected
nn a two-way switch (not shown) for applying S
n or E at the input a2. The positioning of the switch 19 is regulated by
n a signal applied to its input e0 generated by the microcomputer 1 and transmitted by an ANA / NUM wire BUS strand, via an additional door of the adapter 15.An analog input switch usable as a switch 19 is marketed under the reference DG 201 by the firm Siliconix.

The output of this switch 19 is connected to drive an electronic display control switch 20 driving the electroluminescent lamps D1 ... D16. This switch is of the analog type, consisting of a set of 16 comparator amplifiers. An integrated circuit performing this function is marketed under the reference U AA170 by the firm Siemens. The adjustment unit U can also
n comprise a LED indicator 21 driven by an AND function with two inputs to identify if this adjustment unit is being modified by other means than those that are specific to it, and especially via a keyboard located remotely, such as the keyboard 4 if it is provided for this purpose.

The AND gate of the indicator 21 is triggered by the conjunction of the same signal as that which is applied to the input T of the adapter 15 and of an additional signal generated by the microcomputer 1 and transmitted on the MOD wire of the BUS strand. The light-emitting diode of the indicator 21 then starts to flash, warning the user that it is this adjustment unit which is precisely being modified.As we have seen above the wires A, B, C, D constitute as many series output links of the control means 11 on which are transmitted successively and in a predetermined order, in series, the information representative of the storage units corresponding to the control units and selected in one of the groups forming a set of adjustments, by the selector means 10. It is therefore important that the aforementioned cyclic scanning means are perfectly synchronized so that a transfer pulse is applied to the input T of the set
n that the information representative of the corresponding memory unit chosen is actually present on the son A, B, C, D.

For this purpose, the aforementioned cyclic scanning means are arranged in synchronized validation means, in particular by said control means 11 and in particular comprising the two generators RAZ and ADR described above as well as a plurality of validation units 25 of which the step-by-step connection is the above-mentioned chaining. These units are all coupled to the timing signal generator and the start-of-cycle generator, that is, connected to the wires.
ADR and Reset of the BUS Strand More specifically, each validation unit 25 comprises a flip-flop 26, an input S of which is connected to the start-of-cycle signal generator and whose Q output is connected to a first input of an AND type gate. or NAND with three inputs, 27, a second input of which is connected to the clock generator
ADR and whose third input is connected to the output of the flip-flop of an adjacent validation unit via an inverter 28; the output of said gate being connected to the aforesaid transfer input T of said controlled door system and another input R of said flip-flop being connected to the output of said door via a monostable valve 29. Operation is the next. At the beginning of a cycle, all the flip-flops 26 are activated: Q = 1, by the pulse
Reset so that unit U1 sees its control pulse appearing
CTE of the input T from the first ADR pulse, after which the toggle of this first unit changes state under the control of the monostable, which validates the entry of the AND gate of the neighboring unit thanks to the insert 28 and therefore allows the CTE command of the next unit to be en gendrée at the appearance of the next ADR pulse, and so on, the flip-flops 26 all changing state, step by step during a cycle. It should be noted that the initialization of the cycle at UO requires maintaining the input of its AND gate 27 which is part of the chaining 5 at a logical level 1.

 The microcomputer 1 comprises means for calculating and re-registering in memory cabled to add or subtract a unit to a number represented in a storage unit chosen by the selector means 10. This circuit 30 is thus interconnected to the memory 2 and is accessible from the corresponding control units by means of two INC and DEC wires of the BUS strand. In this way, the circuit is associated with the two control buttons R +, R- respectively connected to two inputs of two respective doors, 31, 32, of the type ET or NAND has two inputs, the other two inputs being connected to the means cyclic exploration above and more particularly at the exit of the AND gate 27.

The outputs of the doors 31 and 32 are respectively connected to the wires
INC and DEC, that is to say the circuit 30 to respectively control the incrementation or decrementation of the circuit 30 and the re-registration in memory. Thus, if the key R + of one of the adjustment units is actuated, an incrementation of the content of the corresponding storage unit will occur gradually and the state of the potentiometric arrangement (the switch 16) will evolve in one direction. Pressing the R- key will change the other way. To generate the signals at the inputs of the gates 31 or 32, it is possible to use simple inverters of the CMOS type (integrated circuit 33) rectifying the alternating current of the sector present in the human body so that the application of the finger on the key will cause the the desired result. An integrated circuit of CMOS inverters is marketed under the reference
MM74C04N by the firm National Semiconductors. The system is designed so that the rate of change is approximately one position (incrementation or decrementation) every half-second. It can be seen that the key control system R +, R- acts in fact on the state of the memory, which is read continuously by the microcomputer 1 to come to position and possibly reactualize cyclically all the adjustment units as a function of the values (modifiable) of a preset and selected set of settings.

