US2993556A - Simulated stereophonic loud-speaker - Google Patents

Simulated stereophonic loud-speaker Download PDF

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Publication number
US2993556A
US2993556A US680163A US68016357A US2993556A US 2993556 A US2993556 A US 2993556A US 680163 A US680163 A US 680163A US 68016357 A US68016357 A US 68016357A US 2993556 A US2993556 A US 2993556A
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Prior art keywords
speaker
loud
equal
diaphragm
diaphragms
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Expired - Lifetime
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US680163A
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English (en)
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Edward C Wente
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Individual
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Individual
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Priority to NL230791D priority Critical patent/NL230791A/xx
Priority to NL111179D priority patent/NL111179C/xx
Application filed by Individual filed Critical Individual
Priority to US680163A priority patent/US2993556A/en
Priority to GB25056/58A priority patent/GB842234A/en
Priority to DEW23963A priority patent/DE1100699B/de
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
    • H04R1/32—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only
    • H04R1/40—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by combining a number of identical transducers
    • H04R1/403—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by combining a number of identical transducers loud-speakers

Definitions

  • SIMULATED STEREOPHONIC LOUD-SPEAKER Filed Aug. 26, 1957 2 Sheets-Sheet 1 T 1 1 INVENTOR ATTORNEYS United States Patent ce SIMULATED STEREOPHONIC LOUD-SPEAKER Edward C. Wente, 42 Colt Road, Summit, NJ. Filed Aug. 26, 1957, Ser. No. 680,163 3 Claims. (Cl. 181-31)
  • the present invention relates to a loud;speaker system that is particularly serviceable as an instrument for the faithful reproduction of music in a living-room or a small music chamber.
  • Such an instrument should not only have a uniform response and be free from non linear distortion over a wide power level and audiofrequency range, but any part of the equipment exposed inthe living-room should be small, unobstrusive and adaptable to the general decor of living-room furnishings. Another requirement is that the reproduced sound should be appropriately diffused within the listening room. The character of this diffusion should ideally be such that a listener will experience the aural illusion of having been transported into the pick-up room where the' sound originates. The degree to which this objective can be achieved depends, of course, also on the type of pick-up microphone that is used and its placement, but with that problem we are here not concerned.
  • a general purpose of the invention is to satisfy the above requirements. Another object is to provide a compact high-fidelity loud-speaker system which does not require large baflies or cabinets or a large number and variety of loud-speaker units.
  • FIG. 1 shows a loud-speaker arrangement according to the invention
  • FIG. 2 shows one of the panels of FIG. 1;
  • FIG. 3 is a graph of resistance and reactance characteristics
  • FIG. 4 is a schematic connection diagram of 3 loudspeakers
  • FIG. 5 is a graph of power output versus frequency
  • FIGS. 6 and 7 are circuit diagrams of equalizing networks.
  • a structure that is substantially equivalent in operation is one wherein the pulsating spherical diaphragm has been replaced by a rigid spherical shell of the same dimensions in which closely and evenly spaced holes have been cut and then closed with flush mounted diaphragms having rigid central and flexible rim portions, each of the diaphragms being provided with a separate driving unit, preferably of the moving coil type.
  • this structure would differ from the other one in two respects. The radiation pattern throughout the trihedral projection angle would not be so uniform and the radiation impedance would be lower.
  • Each diaphragm with its rigid central and flexing rim portions acts like a piston from which the radiated sound becomes progressively more columnar with increasing frequency.
  • the effect of this behavior on the uniformity of the sound field would be reduced to a minimum by an increase in the number and a corresponding decrease in the size of the diaphragms.
  • the nonuniformity in the sound field resulting from the use of relatively large diaphragms need not impair the quality of the reproduced sound an appreciable amount.
  • a more serious disadvantage of the multi-diaphragm structure is its lower radiation impedance.
  • This impedance is equal to that of the vibrating shell as given by the Expression 1, above, multiplied by the square of the ratio of the live, or effective, area to the total area of the shell.
  • the effective area of an acoustic diaphragm is defined as the ratio of its volume displacement to its amplitude of motion. In the diaphragms here considered the effective area is less than the superficial area because the flexing annular portion does not take a full part in the motion of the rigid central portion. If the maximum linear amplitude of motion is specified then the required radial width of the flexing annulus is practically independent of the size of the diaphragm.
  • the flexing area therefore, varies linearly with the diameter of the diaphragm whereas the central area varies as-the square of its diameter.
  • the ratio of the effective area to the superficial area of each diaphragm increaseswith the size of the diaphragm. Then in order to keep this ratio as near to unity as possible it is of advantage to use a few large diaphragms rather than a multiplicity'of small ones.
  • the effective area of the entire shell is equal to the sum of the effective areas of all the diaphragms.
  • Two diaphragms could not be so mounted in the spherical shell that they would generate a progressive wave that would be symmetrical with respect to the axis of the corner.
