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JP2013135238

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DESCRIPTION JP2013135238
PROBLEM TO BE SOLVED: To provide a channel divider capable of appropriately setting a
crossover frequency when using a multi-way speaker system capable of bi-wiring connection
including a network circuit. SOLUTION: A channel divider divides a voice signal into a first output
signal on the bass side and a second output signal on the high side and outputs the low pass
filter LPF and the high pass filter HPF, respectively. When specifying an arbitrary crossover
frequency fc0 defining a band division, including a control circuit for controlling these, the
control circuit sets the cutoff frequency fcL of the LPF to about 1/6 to 1 octave more than fc0.
An audio output mode in which the HPF cut-off frequency fcH is set to be approximately high,
and is set about 1/6 to 1 octave lower than fc0, and the first output signal and the second output
signal including both frequency bands fcL-fcH are output. Have. [Selected figure] Figure 1
Channel divider, audio reproduction system including the same, and method of setting crossover
frequency of channel divider
[0001]
The present invention relates to a channel divider for use in audio signal reproduction by a multiway speaker system and a method for setting the crossover frequency thereof, particularly when
using a speaker system capable of bi-wiring connection including a network circuit. The present
invention relates to a channel divider capable of setting a crossover frequency of the channel
divider to enable good sound reproduction.
[0002]
09-05-2019
1
In multi-way speaker systems that include a woofer for low range playback and a tweeter for
high range playback, it is common to include a network circuit that divides the audio signal
amplified by the amplifier according to the playback frequency range of each speaker unit. It is.
In recent years, a speaker system compatible with bi-wiring connection has been widely used, in
which a network circuit corresponding to the woofer and a network circuit corresponding to the
tweeter can be independent, respectively, and provided with input terminals connected to each
Abbreviated as ring SS). In the bi-wiring connection, bi-amplifier drive using a power amplifier
connected to the network circuit of the woofer and another power amplifier connected to the
network circuit of the tweeter is adopted.
[0003]
On the other hand, as a method of realizing multi-amplifier (bi-amplifier) driving without using
the network circuit of the speaker system, there is a case where a channel divider is provided in
front of the power amplifier and the audio signal is band divided by this channel divider. In the
audio reproduction system of the multi-amplifier multi-way speaker system as described above,
the channel divider divides the input audio signal into at least a low band output signal and a
high band output signal and outputs it to the multi amplifier Do. By using a channel divider, it is
possible to set an LPF (low-pass filter) or HPF (high-pass filter) having a steeper transition band
than the speaker system network, and to set the crossover frequency relatively freely, etc. (For
example, Patent Document 1). Also, when a channel divider is adopted, the amplifier circuit for
the low band and the amplifier circuit for the high band are independent, so the intermodulation
distortion generated by superposing the low sound component and the high sound component is
reduced, and the reproduction sound quality Is said to have the advantage of being superior.
[0004]
In recent years, there have been attempts to provide a DSP with a channel divider function so
that a speaker system not equipped with a network circuit can be connected using an AV receiver
including a DSP and a multi-amplifier, etc. 3). When the channel divider is realized by a digital
filter, it may be by an FIR filter or an IIR filter. In order to use a channel divider, it is necessary to
set the crossover frequency appropriately by measuring the reproduction band of each speaker
unit of the speaker system using a microphone or the like (Patent Document 4 and Patent
Document 5).
09-05-2019
2
[0005]
In some conventional channel dividers, when a crossover frequency is set between the woofer
and the tweeter, this is automatically applied to the cutoff frequency of the low-pass LPF and the
high-pass HPF. Of course, there are also channel dividers that can independently set the cutoff
frequency of the low-pass LPF and the cutoff frequency of the high-pass HPF. However, in use
conditions that do not use network circuits, the bands that can be reproduced by the woofer and
the tweeter often overlap, so the cutoff frequency of the filter that is in charge of these adjacent
frequency bands is in the overlapping band. It is often set to the same set value of frequency.
[0006]
However, even if it is going to adopt a channel divider as an audio reproduction system, for
general users except for a part, configure a speaker system which omits a network circuit
(remodeling a commercial product, making only with a unit, etc.). And setting an appropriate
crossover frequency using a microphone has the problem of high hurdles, and in a home audio
device such as an AV receiver, a bi-amplifier drive using a multi-channel amplifier circuit is
necessary. Even if possible, the function of the channel divider is hardly adopted.
[0007]
On the other hand, there is a problem that setting of the crossover frequency is difficult in
practice when attempting to realize bi-amplifier driving using a bi-wiring SS including a widely
spread network circuit and a channel divider. Since the bi-wiring SS is designed to obtain
predetermined flat synthesis characteristics including the network circuit, if the crossover
frequency is set and banded before the multi-channel amplifier circuit by the channel divider, As
a result, dips may occur on the sound pressure frequency characteristics. If the crossover
frequency set by the channel divider deviates from the crossover frequency of the bi-wiring SS,
the dip on the sound pressure frequency characteristic becomes considerably large, and there is
a problem that the band which is not properly reproduced becomes wide. Also, without
microphones and measuring instruments such as level meters and FFT analyzers, it is difficult for
general users to know the unknown crossover frequency of bi-wiring SS, and for general users,
the crossover frequency in channel dividers May be difficult to set.
09-05-2019
3
[0008]
JP, 2005-109969, A JP, 2002-111399, A JP, 2005-184149, A Patent No. 4321315 Japanese
Utility Model Application Publication No. 5-39097
[0009]
The present invention has been made to solve the above-mentioned problems of the prior art,
and its object is to set a channel divider for use in audio signal reproduction by a multi-way
speaker system and a crossover frequency of the channel divider. In particular, it is an object of
the present invention to provide a channel divider capable of appropriately setting the crossover
frequency of the channel divider when using a bi-wiring connectable speaker system including a
network circuit.
[0010]
The channel divider of the present invention divides the input audio signal into at least a first
output signal on the high frequency band side and a second output signal on the high frequency
band side of the first output signal, and outputs the first output terminal. And a low pass filter
LPF and a high pass filter HPF that are output to the second output terminal, and a control circuit
that controls these, and specify an arbitrary crossover frequency fc0 that defines band division If
so, the control circuit sets the cutoff frequency fcL of the low pass filter LPF higher by about 1/6
to 1 octave than the crossover frequency fc0, and the cutoff frequency fcH of the high pass filter
HPF is crossover It is set to be about 1/6 to 1 octave lower than the frequency fc0, and is the
first output that includes both the frequency bands fcL-fcH. An audio output mode for outputting
a signal and a second output signal to a first output terminal and a second output terminal,
respectively.
[0011]
Preferably, the channel divider of the present invention further includes a test signal generation
circuit generating a test signal including a predetermined band, and the test signal is formed by
connecting a low pass filter LPF and a high pass filter HPF in series. A band pass filter BPF is
passed, and an output signal of the narrow band pass filter BPF is output only from the first
output terminal, or output only from the second output terminal, or the output signal of the first
output terminal and the second output terminal It has a test signal output mode in which the
control circuit switches so as to output from both.
[0012]
In addition, preferably, the channel divider of the present invention comprises a level adjustment
circuit in which the low pass filter LPF and the high pass filter HPF perform level adjustment of
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the first output signal or the second output signal; The phase inversion circuit that inverts the
phase of the two output signals and the delay circuit that adjusts the delay time of the first
output signal or the second output signal are included.
