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DESCRIPTION JPH08242496

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DESCRIPTION JPH08242496
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker system having a feedback circuit for improving bass reproduction capability.
[0002]
2. Description of the Related Art In recent years, with the digitization of sound output devices,
the expansion of the bass reproduction band has been desired. Therefore, conventionally, the
vibration system mass of the speaker unit is made heavier to expand the bass reproduction band,
or electrical signal processing is performed to artificially increase the vibration system mass of
the speaker unit to enlarge the bass reproduction band. Speaker systems have been used,
including circuits.
[0003]
Below, the Kelton type speaker system provided with the conventional feedback circuit is
demonstrated using FIG.
[0004]
As shown in FIG. 6, the Kelton cabinet 2 (the inside of the cabinet is divided into the cavity 2a
and the cavity 2b by the cavity division member 2c, the speaker unit 1 is attached to the cavity
division member 2c, and the baffle surface of the cabinet 2 is The magnetic circuit 4 of the
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operation detecting means for outputting a voltage proportional to the vibration system speed is
attached to the passive radiator 3 attached to the cabinet) to which the passive radiator 3 is
attached, and the detected voltage is transformed as it is or The feedback circuit 5 negatively
feeds back to the power amplifier 7 for driving the speaker unit 1 through the above.
[0005]
However, in the above-described conventional configuration, when outputting a voltage
proportional to the vibration system speed of the bass enhancement member, a coil is disposed at
the center of the vibrating portion 31 of the bass enhancement member as shown in FIG. It is
necessary to have a magnetic circuit consisting of the magnet 33, the center pole 34, the top
plate 35 and the yoke 36 so that the magnetic field is orthogonal to the winding 32.
Therefore, there is a problem that the end portion of the coil-like winding 32 collides with the
yoke 36 of the magnetic circuit when the vibration of the low range enhancer is increased.
[0006]
The present invention solves the above-mentioned conventional problems, sufficiently follows the
vibration of the bass enhancement member, and at the low frequency reproduction frequency
without increasing the vibration system mass of the speaker unit or the bass enhancement
member. SUMMARY OF THE INVENTION It is a first object of the present invention to provide a
speaker system which can be enlarged and which can suppress cabinet vibration which increases
in proportion to the vibration system mass of the speaker unit or the bass range enhancing
member.
[0007]
A second object is to provide a speaker system that can be controlled to operate only on the bass
enhancement member in addition to the first object.
[0008]
The third object is to control sound pressure frequency characteristics of a plurality of speaker
units or a plurality of low frequency range enhancing members by one operation detecting
means and one sound pressure detecting means, and simultaneously reproduce different
reproduction bands. It is in providing a speaker system.
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[0009]
A fourth object is to provide a speaker system in which control can be made to work only with
respect to the bass enhancement member in addition to the third object.
[0010]
SUMMARY OF THE INVENTION In order to achieve the above first object, the speaker system of
the present invention is a cabinet in which the components other than the low frequency range
enhancing member are sealed, and the vibration system speed or vibration of the speaker unit
attached to the cabinet The system includes an operation detecting means for detecting a signal
proportional to a system acceleration, and a sound pressure detecting means for detecting a
sound pressure output signal in a cabinet generated by the bass range enhancing member and
the speaker unit. The amplifier circuit has a configuration (first configuration) provided with a
feedback circuit that amplifies each of the signals individually or feeds it back to the power
amplifier that drives the speaker unit through the differential integrator.
[0011]
In addition to the configuration of the first speaker system, the speaker system according to the
present invention combines the detection signal of the operation detection means and the
detection signal of the sound pressure detection means in order to achieve the second object. A
configuration (second configuration) is provided with a feedback circuit that feeds back only a
signal proportional to the vibration system velocity or vibration system acceleration of the range
enhancing member to the power amplifier.