  • a further disadvantage of this arrangement would be that the total effective area of the two diaphragms would be a relatively small fraction of the area of the shell because two equal circles cannot be drawn without overlap on a rectangular octant of a spherical surface so as to cover as much as /8 of its surface.
  • Three circles of equal size can, however, be drawn without overlap on such a surface so as to cover about 90% of the area. This amount of symmetrical coverage would be attained if one circle were placed in each of the three corners of the right spherical triangle that defines the boundary of the spherical ootant and were made as large as possible without any over-lapping. No greater fraction of the surface could be covered symmetrically by the use of a larger number of equal circles.
  • a loud-speaker system with the diaphragms of three cone-type loud-speakersmounted ina corresponding manner in the corner of a room thus has unique advantages.
  • FIG. 1 shows the installation of three loud-speaker diaphragms in the trihedral, cornerof the room in accordance with the above principles. They are not shown mounted in a spherical shell, but each one is flush mounted in a quadralateral, plate of the dimensions given in FIG. 2. When these plates are fitted into the corner in the manner indicated, the diaphragms will have the same positions relative to the walls of the room. as they would have if mounted in a spherical shell as previously described.
  • the distance, R from the vertex of the corner to each diaphragm is equal to 1.305 D where D is the rim diameter of the diaphragms clamping rings.
  • the solidlined circles 2426 in FIGS. 1 and 2 represent openings in the bafflles 18-20 opposite the live portions of. the diaphragms -17 through which the sound emerges into the room.
  • the dotted lined circles show the positions of the rims ofthe diaphragm clamping rings 21, 22, 23.
  • a particular loud-speaker which may be used is one that is manufactured by the Phillips Co. of Holland under the code. number 9710M. Its use in a high fidelity system is: described in the Phillips Technical Review of Marchv 23, 1957, p. 285. This unit has thefollowing principal properties:
  • the driving coils of the three loud-speakers may be connected either in series or in parallel and coupled to the output circuit of an amplifier. We shall here assume that they are connected in series as indicated in FIG. 4.
  • the output resistance of the amplifier or voltage source and the resistance of each of the loud-speaker coils are designated 3R and R respectively. It is assumed that over the frequency range of interest the amplifier develops an open-circuit voltage of a constant value, E, when an of fixed potential is applied to its input.
  • the velocity is equal to the driving force that would act on the system, if its motion were completely suppressed, divided by the total mechanical impedance, i.e., the blocked plus the motional impedance.
  • the blocked impedance is the mechanical impedance of the system when the coil circuit is opened.
  • the motional impedance is equal to the force per unit velocity that would obtain if the impedance of the mechanical parts and the driving voltage, E, where both equal to zero but the driving circuit were closed in the normal way. It has been shown to be equal to the square of the force factor divided by the electrical impedance of the driving circuit, by R.
  • the three unit speaker assembly as described has a radiation resistance of 1170 c.g.s. units at this frequency.
  • the diaphragms when delivering 0.15 watt would be 36 cm. per sec. which is 0.1% of the speed of sound.
  • the frequency modulation that a high frequency tone would suffer through the Doppler effect by this amount of motion at 50 c.p.s. would be practically unobservable.
  • Eq. 4 in the form
  • the first factor gives the power that the amplifier would deliver if the vibrating system were blocked. It is the maximum power that the amplifier can deliver to the loud-speakers for a given value of E.
  • the second factor gives the fraction of this power that is projected as sound. It may thus be taken as the acoustic efficiency of the system. For the particular system disclosed here it has a maximum value at about c.p.s. Substituting numerical values appropriate to this frequency we obtain a value of 10% for the efiiciency, a respectably high value for a loud-speaker operating without a horn.
  • each stage would ordinarily be adjusted so that at its maximum gain the output voltage, V, would be equal to the input voltage, E. Such adjustment would be made by control of the feed-back through the cathode resistors, R The large amount of feed-back required for this setting will reduce distortion in the network and increase its stability.
  • the networks include several stages, the circuit elements are of the inexpensive sort; Because of the multiplicity of stages they need not individually beheld very exactly to specified values.
  • Each loud-speaker diaphragm in efiect operates in the throat of a conical horn having a solid angle equal.
  • a loud-speaker system comprising a unitary baflle comprising three equal planar parts eachhaving the form of a. face of a 24 equal-faced convex polyhedron, the three parts being contiguous in just thesame way that three corresponding faces are. contiguous:- in said polyhedron, each of the three parts of the battle-having a centrally located opening for the reception of a directradiating loud-speaker, the whole. baffle being mountable in a trihedral corner of a room and adapted to contact the walls thereof.
  • a system according to claim 1, comprising a plurality of loud-speaker diaphragms each attached to one of said parts of the bafile containing one of'said openings.
  • a loud-speaker system comprising a unitary baflle having three openings each being in and occupying a major portion of each of three contiguous faces of a 24 equal-faced convex polyhedron, each of said openings being centrally located with respect to one of said faces for the reception of a direct radiating loud-speaker, the whole bafile being mountable in a trihedral corner of a room and adapted to contact the walls thereof.

