JP2006270698

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DESCRIPTION JP2006270698
The present invention provides a bass enhancing apparatus that compensates for a reduction in
low frequency characteristics of a speaker and enhances bass feeling without increasing the size
of the loudspeaker and a power amplifier for driving the same. SOLUTION: A low frequency
signal outside the reproduction frequency band of a speaker is extracted by a phase inverting
means 3 and a first low pass filter 4, and an input / output characteristic is on the origin by the
harmonic wave generating means 5 To perform an origin-asymmetric non-linear operation
having a break point at at least one place other than the origin, and performing subtraction
processing on the signal subjected to the non-linear operation and the extracted signal at an
appropriate magnification. Thus, the fundamental wave is attenuated to generate the second
harmonic and the third harmonic, and the generated harmonics are added to the original signal.
[Selected figure] Figure 1
Bass boost device
[0001]
The present invention relates to a bass enhancing apparatus that acoustically compensates for
degradation of low frequency characteristics of a loudspeaker and enhances bass feeling without
increasing the size of the loudspeaker and a power amplifier for driving the loudspeaker.
[0002]
In recent years, the miniaturization of audio devices has progressed, and there has been a
problem that sufficient low-frequency reproduction can not be performed particularly due to the
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restriction of the size of the speaker.
In order to solve this problem, a system equipped with a speaker for low-frequency reproduction
that can be installed at a position other than the front and a power amplifier that drives it is also
available by utilizing the vague directivity of the low-frequency region. Although it is sold, it has
problems such as requiring an installation site and being expensive, and also in such a system,
the demand for miniaturization is increasing.
[0003]
As the method of compensating for the deterioration of the low frequency characteristic of the
speaker and enhancing the bass feeling, the simplest method is to increase the low frequency
gain using an equalizer. However, in order to enhance the bass feeling outside the reproduction
frequency band of the speaker, it is necessary to raise the low band gain significantly, a large
power output is required, and there is a problem that the power amplifier for driving the speaker
becomes large. doing. Also, along with that, it is necessary to increase the allowable input of the
speaker, and there is a problem that the speaker is also enlarged.
[0004]
To solve such problems, low-frequency signals outside the speaker's playback frequency band
are extracted as a method to enhance the bass feeling outside the speaker's playback frequency
band without increasing the size of the speaker and the power amplifier that drives it. Patent
Document 1 discloses a method of adding the harmonics thereof. FIG. 15 is a block diagram of a
bass boost device disclosed in Patent Document 1. Hereinafter, a conventional bass boost device
will be described with reference to FIG.
[0005]
First, the left and right audio signals input to the apparatus are input to the second addition
means 32, and the left and right signals are added. The signal output from the second addition
means 32 is input to the first low pass filter 33, and a low band signal outside the reproduction
frequency band of the speaker is extracted. The signal output from the first low pass filter 33 is
input to the full wave rectifier 35 which is the harmonic wave generating means 34, and the
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input / output characteristics are even functions symmetrical with respect to the output axis. It is
converted to the second harmonic. The signal output from the full-wave rectifier 35 is input to
the second low pass filter 36, and harmonics other than the second harmonic are cut, and only
the second harmonic is extracted. The signals output from the second low pass filter 36 are input
to the first addition means 37 and 38, and are added to the left and right signals input to the
apparatus. In this way, the second harmonic of the low-frequency signal outside the reproduction
frequency band of the speaker can be added to the input audio signal.