 The system as it has been described so far, is of interest for all applications where a set of attenuation settings, obtained once, is to be kept to be made active again at any time after another use of the adjustment units.

It should be noted that in the improved embodiment which is presently described, the memory 60 is coupled to the microcomputer
I in the same way as the keyboard 4, that is to say, to provide its information to the relay memory 2 and not directly to the adjustment units. It is then the cyclic reading at very high speed of the relay memory 2 which gives the microcomputer the information necessary to change the settings of all the adjustment units Uo ... Un.

The selector means 10 must therefore comprise means for decoding the addresses of the adjustment units concerned in order to select the corresponding memory units in the relay memory and must be coupled to the circuit 30 so that the modifications of settings written on the magnetic strip of the memory 60 are reported in the relay memory 2.

 FIG. 3 more specifically shows an adjustment unit (for example the adjustment unit U (i 19 of the subassembly 70, shown connected to its filter F 1) receiving the initial adjustment signal from the microphone 53, that is, that is to say with the switches I1, I2, 13> I4 (not shown in FIG. 3) in the respective inverse positions of those shown in FIG. 1). More specifically, in normal reproduction, the system has its switch li closed, the switch 12 is in a position connecting the output SO to the inputs of the filters, while the switches I3 and I4 are open to invalidate the operation of the inputs E4 and E. During the initial adjustment period, on the other hand, the positions of all these Switches are: inverted, which is equivalent to the assembly of FIG. 3. The adjustment unit U (i 1) differs from the unit A described in FIG. 2 only by the circuits terminating in the doors 31 and 32 (FIG. that is, INC and DEC strand wires BUS) and in which the rectifiers Rel, Re2 and the respective threshold detectors Se1, Se2 are integrated. Thus, the rectifier Re] here consists of a simple diode 58 connected to charge a capacitor 59. The voltage available at the terminals of this capacitor is taken by a potentiometer 60 and applied to the input of a logic inverter 61 which embodies the In other words, the above-mentioned threshold is neither more nor less than the switching threshold of this inverter and the potentiometer 60 realizes the necessary level adaptation. If the inverter 61 displays a logical ZERO at its output, it means that the signal available at the output S (i 1) is greater than a predetermined level and that a lowering command must be applied to the unit. This is achieved by the fact that the output of the inverter 61 is connected to an input of the NAND gate 32 via a NAND gate 62 with two inputs. an inverter 63 and another NAND gate 64 with two inputs, successively. The other input of the gate 64 is connected to the manual control key R via another rectifier similar to the rectifiers Rel, Re2 (here constituted by a diode 65 charging a capacitor 66 connected in parallel with a resistor 66a) and an inverter 67. When pressing the R key is injected, by the finger, a current that is rectified by the diode 65 and which unlocks the inverter 67. A logic ZERO present at the output of this inverter is therefore applied to the input of the gate 64 which transmits a level reduction command on the wire DEC, via the gate 32. The arrangement is similar for the manual control of level increase (R + key) with a diode 68, a capacitor 69, a resistor 69a, an inverter 70 and a NAND gate 71 which cooperate in the same way as the diode 65, the capacitor 66, the resistor 66a, the inverter 67 and the gate 64. The output of the gate 71 is connected to an input of the NAND gate 31, for the co level increase.

In a similar manner to that described above, the rectifier Re2 here consists of a diode 72 charging a capacitor 73 having a resistor 73a connected to its terminals and the threshold detector.
Se2 is constituted by the NAND gate 74 with two inputs. Since the threshold determining the control of a level increase can be very low and this threshold is not critical, it is not necessary to provide a level matching potentiometer at the entrance of the door 74. A logic ZERO present at the output of the gate 74 generates a level increase command which is applied to the INC wire by means of an inverter 75, a NAND gate 76 with two inputs, of the gate 71 (the output of the gate 70 being connected to the second input of the door 71) and the door 31.

 The connection between the output of the gate 61 and the second input of the gate 74 constitutes a blocking circuit of the level increase control means. Indeed, a logical ZERO at the output of the inverter 61 blocks the gate 74 to ONE regardless of the logic signal present on the other input-and which is representative of the ambient noise in the room 50 since the diode 72 is connected to the microphone 53. This means that the level reduction command (E-) when it exists, takes precedence over the level increase control (E +) which is otherwise still present (cause of the noise level in the room) and tends to set all setting units to a maximum level setting. This almost permanent action of the level increase control (E +) during the initial setting period, however, can be blocked when a signal UN logic is applied on the conductor 77 which is connected to a second input of the door 62 and a second input of the door 76 via an inverter 78. In these conditions, whenever the threshold detector Se1 (60, 61) is triggered the level decrease control operates to lower the level at the output 5 (here) until the state of charge of the capacitor 59 falls below the predetermined threshold. But at this moment, the level increase control being blocked, the state of the control unit can only go down further, until the end of the analysis process, as and when the increased level of pink noise in the room. This mode of operation can be advantageously chosen at the end of the process, especially for the lower frequency bands.

