EP0133948B1 - Verfahren und Einrichtung zur Gegenkopplung der Bewegungsspannung eines Lautsprechers - Google Patents

Verfahren und Einrichtung zur Gegenkopplung der Bewegungsspannung eines Lautsprechers Download PDF

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Publication number
EP0133948B1
EP0133948B1 EP84108638A EP84108638A EP0133948B1 EP 0133948 B1 EP0133948 B1 EP 0133948B1 EP 84108638 A EP84108638 A EP 84108638A EP 84108638 A EP84108638 A EP 84108638A EP 0133948 B1 EP0133948 B1 EP 0133948B1
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EP
European Patent Office
Prior art keywords
loudspeaker
voltage
network
movement induced
current
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.)
Expired
Application number
EP84108638A
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German (de)
English (en)
French (fr)
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EP0133948A1 (de
Inventor
Burkhard Dick
Dr. Paul Scherer Erbengemeinschaft
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BURKHARD DICK TE HAMBURG EN ERBENGEMEINSCHAFT DR.
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Individual
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Priority to AT84108638T priority Critical patent/ATE46600T1/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
    • 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 a method for negative feedback of the dynamic voltage of a dynamic loudspeaker with respect to the signal voltage, with the aid of a network in which the dynamic voltage is obtained by forming the difference between the loudspeaker terminal voltage and a compensation voltage, and a device for carrying out the method.
  • the loudspeaker diaphragm does not exactly follow the applied signal voltage, because the mechanical oscillation circuits, which are more or less firmly coupled to the diaphragm, tend to vibrate naturally when triggered by impulses, which are still disruptive even if they are caused by damping are significantly smaller than the actual signal.
  • the mass-affected speaker membrane has difficulties, e.g. B. to follow pulse-shaped signal voltages.
  • the transparency of the reproduction depends at least in the mid-range (200 Hz to 1 kHz) on the correct phase behavior, i.e.
  • a loudspeaker should be able to reproduce rectangular sound pressure profiles to a certain extent correctly in this frequency range. This means that the loudspeakers of the low and mid-range parts must be installed closely adjacent to avoid differences in delay, which generally leads to small loudspeaker housings. Because of the volume required of the woofer, the control of the diaphragm movement becomes even more urgent.
  • a voltage amplifier is connected upstream of the loudspeaker, a negative current feedback circuit and a negative voltage feedback circuit also being matched to one another in such a way that the weakening of the voltage circuit essentially corresponds to the amplification of the circuit.
  • Two networks are therefore provided, but none of them is a network that simulates the voltage drop at the impedance of the loudspeaker that is locked.
  • a contact of the loudspeaker is potentially controlled so that the internal resistance of the voltage source connected upstream is compensated for.
  • the circuit thus behaves like an amplifier with a negative output resistance (steel method). This is usually implemented by positive feedback.
  • the special type of feed-forward prevents a possible instability of the circuit at the expense of a second power amplifier.
  • the voltage controlled current source only serves to convert the loudspeaker current into a proportional voltage (i.e. to measure the loudspeaker current) which controls the mentioned (lower) contact of the load via amplifier 16. In the simplest case, it can be replaced by an ohmic resistor.
  • the voltage-controlled current source is included in the negative feedback of the amplifier, the load is also operated on a voltage source with a very low internal resistance. Furthermore, the braked impedance is approximated by an ohmic resistance, so that the imaginary part, which is particularly important at frequencies above the resonance frequency, is disregarded. It is not a negative feedback system, in which a correction signal would be generated by means of a comparable controlled variable with an input signal. The system behaves in such a way that the control and input variables are approximately proportional, which is not desirable over the entire frequency range.
  • the object of the invention is to develop a method and a device for negative feedback of the dynamic voltage of a dynamic loudspeaker in such a way that a higher fidelity and thus a higher transparency of the reproduction is achieved.
  • the above-mentioned object is achieved in a method of the type mentioned at the outset in that the electrical signal to be reproduced is supplied to the loudspeaker as an impressed current, that the input of a capacitor, resistors and operators, at its output the voltage drop at the impedance of the braked After the speaker a voltage proportional to the impressed current is fed to the network and the output voltage of the network is used as a compensation voltage for difference formation.
  • a device provides that the loudspeaker is connected to a voltage-controlled current source with high internal resistance, that at the input of the network of capacitors, resistors and operators a current-tapped loudspeaker is present at the loudspeaker and is proportional to the current and that the output of the network is present at a subtractor amplifier .
