US3684835A - Four channel stereo synthesizer - Google Patents
Four channel stereo synthesizer Download PDFInfo
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- US3684835A US3684835A US59186A US3684835DA US3684835A US 3684835 A US3684835 A US 3684835A US 59186 A US59186 A US 59186A US 3684835D A US3684835D A US 3684835DA US 3684835 A US3684835 A US 3684835A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04S—STEREOPHONIC SYSTEMS
- H04S5/00—Pseudo-stereo systems, e.g. in which additional channel signals are derived from monophonic signals by means of phase shifting, time delay or reverberation
- H04S5/02—Pseudo-stereo systems, e.g. in which additional channel signals are derived from monophonic signals by means of phase shifting, time delay or reverberation of the pseudo four-channel type, e.g. in which rear channel signals are derived from two-channel stereo signals
Definitions
- a stereo synthesizer according to which a four-chan- C(il ..l79/l Gkggillgg nel usunourld stereo" is developed from either [58] Field of Search 179/1 0, l GA, 16?, 15 BT channel mums-
- the system performs a number of transformations on Referfllces Cited the source material, and the resulting signals are reproduced through two sets of loudspeakers, one set UNITED STATES PATENTS of these loudspeakers being located in front of the 2,819,342 l/l958 Becker ..l79/l G listener and the other set of loudspeakers being 2,845,491 7/ B r ram G located behind the listener.
- the invention of the aforesaid earlier filed application describes a stereo synthesizer system that is especially adapted for converting monophonic, i.e. singlechannel, sound signals into stereophonic sound signals so that the signals so converted may be reproduced and presented in a variety of forms.
- the source of monophonic sound signals is connected to two independent sound channels; moreover, the signals are applied directly to the two sound channels, and also in delayed fashion thereto, by means of a special network transfer function, whereby the direct and delayed signals are combined so as to provide reinforcement in one channel and to be opposed in another channel as a function of frequency.
- the specialized nature or character of the network transfer function is such that the amplitude of the frequency response is independent of frequency; in other words, there is a flat frequency response.
- the phase response is readily varied as a function of frequency; in other words, different frequency bands have their corresponding delayed signals independently adjusted in accordance with their position in the frequency spectrum.
- phase shifting arrangement described above is very flexible and economical. Moreover, it is electrical in nature, is extremely effective in the short delay range, and as noted above, can be widely adjusted throughout the frequency spectrum.
- the essential components of the network transfer function mentioned previously include a processor in which a succession or cascade of individual phase shift networks are provided in order to produce a readily adjustable set of cross-over points in the range or spectrum of sound frequencies.
- Another component of the network transfer function is a matrixing means which operates on the output as provided by the phase shift networks, and suitably combines the direct signals with the delayed signals that have been operated upon by the processor.
- the stereo synthesizer of application, Ser. No. 25,775 has been found useful for a great number of applications involving two output devices, such as two loudspeakers appropriately spaced in front of a listener, it has been found that an improved sense of space can be achieved by reorganizing the stereo synthesizer system to produce an output having several speakers located in front of the listener, such speakers being fed by one group of signals and by having another group of speakers at the rear of the listener, the latter group having supplied to them signals differing from those applied to the first group. Accordingly, in an illustrative embodiment of the present invention, the output from a stereo synthesizer, as described in application Ser. No. 25,775 is applied to the front pair of speakers.
- This kind of arrangement is especially adapted to a situation in which only a monophonic source of sound is to be utilized.
- the principle of the present invention can also be applied to systems in which a stereophonic source is available and is to be utilized; that is to say, plural independent channels or inputs are available, as will be made clear hereinafter.
- the stereo inputs supplied to the front pair of speakers are also combined for application as if they were a monophonic source and are then operated upon and connected to a rear group of speakers. In this way the listener is afforded a sense of space and dimension which is superior to that when only a front group of speakers are employed.
- phase quadrature generator per se well-known, which is so arranged to produce widely diffused, yet non-directional sound from the rear speakers.
- the quadrature generator which is a pair of phase-shifters so arranged as to give a constant phase difference of between their outputs throughout the audible range of 20-20,000 Hz, is fed by a combination of the direct signal emanating from the front speakers and the same signal processed through a reverberation generator.
- the reverberation generator provides a simulation of the natural reverberation in a large hall. However, more direct sound than reverberated sound is introduced to the rear speakers in order to avoid seriously upsetting the ratio of a direct to reverberated sound existing in the original recording.
- phase shifts and delays also help introduce a sense of large space into the four-channel reproduction. In combination with the diffusion of the rear information caused by the quadrature generator, these characteristics of the present invention create a sense of overall acoustical environment.
- FIG. 1 is a diagram illustrating the listening set-up for the enjoyment of the system of the present invention.
