US3037081A - Vented enclosure type loudspeaker system providing improved low frequency response - Google Patents

Vented enclosure type loudspeaker system providing improved low frequency response Download PDF

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Publication number
US3037081A
US3037081A US458651A US45865154A US3037081A US 3037081 A US3037081 A US 3037081A US 458651 A US458651 A US 458651A US 45865154 A US45865154 A US 45865154A US 3037081 A US3037081 A US 3037081A
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loudspeaker
vibratory
air
port
resonator
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US458651A
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English (en)
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Carlsson Stig
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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
    • H04R1/2815—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 loudspeaker and loudspeaker enclosure, wherein the loudspeaker enclosure is an acoustic resonator of small dimensions, being well controlled by the loudspeaker mechanism.
  • Another object of the invention is to provide an inexpensive loudspeaker, which at low frequencies has a smooth frequency response curve, good transient response and low non-linear distortion.
  • Still another object of the invention is to obtain the two aims above without affecting the response of the loudspeaker mechanism for medium and high audio frequencies.
  • the subjects of the invention are the design dimensions of the enclosure of the loudspeaker, and the amount of resistive damping introduced to the motion of the loudspeaker diaphragm.
  • the enclosure of the loudspeaker is an acoustic resonator (Helmholz resonator), the diaphragm of the loudspeaker mechanism forming a part of the wall of the resonator.
  • the enclosure of the loudspeaker according to the invention differs from the ordinary bass reflex enclosures by being much smaller and having an equivalent mechanical resistance, larger than usual, in series with the mass of the loudspeaker diaphragm in the equivalent mechanical circuit.
  • the loudspeaker mechanism may for instance be an ordinary moving coil direct radiator loudspeaker mechanism.
  • FIG. 1 is a symbolic sectional view of a loudspeaker according to the present invention.
  • FIG. 2 is the equivalent low frequency mechanical circuit of FIG. 1, reduced to the moving members of the loudspeaker mechanism.
  • FIG. 3 is a diagrammatic representation of the system showing an amplifier 1, connected to a loudspeaker 2 of the vented enclosure type shown in FIG. 1.
  • r the mechanical radiation resistance of the diaphragm (negligible compared to other impedances)
  • r the equivalent mechanical resistance due to a layer of acoustic absorbing material (e.g. rockwool) covering the back of the loudspeaker mechanism
  • the mechanical circuit in FIG. 2 has two series resonant frequncies f and f and one parallel resonant frequency f f is the resonant frequency of the enclosure:
  • volume parameter v v
  • the volume parameter v is proportional to the enclosure volume V when the loudspeaker mechanism and the resoant frequency f are given.
  • volume parameter v to characterize bass reflex and other types of resonator enclosure designs and published design principles, it has been found that their volume parameters v are never less than 1.0, and usually have values between 1 and 2.
  • the effect of the volume parameter v is that a decrease of the parameter v raises the resonant frequency f increases the acoustic efliciency at f and decreases the acoustic efiiciency at h. If a loudspeaker mechanism with customary efficiency is used the decreasing of the parameter v to a small value makes the acoustic ethciency at f so small compared to the efficiency at f that the resonator may seem inoperative. This is Why small values of the volume parameter v have not been considered appropriate.
  • the volume parameter v and hence the volume of the enclosure, is reduced from the value used so far to a fraction of it, and the equivalent mechanical damping resistance in series with the loudspeaker diaphragm in the equivalent mechanical circuit is substantially increased.
