EP0171065A2 - Disposition pour la contre-réaction acoustique de haut-parleurs - Google Patents

Disposition pour la contre-réaction acoustique de haut-parleurs Download PDF

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Publication number
EP0171065A2
EP0171065A2 EP85109881A EP85109881A EP0171065A2 EP 0171065 A2 EP0171065 A2 EP 0171065A2 EP 85109881 A EP85109881 A EP 85109881A EP 85109881 A EP85109881 A EP 85109881A EP 0171065 A2 EP0171065 A2 EP 0171065A2
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EP
European Patent Office
Prior art keywords
microphone
loudspeaker
arrangement according
membrane
attached
Prior art date
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.)
Withdrawn
Application number
EP85109881A
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German (de)
English (en)
Other versions
EP0171065A3 (fr
Inventor
Friedrich Müller
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Individual
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Individual
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Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of EP0171065A2 publication Critical patent/EP0171065A2/fr
Publication of EP0171065A3 publication Critical patent/EP0171065A3/fr
Withdrawn legal-status Critical Current

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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
    • H04R3/00—Circuits for transducers, loudspeakers or microphones
    • H04R3/002—Damping circuit arrangements for transducers, e.g. motional feedback circuits

Definitions

  • the invention relates to an arrangement for acoustic negative feedback of loudspeakers with at least one microphone, which supplies a voltage proportional to the sound pressure generated by the loudspeaker, with a microphone amplifier, with a summing point, which adds the amplified microphone voltage in phase opposition to the control signal of the loudspeaker, with one downstream of the summing point PI controller and with a subsequent power amplifier to control the loudspeaker.
  • a negative feedback leads to an improvement in the frequency response, the distortion factor and the pulse fidelity of the loudspeaker, which leads to a lifelike reproduction.
  • a loudspeaker circuit with acoustic negative feedback in which the negative feedback signal is obtained with a microphone from the sound field in front of the loudspeaker, this signal is added in phase opposition to the control signal of the loudspeaker and the sum voltage is fed to the loudspeaker via an amplifier (German Offenlegungsschrift 31 37 747). .
  • the microphone is spaced in front of the speaker. Which are presented The resulting propagation time of the sound from the loudspeaker to the microphone has an effect in the control loop as a frequency shift, negative phase shift. Even at relatively low frequencies, this leads to inadequate stability of the control loop, which manifests itself in the tendency of the circuit to oscillate. Attempts are being made to counter this problem by specifically setting the frequency response of the open control loop.
  • a disadvantage of the known methods for acoustic negative feedback from loudspeakers is that the inevitable transit times of the sound from the loudspeaker to the microphone generally result in an inadequate stability of the control loop, which is difficult to control.
  • the constantly changing distance between the loudspeaker membrane and the microphone results in additional amplitude and intermodulation distortions. Since strong air currents occur in the area in front of the loudspeaker diaphragm, the microphone also picks up unwanted noise.
  • the present invention has for its object to propose an arrangement for acoustic negative feedback of speakers that does not have the disadvantages mentioned; in particular, the negative feedback circuit should be characterized by improved stability.
  • an arrangement for acoustic negative feedback of loudspeakers is assumed and is achieved in that the microphone is attached to the loudspeaker diaphragm.
  • the microphone thus moves with the loudspeaker membrane; the effective distance between the two is practically reduced to zero.
  • the propagation time of the sound between the loudspeaker membrane and the microphone is negligible, so that a negative effect on the stability behavior of the negative feedback circuit is excluded.
  • the arrangement according to the invention thus makes it possible for the first time to use the principle of acoustic negative feedback by means of a signal obtained from the sound field of the loudspeaker, without at the same time having to accept difficult control problems with regard to the stability of the control loop. Amplitude and intermodulation distortions are also excluded due to the unchangeable position of the microphone on the loudspeaker membrane. Since the microphone is no longer in the area of strong air currents, it also absorbs less noise.
  • the microphone is attached in an advantageous embodiment of the invention in the region of the edge of the loudspeaker diaphragm.
  • electret microphones are advantageously used for mounting on the loudspeaker membrane.
  • an electret microphone also acts as an accelerometer during a movement perpendicular to its microphone membrane
  • its membrane is expediently attached in the direction of movement of the loudspeaker membrane.
  • two identical microphones are advantageously arranged mechanically antiparallel, with their microphone voltages being added electrically. This largely compensates for structure-borne noise.
  • a stationary plate is arranged in front of the loudspeaker membrane in the area of the microphone.
  • this plate does not shade external noises generated by the loudspeaker, on the other hand it causes an increase in the sound pressure in the surface due to the sound reflections on its surface opposite the loudspeaker membrane Area of the microphone; this effectively improves the ratio between the interference signal and the useful signal of the microphone.
  • the stationary plate is expediently arranged essentially perpendicular to the direction of movement of the loudspeaker diaphragm.
  • the fixed plate covers about a quarter of the area of the loudspeaker diaphragm and the microphone is located approximately in the middle of this covered area. This dimensioning already achieves a significant improvement in the signal-to-noise ratio of the microphone without too much interference with the free sound radiation from the loudspeaker.
  • the plate works well with a minimum distance of around 1 cm between the plate and the moving speaker cone.
  • FIG. 1 The principle of acoustic negative feedback of a loudspeaker 1 is shown in FIG.
  • a microphone 2 which supplies a voltage proportional to the sound pressure.
  • this voltage is added in a summing point 4 in phase opposition to the control signal of the loudspeaker 1.
  • a PI controller 5 Downstream of the summing point is a PI controller 5, which is set in such a way that it increases the low frequencies, which contributes to the stability of the control loop.
  • a power amplifier 6 amplifies the control signal as far as is required to operate the loudspeaker 1.
  • the microphone 2 is attached directly to the front of the loudspeaker membrane 7.
  • An arrangement is shown here using a small electret microphone in the area of the edge 8 of the loudspeaker membrane 7, the membrane of which is attached to the loudspeaker membrane 7 in the direction of movement 9.
  • the attachment of the microphone 2 on the surface of the speaker diaphragm 7 is done in the simplest case by gluing; however, additional fasteners can also be used.
  • microphone 2 instead of the individual microphone 2, several, preferably two, microphones can also be attached, which are either arranged mechanically antiparallel or whose microphone membranes can be electrically polarized in opposite directions.
  • the effective distance between the two is vanishingly short, so that the duration of the sound between speaker membrane 7 and microphone phon 2 becomes negligible. There is therefore no dead time in the negative feedback circuit (see FIG. 1), which brings about a decisive improvement in the stability behavior of the control circuit compared to previously known arrangements.
  • the stability can be additionally increased by appropriate setting of the PI controller 5, it making sense to limit the frequency increase to very low frequencies (so-called counter).
  • a stationary plate 10 is arranged perpendicular to the direction of movement 9 in the area of the microphone 2 in front of the loudspeaker membrane 7.
  • the surface 11 of the loudspeaker membrane 7 covered by the plate 10 is drawn in with dashed lines.
  • the area 11 is approximately a quarter of the total area of the speaker diaphragm 7.
  • the microphone 2 is located approximately in the middle of the area 11.
  • the distance of the plate 10 from the edge 8 of the speaker diaphragm 7 is approximately 1 cm at its maximum deflection.
  • the plate 10 results in an improved signal-to-noise ratio of the sound signal picked up by the microphone 2.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)
EP85109881A 1984-08-08 1985-08-06 Disposition pour la contre-réaction acoustique de haut-parleurs Withdrawn EP0171065A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3429147 1984-08-08
DE19843429147 DE3429147C2 (de) 1984-08-08 1984-08-08 Anordnung zur akustischen Gegenkopplung von Lautsprechern