[0006]
Also, as a method of controlling the level of the generated harmonics, after adding an offset to
the extracted signal and then multiplying the positive and negative half wave components by an
appropriate value, the signal is added to the extracted signal to generate a harmonic. A method is
shown in Patent Document 2. Patent Document 1: Japanese Patent Application Laid-Open No. 8237800 Patent Document 3: Japanese Patent No. 3462590
[0007]
However, the method described in Patent Document 1 adds only the second harmonic. In
psychoacoustics, it is known that human beings can feel the fundamental sound even if only the
harmonics are emitted without the fundamental sound (fundamental wave) being emitted. For
example, in a speaker that can not reproduce 70 Hz or less, when reproduction is performed with
the second harmonic of 50 Hz and the third harmonics of 100 Hz and 150 Hz added, human
beings can feel the fundamental sound of 50 Hz. However, if the second harmonic and the fourth
harmonic, 100 Hz and 200 Hz, are added and played back, the 100 Hz is erroneously recognized
as the fundamental sound and the 200 Hz is erroneously recognized as the second harmonic, and
the fundamental sound is 50 Hz I can not feel In addition, when only the second harmonic, 100
Hz, is reproduced, the 100 Hz is erroneously recognized as a fundamental sound, and the
fundamental sound, 50 Hz, can not be felt. As described above, it is necessary to add the second
harmonic and the third harmonic in order to apply psychoacoustics to compensate for the
deterioration of the low frequency characteristics of the speaker and to enhance the bass feeling.
[0008]
As described above, the method of Patent Document 1 in which only even harmonics mainly
composed of the second harmonic is added has a problem that the effect of enhancing the bass
feeling of the basic sound outside the reproduction frequency band of the speaker is weak.
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[0009]
Further, in order to realize the method described in Patent Document 2, there is a problem that
the scale of the circuit is increased, and not only harmonics but also fundamental waves are
generated from the extracted signal.
[0010]
The basic concept of the present invention is that the second harmonic of the fundamental wave
of the original signal and the third harmonic of the lower part of the reproduction frequency
characteristic of the speaker do not extend to the range of the fundamental wave as shown in
FIG. By generating harmonics, it is recognized as if there is a fundamental wave, and the low
frequency characteristic of the speaker is compensated for and the bass feeling is enhanced
without increasing the size of the speaker and the power amplifier for driving it. It aims to
provide a bass boost device.
[0011]
In order to meet the above object, the bass amplifier according to the present invention
compensates for the deterioration of the low frequency characteristics of the speaker and
enhances the bass feeling without increasing the size of the loudspeaker and the power amplifier
for driving the loudspeaker. A low band signal outside the reproduction frequency band is
extracted, and the extracted signal passes through the origin and is subjected to origin
asymmetric non-linear operation having a break point at at least one point other than the origin,
and the non-linear operation The fundamental wave is attenuated to generate a harmonic
including the second harmonic and the third harmonic by performing subtraction processing of
each of the signal subjected to the step and the extracted signal at an appropriate magnification.
Then, by adding the generated harmonics to the original signal, when the input signal level is
large, a harmonic including the second harmonic and the third harmonic of the low band signal
outside the reproduction frequency band of the speaker Add waves and enter When the force
signal level is low, increasing the low range gain is the most important feature.
[0012]
The bass enhancement apparatus according to the present invention attenuates the fundamental
wave by performing the above-described processing on the low band signal included in the band
in which the low band frequency characteristic of the speaker is degraded, and thereby the
second harmonic and the third harmonic By generating harmonics including harmonics and
adding the generated harmonics to the original signal, it is a small-scale operation, and when the
input signal level is large, low-frequency signals outside the reproduction frequency band of the
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speaker Add harmonics including the second harmonic and the third harmonic, increase the low
frequency gain when the input signal level is small, increase the size of the speaker and the
power amplifier driving it at low cost There is an advantage that it is possible to compensate for
the deterioration of the low frequency characteristics of the speaker and to enhance the bass
feeling.
[0013]
(First Embodiment) FIG. 1 is a block diagram of a bass amplifier according to a first embodiment
of the present invention, FIG. 2 is a circuit diagram of its inverting summing amplifier, and FIG. 3
is a circuit diagram of its non-linear operation means. 6 is an input / output characteristic
diagram of the non-linear operation means of FIG. 3, FIG. 5 is a spectrum diagram when a single
sine wave is input to the non-linear operation means of FIG. 3 similarly, FIG. 7 is an input /
output characteristic diagram of the harmonic generation means of FIG. 6, and FIG. 8 is a
spectrum diagram of the case where a single sine wave is input to the harmonic generation
means of FIG.
