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JPH08317490

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DESCRIPTION JPH08317490
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
horn speaker system capable of eliminating air distortion caused by an overload on air in a horn
and a compression driver and realizing high-fidelity reproduction with respect to an input signal.
It is about
[0002]
BACKGROUND OF THE INVENTION A conventional horn speaker system will be described with
reference to FIG. FIG. 5 is a block diagram modeling the input signal and the output sound
pressure in the horn speaker. Here, when an input signal of the horn speaker 51 is x (t) and an
output sound pressure radiated from the horn speaker is an output signal y (t), the input signal x
(t) and the output signal y (t) The relationship is as illustrated. That is, in the horn speaker 51, the
system 52 of the transfer function H1 of the horn speaker without distortion, the system 53 of
the transfer function H2 representing the secondary distortion of the horn speaker, and the two
systems 52 and 53 are added by the adder 54. Expressed as a thing.
[0003]
First, the input / output relationship of the horn speaker 51 will be described. An input signal x
(t), which is an electrical signal from an acoustic signal source, is input to the horn speaker 51.
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1
The input signal x (t) is converted from the electrical signal to the sound pressure output signal y
(t), and the listener listens to the output signal y (t). In the horn speaker, the input signal x (t) is
electroacoustically converted by, for example, a built-in dome type speaker, a sound wave is
output from the diaphragm, and the sound is emitted to the outside through the horn. Therefore,
distortion occurs in the sound pressure due to an overload on air in the horn and in the
compression driver which is a dome-shaped speaker. The transfer function of the horn speaker
51 in consideration of this distortion is shown in FIG.
[0004]
Thus, the horn speaker 51 can be expressed as a superposition of the system 52 of the transfer
function H1 and the system 53 of the transfer function H2 representing the second-order
distortion of the horn speaker. If this is expressed by an equation, the relationship between the
input signal x (t) of the horn speaker 51 and the output signal y (t) is as shown in equation (5).
Here, X (m) is obtained by discretizing the input signal x (t) at the frequency m and performing
digital Fourier transform, and the variable m represents the frequency. Also, Y (m) is obtained by
discretizing the output signal y (t) and expressing it by digital Fourier transform. H1 (m) is the
transfer function of the distortion-free horn speaker system 52, and H2 (m1, m2) is the transfer
function of the distortion system 53 representing second-order distortion of the horn speaker.
Here, the given frequency m is decomposed into a sum and a difference of arbitrary frequencies,
and the values are made m1 and m2. Therefore, m = m1 + m2 or m = ¦ m1-m2 ¦. Also, the second
term of this equation is the sum of all combinations that satisfy m = m1 + m2 or ¦ m1-m2 ¦.
[0005]
The first term of the equation (5) represents a linear output signal component according to the
transfer function H1 of the horn speaker with respect to the input signal X (m) of frequency m.
The second term of the equation (5) is generated by the input signal X (m1) of the frequency m1
and the input signal X (m2) of the frequency m2, and indicates a non-linear output signal
component by the transfer function H2. This term represents second harmonic distortion and
intermodulation distortion that occur due to an overload on air in the horn and in the
compression driver.
[0006]
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2
Here, second-order harmonic distortion refers to an output signal component of frequency 2 *
m1 for an input signal of frequency m1 and an output signal component of frequency 2 * m2 for
an input signal of frequency m2. The intermodulation distortion is an output signal component of
frequency (m1 + m2) and an output signal component of frequency ¦ m1-m2 ¦ with respect to
input signals of frequencies m1 and m2.
[0007]
In the conventional horn speaker system, in order to reduce the distortion caused by an overload
to air in the horn and in the compression driver, the mass of the diaphragm, the cross sectional
area of the diaphragm, the cross sectional area of the throat of the horn, the spread of the horn A
method has been adopted in which the shape or the like is designed in accordance with an
allowable distortion amount and a target efficiency.
[0008]
However, in the above-mentioned conventional horn speaker system, the shape and the material
of the horn and the diaphragm are restricted depending on the allowable distortion amount.