The use of subassembly 70 which has just been described during a very brief adjustment period, for example before each show but in the presence of the public, is as follows. The presence of even weak ambient sound in the room 50 generates a signal on all the inputs Ev and positions at most all the adjustment units. This level of control mode by the sound in the room is advantageous because it is thus ensured that no attenuation is initially introduced by a particular tuning unit and which pink noise will be received and analyzed by not having It has been disturbed only by the acoustics of the room. However, the prior positioning of the control units could be controlled by a signal internal to the room-independent apparatus. The level of the pink noise produced by the generator 51 is then gradually increased. The resulting electrical signal at the output 54 of the microphone is then filtered in frequency bands by means of the filters F1, F2,... A plurality of filtered signals are thus obtained which are applied to the respective adjustment units. At the respective outputs S1, S2, -... Sm of these uni
In addition, the filtered signals are rectified so as to produce variable DC voltages which as soon as they exceed the threshold values of the threshold detectors Sel, control the lowering of the level setting of the corresponding adjustment units. the adjustment units have thus undergone a lowering of the level adjustment, it is possible to stop the adjustment process since the initial adjustment values of all the adjustment units which constitute a coherent set of adjustments, representative of the acoustic characteristics of the room, have have been simultaneously entered in the relay memory 2 at the addresses corresponding to the setting units U1 ... U (i 1) * After this initial setting, it is possible to switch to broadcasting the show by switching the switches II, I2 I3 and 14 in their positions illustrated in Figure 1, by applying the sound signal of this show to the input Eo and putting into operation the memory 60 whose synchronization with the show must be effective but not critical.At this moment, all the special effects that have been programmed on the magnetic tape will occur as the course of the latter, by varying the settings of the units Ul ... A ... Um ... for the effects concerning the directivity of the sounds and by varying the settings of the units
U1 ... U (i 1) for special effects concerning timbre modifications of these sounds.

It is also important to note that the system as described above also allows the development of the magnetic strip of the memory 60. For this purpose, the memory 60 is arranged in a coupled recorder-reader (in the recording function) to the microcomputer 1 for cyclically recording the address codes and the contents of the storage units of the relay memory 2 during a viewing of the show during which an experienced operator will generate the special effects himself, depending on the particularities and the evolution of the action, for example by action on the R + keys,
R units of adjustment. This procedure can be used, for example, to repackage the soundtrack of a film not originally intended for this purpose.

 One can also find a particularly advantageous application to this system when it is used at the very moment of the performance of a show (theater, music hall, etc.) for the purpose of recording (cinema or video recorder). that is, when the operator intervenes at a time when the sounds have their own spatial and spectral characteristics in the same room where the show will then be rebroadcast (or in a comparable room). It suffices then to have the microphones in front of the main sound sources and to use the signals picked up by these microphones to drive the development of the magnetic tape of the memory 60, (the signals picked up being applied, after appropriate processing, to the setting) by making the status of the relay memory 2, which is "copied" cyclically and permanently by recording the magnetic tape of the memory 60, throughout the show.

Claims (16)