[0014]
Hereinafter, the bass enhancer according to the present invention will be described with
reference to FIGS. 1 and 2 to 8.
First, the left and right audio signals input to the bass enhancement device are divided into two
signals, which are input from the input terminals T1 and T2 to the first addition means 11 and
12 and to the harmonic addition unit 1, respectively. Bifurcated.
[0015]
The harmonic adding unit 1 includes a second adding unit 2, a phase inverting unit 3, a first low
pass filter 4, a harmonic generating unit 5, and a second low pass filter 10. The left and right
audio signals input to the adding unit 1 are input to the second adding unit 2 and added.
The signal output from the second adding means 2 is input to the phase inverting means 3 and
the phase is inverted.
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[0016]
FIG. 2 is a circuit diagram of the inverting addition amplifier, and the functions of the second
adding means 2 and the phase inverting means 3 are used in common.
An audio signal is added and added to one end of each of the resistors R11 and R12, and is
added to the inverting input terminal of the IC 11. The noninverting input of the IC 11 is
grounded.
Also, a resistor R13 is connected from the output end to the inverting input end.
[0017]
The signal output from the phase inverting means 3 is input to the first low pass filter 4 and the
cutoff frequency is set so as to extract a low band signal outside the reproduction frequency
band of the speaker.
In order not to increase the circuit scale, the first low pass filter 4 uses a second order one.
Here, there is no phase delay in the pass band due to the first low pass filter 4 and the phase is
delayed by 180 ° in the stop band. Including the phase inversion action by the phase inversion
means 3, the phase advances by 180 ° in the low band outside the reproduction frequency band
of the speaker, which is a band below the cutoff frequency of the first low pass filter 4, and the
first low pass There is no phase delay in the band within the reproduction frequency band of the
speaker, which is a band higher than the cutoff frequency of the filter 4.
[0018]
The signal output from the first low pass filter 4 is input to the harmonic generation means 5.
The harmonic generation unit 5 is configured by a non-linear operation unit 6, a first coefficient
unit 7, a second coefficient unit 8, and a linear operation unit 9.
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[0019]
The non-linear operation means 6 is composed of a positive / negative asymmetrical limiter
circuit so that its input / output characteristic passes on the origin, has a break point at at least
one place other than the origin, and becomes origin asymmetrical. In the circuit diagram of the
non-linear operation means 6 of FIG. 3 showing one example, a diode limiter circuit using a
parallel circuit of a resistor R20 and a diode D21 connected in series with the resistor R21 is
used. Here, when the input voltage is equal to or less than a constant negative voltage, as shown
in FIG. 4, the diode D21 is turned on and the output amplitude is limited. As a result, the input /
output characteristics pass on the origin, become asymmetric at the origin and asymmetric with
respect to the output axis, and it is possible to generate odd harmonics and even harmonics.
[0020]
The spectrum when a single sine wave is input to the non-linear operation means 6 is, as shown
in FIG. 5, a signal output from the non-linear operation means 6 having the same frequency
signal as the signal input to the non-linear operation means 6 Some fundamental waves are also
included. Here, when the fundamental wave is contained in a large amount, when the signal is
output from the high frequency adding unit 1, the audio signal input from the input terminals T1
and T2 to the first addition means 11 and 12 described later Even though the signal is added and
the low frequency signal outside the reproduction frequency band of the speaker, the gain is
increased and output from the device, which causes a load on the speaker and an amplifier for
driving the large output.