  • damping resistance controls, in a certain manner, the acoustic efiiciency of the loudspeaker at the frequency f but does not noticeably influence the efiiciency at the frequency f
  • an appropriately chosen resistance provides a loudspeaker having a smooth, or smoothly sloped, frequency response curve at low audio frequencies down to f
  • the essential of the present invention is the combination of a low value of the volume parameter v of the loudspeaker, v less than 0.8, and arrangements to increase the equivalent mechanical resistance in series with the loudspeaker diaphragm in the equivalent mechanical circuit of the loudspeaker.
  • the loudspeaker is fed from an amplifier having a negative internal output impedance
  • Q is the ratio at resonance between the positive equivalent mechanical reactance and the equivalent mechanical series resistance of the loudspeaker driven by its proposed amplifier and having its resonator port closed.
  • This limiting value of Q corresponds to the loudspeaker mechanism having a Q-value of about 0.75 when mounted in a large bafile and connected to an amplifier having zero internal output impedance.
  • a lower Q-value means that the loudspeaker mechanism has an efiiciency higher than usual or is equipped with an unusual damping device.
  • the invention is not restricted to a complete loudspeaker construction but it also relates to a separate enclosure designed to make part of a loudspeaker according to the invention.
  • the resonant frequency of the enclosure should coincide with that of the loudspeaker mechanism:
  • the inventor has found the parameter values v from 0.2 to 0.5 to be of special interest.
  • the value v:0.3 has been used by the inventor in a number of loudspeakers of very good performance.
  • the loudspeaker may be given a low audio frequency response curve, down to f close to the voltage frequency response curve developed across the resistance in a voltage fed series circuit of a resistance and a capacitance.
  • the damping resistance is to be chosen to give A frequency response curve of this type is easily compensated in the amplifier in order to get a flat resulting low audio frequency response curve down to f
  • the performance of loudspeakers having resonator enclosures will be illustrated, as a function of the volume parameter v, by results from theoretical investigations:
  • the efficiency at the frequency f The tree field pressure response of the loudspeaker for the frequency f is equal to v times the free field pressure response for low medium frequencies, if the resistive losses of the resonator elements are low, which they were in the experimental loudspeakers according to the invention.
  • the distortion of the driving amplifier was negligible, and its internal output impedance was close to zero. In both cases a quite ordinary loudspeaker mechanism was used, but the compliance C was somewhat increased.
  • Loudspeaker 1 A 6.5" loudspeaker mechanism was mounted in an enclosure having a resonator volume of 8 dm. (outside dimensions: a cube 24 x 24 x 24 emf); the resonator was tuned to 3:70 c.p.s. Measured in an anechoic room the loudspeaker produced 5% harmonics when the sound intensity 1 meter from the loudspeaker was at 60 c.p.s. 78 db above 10- W./cm. 80 c.p.s. db above 10 W./cm. 110 c.p.s. db above l0- W./crn.
  • a sound reproducing device means forming a single acoustic resonator with at least one port, at least one electrically actuated vibratory air actuator disposed as part of the wall of said acoustic resonator, the internal volume of said acoustic resonator being so small as to represent a greater stiflness to said vibratory air actuator than the suspension system of said vibratory air actuator,
  • the dimensions of said port being such as to make the air in said port and the air load thereon represent a greater mass to said vibratory air actuator than the vibratory mass of said vibratory air actuator and the air load thereon, an amplifier driving said vibratory air actuator, means making the equivalent mechanical series resistance of said vibratory air actuator greater than the reactance of the vibratory mass of said vibratory air actuator and the air load thereon at resonance when said port is closed.