[0013]
In addition, preferably, the channel divider of the present invention further includes a
microphone for converting voice into an audio signal and inputting it as a measurement signal to
the control circuit, and a display circuit for displaying the level of the measurement signal from
the microphone In the signal output mode, a test signal which is an output of the narrow band
pass filter BPF is measured when outputting from only the first output terminal, and measures
when outputting from only the second output terminal. The control circuit compares the
measured level with a display indicating that the display circuit changes or holds the crossover
frequency fc0, or the control circuit changes or holds the crossover frequency fc0. Set.
[0014]
Also preferably, in the test signal output mode, the channel divider of the present invention
measures the third output signal when the test signal output from the narrow band pass filter
BPF is output from both the first output terminal and the second output terminal. The control
circuit compares the measurement level, the first measurement level, and the second
measurement level, and if the third measurement level is lower than the first measurement level
or the second measurement level, the display circuit Provides an indication to change to the
reverse phase connection, or the control circuit performs phase inversion of the first output
signal or the second output signal.
[0015]
In addition, preferably, in the audio output mode, the channel divider of the present invention
outputs only the first output signal from the first output terminal or outputs only the second
output signal from the second output terminal. In addition,
[0016]
In addition, preferably, the channel divider of the present invention is configured such that the
input audio signal is a third output signal on the bass side of the first output signal and / or a
fourth output signal on the treble side of the second output signal. The above-mentioned channel
divider which performs band division into output signals and further outputs them to the third
output terminal and / or the fourth output terminal, respectively, wherein the low pass filter LPF
and the high pass filter HPF are respectively connected in series A band pass filter BPF is
configured in combination with another high pass filter HPF or another low pass filter LPF to be
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output to the first output terminal or the second output terminal, respectively.
[0017]
In addition, the sound reproduction system according to the present invention includes at least
the above-mentioned channel divider, an amplifier including an amplification circuit
corresponding to each output terminal of the channel divider, and at least a woofer and a tweeter
and corresponding network circuits. And a speaker system capable of bi-wiring connection.
[0018]
Further, in the method of setting the crossover frequency of the channel divider of the present
invention, at least the first output signal on the bass side and the second output signal on the
treble side of the first output signal are input. A channel divider including a low pass filter LPF
and a high pass filter HPF which are divided into bands and output to the first output terminal
and the second output terminal respectively, and an amplifier including an amplifier circuit
corresponding to each output terminal of the channel divider And an audio reproduction system
including at least a woofer and a tweeter and a corresponding network circuit, and an amplifier
and a speaker system capable of bi-wiring connection, the woofer and tweeter set in the network
circuit of the speaker system Crossover between A method of detecting a wave number fc and
setting a crossover frequency fc0 of a channel divider, specifying an arbitrary crossover
frequency fc0 defining a band division of the channel divider, and a cutoff frequency of a low
pass filter LPF The step of setting fcL higher by about 1/6 to 1 octave than the crossover
frequency fc0 and the cut-off frequency fcH of the high-pass filter HPF is set lower by about 1/6
to 1 octave than the crossover frequency fc0 Step of serially connecting low pass filter LPF and
high pass filter HPF to constitute narrow band pass filter BPF, generating test signal including a
predetermined band and passing it through narrow band pass filter BPF And the narrow band
pass filter BPF Switching the output signal output from only the first output terminal, or from
only the second output terminal, or from both of the first output terminal and the second output
terminal. .
[0019]
Hereinafter, the operation of the present invention will be described.
[0020]
The channel divider of the present invention divides the input audio signal into at least a first
output signal on the high frequency band side and a second output signal on the high frequency
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6
band side of the first output signal, and outputs the first output terminal. And a low pass filter
LPF and a high pass filter HPF that are output to the second output terminal, and a control circuit
that controls these filters and the overall operation.
The channel divider includes at least an amplifier including an amplification circuit
corresponding to each output terminal of the channel divider, and at least a woofer and a
tweeter, and a corresponding network circuit, and a speaker system capable of bi-wiring
connection with the amplifier. To construct a sound reproduction system.
Therefore, since the user can adjust the channel divider and change the frequency band in which
the woofer and the tweeter are reproduced in duplicate and the reproduction level thereof, there
is an advantage that it is easy to adjust the reproduction sound quality.
The network circuit of the bi-wiring SS is ± 6 to 18 dB / Oct.
The channel divider LPF and HPF are ± 24 to 96 dB / Oct.
The above is also possible, and by introducing a channel divider, the attenuation factor of the
transition zone and the stop zone can be increased.
[0021]
When the channel divider of the present invention designates an arbitrary crossover frequency
fc0 which defines band division, the cutoff frequency fcL of the low pass filter LPF is higher by
about 1/6 to 1 octave than the crossover frequency fc0. The first output signal and the second
output signal including both of the frequency bands fcL-fcH are set, and the cutoff frequency fcH
of the high pass filter HPF is set lower than the crossover frequency fc0 by about 1/6 to 1
octave. It has an audio output mode for outputting to the first output terminal and the second
output terminal.
That is, in the audio output mode of this channel divider, when using bi-wiring SS including a
network circuit, the user designates a crossover frequency fc0 close to the crossover frequency fc
between the woofer and tweeter set in the network circuit. Then, the low pass filter LPF outputs a
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signal of a frequency band lower than the cutoff frequency fcL which is about 1/6 to 1 octave
higher than the crossover frequency fc0, and the high pass filter HPF outputs the signal at the
crossover frequency fc0. Also, a signal of a frequency band higher than the cutoff frequency fcH
which is as low as about 1/6 to 1 octave is output.
Therefore, audio signals in the 2/6 to 2 octave range including the crossover frequency fc0 as
the center frequency overlap (overlap), and the first output from the low pass filter LPF and the
high pass filter HPF, respectively. It is output as a signal and a second output signal.
[0022]
As a result, even if the channel divider of the present invention is operated using bi-wiring SS
including a network circuit, it is possible to prevent dips in the sound pressure frequency
characteristics.
That is, even if the crossover frequency set by the channel divider deviates somewhat from the
crossover frequency of the bi-wiring SS, the first output signal which is the output of the low pass
filter LPF and the output of the high pass filter HPF This is because each second output signal
includes an audio signal in the 2/6 to 2 octave range including the crossover frequency as the
center frequency.
Since the bi-wiring SS is adjusted so as to obtain predetermined flat synthesis characteristics
including the network circuit, there is a possibility that a dip may occur on the sound pressure
frequency characteristics even if the channel divider of the present invention is operated. There
is an advantage that
On the other hand, by setting the transition region characteristic steeper than that of the biwiring SS network circuit by the channel divider, the attenuation factor of the transition region
and the stop region becomes large. Even when used, channel dividers can be introduced to adjust
the playback sound quality.
[0023]
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8
The channel divider includes a level adjustment circuit in which the low pass filter LPF and the
high pass filter HPF perform level adjustment of the first output signal or the second output
signal, and phase inversion of the first output signal or the second output signal. And the delay
circuit for adjusting the delay time of the first output signal or the second output signal may be
included, respectively, and the range for adjusting the reproduction sound quality is expanded,
and the widely used bi-wiring SS Will be able to cope with
The channel divider further includes a band-specific audio output mode in which only the first
output signal is output from the first output terminal or only the second output signal is output
from the second output terminal in the audio output mode. May be
In the band-specific audio output mode, the user can adjust the reproduction sound quality while
confirming the difference between the sound reproduced from the woofer and the sound
reproduced from the tweeter.