[0021]
Therefore, the signal inputted to the nonlinear arithmetic means 6 by the first coefficient unit 7
is multiplied by a predetermined magnification, and the signal outputted from the nonlinear
arithmetic unit 6 by the second coefficient unit 8 is multiplied by the predetermined
magnification. By subtracting the signal output from the first coefficient unit 7 from the signal
output from the second coefficient unit 8 by the linear operation unit 9, the fundamental wave
included in the signal output from the non-linear operation unit 6 can be obtained. Attenuate. As
a result, the harmonic generation unit 5 can generate a harmonic including the second harmonic
and the third harmonic with a small signal level of the fundamental wave.
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[0022]
The circuit diagram of the harmonic generation means 5 shown in FIG. 6 shows an example in
which a differential amplifier is used as the linear operation means 9. The first coefficient unit 7
sets the coefficients by the resistors R24 and R25, and the second coefficient unit 8 sets the
coefficients by the resistors R22 and R23. In the linear operation means 9, the differential
amplifier is composed of an IC 21 and resistors R26 and R27, and the output of the first
coefficient unit 7 is on the inverting input side of the IC 21 and the output of the second
coefficient unit 8 is on the non inverting input side Connect to and subtract the former from the
latter. The input / output characteristics of the harmonic generation means 5 are shown in FIG. 7,
and the spectrum when a single sine wave is input to the harmonic generation means 5 is shown
in FIG. It can be seen from FIG. 8 that the signal generation level of the fundamental wave is
reduced and output from the harmonic generation means 5.
[0023]
As can be seen from FIG. 7, in the harmonic wave generation means 5, the input / output
characteristics pass on the origin and have break points at at least one or more points other than
the origin, the origin is asymmetrical, and the absolute value of the input signal level is constant.
When the absolute value of the input signal level is equal to or more than a predetermined value,
the input / output characteristic has the characteristic of being folded back in the direction
crossing the input axis at the time of negative input. Therefore, when the input signal level is
small, the linearity is maintained and the amplitude is not suppressed and no harmonic is
generated. On the other hand, when the input signal level is large, the signal of the negative input
voltage is folded back to a positive output voltage and the peak-to-peak amplitude is suppressed
and a harmonic is generated.
[0024]
That is, when the signal level input to the harmonic generation means 5 is large, the fundamental
wave level with respect to the input signal level is small and the harmonic level becomes large.
On the other hand, when the signal level input to the harmonic generation means 5 is small, the
fundamental level with respect to the input signal level is large and the harmonic level is small.
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[0025]
The coefficients of the first coefficient unit 7 and the second coefficient unit 8 are set so that the
fundamental wave is most attenuated by the linear operation unit 9 when the signal level input to
the harmonic generation unit 5 is maximized. Thus, when the signal level input to the harmonic
generation means 5 is maximum, the fundamental level is reduced and harmonics are generated.
Then, as the signal level input to the harmonic generation unit 5 decreases, the fundamental level
with respect to the input signal level increases and the harmonic level decreases.
[0026]
Since the first low pass filter 4 is constituted by the second order having relatively moderate
characteristics, a low pass signal outside the reproduction frequency band of the speaker in a
band equal to or lower than the cutoff frequency of the first low pass filter 4 Not only the low
frequency signal within the reproduction frequency band of the speaker, which is a band higher
than the cutoff frequency of the first low pass filter 4, is also extracted. However, the signal level
in the reproduction frequency band of the speaker is smaller than the signal level outside the
reproduction frequency band of the speaker. Therefore, when the signal level input to the
harmonic generation means 5 is large, the low band signal outside the reproduction frequency
band of the speaker, which is a band equal to or lower than the cutoff frequency of the first low
pass filter 4, has a large signal level. Therefore, it is converted to a harmonic including the
second harmonic and the third harmonic. The low-pass signal in the reproduction frequency
band of the speaker, which is a band higher than the cut-off frequency of the first low-pass filter
4, decreases in signal level as the frequency increases, so the ratio of generated harmonics
decreases. At the same time, the ratio of fundamental waves increases. In addition, since the
phase delay of the first low pass filter 4 is compensated by the phase inverting means 3, there is
no phase delay of the fundamental wave. Also, when the signal level input to the harmonic
generation means 5 is small, the harmonics are passed without being generated regardless of the
band, but the signal level has a frequency according to the attenuation characteristic of the first
low pass filter 4 Becomes smaller as
[0027]
The signal output from the harmonic generation unit 5 is input to the second low pass filter 10,
unnecessary harmonics are cut, and harmonics of a necessary band are extracted. The cutoff
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frequency of the second low pass filter 10 is set to the cutoff of the first low pass filter 4 in order
to extract up to the third harmonic of the low pass signal extracted by the first low pass filter 4.