  • the signal current impressed on the loudspeaker is sampled at a frequency above the hearing range, and in the switch-off phases the movement voltage at the loudspeaker terminals is sensed at suitable times and regenerated by a downstream low-pass filter, and that the impedance of the stalled loudspeaker caused interference voltage and the simulation network are eliminated.
  • the invention enables further development by means of a loudspeaker with small woofers and mid-range loudspeakers in order to obtain a small acoustic center, through which the radiation of rectangular sound pressure curves is possible on all sides up to frequencies of approx. 3 kHz and with a woofer arranged at the end for use the mirror sound source of the woofer when the housing is mounted on the wall.
  • the device according to FIG. 1 has an adder 1, a voltage-controlled current source 2 with output amplifier, a loudspeaker 3, a network 4 for simulating the voltage drop at the impedance of the stuck loudspeaker and a feedback amplifier 5.
  • the loudspeaker is operated with impressed current, i.e.
  • FIG. 3a shows the typical locus of a loudspeaker that is braked. Their characteristic course is essentially due to the existence of eddy currents in the conductive core and magnet material in the case of an AC coil. According to Lenz's rule, they weaken the original field increasingly with increasing frequency, whereby the electrical energy is converted into thermal energy together with the hysteresis losses in the conductive material. This fact can be represented in an equivalent circuit diagram according to FIG. 3b.
  • R K and L K are frequency independent. At high frequencies, a different spatial field distribution will occur for each frequency f due to the field displacement (skin effect). The flux linkage with the original field and consequently L K and R K become frequency-dependent.
  • the impedance Z K can be described with sufficient accuracy by a network according to FIG. 4. 3 to 5 chain links were sufficient for the speakers previously used.
  • this equivalent circuit diagram does not take into account any non-linearities. Above all, this includes field distortions with large modulation through the hysteresis, the dependence on the respective position of the voice coil due to the inhomogeneous field profile and temperature influence.
  • R is the resistance over which the loudspeaker current is measured.
  • FIG. 6 An application example for a 13 cm woofer is shown in Fig. 6.
  • the movement voltage UM induced in the voice coil (FIG. 2) contains, in addition to the distortion-related deviations, above all the portion that is determined by the mechanical resonance system (membrane together with voice coil, suspension) and the coupled housing (FIG. 2b). This can be indicated by an electrical resonant circuit with a constant loss resistance, as long as the frequency-dependent losses due to radiation in the range of the fundamental resonance can be neglected. If one therefore only wants to correct the basic behavior of a loudspeaker in which the influence of the linear mass-spring system dominates by far over the non-linearities, it is sufficient to do this by a network A ' M (Fig.
  • FIG. 8 An application example for a mid-tone dome is shown in FIG. 8.
  • a further development for gaining the movement tension is to operate the loudspeaker in time multiplex as both a transmitter and a receiver.
  • the terminal voltage U L is keyed to the loudspeaker.
  • the key frequency must be outside the listening area, e.g. B. 38 kHz.
  • the principle is first explained using a voltage source with a purely ohmic internal resistance (FIG. 9).
  • the circuit has a linear gate circuit 11 and a power amplifier 12, a voltage source 13 with ohmic resistor 11 and a low-pass filter 14.
  • the internal induction voltage can then be sampled in proportion to the current using a small measuring resistor (FIG. 10a).
  • the impedance of the braked loudspeaker itself contains inductances, the stored inductive energy results in a time-increasing decaying interference voltage after switching off the terminal voltage, the effect of which disturbs the measurement of the movement voltage (Fig. 10b).
  • the stored reactive energy reduces the crosstalk attenuation between the "transmit and receive channel".
  • One possibility of improving the "crosstalk” is to select the sampling time during the switch-off phase in such a way that the lowest-interference value of the movement voltage is detected (FIG. 10b). This is then regenerated by a downstream low-pass filter.
  • Another option is to take measures which, despite the inductances, cause the transmission current to drop as quickly as possible to "zero" as a result of "countermeasures". This can be done e.g. B. achieve by a differentiator, which is connected upstream of the power amplifier. However, it is better to impress the loudspeaker current directly using a voltage-controlled current source.
  • FIG. 11 A detailed block diagram, in which FIG. 2 was used, is shown in FIG. 11. There are: adding 1, a linear gate circuit 2, a voltage-controlled current source 3 with output amplifier, a loudspeaker 4, a simulation network 5, an ideal scanner 6, a low pass 7 and a feedback amplifier 8.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Circuit For Audible Band Transducer (AREA)
  • Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
EP84108638A 1983-07-22 1984-07-21 Verfahren und Einrichtung zur Gegenkopplung der Bewegungsspannung eines Lautsprechers Expired EP0133948B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT84108638T ATE46600T1 (de) 1983-07-22 1984-07-21 Verfahren und einrichtung zur gegenkopplung der bewegungsspannung eines lautsprechers.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3326494 1983-07-22
DE19833326494 DE3326494A1 (de) 1983-07-22 1983-07-22 Kontrolle der membranbewegung des dynamischen lautsprechers durch ein verbessertes netzwerk zur nachbildung seiner eingangsimpedanz

