US3186509A - High fidelity loudspeaker system - Google Patents

High fidelity loudspeaker system Download PDF

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Publication number
US3186509A
US3186509A US256336A US25633663A US3186509A US 3186509 A US3186509 A US 3186509A US 256336 A US256336 A US 256336A US 25633663 A US25633663 A US 25633663A US 3186509 A US3186509 A US 3186509A
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United States
Prior art keywords
chamber
acoustic
passage
speaker
air pocket
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US256336A
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English (en)
Inventor
Dudognon Jean-Pierre
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Individual
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Individual
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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
    • H04R1/22—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only 
    • H04R1/28—Transducer mountings or enclosures modified by provision of mechanical or acoustic impedances, e.g. resonator, damping means
    • H04R1/2807—Enclosures comprising vibrating or resonating arrangements
    • H04R1/2811—Enclosures comprising vibrating or resonating arrangements for loudspeaker transducers
    • 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
    • H04R1/22—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only 
    • H04R1/26—Spatial arrangements of separate transducers responsive to two or more frequency ranges
    • 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
    • H04R1/22—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only 
    • H04R1/28—Transducer mountings or enclosures modified by provision of mechanical or acoustic impedances, e.g. resonator, damping means
    • H04R1/2807—Enclosures comprising vibrating or resonating arrangements
    • H04R1/2815—Enclosures comprising vibrating or resonating arrangements of the bass reflex type
    • H04R1/2819—Enclosures comprising vibrating or resonating arrangements of the bass reflex type for loudspeaker transducers