[0024]
Further, the channel divider of the present invention preferably further comprises a test signal
generating circuit for generating a test signal including a predetermined band, and the low pass
filter LPF and the high pass filter HPF for setting the test signal as described above. The output
signal of the narrow band pass filter BPF is output from only the first output terminal, or is
output from only the second output terminal, or is passed through the narrow band pass filter
BPF configured in series connection, or the first output It has a test signal output mode switched
to output from both the terminal and the second output terminal. That is, even when the
crossover frequency set in the bi-wiring SS network circuit is unknown, the user generates a test
signal including a predetermined band and passes it to the narrow band pass filter BPF to obtain
a narrow band pass filter BPF. When switching is made to output the test signal output of only
the first output terminal, output only from the second output terminal, or output from both the
first output terminal and the second output terminal, the woofer The unknown crossover
frequency can be known by comparing the sound pressure level to be reproduced with the sound
pressure level to be reproduced from the tweeter.
[0025]
The reason is that the crossover frequency set by the channel divider means the center frequency
09-05-2019
9
of the narrow band pass filter BPF, and the center frequency of the narrow band pass filter BPF
substantially matches the crossover frequency of the network circuit. The limitation is that the
sound pressure level reproduced from the woofer almost matches the sound pressure level
reproduced from the tweeter. Therefore, by repeating the step of changing the crossover
frequency set by the channel divider, the unknown crossover frequency of the bi-wiring SS can
be known.
[0026]
When the channel divider includes a microphone that measures the reproduced sound of the test
signal that is the output of the narrow band pass filter BPF, the level of the measurement signal
from the microphone may be displayed by the display circuit. The control circuit compares the
first measurement level measured when outputting only from the first output terminal with the
second measurement level measured when outputting only from the second output terminal, and
the crossover frequency is displayed on the display circuit. An indication may be given that
suggests changing fc0, or an indication indicating that it should be kept. Alternatively, the
channel divider circuit may set or change the crossover frequency fc0.
[0027]
It should be noted that if the sound pressure level synthesized in the case of simultaneous
reproduction from the woofer and the tweeter is lower than the sound pressure level in each
case, it may also be in a reverse phase relationship in which the respective reproduced sound
waves cancel each other. It can be determined. That is, in the test signal output mode, the control
circuit measures the third measurement level measured when the test signal is output from both
the first output terminal and the second output terminal, the first measurement level, and the
second measurement level. If the third measurement level is lower than the first measurement
level or the second measurement level by a predetermined value or more in comparison, the
display circuit may perform display indicating that the connection is reversed. . Alternatively, the
control circuit may perform phase inversion of the first output signal or the second output signal.
[0028]
Also, the channel divider of the present invention is not limited to the one applied to 2-way bi-
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10
wiring SS including woofer and tweeter. The channel divider is configured to correspond to a 3-5
way multi-way speaker including a subwoofer and / or a midrange and / or a super tweeter, so
that the input audio signal is placed on the third side lower than the first output signal. Even if
the signal is divided into the output signal and / or the fourth output signal higher on the high
frequency side than the second output signal, and the signal is further output to the third output
terminal and / or the fourth output terminal, respectively. Good. A low pass filter LPF and a high
pass filter HPF corresponding to a woofer and tweeter in a 2-way bi-wiring SS band pass in
combination with another high pass filter HPF or other low pass filter LPF respectively connected
in series By configuring the filter BPF, it is possible to prevent dips in the sound pressure
frequency characteristics even if the channel divider is operated even if the bi-wiring SS including
the network circuit is a 3-way to 5-way multiway speaker. .
[0029]
The channel divider of the present invention can set the crossover frequency of the channel
divider appropriately, particularly when using a bi-wiring connectable speaker system including a
network circuit, and a dip occurs on the sound pressure frequency characteristic. There is no fear
and good voice reproduction can be enabled.
[0030]
It is a figure explaining the sound reproduction system containing amplifier device 1 by a
desirable embodiment of the present invention.
(Example 1) It is a graph explaining the sound pressure frequency characteristic of the speaker
system 8 which comprises the sound reproduction system by preferred embodiment of this
invention. (Example 1) It is a graph explaining the crossover characteristic (When the cutoff
frequency fcL of the low pass filter LPF and the cutoff frequency fcH of the high pass filter HPF
are set equal) of the channel divider 12 of the amplifier device 1 . (Example 1) Sound pressure
frequency characteristics of the speaker system 8 when the channel divider 12 of the amplifier
device 1 is used (the cutoff frequency fcL of the low pass filter LPF and the cutoff frequency fcH
of the high pass filter HPF are set equal Case) is a graph to explain. (Example 1) A graph for
explaining the crossover characteristics (when the cutoff frequency fcH of the high pass filter
HPF is set lower than the cutoff frequency fcL of the low pass filter LPF) by the channel divider
12 of the amplifier device 1 is there. (Example 1) Sound pressure frequency characteristics of the
speaker system 8 when the channel divider 12 of the amplifier device 1 is used (the cutoff
frequency fcH of the high pass filter HPF is lower than the cutoff frequency fcL of the low pass
filter LPF) (A case of setting) (Example 1) FIG. 6 is a diagram for explaining a filter configuration
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in a test signal output mode of the channel divider 12 of the amplifier device 1 according to a
preferred embodiment of the present invention. (Embodiment 2) FIG. 7 is a diagram for
explaining a display circuit 6 of an amplifier device 1 according to another preferred
embodiment of the present invention. (Embodiment 3) FIG. 7 is a flow chart for explaining the
operation of the channel divider 12 of the amplifier 1 according to a preferred embodiment of
the present invention in a test signal output mode. (Example 3)
[0031]
Hereinafter, a channel divider according to a preferred embodiment of the present invention, an
audio reproduction system including the same, and a method of setting a crossover frequency of
the channel divider will be described, but the present invention is not limited to these
embodiments.
[0032]
FIG. 1 is a diagram for explaining a sound reproduction system according to a preferred
embodiment of the present invention.
Specifically, the sound reproduction system includes an amplifier device 1 including a channel
divider, a speaker system 8 and a microphone 9 connected to the amplifier device 1, and FIG. 1 is
a block diagram showing an internal configuration of each. . 2, 4 and 6 are graphs for explaining
the sound pressure frequency characteristics of the speaker system 8, and FIGS. 3 and 5 are
graphs for explaining the crossover characteristics of the channel divider of the amplifier device
1. . In addition, illustration and description are abbreviate | omitted about the one part structure
unnecessary for description, an internal structure, etc. FIG.
[0033]
The sound reproduction system includes an amplifier device 1 and a speaker system 8 connected
to the amplifier device 1, converts digital signal data adata input to the amplifier device 1 into
stereo audio signals L and R, and the amplifier device 1 It is an audio reproduction system which
reproduces stereo sound by a speaker system 8 consisting of two speakers 8L and 8R after
amplification. The amplifier device 1 includes a DSP and a multi-amplifier, and is capable of
multi-amplifier connection operating a channel divider. Further, the speaker system 8 is a 2-way
bi-wiring SS including the woofer WO and the tweeter TW, and the amplifier device 1 is bi-wiring
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connected by a speaker cord. Therefore, the user who uses the amplifier device 1 can adjust the
channel divider and change the frequency band in which the woofer and the tweeter overlap to
reproduce and the reproduction level thereof, and can adjust the reproduction sound quality of
the speaker system 8 Become.