Set about 3 times the frequency. In order not to increase the circuit size, the second low pass
filter 10 uses a second order.
[0028]
Due to the second low pass filter 10, there is no phase delay in the pass band and 180 ° in the
stop band. Including the phase change due to the phase inversion means 3 and the first low pass
filter 4, the phase is 180 ° in the low band outside the reproduction frequency band of the
speaker which is a band below the cutoff frequency of the first low pass filter 4. There is no
phase delay in the low band in the reproduction frequency band of the speaker, which is a band
between the cutoff frequency of the first low pass filter 4 and the cutoff frequency of the second
low pass filter 10, In the middle and low band in the reproduction frequency band of the speaker,
which is a band higher than the cutoff frequency of the low pass filter 10, the phase is delayed
by 180 °.
[0029]
When the signal level input to the harmonic adding unit 1 is large, a low frequency signal outside
the reproduction frequency band of the speaker, which is a band lower than the cutoff frequency
of the first low pass filter 4, is a second harmonic. It is converted to a harmonic including the
third harmonic. A low band signal in the reproduction frequency band of the speaker, which is a
band between the cutoff frequency of the first low pass filter 4 and the cutoff frequency of the
second low pass filter 10, is generated as the frequency increases. As the ratio of harmonics
decreases, the ratio of fundamental waves increases. There is no delay in the phase of the
fundamental wave. The middle low band signal within the reproduction frequency band of the
speaker, which is a band higher than the cutoff frequency of the second low pass filter 10, passes
through with a 180 ° phase lag because the signal level decreases.
[0030]
When the signal level input to the harmonic adding unit 1 is small, the low band signal outside
the reproduction frequency band of the speaker, which is a band equal to or lower than the
cutoff frequency of the first low pass filter 4, passes 180 ° in phase. Do. The low band signal in
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the reproduction frequency band of the speaker, which is a band between the cut-off frequency
of the first low-pass filter 4 and the cut-off frequency of the second low-pass filter 10, has a small
signal level and a phase delay It passes without being fundamental wave. The middle low band
signal in the reproduction frequency band of the speaker, which is a band higher than the cut-off
frequency of the second low pass filter 10, has a smaller signal level and passes 180 ° out of
phase.
[0031]
The signals output from the second low pass filter 10 which is the final stage of the harmonic
adding unit 1 are input to the first addition means 11 and 12 and are respectively added to the
left and right signals input to the input terminals T1 and T2. It is added.
[0032]
When the input signal level is large, the low band signal outside the reproduction frequency band
of the speaker, which is a band equal to or lower than the cutoff frequency of the first low pass
filter 4, is second-order A harmonic including the harmonic and the third harmonic is added.
The low band signal in the reproduction frequency band of the speaker, which is a band between
the cutoff frequency of the first low pass filter 4 and the cutoff frequency of the second low pass
filter 10, has the second harmonic and the third harmonic. While the harmonic including the
second harmonic is slightly added, the signal level of the fundamental wave is slightly increased
and output. The middle low band signal within the reproduction frequency band of the speaker,
which is a band higher than the cutoff frequency of the second low pass filter 10, is output with a
phase delay of 180 ° from the harmonic adding unit 1, but the signal level is small. , And hardly
affect the signals output from the first addition means 11 and 12.