For this reason, there remains a problem that it is not possible to design a horn speaker system
that satisfies desired acoustic characteristics and shape.
[0009]
The present invention has been made in view of such conventional problems, and it is an object
of the present invention to provide a horn speaker system capable of eliminating sound
distortion caused by an overload on air in a horn or in a compression driver. With the goal.
[0010]
The invention according to claim 1 of the present application is a horn speaker system in which a
distortion removing device is connected to a signal input portion of a horn speaker, and the
distortion removing device converts an analog audio signal into a digital signal. A / D converter, a
first filter that performs one-dimensional convolution on the output signal of the A / D converter,
and two-dimensional convolution on the output signal of the A / D converter A second filter, an
adder for adding an output signal of the first filter and an output signal of the second filter, and a
D / A converter for converting the output signal of the adder into an analog signal and giving it
to a ho speaker And is characterized by comprising.
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3
[0011]
The invention of claim 2 of the present application is a horn speaker system in which a distortion
removal device is connected to a signal input unit of a horn speaker, the distortion removal
device converting the analog audio signal into digital, and A A second filter for performing a twodimensional convolution operation on the output signal of the / D converter, an adder for adding
the output signal of the A / D converter and the output signal of the second filter, and And D / A
converter for converting an output signal into an analog signal and supplying it to a horn
speaker.
[0012]
The invention according to claim 3 of the present application is a horn speaker system in which a
distortion removing device is connected to a signal input unit of a horn speaker, the distortion
removing device converting A / D converter for converting analog audio signals into digital A low
band limit filter for blocking components below a specific frequency among output signals of the
I / D converter, a first filter for performing a one-dimensional convolution operation on an output
signal of the low band limit filter, and a low band A second filter that performs a two-dimensional
convolution operation on the output signal of the limiting filter, an adder that adds the output
signal of the first filter and the output signal of the second filter, and an output signal of the
adder And D / A converter for converting into an analog signal and supplying it to a horn
speaker.
[0013]
The invention according to claim 4 of the present application is a horn speaker system in which a
distortion removing device is connected to a signal input unit of the horn speaker, and the horn
speaker has a temperature sensor for detecting the temperature of air in the compression driver
or in the horn. The distortion removing device comprises an A / D converter for converting an
analog voice signal into a digital form, a first filter for performing a one-dimensional convolution
operation on an output signal of the A / D converter, and A / D converter. A second filter that
performs a two-dimensional convolution operation on the output signal of the D converter, a
temperature measurement device that outputs a temperature signal when the output of the
temperature sensor changes, a first filter, and a second filter A storage device for storing a
plurality of sets of filter tap coefficients, and a filter of a first filter and a second filter stored in
the storage device based on a temperature signal of a temperature measuring device An updating
device for selecting the up coefficients and updating the filter tap coefficients of the first filter
and the second filter; and an adder for adding the output signal of the first filter and the output
signal of the second filter; And D / A converter for converting an output signal of the adder into
an analog signal and giving the same to a horn speaker.
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4
[0014]
The invention of claim 5 of the present application is a horn speaker system in which a distortion
removing device is connected to a signal input unit of the horn speaker, and the horn speaker
has a temperature sensor for detecting the temperature of air in the compression driver or in the
horn. The distortion removing device comprises an A / D converter for converting an analog
audio signal into a digital form, a second filter for performing a two-dimensional convolution
operation on an output signal of the A / D converter, and a temperature sensor A temperature
measurement device for outputting a temperature signal when the output of the second filter
changes, a storage device for storing a plurality of sets of filter tap coefficients of the second
filter, and a second stored in the storage device based on the temperature signal of the
temperature measurement device. An updating device for selecting the filter tap coefficients of
the filter and updating the filter tap coefficients of the second filter, the output signal of the A / D
converter and the second An adder for adding the output signal of the filter, and converts the
output signal of the adder into an analog signal, is characterized in that it comprises a and a D /
A converter to be supplied to the horn speaker.