[0034]
The amplifier device 1 has a DSP (digital signal processor) 10 that processes digital signal data
adata, a D / A converter 2 that receives outputs of four channels of the DSP 10 and converts
them into analog signals, and analog signals of these And at least an amplifier circuit 3 for
amplifying and outputting to the speaker system 8. The stereo audio signals L and R may be
supplied to the DSP 10 via an A / D converter (not shown) as stereo signals (left signal L and
right signal R) supplied in analog. The amplifier device 1 includes a CPU 4 that is a control circuit
that controls the entire system, an operation unit 5 connected to the CPU 4 to receive an
instruction input from a user, a display circuit 6 including a display, and a microphone amplifier
circuit 7 to which a microphone 9 is connected. And. Specifically, the amplifier device 1 can be
configured by a DSP compatible with multi-channel audio, an AV receiver incorporating a multichannel amplifier circuit, and the like. The operation unit 5 includes an input device such as a
switch, a jog dial, or a remote control device. The display circuit 6 may be a built-in FL display, a
liquid crystal display or the like, or may be a display device connected to another. Of course, the
amplifier device 1 may be configured by another sound reproducing device including the DSP 10,
the D / A converter 2, the multichannel amplifier circuit 3, and the CPU 4 such as a
microcomputer. In addition, as described later, the microphone 9 connected to the microphone
terminal M of the amplifier device 1 may not necessarily be provided.
[0035]
The speaker system 8 is a 2-way bi-wiring SS including the woofer WO and the tweeter TW, and
includes a network circuit and an input terminal corresponding to each speaker unit. The woofer
WO for the bass range reproduction of the left speaker 8L and the right speaker 8R is connected
to the input terminal tL and the network circuit nL. Further, the tweeter TW for high range
reproduction is connected to the input terminal tH and the network circuit nH. The network
circuit nL, together with the woofer WO, constitutes a low pass filter LPF for passing a low
frequency band. Also, the network circuit nH, together with the tweeter TW, constitutes a high
pass filter HPF that passes the high range. The network circuits nL and nH are analog filters
including coils, resistors, and capacitors.
09-05-2019
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[0036]
FIG. 2 is a graph for explaining the sound pressure frequency characteristics of the speaker
system 8. The woofer WO and the tweeter TW of the speaker system 8 of the present
embodiment mainly divide the frequency band for reproducing sound by the network circuits nL
and nH at the crossover frequency fc. The network circuit nL is −12 dB / Oct. At a frequency
higher than the crossover frequency fc. Is a second-order LPF filter showing transition region
characteristics of Also, the network circuit nH is 12 dB / Oct. At a frequency lower than the
crossover frequency fc. It is a second-order HPF filter which shows the transition zone
characteristic of. Therefore, the woofer WO for the bass range reproduction mainly reproduces
the frequency band lower than the crossover frequency fc, and the tweeter TW mainly
reproduces the frequency band higher than the crossover frequency fc. The speaker system 8
has a relatively flat synthetic sound pressure frequency characteristic (shown in the drawing)
when the same signal is input using the network circuits nL and nH (that is, when the input
terminals tL and tH are connected and input). Are adjusted to realize WO + TW). In the case of
the present embodiment, the crossover frequency fc is about 1.8 kHz. Since the network circuits
nL and nH of the speaker system 8 are second-order filters exhibiting gradual transition
characteristics, the reproduced sound of the speaker system 8 near the crossover frequency fc is,
as illustrated in FIG. The reproduced sound from the woofer WO and the reproduced sound from
the tweeter TW will overlap widely.
[0037]
The DSP 10 is connected to a decoder 11 for converting input data adata into stereo signals L
and R, a channel divider 12 including a digital filter, and the decoder 11 to be replaced by stereo
signals (left signal L and right signal R) and test signals. And a test signal source 13 for inputting
the signal to the channel divider 12. The DSP 10 outputs the output terminals (DL 1, DL 2, DR 1,
DR 2) for four channels of the channel divider 12 to the D / A converter 2. The channel divider
12 includes a low pass filter LPF and a high pass filter HPF respectively corresponding to the left
signal L and the right signal R, and switches SW1 to SW4. The filter settings of the low pass filter
LPF and the high pass filter HPF of the channel divider 12 of the DSP 10 and the switching of the
switches SW1 to SW4 are controlled by the CPU 4.
[0038]
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The low pass filter LPF and the high pass filter HPF of the channel divider 12 are digital filters
configured by an FIR filter or an IIR filter. The low pass filter LPF and the high pass filter HPF are
preferably Butterworth filters, Linkwitz-Riley filters, etc., and may include linear phase
characteristics by an FIR filter. The low-pass filter LPF and the high-pass filter HPF each perform
level adjustment (not shown) and phase inversion, and the phase inversion is performed so that
the range for adjusting reproduction sound quality is expanded and wide bi-wiring SS can also be
supported. A phase inverting circuit (not shown) to be performed and a delay circuit (not shown)
for adjusting the delay time may be included.
[0039]
The switch SW1 switches the signal input to the high pass filter HPF to one of the branch of the
input signal to the low pass filter LPF and the output of the low pass filter LPF. The switch SW2
switches whether to output the output of the low pass filter LPF to the first output terminal (DL1,
DR1). The switch SW3 outputs the output of the high pass filter HPF to the second output
terminal (DL2, DR2) connected to the D / A converter 2 on the high range side, or the D / A
converter 2 on the low range side Switch to output to the output terminal (DL1, DR1) connected
to. The switch SW4 switches between shorting or opening between the output terminals (DL1,
DL2) and between (DR1, DR2).
[0040]
During normal audio reproduction, the switches SW1 to SW4 of the channel divider 12 connect
the low pass filter LPF and the high pass filter HPF in parallel as shown in FIG. The outputs of the
low pass filter LPF and the high pass filter HPF are switched so as to be output to the D / A
converter 2. In other words, the switch SW1 is closed, and the same input signal as the input
signal to the low pass filter LPF is input to the high pass filter HPF, and the switches SW2 and
SW3 are closed, respectively. The output of the filter LPF is output to the first output terminal
(DL1, DR1), the output of the high pass filter HPF is output to the second output terminal (DL2,
DR2), and the switch SW4 is opened. In the present embodiment, the above-described switch
connection state in which the channel divider 12 is operated to reproduce the sound is referred
to as a "normal sound reproduction mode". In the “normal sound reproduction mode”, the user
operates the channel divider 12 to adjust the reproduction sound quality while checking the
synthesized sound of the sound reproduced from the woofer WO of the speaker system 8 and the
sound reproduced from the tweeter TW be able to.
09-05-2019
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[0041]
The switches SW2 and SW3 respectively switch On / Off to output the output of the low pass
filter LPF only to the output terminal (DL1, DR1), or the output of the high pass filter HPF is
output terminal (DL2, The channel divider 12 can also be operated in a "band specific audio
output mode" which can only be output to DR2). When the switch SW2 is closed to output the
output of the low pass filter LPF to the output terminals (DL1, DR1) and the switch SW3 is
opened, the sound is reproduced only from the woofer WO of the speaker system 8. On the other
hand, when the switch SW2 is opened and the switch SW3 is closed to output the output of the
high pass filter HPF to the output terminals (DL2, DR2), the sound is reproduced only from the
tweeter TW of the speaker system 8. In the “band-specific audio output mode”, the user can
adjust the reproduction sound quality while confirming the difference between the sound
reproduced from the woofer WO of the speaker system 8 and the sound reproduced from the
tweeter TW.