Publications (2)

Publication Number Publication Date
EP0133948A1 EP0133948A1 (de) 1985-03-13
EP0133948B1 true EP0133948B1 (de) 1989-09-20

Family

ID=6204681

Family Applications (1)

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EP84108638A Expired EP0133948B1 (de) 1983-07-22 1984-07-21 Verfahren und Einrichtung zur Gegenkopplung der Bewegungsspannung eines Lautsprechers

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EP (1) EP0133948B1 (nl)
AT (1) ATE46600T1 (nl)
DE (2) DE3326494A1 (nl)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4638258A (en) * 1982-02-26 1987-01-20 Barcus-Berry Electronics, Inc. Reference load amplifier correction system
GB2196815B (en) * 1986-09-25 1989-01-11 David Robin Birt Motional feedback system for loudspeakers
DE102004021546A1 (de) * 2004-05-03 2005-12-08 Avantgarde Acoustic Lautsprechersysteme Gmbh Hornlautsprecher
WO2008007312A1 (en) * 2006-07-10 2008-01-17 Bobinados De Transformadores S.L. Power amplifier

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2345544C3 (de) * 1972-09-11 1976-12-23 Matsushita Electric Ind Co Ltd Schallwiedergabesystem
DE2420689C3 (de) * 1974-04-29 1984-09-20 Arndt 7500 Karlsruhe Klingelnberg Verfahren und Anordnung zur Verbesserung der Eigenschaften elektrodynamischer Wandler durch Bewegungsgegenkopplung
AU512725B2 (en) * 1976-06-08 1980-10-23 E. Hermann Keith Voice coil amplifier
DE2828520C2 (de) * 1978-06-29 1985-09-05 Hermann Dipl.-Ing. 6837 St Leon-Rot Tropf Regelung der Membranbewegung von getaktet betriebenen elektrodynamischen Lautsprechern
DE2922112A1 (de) * 1979-05-31 1980-12-04 Wolfgang Scholl Regelungsverfahren fuer lautsprecher
JPS6134749Y2 (nl) * 1979-09-28 1986-10-09
DE3021007C2 (de) * 1980-05-31 1984-05-17 ANT Nachrichtentechnik GmbH, 7150 Backnang Schaltungsanordnung mit Verstärker und Übertrager

Also Published As

Publication number Publication date
DE3326494C2 (nl) 1991-02-14
DE3479855D1 (en) 1989-10-26
DE3326494A1 (de) 1985-01-31
ATE46600T1 (de) 1989-10-15
EP0133948A1 (de) 1985-03-13

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