[0012]
Further, in order to achieve the above third object, the speaker system of the present invention is
a cabinet in which a portion other than a plurality of bass range enhancing members is sealed,
and vibration speed or vibration of one of a plurality of speaker units attached to the cabinet
Motion detection means for detecting a signal proportional to the system acceleration, and sound
pressure detection means for detecting a sound pressure output signal in a cabinet generated by
a pair of low frequency range enhancing members and the speaker unit, including a speaker unit
, Each detection signal is amplified individually and then synthesized as it is or through a
differential integrator, and a feedback circuit to be fed back to each power amplifier driving the
speaker unit, and it is left as it is or attenuated when fed back It has the structure (3rd structure)
provided with the attenuator.
[0013]
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In addition to the configuration of the third speaker system, the speaker system according to the
present invention combines the detection signal of the operation detection means and the
detection signal of the sound pressure detection means to achieve the fourth object, and A
configuration (fourth configuration) is provided with a feedback circuit that feeds back only the
signal proportional to the vibration system velocity or vibration system acceleration of the range
enhancing member to the power amplifier.
[0014]
In the first configuration described above, a signal proportional to the vibration system velocity
or vibration system acceleration detected by the motion detection means attached to the speaker
unit is further transmitted through the differentiator or integrator in the feedback circuit to the
vibration system. The velocity is converted to vibration system acceleration, or vibration system
acceleration is converted as a signal proportional to vibration system velocity.
In addition, a sound pressure output signal detected by sound pressure detection means mounted
in the cabinet (a signal proportional to the vibration system acceleration of the speaker unit
minus a signal proportional to the vibration system acceleration of the bass enhancement
member) Is also converted as a signal proportional to the oscillating system velocity through an
integrator in the feedback circuit.
Then, the signals output from the respective feedback circuits are synthesized and fed back to
the power amplifier.
As a result, an action corresponding to an increase in the vibration system mass of the speaker
unit or the low range enhancement member occurs, and the low frequency reproduction
frequency can be expanded without increasing the vibration system mass of the speaker unit or
the low range enhancement member. The vibration of the cabinet that increases in proportion to
the vibration system mass of the speaker unit or the low frequency range enhancing member can
be suppressed.
[0015]
Further, in the second configuration, only the signal proportional to the vibration system velocity
or vibration system acceleration of the bass region enhancement member is fed back to the
power amplifier, thereby increasing the vibration system mass of the bass region enhancement
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member. A corresponding effect occurs, and the low frequency reproduction frequency can be
expanded without increasing the vibration system mass of the low frequency region
enhancement member, and the cabinet vibration which increases in proportion to the vibration
system mass of the low frequency region enhancement member can be suppressed. .
[0016]
Further, in the third configuration, the speaker unit or the speaker unit or the sound pressure
detection unit is a set of operation detection means and sound pressure detection means by
attenuating each power amplifier as it is or through an attenuator and feeding back different
amounts of feedback signals. An effect corresponding to the increase of the vibration system
mass of the low frequency range enhancement member occurs, and the low frequency
reproduction frequency can be expanded without increasing the vibration system mass of the
speaker unit or the low frequency range enhancement member, and the speaker unit or low
frequency range The vibration of the cabinet, which increases in proportion to the vibration
system mass of the reinforcing member, can be suppressed, and regeneration of a plurality of
different bands can be performed, and the regeneration band can be expanded.
[0017]
In the fourth configuration, only a signal proportional to the vibration system velocity or
vibration system acceleration of the bass enhancement member is attenuated to each power
amplifier as it is or through an attenuator, and is fed back as a different amount of feedback
signal. Thus, the action detection means and the sound pressure detection means produce an
action corresponding to an increase in the vibration system mass of the low range enhancement
member, and the low range without increasing the vibration system mass of the low range
enhancement member The reproduction frequency can be expanded, the cabinet vibration that
increases in proportion to the vibration system mass of the low range enhancer can be
suppressed, the reproduction of a plurality of different bands can be performed, and the
reproduction band can be expanded.
[0018]
An embodiment of the present invention will be described below with reference to the drawings.
[0019]
FIG. 1 is a block diagram showing the configuration of a speaker system according to a first
embodiment of the present invention.