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  • Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
  • Diaphragms For Electromechanical Transducers (AREA)
US680163A 1957-08-26 1957-08-26 Simulated stereophonic loud-speaker Expired - Lifetime US2993556A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
NL230791D NL230791A (en:Method) 1957-08-26
NL111179D NL111179C (en:Method) 1957-08-26
US680163A US2993556A (en) 1957-08-26 1957-08-26 Simulated stereophonic loud-speaker
GB25056/58A GB842234A (en) 1957-08-26 1958-08-05 Loud-speaker systems
DEW23963A DE1100699B (de) 1957-08-26 1958-08-23 Lautsprecheranordnung mit mehreren Lautsprechern auf einer Schallwand in einer Raumecke

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US680163A US2993556A (en) 1957-08-26 1957-08-26 Simulated stereophonic loud-speaker

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US2993556A true US2993556A (en) 1961-07-25

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US (1) US2993556A (en:Method)
DE (1) DE1100699B (en:Method)
GB (1) GB842234A (en:Method)
NL (2) NL111179C (en:Method)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4083426A (en) * 1974-10-17 1978-04-11 Peugh H Mark Loud speaker apparatus

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3379276A (en) * 1966-12-02 1968-04-23 Adam D. Goettl Speaker installation means

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1984550A (en) * 1928-08-29 1934-12-18 Western Electric Co Loud speaker
GB447749A (en) * 1934-10-17 1936-05-18 Paul Gustavus Adolphus Helmuth Improvements in means for converting electrical energy into sound
FR842376A (fr) * 1938-02-11 1939-06-12 Cie Radio Cinema Disposition combinée de haut-parleurs pour salles de cinéma sonore et analogues
US2602860A (en) * 1947-11-18 1952-07-08 Doubt Leon Stewart Loud-speaker structure
DE915460C (de) * 1948-10-03 1954-07-22 Alexander Schaaf Lautsprecherkombination mit gleichmaessigem Schallfeld
US2824617A (en) * 1952-09-15 1958-02-25 Philips Corp Sound reproducing device
US2915588A (en) * 1956-08-06 1959-12-01 Amar G Bose Pressure wave generation

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1930577A (en) * 1931-09-15 1933-10-17 Magnavox Co Loud speaker mounting
AT165502B (de) * 1948-09-25 1950-03-10 Henry Radio Heinrich & Co Lautsprecherkombination

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1984550A (en) * 1928-08-29 1934-12-18 Western Electric Co Loud speaker
GB447749A (en) * 1934-10-17 1936-05-18 Paul Gustavus Adolphus Helmuth Improvements in means for converting electrical energy into sound
FR842376A (fr) * 1938-02-11 1939-06-12 Cie Radio Cinema Disposition combinée de haut-parleurs pour salles de cinéma sonore et analogues
US2602860A (en) * 1947-11-18 1952-07-08 Doubt Leon Stewart Loud-speaker structure
DE915460C (de) * 1948-10-03 1954-07-22 Alexander Schaaf Lautsprecherkombination mit gleichmaessigem Schallfeld
US2824617A (en) * 1952-09-15 1958-02-25 Philips Corp Sound reproducing device
US2915588A (en) * 1956-08-06 1959-12-01 Amar G Bose Pressure wave generation

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4083426A (en) * 1974-10-17 1978-04-11 Peugh H Mark Loud speaker apparatus

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Publication number Publication date
DE1100699B (de) 1961-03-02
NL230791A (en:Method)
NL111179C (en:Method)
GB842234A (en) 1960-07-20

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