[0015]
The invention of claim 6 of the present application is a horn speaker system in which a distortion
removing device is connected to a signal input unit of the horn speaker, and the horn speaker
has a temperature sensor for detecting the temperature of air in the compression driver or in the
horn. The distortion removing device comprises an A / D converter for converting an analog
voice signal into a digital signal, and a low band-limiting filter for blocking components of the
output signal of the A / D converter below a specific frequency. A first filter that performs a onedimensional convolution operation on the output signal of the low band-limiting filter, a second
filter that performs a two-dimensional convolution operation on the output signal of the low
band-limiting filter, and an output of the temperature sensor A temperature measuring device for
outputting a temperature signal when the value of the signal changes, and a storage device for
storing a plurality of sets of filter tap coefficients of the first filter and the second filter An update
device for selecting the filter tap coefficients of the first filter and the second filter stored in the
storage device based on the temperature signal of the temperature measuring device, and
updating the filter tap coefficients of the first filter and the second filter , An adder for adding the
output signal of the first filter and the output signal of the second filter, and a D / A converter for
converting the output signal of the adder into an analog signal and providing it to the horn
speaker It is characterized by doing.
[0016]
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5
The electroacoustic transducing characteristic of a horn speaker is generally expressed as a
parallel connection of a distortion-free transfer function and a transfer function representing
second-order distortion.
Therefore, in order to electrically cancel out this second-order distortion, a distortion removing
device is connected to the signal input portion of the horn speaker.
[0017]
According to the first and second aspects of the invention, in the distortion removal apparatus,
when an analog audio signal is input, the A / D converter converts the analog audio signal into a
digital signal for digital Fourier transform.
The first filter performs a one-dimensional convolution operation on the output signal of the A /
D converter, and the second filter performs a two-dimensional convolution operation.
These convolution operations are converted into an audio signal that cancels out second-order
distortion components.
When the output signals of the first and second filters are added by an adder, and this signal is
converted into an analog signal by a D / A converter and applied to a ho speaker, overload on air
in the horn or in the compression driver Because of the distortion that occurs.
Thus, the audio signal output from the signal source is reproduced with high fidelity.
[0018]
According to the invention of claims 4 to 6, a temperature sensor is attached to the inside of the
horn speaker, and when the horn speaker is driven at a high input, the temperature of air in the
compression driver or in the horn is detected.
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The temperature measuring device provides a temperature signal to the updating device
according to the temperature detected by the temperature sensor.
The updating device selects the first and second filters stored in the storage device and updates
the first and second filter tap coefficients. As a result, even if the internal temperature of the horn
speaker rises and the transfer function changes, an audio signal that cancels out the secondorder distortion component is stably generated.
[0019]
According to the invention of claim 3, by providing a low band limit filter at the output of the A /
D converter, components of the input audio signal below a specific frequency are cut off.
Therefore, the distortion removing device can also function as a channel divider, and damage to
the horn speaker due to low frequency and large amplitude driving can be protected.
[0020]
Embodiment 1 A horn speaker system according to a first embodiment of the present invention
will be described with reference to FIG. FIG. 1 is a block diagram schematically showing the
configuration of the horn speaker system of the first embodiment. As shown in the figure, the
horn speaker system includes the distortion removing device 10 and the horn speaker 16.
[0021]
The distortion removing device 10 is a signal processing device that simultaneously performs a
one-dimensional convolution operation and a two-dimensional convolution operation and
provides an output signal z (t) to the horn speaker 16 when the input signal x (t) is input. . The
distortion removing device 10 is configured by an A / D converter 11, a first filter 12, a second
filter 13, an adder 14, and a D / A converter 15.