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[0020]
In the cabinet 12, the inside of the cabinet is divided into the cavity 12a and the cavity 12b by
the cavity division member 12c, the speaker unit 11 is attached to the cavity division member
12c, and a passive radiator which is a bass region enhancement member at the opening of the
cabinet 12 It is equipped with thirteen.
In this configuration, the sound radiated from the speaker unit 11 propagates inside the cavity
12 b and is radiated from the passive radiator 13 which is a low-frequency range enhancing
member, and the in-cavity air compliance component of the cavity 12 a and the cavity 12 b The
resonance of the vibration system mass component of the passive radiator 13 provides a
frequency characteristic with a band pass acoustic filter of about 12 dB / oct.
In addition, the speaker unit 11 is driven by the power amplifier 17. During this time, the fixed
resistors R1, R2 and R3, the bridge circuit 14 whose side is the speaker unit 11 and the fixed
resistor Rs in parallel with the speaker unit 11 An impedance correction circuit 18 in which Cs is
disposed is inserted.
16 is a signal source.
[0021]
The detection voltage from the bridge circuit 14 is proportional to the speed of the vibration
system of the speaker unit 11, and the feedback circuit 15a combines this detection voltage with
a transformation as it is and a transformation through a one-time differentiator. It is fed back to
the power amplifier 17.
At this time, a voltage proportional to the vibration system acceleration can be obtained by
passing the differentiator once.
Further, the impedance correction circuit 18 arranged in parallel with the speaker unit 11
flattens the gradual rise of the electrical impedance from the middle to high range (near 400 Hz)
due to the voice coil inductance of the speaker unit 11 and is detected by the bridge circuit 14
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Suppress voltage changes and phase rotation.
This prevents oscillation of the power amplifier 17 when it is fed back.
[0022]
Furthermore, the sound pressure in the cavity 12 b generated by the speaker unit 11 and the
passive radiator 13 is the sound pressure output signal detected by the sound pressure detection
microphone 19 (from the signal proportional to the vibration system acceleration of the speaker
unit 11, the passive radiator 13 The signal proportional to the vibration system acceleration is
subtracted), and it is also converted as a signal proportional to the vibration system speed
through the integrator in the feedback circuit 15b.
[0023]
At this time, the phases of the signals output from the respective feedback circuits 15a and 15b
are opposite to each other.
[0024]
Here, assuming that a signal proportional to the velocity or acceleration of the vibration system
of the speaker unit 11 is S1, and a signal proportional to the velocity or acceleration of the
vibration system of the passive radiator 13 is S2, the signal detected from the bridge circuit 14 is
S1. A signal detected by the sound pressure detection microphone 19 is expressed as γ · (S1-S2)
(γ is an amplification amount of the sound pressure detection microphone 19).
Each feedback circuit 15a, 15b has a function of amplifying the signals detected by the bridge
circuit 14 and the sound pressure detection microphone 19 (here, the amplification amounts are
α times and β times.
), And the output signals are converted into α · S1 and β · γ · (S1-S2), respectively.
[0025]
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Then, by synthesizing the signals output from the respective feedback circuits 15a and 15b (α ·
S1−β · γ · (S1−S2)), a signal proportional to the vibration system velocity or vibration system
acceleration of the speaker unit 11 A signal proportional to the vibration system velocity or
vibration system acceleration of the passive radiator 13 is fed back to the power amplifier 17.
This is an operation equivalent to increasing the vibration system mass of the speaker unit 11 or
the passive radiator 13, and expansion of the low frequency reproduction frequency can be
achieved without increasing the vibration system mass of the speaker unit 11 or the passive
radiator 13. The vibration of the cabinet 12, which increases in proportion to the vibration
system mass of the unit 11 or the passive radiator 13, can be suppressed.
[0026]
Although the bridge circuit is used to detect the vibration system speed of the speaker unit 11 in
this embodiment, the vibration system acceleration of the speaker unit 11 may be detected using
this as an acceleration sensor.
[0027]
Next, a second embodiment of the present invention will be described.