 A single room sound system comprising a plurality of independent amplification channels supplying a plurality of loudspeakers arranged at different locations of said room, characterized in that it comprises a plurality of digitally controlled control units comprising each an analog signal output connected to an input of one of the aforementioned amplification channels and an analog signal input, at least some of these analog signal inputs being connected together to receive a common signal to be amplified in a report different and variable for each channel, determined by the setting value of the corresponding setting unit, and that each adjustment unit has at least one level digital control input connected to a preprogrammed memory in which are recorded variations of all the setting values, according to a predetermined chaining.  A public address system according to claim 1, characterized in that said preprogrammed memory has a signal output connected to said digital level control inputs via multiplexing type control means.  3. PA system according to claim 1 or 2, characterized in that said memory comprises a magnetic stripe reader and that the magnetic strip of this reader carries coded information representative of at least the level adjustment of each adjustment unit and its evolution.  4. PA system according to one of claims 2 or 3, characterized in that said memory is embodied by a part of a sound track of a film simultaneously projected in said room, a reading device associated with the film projector being connected to said multiplexing control means.  5. Sound system according to one of the preceding claims, characterized in that it further comprises an equalizer device inserted upstream of said interconnected signal inputs, said equalizer device delivering said common signal and comprising a series of bandpass filters tuned to adjacent frequency bands: the audible spectrum, each filter being associated with a level adjustment unit, to ensure different amplification ratios of sound in said frequency bands considered according to the acoustic characteristics of said room.  A public address system according to claim 5, characterized in that the signal input of said equalizing device is connected to the signal output of a particular control unit acting as a preamplifier, and an analog signal input of which is connected to receive an audiofrequency signal to be broadcast in said room.  7. PA system according to one of claims 2 to 5, characterized in that it comprises an encoded information memory or relay memory, comprising at least one storage unit for each adjustment unit of said amplification channels at less and preferably also of said equalizer device, each storage unit being at each moment in a state representative of the adjustment value of the adjustment unit which corresponds to it, that said control means comprise means of inscription in said memory relay, connected to said signal output of said preprogrammed memory to be controlled by it and in that said control means comprises a particular clock signal generator synchronizing the cyclic reading of said buffer memory to reflect a possible evolution. the state of a storage unit to the corresponding setting unit.  8. PA system according to claims 6 or 7 characterized in that said particular adjustment unit is of the same nature as the control units of the amplification channels and / or said equalizer device and is associated with a storage unit of said relay memory, so that its state can possibly be modified via said preprogrammed memory during a reading thereof.  9. PA system according to one of claims 2 to 8, characterized in that, in a manner known per se, a said adjustment unit comprises an electronic switch coupled to gain control means, such as for example a mounting potentiometric to control them, that this switch comprises at least one control input enaa it comprises a door system controlled at least one input connected to said control means and an output connected to said control input of said switch by the intermediate buffer memory means and at least one transfer input connected to cyclic scanning means of all control units.  10. PA system according to claim 9, characterized in that said electronic switch is of the type having a certain input capacitance and a very large input impedance, such as a switch with CMOS technology, and that said capacitor input constitutes said buffer memory means.  11. A sound system according to claim 10, characterized in that the state of a said adjustment unit being written in said relay memory in a decimal-coded-binary code, the corresponding storage unit comprises at least four memories The aforementioned electronic switch of this control unit has the same number of control inputs mentioned above, whereas each system of controlled doors has the same number of inputs connected to said control means and as many outputs respectively connected to the control inputs. control inputs of the electronic switch.  12. PA system according to claim 10 or 11, characterized in that the input or each entry of the same rank of each system of controlled doors is connected to the same serial output link of said control means on which are transmitted successively. , in series, and in a predetermined order, at least a portion of the information representative of the state of said storage units and that the aforementioned cyclic scanning means are arranged in validation means synchronized in particular by said control means for enabling said transfer input only when a signal representative of the state of at least a portion of the corresponding storage unit is present on said serial output link.  13. Public address system according to claim 12, characterized in that these validation means comprise, in a manner known per se - the above-mentioned clock signal generator - a start-of-cycle signal generator operating at a frequency m times less than that of the clock generator, m being the number of adjustment units, and - a chain of validation units associated respectively with the control units, interconnected step by step and coupled respectively to the signal generator clock and start cycle generator.  14. Public address system according to claim 3, characterized in that each validation unit comprises a latch whose input is connected to the cycle start signal generator and whose output is connected to a first input of a gate of the ET type or Three-input NAND, a second input of which is connected to the clock generator and a third input of which is connected to the output of the flip-flop of an adjacent enable unit via an inverter ; the output of said gate being connected to the aforementioned transfer gate of said system of controlled doors and another input of said latch being connected to the output of said gate via a monostable.  15. PA system according to one of claims 5 to 14, characterized in that said adjustment units of said equalizer device are of the same nature as the adjustment units of said amplification channels, each further comprising as known, electric control input level increasing control means and electric control input leveling control means and said bandpass filters having their switchably connected signal inputs. to the same electrical signal source representative of a sound captured in said room during a corresponding adjustment phase and their signal outputs respectively connected to the analog signal inputs of said control units, and in that it further comprises means to emit a sound of predetermined spectral characteristics in said room at least one transducer constituting at least in part e said electrical signal source and DlacP for capturing this sound of predetermined spectral characteristics, and in that, for each adjustment unit of the equalizer device, the analog signal output is looped back to the control input of said control means of lowering level through a first threshold detector, while the control input of said level increase control means receives a permanent control command, when said signal input is actually connected to the source of electrical signal; for positioning the adjusting units of the equalizer device at initial amplification ratios depending on the acoustic characteristics of the room at a chosen time, especially at the beginning of the implementation of the aforementioned preprogrammed memory.  16. A sound system according to claim 15, characterized in that said means for emitting a sound of predetermined spectral characteristics comprise a pink noise generator, known per se.