Publications (2)

Publication Number Publication Date
EP0171065A2 true EP0171065A2 (fr) 1986-02-12
EP0171065A3 EP0171065A3 (fr) 1986-11-20

Family

ID=6242575

Family Applications (1)

Application Number Title Priority Date Filing Date
EP85109881A Withdrawn EP0171065A3 (fr) 1984-08-08 1985-08-06 Disposition pour la contre-réaction acoustique de haut-parleurs

Country Status (2)

Country Link
EP (1) EP0171065A3 (fr)
DE (1) DE3429147C2 (fr)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4139681A1 (de) * 1991-12-02 1992-07-02 Czerny Heribert Schallwandler mit kompensationsantrieb
FR2673800A1 (fr) * 1991-03-07 1992-09-11 Lan Yan Fock Alain Dispositif electro-acoustique de reproduction sonore, asservi electroniquement, utilisant un haut-parleur a pavillon muni de microphones.
GB2268356A (en) * 1992-06-23 1994-01-05 Itzhak Chavet High-fidelity loudspeaker.
DE4334040A1 (de) * 1993-10-06 1995-04-13 Klippel Wolfgang Schaltungsanordnung zur selbständigen Korrektur des Übertragungsverhaltens von elektrodynamischen Schallsendern ohne zusätzlichen mechanischen oder akustischen Sensor
GB2292854A (en) * 1994-08-12 1996-03-06 Motorola Ltd Control of audio output using motional feedback and ambient noise detection
WO1997003536A1 (fr) * 1995-07-07 1997-01-30 University Of Salford Circuit de haut-parleur dote d'un dispositif de controle de la pression au niveau de la membrane du haut-parleur, d'un dispositif de controle de la vitesse de la membrane du haut-parleur et d'un circuit de retour
WO1997009847A1 (fr) * 1995-09-02 1997-03-13 New Transducers Limited Haut-parleurs en forme de panneau
EP0941013A1 (fr) * 1998-03-05 1999-09-08 Alcatel Terminal de radiotélécommunication

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2667634B1 (fr) * 2012-05-25 2015-07-08 AKG Acoustics GmbH Écouteur à suppression active du bruit ambiant