- FIG. 2 is a functional diagram of the system of the present invention according to one embodiment in which the monophonic source and the two channels connected to the front speakers are provided by utilizing the stereo synthesizer in accordance with a prior invention.
- FIG. 3 is a functional diagram of another embodiment in which a stereophonic source or inputs exist, and one set of speakers are connected directly to such stereophonic source. 7
- FIG. 4 is a schematic diagram of the phase quadrature generator as utilized in the system of the present invention.
- FIG. 5 is a functional diagram partly in block form, illustrating the interconnections in order to provide either mode or embodiment of the present invention, that is, to translate from either a monophonic source or from a two-channel stereo source, to a four-channel output.
- FIG. 1 there is shown a typical listening set-up to be used in connection with the present invention.
- the listener is surrounded by a number of loudspeakers, two of which are normally placed to the front and connected in a manner to be described.
- Another set of speakers is placed to the rear of the listener and their output is varied from that supplied to the front speakers.
- FIG. 2 there is shown an illustrative embodiment in which a stereophonic sound source, comprising two independent inputs, is available and is to be suitable connected to produce a four-channel output system according to the present invention.
- suitable leads are connected to a pair of loudspeakers designated front pair and the inputs are ap plied to a typical combining or summing device for the purpose of converting to a monophonic input source. Thence, from the output of the device 10, the single output is taken to two independent channels in each of which a special function is provided.
- a simulation of the reverberation ordinarily encountered in a large concert hall is achieved by a suitable reverberation generator 22, the output of which is connected through a potentiometer 24 and thence to a stereo synthesizer 26.
- the stereo synthesizer 26 is of the'type already described in previously filed application, Ser. No. 25,775, in the name of the present inventor.
- the detailed description of the stereo synthesizer is incorporated herein by reference, such detailed description being unnecessary for an understanding of the present invention.
- a stereo synthesizer essentially comprises an arrangement for synthesizing a stereo output from a monophonic input, according to which the source of monophonic sound signals is connected to two independent sound channels, the signals being applied directly to the two sound channels, and also in delayed fashion thereto, by means of a network transfer function so as to reinforce the direct signals in one channel, and oppose them in another channel as a function of frequency.
- the network transfer function is such that the amplitude of the frequency response is independent of frequency while the phase response varies as a function of frequency.
- quadrature generator 34 In the lower channel 30, another potentiometer 32 is provided at the input to quadrature generator 34.
- This quadrature generator which will be described hereinafter, enables the generation of widely diffused yet non-directional sounds. Essentially, it consists of two all-pass networks whose time constants are staggered in such a way that the phase difference between the outputs of the networks is closely equal to 90 throughout the usual audible range of 20,000 Hz.
- the two outputs from the quadrature generator 34 are combined with the two outputs from the stereo synthesizer previously explained in a pair of summing devices 40 and 42.
- the output from each of the summing devices is connected to a loudspeaker. This pair or set of speakers is usually located to the rear of the listener.
- the stereo synthesizer 26 may be eliminated.
- the output from the reverberation generator 22 may be connected as indicated by dotted line 33, and the reverberated signal may be processed through the quadrature generator 34 along with the direct signal.
- stereophonic inputs are not involved but only a monophonic input, such monophonic input being connected in one channel by way of line 52 to a stereo synthesizer 54 which is another piece of equipment of the type already noted.
- the monophonic input is converted or translated into a simulated stereophonic output which is applied to a set of loudspeakers designated front pair.”
- the monophonic input is also applied in parallel to a two channel arrangement identical to that previously shown in FIG. 2, the parts of which have been designated with identical numerals.
- several alternate connections can be provided in connection with the FIG. 3. embodiment, as was the case previously with the embodiment of FIG. 2.
- the stereo synthesizer 26 may be eliminated, and the output from the reverberation generator 22 may be processed through the quadrature generator 34 by way of line 33.
- the stereo synthesizer 54 may be eliminated and both lines to the front pair of speakers may be driven directly; or the stereo synthesizer 54 can be replaced by a wide band phase-shifter or other pseudo-stereo generator.
- FIG. 4 a schematic diagram is provided of the quadrature generator 34.
- This generator consists essentially of two all-pass networks arranged so that the phase difference of their outputs is approximately at frequencies from 20-20,000 Hz.
- each of the stages in the upper and lower channels consists of pairs of transistors.
- the upper channel is defined by the five stages comprising the pairs Ql-Q2 through 09-010 and similarly, the lower channel is defined by the transistor pairs Qll-Q12 through 019-020.
- Each of the aforesaid stages possesses almost exactly unity gain from its input to its output.
- the separate outputs from the quadrature generator 34 are applied, together with the A and B outputs from the stereo synthesizer 26, to the summing network 40 and 42, whereby the desired output signals to the rear pair of speakers is obtained.