  • a sound reproducing device means forming a single acoustic resonator with at least one port, at least one electrically actuated vibratory air actuator disposed as part of the wall of said acoustic resonator, the internal volume of said acoustic resonator being so small as to represent a greater stiffness to said vibratory air actuator than the suspension system of said vibratory air actuator, the dimensions of said port being such as to make the air in said port and the air load thereon represent a greater mass to said vibratory air actuator than the vibratory mass of said vibratory air actuator and the air load thereon, an amplifier having a negative internal output impedance driving said vibratory air actuator.
  • Loudspeaker system comprising means forming a single acoustic resonator with at least one port, at least one electrically actuated vibratory air actuator disposed as part of the wall'of said acoustic resonator, the internal volume of said acoustic resonator being so small as to represent a greater stiifness to said vibratory air actuator than the suspension system of said vibratory air actuator, the dimensions of said port being such as to make the air in said port and the air load thereon represent a greater mass to said vibratory air actuator than the vibratory mass of said vibratory air actuator and the air load thereon, means making the equivalent mechanical series resistance of said vibratory air actuator greater than the reactance of the vibratory mass of said vibratory air actuator and the air load thereon at resonance when said port is closed and said vibratory air actuator is driven by an amplifier whose internal output impedance is close to zero.
  • Loudspeaker system as claimed in claim 7 wherein the dimensions of said port make the air in said port and the air load thereon represent a mass to said vibratory air actuator that is at least 25 percent greater than the vibratory mass of said vibratory air actuator and the air load thereon.
  • Loudspeaker system as claimed in claim 7 wherein the dimensions of said port make the air in said port and the air load thereon represent a mass to said vibratory air actuator that is at least twice the vibratory mass of said vibratory air actuator and the air load thereon.
  • Loudspeaker system comprising means forming an acoustic resonator with at least one port, at least one electrically actuated vibratory air actuator disposed as part of the wall of said acoustic resonator, the internal volume of said acoustic resonator being so small as to represent a greater stifiness to said vibratory air actuator than the suspension system of said vibratory air actuator, the dimensions of said port being such as to make the air in said port and the air load thereon represent a greater mass to said vibratory air actuator than the vibratory mass of said vibratory air actuator and the air load thereon, means providing an acoustical damping resistance between said vibratory air actuator and the interior of said acoustic resonator and located immediately adjacent said vibratory air actuator.
  • Loudspeaker system as claimed in claim 10 wherein the dimensions of said port make the air in said port and the air load thereon represent a mass to said vibratory air actuator that is at least 25 percent greater than the vibratory mass of said vibratory air actuator and the air load thereon.
  • Loudspeaker system as claimed in claim 10 wherein the dimensions of said port make the air in said port and the air load thereon represent a mass to said vibratory air actuator that is at least twice the vibratory mass of said vibratory air actuator and the air load thereon.
  • a sound reproducing device comprising an enclosure forming an acoustic resonator, said enclosure including a port in the form of a duct, one wall of said enclosure providing a bafile for the mounting of a loud speaker, a loud speaker mounted on said baflie and having a diaphragm forming a part of the wall of said enclosure, and a layer of acoustic absorbing material mounted on said battle and closely surrounding said loud speaker to totally enclose the back of same so as to provide an acoustic damping resistance between said diaphragm and said duct without materially reducing the volume of said resonator.