The second embodiment is the same as the first embodiment except for the amplification amount
of the signals output from the feedback circuits 15a and 15b.
The amplification amount α of the signals of the feedback circuits 15a and 15b so that the
signal S1 proportional to the vibration system velocity or vibration system acceleration of the
speaker unit 11 is canceled by combining the signals output from the respective feedback
circuits 15a and 15b. , Β is controlled.
That is, by setting the amplification amount α to α = β · γ, only the signal S2 proportional to
the vibration system velocity or vibration system acceleration of the passive radiator 13 is fed
back to the power amplifier 17 (feedback circuits 15a and 15b The combined result of the
signals output from the circuit is α · S 1 −α · (S 1 −S 2) = α · S 2).
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This is an action equivalent to increasing the vibration system mass of the passive radiator 13,
and expansion of the low frequency reproduction frequency can be achieved without increasing
the vibration system mass of the passive radiator 13, and proportional to the vibration system
mass of the passive radiator 13. Thus, the vibration of the cabinet 12 can be suppressed.
[0028]
FIG. 2 shows sound pressure frequency characteristics of the speaker system of this
configuration.
a is a characteristic before feedback, b is a characteristic after feedback. Further, FIG. 3 shows the
vibration acceleration of the baffle surface of the cabinet 12 to which the passive radiator 13 is
attached. a is a characteristic obtained by adding an additional mass to the passive radiator 13,
and b is a characteristic obtained when a sound pressure frequency characteristic equivalent to
that of a is realized by feedback without adding the additional mass to the passive radiator 13. It
can be seen that by applying the feedback, the low frequency reproduction frequency is
expanded and the vibration acceleration is decreased.
[0029]
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 4
is a block diagram showing the configuration of a speaker system according to a third
embodiment of the present invention.
[0030]
The second embodiment is the same as the first embodiment except that the cabinet 22 and the
speaker units 21a and 21b are driven by the power amplifiers 27a and 27b, respectively. The
cabinet 22 is divided into a cavity 22a, a cavity 22b and a cavity 22d by a cavity division member
22c inside the cabinet. The speaker units 21a and 21b are attached to the cavity division
member 22c, the passive radiator 23a is attached to the opening of the cabinet 22 via the cavity
22d, and the passive radiator 23b is attached to the cavity 22b.
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[0031]
A bridge circuit 24 and a sound pressure detection microphone 29 for feedback are provided for
one set of the speaker unit 21b and the passive radiator 23b. The detection signals detected from
each are amplified individually and synthesized as they are in the first embodiment as they are or
through feedback circuits 25a and 25b having differential integrators, respectively, to drive
speaker units 21a and 21b. It is fed back to the power amplifiers 27a and 27b. Then, when being
fed back, it is attenuated by the attenuator 30 as it is. Here, the attenuator 30 makes the amount
of the signal fed back to the power amplifier 27a different from the amount of the signal fed
back to the power amplifier 27b, and the speaker unit 21a and the speaker unit 21b, or the
passive radiator 23a and the passive radiator 23b. To change the reproduction band of By
performing feedback, it becomes an action equivalent to increasing the vibration system mass of
the speaker units 21a and 21b or the passive radiators 23a and 23b, and increases the vibration
system mass of the speaker units 21a and 21b or the passive radiators 23a and 23b. Therefore,
the low frequency reproduction frequency can be expanded, and the vibration of the cabinet 22
which increases in proportion to the vibration system mass of the speaker units 21a and 21b or
the passive radiators 23a and 23b can be suppressed.
[0032]
Although the bridge circuit is used to detect the vibration system velocity of the speaker unit 21
in this embodiment, the vibration system acceleration of the speaker unit 21b may be detected
using this as an acceleration sensor.
[0033]
Next, a fourth embodiment of the present invention will be described.