[0042]
FIG. 3 is a graph for explaining the crossover characteristic of the channel divider 12 of the
amplifier device 1. FIG. 3 illustrates the case where the cutoff frequency fcL of the low pass filter
LPF and the cutoff frequency fcH of the high pass filter HPF are set equal to each other in the
above-described normal voice reproduction mode to set the crossover frequency fc0. It is a
graph. The low pass filter LPF has a frequency of -96 dB / Oct. It is an LPF filter which shows the
transition area characteristic of. Also, the high pass filter HPF has a frequency of 96 dB / Oct. It is
an HPF filter which shows the transition zone characteristic of. In the graph of FIG. 3, at the
crossover frequency fc0 to be set, the respective output characteristics cross at a level of -6 dB as
compared to the passbands of the low pass filter LPF and the high pass filter HPF. As described
later, the case where the cutoff frequency fcL of the low pass filter LPF and the cutoff frequency
fcH of the high pass filter HPF are set equal to each other as described above is referred to as
“no overlap”.
[0043]
FIG. 4 is a graph for explaining the sound pressure frequency characteristics of the speaker
system 8 when the channel divider 12 of the amplifier device 1 is used. In the case illustrated in
FIGS. 3 and 4, the crossover frequency fc0 of the channel divider 12 is higher than the crossover
frequency fc (= 1.8 kHz) of the network circuit of the speaker system 8, and is approximately 2.0
09-05-2019
16
kHz. Do. That is, in the above-mentioned normal voice reproduction mode, in the case of “no
overlap” in which the cutoff frequency fcL of the low pass filter LPF and the cutoff frequency
fcH of the high pass filter HPF are set equal (= fc0), As a result, dips may occur in the synthesized
sound pressure frequency characteristics (WO + TW shown) of the speaker system 8. This is a
problem that occurs when the crossover frequency fc0 set in the channel divider 12 deviates
without being matched with the crossover frequency fc of the network circuit of the speaker
system 8 which is the bi-wiring SS. This is because, in this sound reproduction system, the band
division filter of the channel divider 12 of the amplifier device 1 and the band division filter of
the network circuit of the speaker system 8 are connected in series. When the crossover
frequency fc0 set in the channel divider 12 shifts with "no overlap" with respect to the crossover
frequency fc of the bi-wiring SS, the dip on the sound pressure frequency characteristic becomes
considerably large, and the band is not reproduced properly. May be wider. When the filter set
by the channel divider 12 becomes steep, the dip may be deep.
[0044]
FIG. 5 is a graph for explaining the crossover characteristics of the channel divider 12 of the
amplifier device 1. The cutoff frequency fcL of the low pass filter LPF and the cutoff frequency
fcH of the high pass filter HPF are set to be different. It is a figure explaining the case of "with an
overlap." In FIG. 5, when the crossover frequency fc0 defining the band division is designated in
the above-mentioned normal sound reproduction mode, the cutoff frequency fcL of the low pass
filter LPF is about 1/3 octaves the crossover frequency fc0. The cutoff frequency fcH of the high
pass filter HPF is set to be higher by about 1/3 octave lower than the crossover frequency fc0.
For example, when the crossover frequency fc0 = 2 kHz is specified, the cutoff frequency fcL of
the low pass filter LPF is set to 2.5 kHz, and the cutoff frequency fcH of the high pass filter HPF
is set to about 1.6 kHz. . Note that the low pass filter LPF is -96 dB / Oct. At a frequency higher
than the crossover frequency fc0. It is an LPF filter which shows the transition area characteristic
of. Also, the high pass filter HPF has a frequency of 96 dB / Oct. It is an HPF filter which shows
the transition zone characteristic of. The CPU 4 controls the DSP 10 to set “without overlap” or
“with overlap”.
[0045]
In the graph of FIG. 5, the passbands of the low pass filter LPF and the high pass filter HPF
overlap and overlap at the crossover frequency fc0 to be set. Thus, the cutoff frequency fcL of
the low pass filter LPF is set higher than the crossover frequency fc0 by about 1/6 to 1 octave,
and the cutoff frequency fcH of the high pass filter HPF is higher than the crossover frequency
09-05-2019
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fc0. If it is set as low as about 1/6 to 1 octave and set to "with overlap", the first output (DL1,
DR1) of the low pass filter LPF and the second output (DL2, DL2 of the high pass filter HPF) Both
DR2) include frequency bands fcL-fcH. Therefore, the frequency band components around the
crossover frequency fc = 1.8 kHz of the network circuit of the speaker system 8 are the output
(DL1, DR1) of the low pass filter LPF and the output (DL2, DR2) of the high pass filter HPF.
Included in both.
[0046]
FIG. 6 is a graph for explaining the sound pressure frequency characteristics of the speaker
system 8 in the case of using the channel divider 12 of the amplifier device 1 of the present
embodiment, wherein the cutoff frequency fcL of the low pass filter LPF and the high pass filter
It is a figure explaining the case of "with overlap" which sets up cutoff frequency fcH of HPF
differently. Even if the crossover frequency fc0 = 2 kHz set in the channel divider 12 is slightly
deviated from the crossover frequency fc = 1.8 kHz of the network circuit of the speaker system
8, “overlap is present”, as shown in FIG. As illustrated, the dip does not occur in the
synthesized sound pressure frequency characteristic (WO + TW illustrated) of the speaker system
8. In the case where the speaker system 8 is bi-wiring SS, the channel divider 12 is set to
“overlap” normal audio because it is adjusted to include flat network characteristics including
the network circuits nL and nH. When set in the reproduction mode, no dip occurs on the sound
pressure frequency characteristic.
[0047]
As in the present embodiment, in the "overlap" normal sound reproduction mode of the channel
divider 12, the transition band characteristic (± 12 dB / Oct. Transition region characteristic (±
96 dB / Oct. Since the attenuation factor of the transition zone and stop zone becomes large
when setting), the sound pressure frequency characteristic of the basic speaker system 8 is
adjusted without changing it, and it is adjusted to change the reproduction sound quality of the
sound reproduction system be able to. As in the present embodiment, when stereo sound is
reproduced in the 2 way speaker system 8, the reproduction band of the vocal sound of the
singer exists so as to cross the crossover frequency fc. When set, the interference between the
woofer WO's playback sound and the tweeter TW's playback sound is substantially reduced, and
the user is more likely to be the singer's vocal size compared to when the channel divider 12 is
not functioning It is possible to obtain a sound image feeling that becomes smaller.
09-05-2019
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[0048]
Preferably, the crossover frequency fc of the low pass filter LPF and the high pass filter HPF of
the channel divider 12 can be set finely, for example, about 1/3 octave according to the JIS
standard (or ISO / IEC standard), Alternatively, it may be set in steps of about 1/6 octave. In the
case of "with overlap", the cutoff frequency fcL of the low pass filter LPF is set higher than the
crossover frequency fc0 by about 1/6 to 1 octave, and the cutoff frequency fcH of the high pass
filter HPF is crossed. Even if the frequency is set to about 1/6 to 1 octave lower than the over
frequency fc0, the effect of the sound quality adjustment by the channel divider 12 is enhanced
by narrowing the overlapping overlapping frequency band. On the other hand, when the network
circuit of the speaker system 8 has a gradual transition band characteristic, dips can be made
less likely to occur on the sound pressure frequency characteristic by widening the overlapping
frequency band to about 2 octaves .