[0022]
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The first filter 12 is a digital filter that performs a one-dimensional convolution operation of the
voice signal digitally converted by the A / D converter 11 with a transfer function G1, and uses a
frequency m as a parameter. Similarly, the second filter 13 is a digital filter that performs a twodimensional convolution operation of the voice signal digitally converted by the A / D converter
11 with the transfer function G2, and has frequencies mi and mj (where m = mi + mj or m). Let
the combination) which becomes = ¦ mi-mj ¦ be a parameter. These filters are composed of, for
example, an FIR filter with N × N taps. The adder 14 adds the outputs of the filters 12 and 13
and the output is given to the horn speaker 16 through the D / A converter 15.
[0023]
The horn speaker 16 is a speaker that outputs an output signal y (t) as a sound pressure signal
when an audio signal z (t) is input, and as in the conventional example, a system of transfer
function H1 without distortion of the horn speaker 17 and the system 18 of the transfer function
H2 representing the second-order distortion of the horn speaker can be equivalently expressed
as the addition by the adder 19.
[0024]
First, the input / output characteristics of the horn speaker 16 will be described.
When the signal z (t) is input to the horn speaker 16, the output signal y (t) can be expressed as
equation (6). Here, Z (m) is a digital Fourier transform of z (t), and Y (m) is a digital Fourier
transform of y (t). H1 (m) represents the transfer function of the system 17 of the horn speaker
16, and H2 (m1, m2) represents the distortion generated in the horn, which is the transfer
function of the system 18. Also, the second term of this equation is the sum of all combinations
that satisfy m = m1 + m2 or ¦ m1-m2 ¦.
[0025]
When the frequency m is decomposed into the sum of the arbitrary frequencies or the difference
of the frequencies, the values are m1 and m2. In this case, m = m1 + m2 or m = ¦ m1-m2 ¦. The
first term of equation (6) represents the linear output signal component of the horn speaker for
the input signal Z (m) of frequency m. The second term of the equation (6) indicates the
nonlinear output signal component of the horn speaker with respect to the input signals Z (m1)
02-05-2019
8
and Z (m2). This second term represents the second-order distortion that occurs due to an
overload on the air in the horn and in the compression driver. An object of the present invention
is to remove distortion of the output signal of the horn speaker according to the second term of
the equation (6).
[0026]
Here, the operation of the distortion removing device 10 will be described. In the distortion
removal apparatus 10, when the input signal x (t) is input to the A / D converter 11, it is
converted into a digital signal. The output signal of the A / D converter 11 is input to the first
filter 12, and a one-dimensional convolution operation is performed by the transfer function G1.
At the same time, the second filter 13 performs a two-dimensional convolution operation with
the transfer function G2. The output signal of the first filter 12 and the output signal of the
second filter 13 are input to the adder 14 and added. Then, the output signal of the adder 14 is
input to the D / A converter 15 and converted again into an analog audio signal. This audio
signal is input to the horn speaker 16 as a signal z (t).
[0027]
Next, the relationship between the input signal x (t) and the output signal z (t) of the distortion
removal apparatus 10 is expressed in the form of digital Fourier transform in equation (7). In
equation (7), X (m) represents the input signal x (t) at a frequency m and is digital Fourier
transformed. Z (m) is a digital Fourier transform obtained by discretizing the output signal z (t).
The first term of the equation (7) is a component of the output signal z (t) by the first filter 12,
and the second term is a component of the output signal z (t) by the second filter 13. . The
addition symbol of the equation (7) indicates the operation of the adder 14. Also, the second term
of this equation is the sum of all combinations that satisfy m = m1 + m2 or ¦ m1-m2 ¦.
[0028]
Next, the transfer function G1 of the first filter 12 and the transfer function G2 of the second
filter 13 will be described using formulas. As described above, since the input / output relation of
the distortion removing device 10 is expressed by the equation (7), and the input / output
relation of the horn speaker 16 is expressed by the equation (6), Z (m) of the equation (7) can be
obtained. Substituting for Z (m) of the equation (6), the following equation (8) is obtained.