Definitions

  • the present invention relates to a substantially aperiodic loudspeaker system including an acoustic chamber which provides high fidelity reproduction of sounds and it is intended chiefly, but not exclusively, for operation with a loud-speaker of the dynamic type uniformly reproducing a broad band of frequencies ranging between about 20 and 12,000 cycles.
  • My invention has more particularly for its object a compact apparatus of conventional shape, the adjustment of which is simple and the cost of which is low, while it operates by virtue of its novel construction over a range of frequencies which extends between extreme low notes and extreme high notes without any marked resonance or attenuation when transmitting any of said frequencies.
  • the acoustic energy fed into the chamber by the loud-speaker is subdivided into two channels, a very short channel arranged coaxially with the generator of acoustic energy and leading to a narrow passage forming an air pocket and a second channel provided with reflectors arranged in herring-bone formation, said second channel leading to the outer end of said air pocket.
  • the pocket-forming passage is provided in the vicinity of the point at which it meets the second channel with adjustable ports and it terminates as an acute dihedral angle so as to prevent the formation of standing waves of a length corresponding to the length of the passage.
  • the second channel provides, through its arrangement of reflectors in herring-bone formation, differences in the lengths of the paths followed by the sound waves according to their angles of incidence.
  • the arrangement is such that the acoustic energy encounters less acoustic impedance traveling in the direction away from the loudspeaker diaphragm, than in the opposite direction in which the efiiciency of transmission is almost zero. This results in the elimination of standing waves.
  • said phenomenon is increased by the fact that the cross sectional area of the first channel in a direction coaxial with the loud-speaker followed by that of the air jacket decreases gradually in a manner such that the ratio between the acoustic energy and the volume inside which said energy is restricted, increases;
  • the air pocket is provided with one or mor adjustable ports which allow adjusting the acoustic contrast, said ports producing a coupling between the inside and the outside of the chamber, which leads to a novel resonating system which has a tendency to oppose the resonating system already extant in the chamber.
  • said chamber provides a very high acoustic efficiency for the loud-speaker together with an excellent reproduction of any transient sound, as ascribable, in particular, to the absence of standing waves, while a very reduced level of vibrations transmitted to the battle board is obtained and it is possible to adjust the ire-echoing and acoustic contrast by modifying the the effective size of the openings of the ports which produce a coupling between the acoustic energy inside and outside the chamber.
  • FIG. 1 is an elevational view of a cabinet enclosing a high fidelity acoustic reproducing system according to my invention.
  • FIG. 2 is a plan sectional view of the acoustic chamber taken on the line AA of FIG. 1.
  • FIG. 3 is a rear view of one half of the cabinet or enclosure.
  • FIG. 4 shows, by way of a modification, an acoustic chamber adapted to be associated with a tape recorder.
  • the cabinet is subdivided into two parts of which the upper part 1 houses the radio receiver including the amplifier (not shown) and, optionally, a tape recorder.
  • the lower part, 2 forms the acoustic chamber for the loudspeaker system according to my invention.
  • the acoustic energy transmitted by the loud-speaker 3, mounted in a bafile board 30, is distributed into two channels: a first very short channel or acoustic pasage 4, defined by first partition means 4a, 4b.
  • the channel or passage 4 is coaxial with respect to the loudspeaker 3 and converges rearwardly, leading at 5 to a passage or air pocket 6 defined by second partition means formed by a wall 6a and the rear wall 2b of the chamber 2.
  • the air pocket 6 has a gradually decreasing cross-section proceeding leftwardly.
  • said reflectors provide differences in the lengths of the paths of the acoustic waves according to the angle of incidence of the latter thereby detuning the second acoustic passage '7 from resonance at any particular frequency within the wide range.
  • the arrangement is such that the acoustic energy travels with excellent efiiciency in the direction of the arrow F away from the loud-speaker diaphragm, whereas the efiiciency of transmission is almost zero in the opposite direction, which eliminates standing waves.
  • the end of this channel 7 forms the area where the density of acoustic ener y is at a maxi e1 mum.
  • the end 9 of the second acoustic passage 7 communicates with a triangular auxiliary channel lltta through an aperture 9a.
  • the auxiliary channel Eda opens downwardly directly above a reflector it) located exteriorly of the chamber 2.
  • the reflector it) is connected to the bottom wall 2a of the chamber 2 by a hinge 1%.
  • the hinge Zltib permits angular displacement of the reflector it) about a horizontal axis located near and extending parallel to the rear wall 21) of the chamber 2.
  • the hinge 1% is provided with a locking knob 100 for locking the reflector lit) in any desired position of angular adjustment.
  • the hinge 10b and reflector lltl permit adjustment of the acoustic coupling between the inside and the outside of the chamber 2.
  • the ends and 9 of the channels opening into the air pocket or passage 6 are spaced as far away as possible from each other.
  • the air pocket 6 is provided with ports Itll which are adjustable through the agency of a perforated sliding plate 12 (FIG. 3) and it terminates as an acute dihedral angle at 5 (FIG. 2), whereby no standing wave of a length corresponding to its length can be produced.
  • the arrangement is associated with independent tweeter means 13 for the reproduction of high notes.
  • the chamber described allows damping the rcarwardly directed waves since the waves passing out of the channels 4 and 7 enter the air pocket 6 from opposite directions and show phase differences which vary by reason of the actual progression of waves over the herring-bone reflector structure in the channel '7. Furthermore, there is a damping obtained through the direct dissipation due to the viscosity of the air in the air pocket and to its inertia. The correct reproduction of transient sound is associated directly with the efficiency of said damping.
  • My improved chamber allows furthermore obtaining the return of the energy originally transmitted inside the baflle board to be partly returned to the loud-speaker diaphragm in phase with the latter through the channel 4. This is a phenomenon of diffuse resonance which is obtained for all the frequencies to be transmitted; the efiiciency of the loud-speaker is thus considerably increased.
  • the sound passing out of the channel '7 forms, by reason of the successive reflections to which it is subjected, which reflections lead to different delays, a series of vibratory nodes and loops which have a tendency to constitute a coherent system with the sound passing out of the channel 4, which leads to the phenomenon of diffuse resonance.
  • the fraction of energy dissipated corresponds to the component of the waves which are in phase opposition inside said air pocket, which forms a cause of damping of the rearwardly directed waves.
  • the waves travel over different paths in the channel 7. For a number of said paths, there is a more or less perfect phase coincidence with the waves passing out of the channel 4 and for other paths, there is an opposition in phase and a dissipation of energy.
  • a fraction of the acoustic energy radiated inside the chamber constitutes thus a resonating system, in phase with the loud-speaker diaphragm. For each period, almost one half of said energy is consequently returned to the outside of the chamber by the diaphragm; said phenomenon is very important from a quantitative standpoint, although the energy associated with each cycle of resonance is very unimportant.
  • the resonant systems in the type of chamber considered are immediately cut out upon input of a transient wave by reason:
  • the damping coefficient of the chamber increases consequently until a further ditfuse resonant system is obtained.
  • the increase of the damping factor is ascribable to the consumption of energy required for neutralizing the actual wave system and producing a further system.
  • FIG. 4 illustrates anacoustic chamber adapted to equip an acoustic reproduccr including a loud-speaker t4 the acoustic energy of which is distributed into two channels: a coaxial channel 15 leading to a passage reforming an air pocket provided with one or more adjustable ports 17, and a channel 18 associated with a set of reflectors 19 leading to the end 29 of the passage 16.
  • the operation of said chamber is identical with that of the chamber serving for high fidelity reproduction.
  • a substantially aperiodic loudspeaker system comprising, in combination: means including bafl le board means defining an acoustic chamber, said bafiie board means extending transversely of said chamber at the front thereof; a rearwardly extending dynamic speaker mounted in said baflle board means; first partition means in said chamber defining a first rearwardly convergent acoustic passage efiectively coaxial with said speaker; second partition means defining an air pocket in said chamber extending adjacent to the rear of said chamber substantially throughout the entire width thereof, said first acoustic passage communicating directly with said air pocket at a location adjacent to one side of said chamber; third partition means defining a second acoustic passage extending laterally away from said speaker and communicating directly with said air pocket at a location adjacent to the other side of said chamber, said third partition means including a plurality of wall members of differing lengths which extend from the sides of said second passage at spaced locations therealong obliquely toward the longitudinal axis thereof and
  • prising adjustable means for varying the effective size of said aperture. 10 LEO SMILOW, Primary Examiner.