[0049]
However, the channel divider 12 is not limited to the one applied to the 2-way bi-wiring SS
including the woofer WO and the tweeter TW as in the above embodiment. The channel divider
12 is a bandpass filter BPF for three to five ways to accommodate bi-wiring SS (not shown) which
is a three to five way multi-way speaker including subwoofer and / or midrange and / or super
tweeter. May be included. The band pass filter BPF may be configured by connecting another
high pass filter HPF or another low pass filter LPF in series to the low pass filter LPF and the
high pass filter HPF. That is, by setting the filters to be "overlap" between adjacent band-splitting
filters, the sound pressure frequency can be obtained even if the channel divider is operated
corresponding to the 3- to 5-way bi-wiring SS. It is possible to prevent dips on the characteristics.
[0050]
Of course, the "with overlap" setting of the channel divider 12 is also effective in the case of a
multi-way speaker including a woofer and a tweeter which does not use a network circuit. Also,
even when the speaker system 8 includes a full range speaker that does not use a network
circuit, the setting of “with overlap” is similarly effective. Even when the substantial crossover
frequency fc with other speakers is set corresponding to the level reduction due to the limit of
the reproduced sound pressure frequency characteristic of the full range speaker or the speaker
such as the woofer or tweeter. The crossover frequency fc0 of the channel divider 12 can be set
09-05-2019
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in accordance with this.
[0051]
FIG. 7 is a diagram for explaining the filter configuration on the left signal L side in the “test
signal output mode” of the channel divider 12 of the amplifier device 1 of the above
embodiment. In the test signal output mode, the test signal source 13 of the DSP 10 of the
amplifier device 1 is operated to input the test signal to the channel divider 12 instead of the
stereo signal (left signal L and right signal R). The test signal may be a noise signal such as white
noise or pink noise having a predetermined frequency band component, or a test signal such as a
sweep signal for sweeping a pure tone or an impulse signal. The filter configuration on the right
signal R side is the same, so illustration and description will be omitted.
[0052]
In the test signal output mode of the amplifier device 1, the user operates the amplifier device 1
in the test signal output mode even when the crossover frequency fc set in the network circuits
nL and nH of the speaker system 8 which is bi-wiring SS is unknown. The unknown crossover is
operated by operating the test signal source 13 including the predetermined band of the DSP 10
and changing the open / close state of the switches SW 1 to 4 for changing the connection of the
low pass filter LPF and the high pass filter HPF. The frequency fc can be known. As illustrated in
FIGS. 7A to 7D, the CPU 4 changes the open / close state of the switches SW1 to 4 to filter the
test signal from the test signal source 13 and outputs the speaker system 8 from the output
terminals DL1 and DL2. Output to
[0053]
In the test signal output mode, the low pass filter LPF and the high pass filter HPF are set as in
the case of "with overlap" in the normal sound reproduction mode in the above embodiment.
That is, similarly to the case illustrated in FIG. 6, the cutoff frequency fcL of the low pass filter
LPF and the cutoff frequency of the high pass filter HPF at the output of the low pass filter LPF
and the output of the high pass filter HPF Both frequency bands fcL-fcH between fcH are
included. Therefore, the description of the setting of the low pass filter LPF and the high pass
filter HPF is omitted.
09-05-2019
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[0054]
In FIG. 7A, the open / close states of the switches SW1 to SW4 are the same as in the case of the
above-described normal sound reproduction mode shown in FIGS. Therefore, even in the “test
signal output mode”, the user operates the channel divider 12 to synthesize the synthesized
voice of the voice by the test signal reproduced from the woofer WO of the speaker system 8 and
the voice by the test signal reproduced from the tweeter TW. The playback sound quality can be
adjusted while confirming. Of course, switching the short circuit / open state of the switches SW2
and SW3 as in the above-described band-specific audio output mode makes it possible to use the
test signal reproduced from the woofer WO of the speaker system 8 and the sound from the test
signal reproduced from the tweeter TW. While confirming the difference, it is possible to adjust
the reproduction sound quality in the case of operating the channel divider 12.
[0055]
Next, in the test signal output mode of the amplifier device 1, as illustrated in FIGS. 7B to 7D, the
switch SW1 outputs a signal input to the high pass filter HPF as that of the low pass filter LPF. It
is switched to output. Further, the switch SW2 is opened and switched so as not to output the
output of the low pass filter LPF to the output terminal (DL1, DR1). As a result, a narrow band
pass filter BPF in which the low pass filter LPF and the high pass filter HPF are connected in
series is configured. When the channel divider 12 is operated in the normal sound reproduction
mode, the crossover frequency fc0 to be appropriately set is the center frequency of the narrow
band pass filter BPF described above.
[0056]
Therefore, when the center frequency fc0 of the narrow band pass filter BPF substantially
matches the crossover frequency fc of the network circuit nL and nH of the speaker system 8
which is a bi-wiring SS, the sound pressure level reproduced from the woofer WO The sound
pressure levels to be reproduced from the tweeter TW almost coincide with each other.
Therefore, in the test signal output mode of the amplifier device 1, the sound pressure level
reproduced from the woofer WO and the sound pressure level reproduced from the tweeter TW
are repeated by repeating the step of changing the crossover frequency fc0 set by the channel
divider 12. Since it is possible to confirm the frequencies that substantially coincide with each
other, it is possible to know the unknown crossover frequency fc of the speaker system 8 which
09-05-2019
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is a bi-wiring SS.
[0057]
That is, in the test signal output mode of the amplifier device 1, the test signal including the
predetermined band signal is passed to the narrow band pass filter BPF, and the output of the
narrow band pass filter BPF is output as illustrated in FIG. The output of the narrow band pass
filter BPF is output from only the output terminal DL2 as illustrated in FIG. 7C, or the output of
the narrow band pass filter BPF is illustrated in FIG. 7D. As shown in the figure, when switched to
output from both the output terminal DL1 and the output terminal DL2, the sound pressure level
reproduced from the woofer WO of the speaker system 8 is compared with the sound pressure
level reproduced from the tweeter TW. Thus, even if the crossover frequency fc of the speaker
system 8 is unknown, the channel divider 12 is matched to this. You can set the crossover
frequency fc0.
[0058]
A narrow band pass filter BPF configured by connecting in series a low pass filter LPF having
sharp transition region characteristics and a high pass filter HPF is a 2/6 to 2 octave range
including the crossover frequency fc0 as a center frequency. Since only the test signal is passed,
when the setting of the crossover frequency fc0 is inappropriate, a clear sound pressure level
difference occurs depending on the gain characteristics of the network circuits nL and nH of the
speaker system 8.
When the crossover frequency fc0 to be set is lower than the unknown crossover frequency fc of
the speaker system 8, the sound pressure level reproduced from the woofer WO becomes higher
than the sound pressure level reproduced from the tweeter TW. Alternatively, when the
crossover frequency fc0 to be set is higher than the unknown crossover frequency fc of the
speaker system 8, the sound pressure level reproduced from the woofer WO becomes lower than
the sound pressure level reproduced from the tweeter TW.