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  • Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Obtaining Desirable Characteristics In Audible-Bandwidth Transducers (AREA)
  • Details Of Audible-Bandwidth Transducers (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)
US458651A 1953-10-02 1954-09-27 Vented enclosure type loudspeaker system providing improved low frequency response Expired - Lifetime US3037081A (en)

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Application Number Priority Date Filing Date Title
SE876153A SE176417C1 (de) 1953-10-02 1953-10-02

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US3037081A true US3037081A (en) 1962-05-29

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US458651A Expired - Lifetime US3037081A (en) 1953-10-02 1954-09-27 Vented enclosure type loudspeaker system providing improved low frequency response

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US (1) US3037081A (de)
DE (1) DE1110228B (de)
DK (1) DK105927C (de)
FR (1) FR1255304A (de)
GB (1) GB780810A (de)
SE (1) SE176417C1 (de)

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3712411A (en) * 1972-03-17 1973-01-23 D Monroe Loud speaker cabinet
US3952159A (en) * 1973-03-09 1976-04-20 Zenith Radio Corporation Ducted port reflex enclosure
US3978941A (en) * 1975-06-06 1976-09-07 Curt August Siebert Speaker enclosure
US4139075A (en) * 1976-08-31 1979-02-13 Sansui Electric Co., Ltd. Loudspeaker device
US4268718A (en) * 1979-09-05 1981-05-19 Harris Corporation Housing acoustical amplifier
US4284166A (en) * 1979-04-13 1981-08-18 Gale George A Port devices for bass-reflex speaker enclosures
US4512434A (en) * 1983-05-10 1985-04-23 Yoo Sin Y Aerodynamic bass-reflex enclosure
US4987564A (en) * 1987-12-28 1991-01-22 Yamaha Corporation Acoustic apparatus
US4989187A (en) * 1987-12-28 1991-01-29 Yamaha Corporation Acoustic apparatus
US4997057A (en) * 1988-03-25 1991-03-05 Yamaha Corporation Method and apparatus of expanding acoustic reproduction range
US5004066A (en) * 1988-04-04 1991-04-02 Yamaha Corporation Acoustic apparatus
US5009281A (en) * 1988-03-10 1991-04-23 Yamaha Corporation Acoustic apparatus
US5173575A (en) * 1988-03-25 1992-12-22 Yamaha Corporation Acoustic apparatus
US5191616A (en) * 1989-12-29 1993-03-02 Yamaha Corporation Acoustic apparatus
US5280543A (en) * 1989-12-26 1994-01-18 Yamaha Corporation Acoustic apparatus and driving apparatus constituting the same
US5693916A (en) * 1994-06-30 1997-12-02 Von Sprecken; Richard F. Method for designing loud speaker enclosures
US6470088B2 (en) 2000-12-27 2002-10-22 Koninklijke Philips Electronics, N.V. Vented loudspeaker enclosure with limited driver radiation
US20020193896A1 (en) * 1998-06-17 2002-12-19 Bull Jeffrey A. Speaker apparatus and a computer system incorporating same
US20050145434A1 (en) * 2000-11-16 2005-07-07 Alpine Electronics, Inc. Speaker unit for low frequency reproduction
US20090188745A1 (en) * 2008-01-30 2009-07-30 Paul Wilke Helmholz resonator loudspeaker
US20090296971A1 (en) * 2008-05-29 2009-12-03 Siemens Hearing Instruments, Inc. Hearing Instrument Receiver With Improved Low-Frequency Efficiency
US20110235845A1 (en) * 2010-03-25 2011-09-29 Chao-Lang Wang Audio radiation type reflective sound box structure
WO2012079158A1 (en) 2010-12-16 2012-06-21 Taras Kowalczyszyn Improved housing for containing electronic components therein
US20130277140A1 (en) * 2012-04-17 2013-10-24 Gp Acoustics International Limited Loudspeaker

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3095467A (en) * 1961-02-13 1963-06-25 Wurlitzer Co Sound generating means
FR2188387B1 (de) * 1972-06-07 1974-12-27 Dehay Daniel
DE2552591C3 (de) * 1975-11-24 1984-04-12 Gerhard 5490 Stolberg Wergen Prinzip eines Lautsprechergehäuses für den Tieftonbereich
US5109422A (en) * 1988-09-28 1992-04-28 Yamaha Corporation Acoustic apparatus

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2217279A (en) * 1938-07-23 1940-10-08 Rca Corp Acoustic apparatus
FR1065126A (fr) * 1952-10-29 1954-05-20 Elipson Perfectionnements aux enceintes renfermant un émetteur de sons, et procédé pour le réglage de ces enceintes
US2766839A (en) * 1953-03-16 1956-10-16 Research Corp Loudspeaker system

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB696671A (en) * 1949-09-23 1953-09-09 British Broadcasting Corp Improvements in and relating to loudspeakers

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2217279A (en) * 1938-07-23 1940-10-08 Rca Corp Acoustic apparatus
FR1065126A (fr) * 1952-10-29 1954-05-20 Elipson Perfectionnements aux enceintes renfermant un émetteur de sons, et procédé pour le réglage de ces enceintes
US2766839A (en) * 1953-03-16 1956-10-16 Research Corp Loudspeaker system