- FIG. 5 an interconnection arrangement is illustrated which enables selection of either mode of operation as illustrated in FIG. 2 and FIG. 3.
- the stereo input signals are also applied to the summing amplifier 110, thus implementing the functional block previously shown in FIG. 2.
- the output of summing amplifier 110 is applied to both of the channels and 30, the outputs of each of the channels being applied conjointly to the input of emitter-follower 120 and 122 so as to implement the summing function performed by the functional blocks 40 and 42 of FIG. 2
- the equipment shown in channels 20 and 30 is, of course, identical with that previously described.
- the output signals from the emitter-followers 120 and 122 are transmitted by way of the lines 130 and 132 respectively, to the fixed contacts of the switch 134, i.e. contacts 134f and c and 134s and f, whence they are transmitted to the rear group of speakers by proper positioning of the movable contacts.
- the stereo synthesizer 54 is used to operate upon a monophonic input when such an input appears at mono-in and is applied by way of line 150 to the input of that stereo synthesizer. In the manner already described, the stereo synthesizer provides two output channels in which direct and delayed signals are combined so as to provide reinforcement in one channel, and be opposed in another channel as a function of frequency.
- the outputs of the synthesizer 54 are connected to two amplifiers 56 whose outputs in turn are connected to the fixed switch contacts 1040 and f, which are the contacts appropriate to the monophonic mode of operation.
- a multi-channel stereo synthesizer apparatus for providing an acoustic output which completely surrounds a listener and creates a sense of space comprising:
- means for supplying signals, different from said stereophonically related signals, to said second group of sound reproducers including a. a pair of independent channels having their outputs connected to said second group of sound reproducers,
- a quadrature generator connected in one of said pair of channels, said quadrature generator including two all-pass networks having outputs differing in phase by approximately, at frequencies from 20 20,000 Hz, said outputs being connected to different ones of said second group of sound reproducers.
- Apparatus as defined in claim 3 further including a summing network in each of said channels, one of the outputs of said stereo synthesizer and of said quadrature generator being directly connected to the summing network in said one channel, and the other output of said stereo synthesizer and of said quadrature generator being connected to the summing network in the other channel.
Abstract
Description
Claims (4)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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US5918670A | 1970-07-29 | 1970-07-29 |
Publications (1)
Publication Number | Publication Date |
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US3684835A true US3684835A (en) | 1972-08-15 |
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ID=22021363
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US59186A Expired - Lifetime US3684835A (en) | 1970-07-29 | 1970-07-29 | Four channel stereo synthesizer |
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Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3725586A (en) * | 1971-04-13 | 1973-04-03 | Sony Corp | Multisound reproducing apparatus for deriving four sound signals from two sound sources |
US3787622A (en) * | 1971-02-05 | 1974-01-22 | Sansui Electric Co | Quadrasonic sound system for two channel transmission |
US3798373A (en) * | 1971-06-23 | 1974-03-19 | Columbia Broadcasting Syst Inc | Apparatus for reproducing quadraphonic sound |
US3873779A (en) * | 1972-05-24 | 1975-03-25 | Urbick Robert J | Electronic sound distribution system |
US3885101A (en) * | 1971-12-21 | 1975-05-20 | Sansui Electric Co | Signal converting systems for use in stereo reproducing systems |
US3914790A (en) * | 1972-12-29 | 1975-10-21 | Sony Corp | Four-channel stereo apparatus for switching between two channel and four channel inputs |
US3971890A (en) * | 1975-02-10 | 1976-07-27 | Cbs Inc. | Method and apparatus for quadraphonic enhancement of stereophonic signals |
FR2505534A1 (en) * | 1981-05-08 | 1982-11-12 | Rca Corp | SWITCHING ARRANGEMENT FOR A STEREOPHONIC SYNTHESIZER OF SOUND |
US5085937A (en) * | 1989-08-30 | 1992-02-04 | Minnesota Mining And Manufacturing Company | Particulate monitoring tape |
US5432856A (en) * | 1992-09-30 | 1995-07-11 | Kabushiki Kaisha Kawai Gakki Seisakusho | Sound effect-creating device |