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  • Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Details Of Audible-Bandwidth Transducers (AREA)
US256336A 1962-02-13 1963-02-05 High fidelity loudspeaker system Expired - Lifetime US3186509A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR887871A FR1322235A (fr) 1962-02-13 1962-02-13 Enceinte acoustique, destinée notamment aux chaînes de reproduction sonore à <<haute fidélité>>

Publications (1)

Publication Number Publication Date
US3186509A true US3186509A (en) 1965-06-01

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ID=8772585

Family Applications (1)

Application Number Title Priority Date Filing Date
US256336A Expired - Lifetime US3186509A (en) 1962-02-13 1963-02-05 High fidelity loudspeaker system

Country Status (6)

Country Link
US (1) US3186509A (nl)
BE (1) BE623937A (nl)
FR (1) FR1322235A (nl)
GB (1) GB988456A (nl)
LU (1) LU42585A1 (nl)
NL (1) NL285007A (nl)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3721925A (en) * 1970-05-21 1973-03-20 Sony Corp Sound signal delay device
US3783967A (en) * 1972-02-24 1974-01-08 Us Health Focusing protective enclosure for ultrasonic transducer
US4235301A (en) * 1979-06-04 1980-11-25 Mitchell Robert W Folded column speaker enclosure
US5012889A (en) * 1989-11-30 1991-05-07 Rogersound Labs, Inc. Speaker enclosure
US5036946A (en) * 1989-03-29 1991-08-06 Sanyo Electric Co., Ltd. Speaker system
US5111905A (en) * 1989-11-30 1992-05-12 Rogersound Labs, Inc. Speaker enclosure
US5860483A (en) * 1995-05-24 1999-01-19 Havig; Sven O. Method for installing electronic equipment below soft earth surface
US8256566B1 (en) * 2011-08-19 2012-09-04 Rogersound Labs, LLC Speaker enclosure

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1291790B (de) * 1966-12-24 1969-04-03 Knoedler Gottlob Lautsprecherbox mit einem oder mehreren Lautsprechern
GB2149613A (en) * 1983-09-03 1985-06-12 Torquil Hector Rees Macleod Loudspeaker cabinet
GB2273415B (en) * 1992-12-11 1996-05-15 George James Johnston Loudspeaker enclosure
JPH11220789A (ja) 1998-01-30 1999-08-10 Sony Corp 電気音響変換装置

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2805729A (en) * 1953-09-15 1957-09-10 Read Oliver Loudspeaker enclosure
US3047090A (en) * 1958-05-07 1962-07-31 Robert G Pruden Tuned acoustical device

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2805729A (en) * 1953-09-15 1957-09-10 Read Oliver Loudspeaker enclosure
US3047090A (en) * 1958-05-07 1962-07-31 Robert G Pruden Tuned acoustical device

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3721925A (en) * 1970-05-21 1973-03-20 Sony Corp Sound signal delay device
US3783967A (en) * 1972-02-24 1974-01-08 Us Health Focusing protective enclosure for ultrasonic transducer
US4235301A (en) * 1979-06-04 1980-11-25 Mitchell Robert W Folded column speaker enclosure
US5036946A (en) * 1989-03-29 1991-08-06 Sanyo Electric Co., Ltd. Speaker system
US5012889A (en) * 1989-11-30 1991-05-07 Rogersound Labs, Inc. Speaker enclosure
US5111905A (en) * 1989-11-30 1992-05-12 Rogersound Labs, Inc. Speaker enclosure
US5860483A (en) * 1995-05-24 1999-01-19 Havig; Sven O. Method for installing electronic equipment below soft earth surface
US8256566B1 (en) * 2011-08-19 2012-09-04 Rogersound Labs, LLC Speaker enclosure
US20130043089A1 (en) * 2011-08-19 2013-02-21 Rogersound Labs Llc Speaker enclosure
US8397860B2 (en) * 2011-08-19 2013-03-19 Rogersound Labs, LLC Speaker enclosure

Also Published As

Publication number Publication date
BE623937A (nl)
LU42585A1 (nl) 1962-12-24
FR1322235A (fr) 1963-03-29
NL285007A (nl)
GB988456A (en) 1965-04-07

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