Cited By (30)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3712411A (en) * 1972-03-17 1973-01-23 D Monroe Loud speaker cabinet
US3952159A (en) * 1973-03-09 1976-04-20 Zenith Radio Corporation Ducted port reflex enclosure
US3978941A (en) * 1975-06-06 1976-09-07 Curt August Siebert Speaker enclosure
US4139075A (en) * 1976-08-31 1979-02-13 Sansui Electric Co., Ltd. Loudspeaker device
US4284166A (en) * 1979-04-13 1981-08-18 Gale George A Port devices for bass-reflex speaker enclosures
US4268718A (en) * 1979-09-05 1981-05-19 Harris Corporation Housing acoustical amplifier
US4512434A (en) * 1983-05-10 1985-04-23 Yoo Sin Y Aerodynamic bass-reflex enclosure
US4987564A (en) * 1987-12-28 1991-01-22 Yamaha Corporation Acoustic apparatus
US4989187A (en) * 1987-12-28 1991-01-29 Yamaha Corporation Acoustic apparatus
US5009281A (en) * 1988-03-10 1991-04-23 Yamaha Corporation Acoustic apparatus
US4997057A (en) * 1988-03-25 1991-03-05 Yamaha Corporation Method and apparatus of expanding acoustic reproduction range
US5173575A (en) * 1988-03-25 1992-12-22 Yamaha Corporation Acoustic apparatus
US5004066A (en) * 1988-04-04 1991-04-02 Yamaha Corporation Acoustic apparatus
US5280543A (en) * 1989-12-26 1994-01-18 Yamaha Corporation Acoustic apparatus and driving apparatus constituting the same
US5191616A (en) * 1989-12-29 1993-03-02 Yamaha Corporation Acoustic apparatus
US5693916A (en) * 1994-06-30 1997-12-02 Von Sprecken; Richard F. Method for designing loud speaker enclosures
US20020193896A1 (en) * 1998-06-17 2002-12-19 Bull Jeffrey A. Speaker apparatus and a computer system incorporating same
US20060256994A1 (en) * 1998-06-17 2006-11-16 Bull Jeffrey A Speaker apparatus and a computer system incorporating same
US7567848B2 (en) 1998-06-17 2009-07-28 Micron Technology, Inc. Speaker apparatus and a computer system incorporating same
US20050145434A1 (en) * 2000-11-16 2005-07-07 Alpine Electronics, Inc. Speaker unit for low frequency reproduction
US6955241B2 (en) * 2000-11-16 2005-10-18 Alpine Electronics, Inc. Speaker unit for low frequency reproduction
US6470088B2 (en) 2000-12-27 2002-10-22 Koninklijke Philips Electronics, N.V. Vented loudspeaker enclosure with limited driver radiation
US20090188745A1 (en) * 2008-01-30 2009-07-30 Paul Wilke Helmholz resonator loudspeaker
US20090296971A1 (en) * 2008-05-29 2009-12-03 Siemens Hearing Instruments, Inc. Hearing Instrument Receiver With Improved Low-Frequency Efficiency
US20110235845A1 (en) * 2010-03-25 2011-09-29 Chao-Lang Wang Audio radiation type reflective sound box structure
US8406444B2 (en) * 2010-03-25 2013-03-26 Chao-Lang Wang Audio radiation type reflective sound box structure
WO2012079158A1 (en) 2010-12-16 2012-06-21 Taras Kowalczyszyn Improved housing for containing electronic components therein
EP2653017A4 (de) * 2010-12-16 2017-04-26 Taras Kowalczyszyn Verbessertes gehäuse zur aufnahme elektronischer bauteile
US20130277140A1 (en) * 2012-04-17 2013-10-24 Gp Acoustics International Limited Loudspeaker
US8807268B2 (en) * 2012-04-17 2014-08-19 Gp Acoustics International Limited Loudspeaker

Also Published As

Publication number Publication date
GB780810A (en) 1957-08-07
DK105927C (da) 1966-11-28
SE176417C1 (de) 1961-09-05
FR1255304A (fr) 1961-03-10
DE1110228B (de) 1961-07-06

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