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2626652A1 (de) * 1976-06-15 1977-12-22 Friedemann Dipl Ing Meggl Regelungsanordnung fuer schallsender
WO1984000274A1 (fr) * 1982-06-30 1984-01-19 B & W Loudspeakers Systemes de haut-parleurs s'adaptant a l'environnement
US4445227A (en) * 1981-12-28 1984-04-24 Magnavox Consumer Electronics Company Loudspeaker having improved directional characteristics
WO1984001682A1 (fr) * 1982-10-14 1984-04-26 Matsushita Electric Ind Co Ltd Haut-parleur

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2948778A (en) * 1956-05-07 1960-08-09 Warner W Clements Sound reproducing means
NL294600A (fr) * 1963-06-26
DE2141141A1 (de) * 1971-08-12 1973-02-22 Neumann Gmbh Georg Schaltungsanordnung zur gegenkopplung eines lautsprechers
NL7308103A (fr) * 1973-06-12 1974-12-16
DE2629605C3 (de) * 1976-07-01 1979-10-31 Braun Ag, 6000 Frankfurt Schallwiedergabesystem
DE2803168C3 (de) * 1978-01-25 1982-10-21 Friedemann Dipl.-Ing. Dr. 8069 Jetzendorf Meggl Elektromechanischer Wandler
GB1568026A (en) * 1978-01-27 1980-05-21 Philips Nv Electrodynamic loudspeaker
NL7802687A (nl) * 1978-03-13 1979-09-17 Philips Nv Dreunvrije microfooncombinatie bevattende twee microfoonelementen.
NL8001592A (nl) * 1980-03-18 1981-10-16 Philips Nv Mfb systeem met een overnamenetwerk.
US4404040A (en) * 1981-07-01 1983-09-13 Economics Laboratory, Inc. Short chain fatty acid sanitizing composition and methods
DE3137747A1 (de) * 1981-09-23 1983-03-31 Gerhard Dipl.-Ing. 3002 Wedemark Kock Lautsprecherschaltung mit akustischer gegenkopplung

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2626652A1 (de) * 1976-06-15 1977-12-22 Friedemann Dipl Ing Meggl Regelungsanordnung fuer schallsender
US4445227A (en) * 1981-12-28 1984-04-24 Magnavox Consumer Electronics Company Loudspeaker having improved directional characteristics
WO1984000274A1 (fr) * 1982-06-30 1984-01-19 B & W Loudspeakers Systemes de haut-parleurs s'adaptant a l'environnement
WO1984001682A1 (fr) * 1982-10-14 1984-04-26 Matsushita Electric Ind Co Ltd Haut-parleur

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
FUNKSCHAU, Nr. 25, Dezember 1984, Seiten 64-66, M}nchen, DE; "Mikrofon auf der Bassmembran" *
RADIO FERNSEHEN ELEKTRONIK, Band 34, Nr. 7, Juli 1985, Seite 413, Ost-Berlin, DD; *

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2673800A1 (fr) * 1991-03-07 1992-09-11 Lan Yan Fock Alain Dispositif electro-acoustique de reproduction sonore, asservi electroniquement, utilisant un haut-parleur a pavillon muni de microphones.
DE4139681A1 (de) * 1991-12-02 1992-07-02 Czerny Heribert Schallwandler mit kompensationsantrieb
GB2268356A (en) * 1992-06-23 1994-01-05 Itzhak Chavet High-fidelity loudspeaker.
DE4334040A1 (de) * 1993-10-06 1995-04-13 Klippel Wolfgang Schaltungsanordnung zur selbständigen Korrektur des Übertragungsverhaltens von elektrodynamischen Schallsendern ohne zusätzlichen mechanischen oder akustischen Sensor
GB2292854B (en) * 1994-08-12 1999-08-25 Motorola Ltd Electronic audio device and method of operation
GB2292854A (en) * 1994-08-12 1996-03-06 Motorola Ltd Control of audio output using motional feedback and ambient noise detection
US5771297A (en) * 1994-08-12 1998-06-23 Motorola, Inc. Electronic audio device and method of operation
WO1997003536A1 (fr) * 1995-07-07 1997-01-30 University Of Salford Circuit de haut-parleur dote d'un dispositif de controle de la pression au niveau de la membrane du haut-parleur, d'un dispositif de controle de la vitesse de la membrane du haut-parleur et d'un circuit de retour
WO1997009847A1 (fr) * 1995-09-02 1997-03-13 New Transducers Limited Haut-parleurs en forme de panneau
EP0941013A1 (fr) * 1998-03-05 1999-09-08 Alcatel Terminal de radiotélécommunication
FR2775861A1 (fr) * 1998-03-05 1999-09-10 Alsthom Cge Alcatel Terminal de radiotelecommunication
WO1999045743A1 (fr) * 1998-03-05 1999-09-10 Alcatel Terminal de radiotelecommunication
US6564072B1 (en) 1998-03-05 2003-05-13 Alcatel Radio telecommunication terminal

Also Published As

Publication number Publication date
DE3429147A1 (de) 1986-02-20
DE3429147C2 (de) 1987-04-02
EP0171065A3 (fr) 1986-11-20

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