[0059]
However, when the center frequency fc0 of the narrow band pass filter BPF substantially
matches the crossover frequency fc of the network circuits nL and nH, the sound pressure level
reproduced from the woofer WO and the sound pressure level reproduced from the tweeter TW ,
09-05-2019
22
Almost match. Therefore, even if the user does not use the microphone 9, the crossover
frequency fc0 is changed to substantially match the unknown crossover frequency fc of the
network circuits nL and nH of the speaker system 8 on the basis of the loudness of the auditory
sense. It can be done. As long as the crossover frequency set by the channel divider does not
deviate from the crossover frequency of the bi-wiring SS, no dip occurs on the sound pressure
frequency characteristic, and sound can be appropriately reproduced. In addition, the user can
know the unknown crossover frequency of the bi-wiring SS without measuring instruments such
as microphones and level meters and FFT analyzers, so the channel divider functions to properly
adjust the playback sound quality. It can be done.
[0060]
FIG. 8 is a view for explaining the display circuit 6 of the amplifier device 1 of the above
embodiment. FIG. 9 is a flow chart for explaining the operation of the channel divider 12 of the
amplifier device 1 in the test signal output mode. The amplifier device 1 of this embodiment uses
the microphone 9 connected to the microphone amplifier circuit 7 in the “test signal output
mode” of the channel divider 12 and the crossover frequency fc of the speaker system 8 which
is a bi-wiring SS is unknown. Even if it is, the crossover frequency fc0 of the channel divider 12
can be set appropriately. The “test signal output mode” of the channel divider 12 is the same
as that of the above-described embodiment, and thus the description thereof will be omitted.
[0061]
The microphone amplifier circuit 7 includes an amplification stage 71 which amplifies an input
signal from the microphone 9, and an output circuit 72 which filters the output of the
amplification stage 71 so as to output it to the CPU 4. Therefore, the CPU 4 of the amplifier
device 1 detects an audio signal detected from the microphone 9 in synchronization with the test
signal generated from the test signal source 13 in the test signal output mode as a reproduced
sound of the test signal. Can be displayed. In the test signal output mode, the display circuit 6 at
least includes the window display 80 indicating the crossover frequency fc0 to be set, the
reproduction sound pressure level 81 of the test signal from the woofer WO of the measured
speaker system 8, and the tweeter TW measured. To display the playback sound pressure level
82 of the test signal from and the playback sound pressure level 83 of the test signal that is
simultaneously played back and synthesized from the woofer WO and the tweeter TW, and to
change the crossover frequency fc0 The window display 84 is suggested. The reproduced sound
pressure levels 81 to 83 of the test signal may display the magnitude of the sound pressure level
for the user by bar display as shown in FIG.
09-05-2019
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[0062]
For example, FIG. 8A is a view for explaining the display circuit 6 when the user operates the
operation unit 5 of the amplifier device 1 to set the crossover frequency fc0 of the channel
divider 12 to 2.0 kHz. In the test signal output mode, a test signal including a predetermined
band signal is passed through the narrow band pass filter BPF, switched as shown in FIGS. 7 (b)
to (d), and output. The sound pressure level 81 of the test signal reproduced from the sound
pressure level 82 of the test signal reproduced from the tweeter TW, and the sound pressure
level 83 of the test signal reproduced simultaneously from the woofer WO and the tweeter TW
and synthesized Each can be measured and displayed. In the case of FIG. 8A, the sound pressure
level 81 of the test signal reproduced from the woofer WO is smaller than the sound pressure
level 82 of the test signal reproduced from the tweeter TW. In this case, since the crossover
frequency fc0 of the channel divider 12 is higher than the crossover frequency fc (= 1.8 kHz) of
the speaker system 8, the window display 84 of the display circuit 6 lowers the crossover
frequency fc0 (Down ) To indicate that you want to change.
[0063]
Next, FIG. 8B is a diagram for explaining the display circuit 6 when the user operates the
operation unit 5 of the amplifier device 1 to set the crossover frequency fc0 of the channel
divider 12 to 1.6 kHz. . In the case of FIG. 8B, the sound pressure level 81 of the test signal
reproduced from the woofer WO is larger than the sound pressure level 82 of the test signal
reproduced from the tweeter TW. In this case, since the crossover frequency fc0 of the channel
divider 12 is lower than the crossover frequency fc (= 1.8 kHz) of the speaker system 8, the
window display 84 of the display circuit 6 raises the crossover frequency fc0 (Up ) To indicate
that you want to change.
[0064]
Next, FIG. 8C is a diagram for explaining the display circuit 6 when the user operates the
operation unit 5 of the amplifier device 1 to set the crossover frequency fc0 of the channel
divider 12 to 1.8 kHz. . In the case of FIG. 8C, the sound pressure level 81 of the test signal
reproduced from the woofer WO is almost equal to the sound pressure level 82 of the test signal
reproduced from the tweeter TW. Furthermore, the reproduced sound pressure level 83 of the
09-05-2019
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test signal simultaneously reproduced and synthesized from the woofer WO and the tweeter TW
becomes larger than the sound pressure level 81 or 82 when the woofer WO and the tweeter TW
are independent, respectively. Therefore, it can be inferred that the reproduction sound wave
from the woofer WO and the reproduction sound wave from the tweeter TW are in phase with
each other at the position of the microphone 9. In this case, since the crossover frequency fc0 of
the channel divider 12 substantially matches the crossover frequency fc (= 1.8 kHz) of the
speaker system 8 and is in the preferable in-phase relationship, the window of the display circuit
6 is The display 84 indicates to indicate that the crossover frequency fc0 is kept (Keep).
[0065]
Next, FIG. 8D is a diagram for explaining the display circuit 6 when the user operates the
operation unit 5 of the amplifier device 1 to set the crossover frequency fc0 of the channel
divider 12 to 1.8 kHz. . In the case of FIG. 8C, the sound pressure level 81 of the test signal
reproduced from the woofer WO is almost equal to the sound pressure level 82 of the test signal
reproduced from the tweeter TW, but reproduced simultaneously from the woofer WO and the
tweeter TW. The reproduced sound pressure level 83 of the test signal synthesized and
synthesized becomes smaller than the sound pressure level 81 or 82 when the woofer WO and
the tweeter TW are independent. Since it can be inferred that the reproduced sound wave from
the woofer WO and the sound wave reproduced from the tweeter TW are in antiphase relation
with each other at the position of the microphone 9 and canceled each other, either woofer WO
or tweeter TW has a reverse phase It is preferable to change to connection. Therefore, the
window display 84 of the display circuit 6 displays to indicate that the connection is reversed
(Invert).
[0066]
Therefore, the user repeats the operation of changing the crossover frequency fc0 set by the
channel divider 12 of the amplifier device 1 in accordance with the indication of the window
display 84 of the display circuit 6, whereby the crossover frequency fc of the speaker system 8 is
unknown. Again, the crossover frequency fc0 of the channel divider 12 can be set to
approximately match this. Also, if an appropriate crossover frequency fc0 can be set, the user can
know whether it is preferable to change the woofer WO and tweeter TW to either in-phase
connection or reverse-phase connection. When reproducing, it is possible to adjust the low pass
filter LPF of the channel divider 12 and the phase inverting circuit of the high pass filter HPF so
that a dip does not occur on the passing pressure frequency characteristic. Of course, the level
adjustment circuit of the low pass filter LPF and the high pass filter HPF, and the delay circuit
09-05-2019
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may be adjusted.