[0033]
When the input signal level is small, the low band signal outside the reproduction frequency
band of the speaker, which is a band equal to or lower than the cut-off frequency of the first low
pass filter 4, has harmonics added Since the phase is advanced 180 degrees from the unit 1 and
output, the signal level is reduced and output. The low band signal in the reproduction frequency
band of the speaker, which is a band between the cutoff frequency of the first low pass filter 4
and the cutoff frequency of the second low pass filter 10, is Since the signal is output without
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delay, the signal level is increased and output. The middle low band signal within the
reproduction frequency band of the speaker, which is a band higher than the cutoff frequency of
the second low pass filter 10, is output with a phase delay of 180 ° from the harmonic adding
unit 1, but the signal level is small. , And hardly affect the signals output from the first addition
means 11 and 12.
[0034]
In this manner, when the input signal level is large, the audio signal input to the device is a
harmonic including the second harmonic and the third harmonic of the low-frequency signal
outside the reproduction frequency band of the speaker. The low-pass gain increases when waves
are added and the input signal level is small, so the low-frequency characteristic of the speaker is
compensated for the low-frequency feeling without increasing the size of the speaker and the
power amplifier that drives it. It can be enhanced.
[0035]
Second Embodiment FIG. 9 is a block diagram of a bass enhancement apparatus according to a
second embodiment of the present invention.
[0036]
This will be described below with reference to FIG.
The description of the same parts as in the first embodiment will be omitted, but in the first
embodiment, the volume control means 13 and 14, the additional amount adjustment means 15,
the first filter characteristic switching means 16, and the second filter characteristic. A switching
unit 17, a control unit 18, an audio determination unit 19, and a reproduction unit 20 are added.
[0037]
First, the left and right audio signals input to the bass enhancement device are input to the
volume control means 13 and 14 to adjust the volume.
The volume control means 13 and 14 are composed of electronic volumes. The control unit 18
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instructs the volume control units 13 and 14 to adjust the volume. The low-pass gain is increased
when the input signal level is small, as described in the first embodiment, but the sound volume
adjustment means 13 and 14 are combined with the second addition means 2 and the first one.
The effect of increasing the low range gain at the time of small volume is enhanced by arranging
the stage before the adding means 11 and 12.
[0038]
The left and right audio signals output from the volume control means 13 and 14 are branched
into two signals, one to be input to the first addition means 11 and 12 and the other to be input
to the harmonic addition unit 1.
[0039]
The harmonic adding unit 1 includes a second adding unit 2, a phase inverting unit 3, a first low
pass filter 4, a harmonic generating unit 5, a second low pass filter 10, an additional amount
adjusting unit 15, a first The filter characteristic switching unit 16 and the second filter
characteristic switching unit 17 are provided.
[0040]
The additional amount adjusting means 15 adjusts the magnitude of the signal output from the
second low pass filter 10, and is constituted by an electronic volume.
The control means 18 instructs the additional amount adjustment means 15 to adjust the
additional amount.
The first filter characteristic switching means 16 is for switching the pass characteristic of the
first low pass filter 4, and is configured to switch the constant of the first low pass filter 4. The
control unit 18 instructs the first filter characteristic switching unit 16 to switch the filter
characteristic.
[0041]
The second filter characteristic switching means 17 is for switching the pass characteristic of the
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second low pass filter 10, and is configured to switch the constant of the second low pass filter
10. The control unit 18 instructs the second filter characteristic switching unit 17 to switch the
filter characteristic. Here, although the control means is described as one, it may be controlled by
individual control means.
[0042]
In order to perform an optimal correction according to the type of audio signal input to the
apparatus, the apparatus includes audio determination means 19 for determining a medium on
which the input audio is recorded and the number of channels of audio contained in the medium.