02-05-2019
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[0029]
In the equation (8), the first term of the right side of the output signal Y (m) indicates that the
input signal X (m) passes through the first filter 12 of the distortion removing device 10 and is
transmitted to the horn speaker 16 It is a component that has passed through the system 17
having the function H1. The second term is a component in which the input signals X (m1) and X
(m2) pass through the second filter 13 of the distortion removing device 10 and pass through
the system 17 having the transfer function H1 of the horn speaker 16. The third term is a
component in which the input signals X (m1) and X (m2) pass through the first filter 12 of the
distortion removing device 10 and pass through the system 18 having the transfer function H2
of the horn speaker 16. The fourth term is a system in which the input signals X (m3), X (m4), X
(m5), X (m6) pass through the second filter 13 of the distortion removing device 10 and have the
transfer function H2 of the horn speaker 16 It is an ingredient that passed through 18. The
second and third terms are the sum of all combinations that satisfy m = m1 + m2 or ¦ m1-m2 ¦,
and the fourth term is m1 = m3 + m4 or ¦ m3-m4 ¦, m2 = m5 + m6 or ¦ m5 It is the sum of all
combinations that satisfy -m6.
[0030]
Here, since the fourth term of the equation (8) is a minute signal, if neglected, the equation (8) is
rearranged as the equation (9). The second term is the sum of all combinations that satisfy m =
m1 + m2 or ¦ m1-m2 ¦.
[0031]
In order for the horn speaker system to realize high-fidelity reproduction, X (m) obtained by
digital Fourier transforming the input signal and Y (m) obtained by digital Fourier transforming
the output signal are equal as shown in equation (10). Just do it. Therefore, according to the
equations (9) and (10), when both the equations (1) and (2) hold, the equation (10) is satisfied.
[0032]
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10
When a one-dimensional convolution operation is performed with the transfer characteristic G1
determined as described above and a two-dimensional convolution operation is performed with
the transfer characteristic G2, air overload in the horn of the horn speaker 16 or in the
compression driver is obtained. Distortion of the sound pressure signal due to In this way, the
input / output signal of the horn speaker system is greatly improved, and high fidelity
reproduction of sound becomes possible not only when the output sound pressure is low but also
when the output sound pressure is high.
[0033]
Second Embodiment Next, a horn speaker system according to a second embodiment of the
present invention will be described with reference to FIG. FIG. 2 is a block diagram schematically
showing the configuration of the horn speaker system of the second embodiment. As shown in
the figure, the horn speaker system is configured to include the distortion removing device 20
and the horn speaker 26. Detailed descriptions of blocks and signals having the same names as in
the first embodiment will be omitted.
[0034]
The difference between this embodiment and the first embodiment is that the distortion
removing device 20 is not provided with a first filter for performing a one-dimensional
convolution operation, and is made through. The adder 24 adds the output signal of the A / D
converter 21 and the signal of the second filter 23 having the transfer characteristic G2. The
signal added here is converted to an analog audio signal by the D / A converter 25 and output to
the horn speaker 26.
[0035]
The horn speaker 26 has a system 27 of a transfer function H1 of a horn speaker without
distortion, a system 28 of a transfer function H2 representing a second-order distortion of the
horn speaker, and two systems 27 and 28 as in the prior art. It can be expressed as an addition
at 29.
[0036]
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11
In the present embodiment, the fact that one of the output signals of the A / D converter 21 is
directly input to the adder 24 means that the transfer function G1 of the first filter in the first
embodiment satisfies the equation (3). It is an assumption.
Here, when equation (3) is substituted into equation (2), equation (4) is obtained. Thus, the
transfer function G2 of the two-dimensional convolution operation in the second filter 23 of the
distortion removing device 20 is determined.
[0037]
In the second embodiment, establishing equation (2) means that only the distortion component
of the horn speaker 26 is removed without correcting the basic characteristics of the horn
speaker 26. Therefore, by providing the distortion removing device 20 of the present
embodiment at the front stage of the existing horn speaker 26, only the distortion component
can be removed without changing the basic characteristics of the conventional horn speaker.