[0067]
In the present embodiment, the user operates the operation unit 5 of the amplifier device 1 to
change the crossover frequency fc0 of the channel divider 12. However, even if the CPU 4
automatically changes the crossover frequency fc0. Good. As shown in the flowchart of FIG. 9,
the CPU 4 can control the operation of the channel divider 12 of the amplifier device 1 in the test
signal output mode. When the crossover frequency fc set in the network circuits nL and nH of
the speaker system 8 is unknown, the normal voice reproduction mode of the channel divider 12
is shifted to start the operation of the test signal output mode (S001). The CPU 4 first connects
the low pass filter LPF of the channel divider 12 and the high pass filter HPF in series to set a
narrow band pass filter BPF (S002).
[0068]
Next, the CPU 4 operates the test signal source 13 including the predetermined band of the DSP
10, and switches the open / close state of the switches SW1 to 4 for changing the connection of
the low pass filter LPF and the high pass filter HPF (S003) . For example, after the muting
operation for a predetermined time, the output of the narrow band pass filter BPF is continuously
output for a predetermined time from only the output terminal DL1 to the woofer WO as shown
in FIG. After the mute operation of time, (2) as shown in FIG. 7C, the output terminal DL2 alone
continuously outputs to the tweeter TW for a predetermined time, and after the mute operation
for a predetermined time, (3) FIG. As shown in (d), the switches SW1 to SW4 are switched so as
to continuously output from both the output terminal DL1 and the output terminal DL2 for a
predetermined time. When the sound pressure level by the test signal is measured a
predetermined number of times using the microphone 9 (S004: No), and when this is repeated a
predetermined number of times or more (S004: Yes), the measured woofer It is checked whether
it can be said that the sound pressure level 81 of the test signal reproduced from the WO and the
sound pressure level 82 of the test signal reproduced from the tweeter TW are almost equal (S
005).
[0069]
When the sound pressure level 81 of the test signal reproduced from the measured woofer WO
09-05-2019
26
and the sound pressure level 82 of the test signal reproduced from the tweeter TW are different
(S005: No), the CPU 4 compares the magnitudes of them. If the sound pressure level 81 from the
woofer WO is lower than the sound pressure level 82 from the tweeter (S006: Yes), the crossover
frequency fc0 set by the channel divider 12 is lowered. To change (S007). On the other hand,
when the sound pressure level 81 from the woofer WO is higher than the sound pressure level
82 from the tweeter (S006: Yes), the crossover frequency fc0 set by the channel divider 12 is
changed to be higher. (S008). The CPU 4 determines whether to end the test signal output mode
(S011). If not (S011: No), the process returns to the step of setting the narrow band pass filter
BPF (S002), and the channel divider 12 The above steps are repeated until the crossover
frequency fc 0 of the speaker system 8 substantially matches the crossover frequency fc of the
speaker system 8.
[0070]
As a result, if the measured sound pressure level 81 of the test signal reproduced from the
woofer WO substantially matches the sound pressure level 82 of the test signal reproduced from
the tweeter TW (S005: Yes), the CPU 4 Since the crossover frequency fc0 to be set by the
channel divider 12 has been confirmed, the reproduced sound pressure level 83 of the test signal
simultaneously reproduced and synthesized from the woofer WO and the tweeter TW is
respectively the woofer WO and the tweeter TW alone It is judged whether it is smaller than the
sound pressure level 81 or 82 in the case of (S009). When the synthetic reproduction sound
pressure level 83 of the woofer WO and the tweeter TW is larger than the sound pressure level
81 or 82 of the single case respectively (S009: No), the reproduction sound wave from the
woofer WO and the reproduction from the tweeter TW Since the sound waves are in phase with
each other at the position of the microphone 9, the CPU 4 ends the step of automatically
changing the crossover frequency fc0 (S011: Yes).
[0071]
On the other hand, when the absolute value of these level differences is larger than the
predetermined value (S009: Yes), the reproduced sound wave from the woofer WO and the
sound wave reproduced from the tweeter TW have a reverse phase relationship with each other
at the position of the microphone 9. Since it can be inferred that the CPU 4 makes a negative
phase connection to either the woofer WO or the tweeter TW, the phase inverting circuit of the
low pass filter LPF and the high pass filter HPF is Set (S010). Thereafter, the CPU 4 determines
whether to end the test signal output mode (S011), and if not ended (S011: No), the process
returns to the step of setting the narrow band pass filter BPF (S002). The above steps are
09-05-2019
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repeated until the crossover frequency fc0 of the divider 12 and the crossover frequency fc of
the speaker system 8 substantially match. When ending the test signal output mode (S011: Yes),
the CPU 4 ends the step of automatically changing the crossover frequency fc0 (S012).
[0072]
In the test signal output mode of the channel divider 12 of the amplifier device 1 of the present
embodiment, the CPU 4 controlling this causes the display circuit 6 to make a display indicating
that the crossover frequency fc0 should be changed. Although the case where the crossover
frequency fc0 is changed by operating 5 or the case where the crossover frequency fc0 is
automatically changed has been described, a test signal output mode may be configured by
partially combining these. For example, when the CPU 4 determines that it is preferable to
change either the woofer WO or the tweeter TW to the reverse phase connection, the in-phase
connection and the reverse phase connection are switched a predetermined number of times
automatically. The test signal sound may be measured and then the user may eventually decide
whether to select the in-phase connection or the anti-phase connection. In addition, when
changing the setting of the channel divider 12 in the test signal output mode, if the user operates
the operation unit 5 so as to immediately shift to the normal audio reproduction mode, is the
channel divider 12 properly set? The user may be able to reproduce the sound signal such as
music and check the audition.
[0073]
Further, the configuration of the connection including the switches SW1 to SW4 of the channel
divider 12 is not limited to the configuration described and illustrated in the above embodiment.
That is, in the test signal output mode of the amplifier device 1, the switches SW1 to SW4 pass
the test signal including the predetermined band signal to the narrow band pass filter BPF, and
the output of the narrow band pass filter BPF is If switching is performed so as to output from
only the output terminal DL1 of 1 or from only the second output terminal DL2 or to output from
both the output terminal DL1 and the output terminal DL2, It may be a combination. Also, the
switches SW1 to SW4 may be replaced by multipliers in the signal flow of the DSP 10
constituting the channel divider 12. If the multiplication coefficient of the multiplier is 1, it is
short circuited, and if the multiplication coefficient is 0, it is equivalent to opening.
[0074]
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28
Further, the channel divider 12 of the present invention can set the crossover frequency fc of the
channel divider 12 appropriately, particularly when using the speaker system 8 capable of biwiring connection including a network circuit. Therefore, the user can enable good sound
reproduction without the possibility of dips occurring on the sound pressure frequency
characteristics. The channel divider 12 can selectively reproduce the test signal output of the
narrow band pass filter BPF and compare the sound pressure level reproduced from the woofer
WO of the speaker system 8 with the sound pressure level reproduced from the tweeter TW.
Even if the crossover frequency fc of the system 8 is unknown, it is possible to set a crossover
frequency fc0 that matches this.
[0075]
The channel divider of the present invention is applicable not only to stereo devices that
reproduce stereo audio signals, but also to sound reproduction systems that include multichannel surround sound reproduction devices.
[0076]
DESCRIPTION OF SYMBOLS 1 amplifier apparatus 2 D / A converter 3 amplifier circuit 4 CPU 5
operation part 6 display circuit 7 microphone amplifier circuit 8 speaker system 9 microphone
10 DSP 11 decoder 12 channel divider 13 test signal source
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29
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