Information on the type of voice is communicated to the control means 18. The audio
discrimination means 19 is a medium in which the audio is recorded from the recognition
information such as TOC information of the medium in which the audio to be reproduced by the
reproduction means 20 and input to the apparatus is recorded, ie, CD or DVD video. It
determines whether it is DVD audio or not. In addition, it is determined whether the number of
audio channels included in the medium, that is, whether only 2-channel sound source or 5.1channel sound source is included. Then, the result is transmitted to the control means 18.
[0043]
In general, a movie sound signal contains more low frequency signals than a music signal, and a
stronger bass enhancement effect is required. Therefore, based on the information on the type of
sound transmitted from the sound discrimination means 19, the control means 18 is that the
medium on which the sound is recorded is a DVD video, and the medium includes a 5.1 channel
sound source. The first filter switching means 16 and the second filter to set the cutoff frequency
of the first low pass filter 4 and the second low pass filter 10 lower than in the other cases. The
switching unit 17 is instructed, and the additional amount adjusting unit 15 is instructed to
increase the additional amount. The instruction to the first filter switching means 16 and the
second filter switching means 17 and the instruction to the additional amount adjusting means
15 to increase the additional amount may be performed either simultaneously or both
simultaneously. .
[0044]
Thereby, the optimum correction can be automatically performed in accordance with the type of
audio signal input to the apparatus.
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[0045]
(Third Embodiment) FIG. 10 is a circuit diagram of harmonic generation means 5 of the bass
enhancing apparatus in the third embodiment of the present invention, FIG. 11 is an input /
output characteristic diagram of non-linear operation means 6 in the same, and FIG. FIG. 13 is a
spectrum diagram of the case where a single sine wave is input to the harmonic wave generating
means 5 as well.
The basic configuration of the bass boost device is the same as that of FIG. 1 used in the first
embodiment.
[0046]
Hereinafter, it demonstrates using FIG. 1, FIG. 10-FIG. In the harmonic wave generation means 5
shown in FIG. 10, a resistor R32 is inserted in the feedback portion of the pre-stage amplifier
IC31 of the full wave rectification circuit with diodes D31 and D32 to shift the folding point of
the full wave rectifier The constant of the value is set so that the positive and negative gains are
different. The coefficients of the first coefficient unit 7 and the second coefficient unit 8 are set
by the gain inside the linear operation means 9. R31 to R35 are resistors. Further, the linear
operation means 9 itself constituted by the IC 32 and the resistors R 36 and R 37 is the same as
the one shown in FIG.
[0047]
FIG. 11 is an input / output characteristic diagram of the non-linear operation means 6, but the
characteristic is different from FIG. 4 which is an input / output characteristic diagram of the
non-linear operation means 6 in the first embodiment. In the first embodiment, the characteristic
is to suppress the amplitude for a negative input voltage lower than a predetermined voltage, but
in the third embodiment, the characteristic is to expand the amplitude for a negative input
voltage lower than a predetermined voltage. is there.
[0048]
Therefore, in FIG. 10, unlike in FIG. 6, the input to the harmonic wave generation means 5 is
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connected to the non-inverted input side of the IC 32 of the linear operation means 9, and the
output of the nonlinear operation means 6 is connected to the inverted input side. The latter is
subtracted from the former to obtain the characteristics of FIG.
[0049]
FIG. 12 is an input / output characteristic diagram of the harmonic generation unit 5, but the
characteristic is similar to FIG. 7 which is an input / output characteristic diagram of the
harmonic generation unit 5 in the first embodiment.
That is, the input / output characteristic passes on the origin, has a break point at at least one
place other than the origin, is origin asymmetric, and has linear characteristics when the absolute
value of the input signal level is equal to or less than a fixed value. When the absolute value of
the signal level is equal to or more than a predetermined value, the input / output characteristic
has the characteristic of being folded back in the direction intersecting the input axis at the time
of negative input.