[0038]
(Third Embodiment) Next, a horn speaker system according to a third embodiment of the present
invention will be described with reference to FIG. FIG. 3 is a block diagram schematically showing
the configuration of the horn speaker system of the third embodiment. As shown in the figure,
the horn speaker system is configured to include the distortion removing device 30 and the horn
speaker 36. Detailed descriptions of blocks and signals having the same names as in the first
embodiment will be omitted.
[0039]
The difference between this embodiment and the first embodiment is that the output of the A / D
converter 31 is given to the first filter 32 and the second filter 33 through the high pass filter
310. The high pass filter 310 is a low band limit filter of the transfer function F1, and its cutoff
frequency is higher than the cutoff frequency on the lower side of the reproduction band of the
horn speaker 36.
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12
[0040]
The horn speaker 36 is obtained by adding the system 37 of the transfer function H1 without
distortion of the horn speaker, the system 38 of the transfer function H2 representing the
secondary distortion of the horn speaker, and the two systems 37 and 38 by the adder 39 It can
be expressed as
[0041]
The input signal x (t) of the horn speaker system is input to the A / D converter 31 and converted
into a digital signal.
When this signal is input to the high pass filter 310, a signal equal to or lower than the cutoff
frequency of the horn speaker itself is blocked for the horn speaker 36. The output signal of the
high pass filter 310 is input to the first filter 32 of the transfer function G1 and the second filter
33 of the transfer function G2, and is added by the adder. Then, the output signal of the adder 34
is converted into an analog audio signal by the D / A converter 35 and is given to the horn
speaker 36.
[0042]
Similar to the first embodiment, the relationship between the input signal X (m) and the output
signal Y (m) of the horn speaker system is derived as shown in equation (11). Here, the second
term is the sum of all combinations that satisfy m = m1 + m2 or ¦ m1-m2 ¦. It is needless to say
that in order to realize high fidelity reproduction, the transfer function G1 of the first filter 32 is
expressed by equation (1), and the transfer function G2 of the second filter 33 is expressed by
equation (2).
[0043]
In this case, by providing the distortion removing device 30 in front of the horn speaker 36, a
channel divider is not required for the horn speaker 36. The high pass filter 310 may be a band
pass filter. In this case, the cutoff frequency on the low band side of the band pass filter is higher
than the cutoff frequency on the low band side of the reproduction band of the horn speaker 36.
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[0044]
In the present embodiment, by providing the high pass filter 310, the distortion removing device
30 can also function as a channel divider, and the horn speaker 36 can be protected. Also, since
the distortion removing device 30 can remove the secondary distortion of the horn speaker 36,
high fidelity reproduction is possible.
[0045]
(Embodiment 4) Next, a horn speaker system according to a fourth embodiment of the present
invention will be described with reference to FIG. FIG. 4 is a block diagram schematically showing
the configuration of the horn speaker system of the fourth embodiment. As shown in the figure,
the horn speaker system is configured to include the distortion removing device 40 and the horn
speaker 46. Detailed descriptions of blocks and signals having the same names as in the first
embodiment will be omitted.
[0046]
The present embodiment differs from the first embodiment in that the horn speaker 46 is
provided with a temperature sensor 404 for measuring the temperature of air in the horn and in
the compression driver, and the distortion removing device 40 has a signal from the temperature
sensor 404. Thus, the temperature measuring device 403 for measuring the temperature rise in
the horn speaker 46, and the updating device 401 and the storage device 402 for updating the
values of the transfer functions G1 and G2 based on the measured temperature are provided.
[0047]
The distortion removing device 40 is provided with the first filter 42 of the transfer function G1,
the second filter 43 of the transfer function G2, the adder 44, and the D / A converter 45 in the
same manner as in the first embodiment. It is.