The third embodiment is the same as the third embodiment except for the amplification amount
of the signals output from the feedback circuits 25a and 25b. As in the second embodiment, the
amount of amplification is set so that the signals output from the respective feedback circuits
25a and 25b are combined to cancel the signal proportional to the vibration system velocity or
vibration system acceleration of the speaker unit 21b. By control, only a signal proportional to
the vibration system velocity or vibration system acceleration of the passive radiator 23b is fed
back to the power amplifiers 27a and 27b. This is equivalent to increasing the vibration system
mass of the passive radiators 23a and 23b, and the low frequency reproduction frequency can be
expanded without increasing the vibration system mass of the passive radiators 23a and 23b.
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The vibration of the cabinet 22, which increases in proportion to the mass of the vibration
system, can be suppressed.
[0034]
FIG. 5 shows sound pressure frequency characteristics of the speaker system of this
configuration. a is a characteristic before feedback, b is a characteristic after feedback, and its
component is a combination of the characteristic c output from the passive radiator 23a and the
characteristic d output from the passive radiator 23b.
[0035]
As described above, according to the speaker system of the present invention, the operation for
detecting the signal proportional to the vibration system speed or vibration system acceleration
of the speaker unit attached to the cabinet in which the components other than the bass region
enhancing member are sealed. A detection means and a sound pressure detection means for
detecting a sound pressure output signal in a cabinet generated by a bass range enhancing
member and a speaker unit, the respective detection signals being amplified individually or as
they are, or a differential integrator In the configuration (first and second configurations), a
feedback circuit that feeds back to the power amplifier that drives the speaker unit is provided.
By this, it becomes an action equivalent to increasing the vibration system mass of the speaker
unit or the low frequency range enhancing member, and the low frequency reproduction
frequency can be expanded without increasing the vibration system mass of the speaker unit or
the low frequency range enhancing member. It is possible to suppress cabinet vibration that
increases in proportion to the vibration system mass of the unit or the low range enhancer.
[0036]
In addition, an operation detection means for detecting a signal proportional to the vibration
system speed or the vibration system acceleration for one of the plurality of speaker units
attached to the cabinet in which the plurality of low frequency range enhancing members are
sealed, and a speaker A pair of low-pitched band enhancing members including a unit and sound
pressure detecting means for detecting a sound pressure output signal in a cabinet generated by
the speaker unit, and amplifying each detection signal individually or as it is, or A configuration
(third and fourth configurations) including a feedback circuit that synthesizes through
differential integrators and feeds them back to the respective power amplifiers that drive the
speaker units, and an attenuator that directly or attenuates when fed back. Feed back feedback
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signals of different feedback amount to each power amplifier, enabling regeneration of multiple
different bands, It can be expanded.
[0037]
Brief description of the drawings
[0038]
1 is a block diagram showing the configuration of the speaker system in the first and second
embodiments of the present invention.
[0039]
Sound pressure frequency characteristics of the speaker system according to the second
embodiment of the present invention
[0040]
Fig. 3 Vibration acceleration characteristics of the speaker system according to the second
embodiment of the present invention
[0041]
4 is a block diagram showing the configuration of the speaker system in the third and fourth
embodiments of the present invention
[0042]
Sound pressure frequency characteristics of the speaker system according to the fourth
embodiment of the present invention.
[0043]
Figure 6 is a block diagram showing the configuration of a Kelton-type speaker system using
conventional detection means
[0044]
Fig. 7 Cross-sectional view of a conventional low-frequency intensifying member provided with
motion detecting means
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[0045]
Explanation of sign
[0046]
1, 11, 21a, 21b Speaker units 2, 12, 22 Cabinets 2a, 2b, 12a, 12b, 22a, 22b, Cavities 2c, 12c, 22c
Cavity division members 3, 13, 23a, 23b Passive radiators 4 Magnetic circuit 5 , 15a, 15b, 25a,
25b Feedback circuits 6, 16, 26 Signal sources 7, 17, 27a, 27b Power amplifiers 18, 28
Impedance correction circuits 19, 29 Sound pressure detection microphone 30 Attenuator 31
Vibrating part 32 Coiled winding Line 33 Magnet 34 Center pole 35 Top plate 36 Yoke
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