BE1020249A4 (en) * | 2011-09-14 | 2013-07-02 | Bilteryst Pierre Jean | PROCESS FOR THE "AUTHENTIC" REPRODUCTION OF SOUND COMPOSITE SOUNDS COMPRISING GLOBALLY DETAILED IN SPECTROPHONY BY ELECTRO-ACOUSTIC RESONANCES |
Citations (7)
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US2768237A (en) * | 1955-04-25 | 1956-10-23 | Twentieth Cent Fox Film Corp | Sound system |
US2819342A (en) * | 1954-12-30 | 1958-01-07 | Bell Telephone Labor Inc | Monaural-binaural transmission of sound |
US2845491A (en) * | 1955-12-16 | 1958-07-29 | Telefunken Gmbh | Stereophonic apparatus |
US3067287A (en) * | 1957-06-19 | 1962-12-04 | Percival William Spencer | Stereophonic sound transmission systems |
US3087988A (en) * | 1960-01-28 | 1963-04-30 | Rca Corp | Simulated stereophonic sound translating and recording system |
US3214519A (en) * | 1960-12-19 | 1965-10-26 | Telefunken Ag | Reproducing system |
US3478167A (en) * | 1965-07-12 | 1969-11-11 | Morris Sorkin | Three speaker stereophonic audio system |
-
1970
- 1970-07-29 US US59186A patent/US3684835A/en not_active Expired - Lifetime
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2819342A (en) * | 1954-12-30 | 1958-01-07 | Bell Telephone Labor Inc | Monaural-binaural transmission of sound |
US2768237A (en) * | 1955-04-25 | 1956-10-23 | Twentieth Cent Fox Film Corp | Sound system |
US2845491A (en) * | 1955-12-16 | 1958-07-29 | Telefunken Gmbh | Stereophonic apparatus |
US3067287A (en) * | 1957-06-19 | 1962-12-04 | Percival William Spencer | Stereophonic sound transmission systems |
US3087988A (en) * | 1960-01-28 | 1963-04-30 | Rca Corp | Simulated stereophonic sound translating and recording system |
US3214519A (en) * | 1960-12-19 | 1965-10-26 | Telefunken Ag | Reproducing system |
US3478167A (en) * | 1965-07-12 | 1969-11-11 | Morris Sorkin | Three speaker stereophonic audio system |
Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3787622A (en) * | 1971-02-05 | 1974-01-22 | Sansui Electric Co | Quadrasonic sound system for two channel transmission |
US3725586A (en) * | 1971-04-13 | 1973-04-03 | Sony Corp | Multisound reproducing apparatus for deriving four sound signals from two sound sources |
US3798373A (en) * | 1971-06-23 | 1974-03-19 | Columbia Broadcasting Syst Inc | Apparatus for reproducing quadraphonic sound |
US3885101A (en) * | 1971-12-21 | 1975-05-20 | Sansui Electric Co | Signal converting systems for use in stereo reproducing systems |
US3873779A (en) * | 1972-05-24 | 1975-03-25 | Urbick Robert J | Electronic sound distribution system |
US3914790A (en) * | 1972-12-29 | 1975-10-21 | Sony Corp | Four-channel stereo apparatus for switching between two channel and four channel inputs |
US3971890A (en) * | 1975-02-10 | 1976-07-27 | Cbs Inc. | Method and apparatus for quadraphonic enhancement of stereophonic signals |
FR2505534A1 (en) * | 1981-05-08 | 1982-11-12 | Rca Corp | SWITCHING ARRANGEMENT FOR A STEREOPHONIC SYNTHESIZER OF SOUND |
US5085937A (en) * | 1989-08-30 | 1992-02-04 | Minnesota Mining And Manufacturing Company | Particulate monitoring tape |
US5432856A (en) * | 1992-09-30 | 1995-07-11 | Kabushiki Kaisha Kawai Gakki Seisakusho | Sound effect-creating device |
BE1020249A4 (en) * | 2011-09-14 | 2013-07-02 | Bilteryst Pierre Jean | PROCESS FOR THE "AUTHENTIC" REPRODUCTION OF SOUND COMPOSITE SOUNDS COMPRISING GLOBALLY DETAILED IN SPECTROPHONY BY ELECTRO-ACOUSTIC RESONANCES |
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Owner name: ORBAN ASSOCIATES, INC., 645 BRYANT ST., SAN FRANCI Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:ORBAN, ROBERT A.;REEL/FRAME:003897/0740 Effective date: 19810630 Owner name: ORBAN ASSOCIATES, INC., 645 BRYANT ST., SAN FRANCI Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:ORBAN, ROBERT A.;REEL/FRAME:003897/0741 Effective date: 19810630 |
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Owner name: ORBAN ASSOCIATES, CALIFORNIA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:DELANTONI, JOHN H.;ORBAN, ROBERT A.;REEL/FRAME:005080/0914 Effective date: 19881229 Owner name: SIMMONS HEALTHCARE, INC. Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:ORBAN ASSICIATES, INC., A CORP. OF CA.;REEL/FRAME:005080/0912 Effective date: 19881229 Owner name: DELANTONI, JOHN H. Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:ORBAN ASSICIATES, INC., A CORP. OF CA.;REEL/FRAME:005080/0912 Effective date: 19881229 Owner name: AKG ACOUSTICS, INC., A DE. CORP., CONNECTICUT Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:ORBAN ASSOCIATES, A CA GENERAL PARTNERSHIP;REEL/FRAME:005080/0916 Effective date: 19890426 |