The storage unit 402 is a memory for storing several types of filter tap coefficients
corresponding to the transfer functions of the systems 47 and 48 of the horn speaker 46 at
different temperatures. The updating device 401 reads out the filter tap coefficients of the first
02-05-2019
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filter 42 and the second filter 43 stored in the storage device 402 based on the measured
temperature, respectively, and the updating device 401 of the first filter 42 and the second filter
43 The filter tap coefficient is updated.
[0048]
The horn speaker 46 includes a system 47 of a distortion-free transfer function H1 of the horn
speaker, a system 48 of a transfer function H2 representing a second-order distortion of the horn
speaker, and two systems 47 and 48 as in the conventional example. It can be expressed as an
addition at 49.
[0049]
When the horn speaker is used, the temperature of air in the horn and in the compression driver
changes with time, and the distortion of the horn speaker 46 changes accordingly.
If the first filter 42 and the second filter 43 perform signal conversion using the filter tap
coefficients determined previously as the temperature change amount increases, there is a
problem that the effect of distortion removal decreases. The
[0050]
On the other hand, in the first embodiment, once the filter tap coefficients of the first filter and
the second filter have been determined, their values can not be changed. Therefore, in this
embodiment, a plurality of sets of filter tap coefficients of the first filter 42 and filter tap
coefficients of the second filter 43 corresponding to several kinds of temperatures in the horn
and in the compression driver are stored in advance. .
[0051]
The temperature sensor 404 and the temperature measuring device 403 measure the
temperature in the compression driver or in the horn at regular intervals, and give the result to
the updating device 401. The updating device 401 selects a filter tap coefficient that is adapted
to the temperature closest to the measured temperature from among the plurality of sets of filter
02-05-2019
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tap coefficients stored in the storage device 402, and selects the first filter 42 and the second
filter 43. Update the filter tap coefficients of As a result, even if the temperature in the
compression driver or in the horn changes while using the horn speaker 46, it is possible to
remove the secondary distortion of the horn speaker 46.
[0052]
Note that the temperature measuring device 403 does not measure the temperature every fixed
time and send the measured temperature to the updating device 401, but the difference between
the temperature at a certain time when the filter tap coefficient was updated immediately before
and the current temperature is The method may be such that the measured temperature is sent
to the updating device 401 and the filter tap coefficient is updated when it becomes larger than a
certain amount. Furthermore, such temperature sensor, temperature measuring device, and
updating device can be attached to the horn speaker system shown in FIGS. 2 and 3 to perform
temperature compensation of the transfer function.
[0053]
As described above, according to the present invention, the input signal can be reproduced with
high fidelity by providing the distortion removing device at the front stage of the horn speaker.
Therefore, the system is driven with high power, and harmonic distortion and intermodulation
distortion do not occur even when the output sound pressure is high, and the sound quality can
be significantly improved.
[0054]
Further, by providing a temperature sensor inside the horn speaker and providing a temperature
signal detected by the temperature measurement device to the update device, the transfer
functions of the first and second filters can be set to be optimum. . Therefore, the horn speaker is
driven at a high input, and even if the temperature rises with the passage of time, harmonic
distortion and intermodulation distortion do not occur.
[0055]
Brief description of the drawings
02-05-2019
16
[0056]
1 is a block diagram showing a basic configuration of the horn speaker system in the first
embodiment.
[0057]
2 is a block diagram showing the basic configuration of the horn speaker system in the second
embodiment.
[0058]
<Figure 3> It is the block diagram which shows the basic constitution of the horn speaker system
in 3rd execution example.
[0059]
<Figure 4> It is the block diagram which shows the basic constitution of the horn speaker system
in 4th execution example.
[0060]
5 is a block diagram showing an equivalent circuit of the conventional horn speaker system.
[0061]
Explanation of sign
[0062]
10, 20, 30, 40 distortion removing device 11, 21, 31, 41 A / D converter 12, 32, 42 first filter
13, 23, 33, 43 second filter 14, 19, 24, 29, first filter 34, 39, 44, 49 Adder 15, 25, 35, 45 D / A
converter 16, 26, 36, 46 Horn speaker 17, 18, 27, 28, 37, 38, 47, 48 system 310 high pass filter
402 Storage device 403 Temperature measurement device 404 Temperature sensor
02-05-2019
17
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