[0050]
FIG. 13 is a spectrum diagram in the case where a single sine wave is input to harmonic
generation means 5, but FIG. 8 is a spectrum in the case where a single sine wave is input to
harmonic generation means 5 in the first embodiment Similarly, the signal level of the
fundamental wave is suppressed, and harmonics including the second harmonic and the third
harmonic are generated. The signal level input to the harmonic generation unit 5 is adjusted to
be higher than that in the first embodiment.
[0051]
As described above, according to the present embodiment, regardless of the input / output
characteristics of the non-linear operation unit 6, the input / output characteristics of the
harmonic generation unit 5 pass over the origin and break points at at least one or more points
other than the origin. If the absolute value of the input signal level is below a certain value, it has
linear characteristics, and if the absolute value of the input signal level is more than a certain
value, the input / output characteristics at the time of negative input are the input axis If it has
the characteristic that it is folded back in the direction intersecting with, the signal level of the
fundamental wave is small, and it is possible to generate a harmonic including the second
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harmonic and the third harmonic.
[0052]
In each of the above embodiments, the position of the phase inverting means 3 is not limited to
the illustrated part, and may be disposed in any part in the harmonic adding unit.
Alternatively, they may be arranged in front of the first addition means 11 and 12.
[0053]
Further, the operation of the phase inverting means 3 and the operation of the first addition
means 11 and 12 may be used in combination, and the first addition means 11 and 12 may be
constituted by subtraction means. That is, in each of the above-described embodiments, even if
the action of two or more means is realized by one means, the action of one means may be
realized by two or more means.
[0054]
Furthermore, the input / output characteristic passes on the origin, has a break point at at least
one place other than the origin, is origin asymmetric, and has linear characteristics when the
absolute value of the input signal level is a certain value or less. If the absolute value of the signal
level is equal to or more than a certain value, the circuit exemplified here is limited as long as it
can obtain the characteristic that the input / output characteristic turns back in the direction
crossing the input axis at negative input. is not.
[0055]
The bass enhancing apparatus according to the present invention is used for compensating for a
reduction in low frequency characteristics from a speaker and enhancing a bass feeling in a small
stereo, television, etc. in which it is difficult to upsize a speaker and a power amplifier for driving
the same. Applicable to
[0056]
Block diagram of the bass boost device in the first and third embodiments of the present
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invention. Circuit diagram of the inverting addition amplifier in the first embodiment of the
present invention. Circuit diagram of the non-linear operation means in the first embodiment of
the present invention. Input / output characteristic diagram of the non-linear operation means in
No. 1 Spectrum diagram when a single sine wave is inputted to the non-linear operation means in
the first embodiment of the present invention Circuit diagram of harmonic generation means in
the first embodiment of the present invention The input / output characteristic diagram of the
harmonic wave generation means in the first embodiment A spectrum diagram when a single
sine wave is inputted to the harmonic wave generation means in the first embodiment of the
present invention A bass enhancing apparatus in the second embodiment of the present
invention Block diagram of the circuit diagram of the harmonic generation means in the third
embodiment of the present invention input / output characteristic diagram of the non-linear
operation means in the third embodiment of the present invention Input / output characteristic
diagram of harmonic generation means in the spectrum diagram when single sine wave is
inputted to the harmonic generation means in the third embodiment of the present invention
conceptual diagram of harmonic addition of the present invention block of the conventional bass
boost device Figure
Explanation of sign
[0057]
Reference Signs List 1 harmonic addition unit 2 second addition unit 3 phase inversion unit 4
first low pass filter 5 harmonic generation unit 6 non-linear operation unit 7 first coefficient unit
8 second coefficient unit 9 linear operation unit 10 first 2 low-pass filters 11, 12 first addition
means 13, 14 volume control means 15 addition amount adjustment means 16 first filter
characteristic switching means 17 second filter characteristic switching means 18 control means
19 audio discrimination means 20 reproduction Means 31 harmonic addition unit 32 second
addition means 33 first low pass filter 34 harmonic generation means 35 full wave rectifier 36
second low pass filter 37, 38 first addition means
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