JPS5461903

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DESCRIPTION JPS5461903
Description 1, title of the invention
Transmission frequency time and sexing device
The present invention relates to a transmission frequency characteristic correction apparatus for
correcting, in an audio reproduction system, a change in low range due to a difference in the
installation position of a speaker in a listening room. In general, the transmission frequency
characteristics of the speaker in the listening room change in various ways depending on the
volume of the room, the type of interior material, the installation position of the speaker, the
listening position, and the like. The degree of the change is small in the middle and high tones
and tends to be large in the low tones alone. Moreover, the characteristic of the change is that a
large peak or a lag is likely to occur in the region of 100 to 400I-1z. As an example, FIG. 1 shows
changes in transmission frequency characteristics due to differences in the installation position
of the speed and the speed in a room with a size of about 6 mats. According to this, in the case of
the installation positions S1 and S3 of the speakers, it can be seen that a large peak or gap is
generated in the 100 to 400 Hz band. In such a case, despite the fact that the speakers and so on
are emitting sound at various levels, at the listening position there is a noticeable excess or
deficiency of bass. The following remedies have been used for such problems, but each method
has one practical disadvantage. (1) A method of changing the installation position of the speaker
is convenient and acoustically effective. However, it is difficult to secure the optimum installation
position of the speaker in the listening room of EndPage: 1 in Japan where the room volume is
small and there are many cases where furniture and furniture are provided and doubles as a
living room. It is not limited to practicality. (2) Method of removing harmful reflected sound It is
also possible to remove acoustically harmful reflective surface by absorbing sound to the wall
where the reflected sound gives harmful level change to the frequency characteristic of the bass
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region. . However, in general, sound absorption methods for the low frequency range require
special acoustic materials and installation methods, and thus are often available for general
household listening rooms. (3) Method of Using Graph Ink Equalizer A conventional graphic
equalizer is capable of level adjustment for each of the ? and ? ? ? ? ? octave bands.
Therefore, there are various applications other than the correction of the bass level. However, the
price is too high compared to audio equipment and is hardly used in general homes. (4) Method
using tone control Generally, as shown in FIG. 2, the 1-tone control device built in the audio
equipment has a constant gradient in the range below (or above) a certain cutoff frequency. To
adjust the level increase and decrease.
Therefore, it is fd unbearable to correct the change of the peak and dip in the 100-400 I-Iz band
which is likely to occur in the general writing room. Therefore, as a device that corrects the
change in the low-end feeling to the peak dip in the low-end range, a constant frequency band in
the low-end range, for example, 100 to 400 I ? (the position of the center frequency of the peak
dip in the z-band, The inventors have devised a transmission frequency characteristic correction
device configured using peak-dip filters whose levels and bandwidths can be varied
independently. According to this apparatus, since the bandwidth can be changed, it is possible to
correct the frequency characteristic of the bass region more accurately, even if the shape of the
peak dip is gentle or steep. However, when using this device to change the level and bandwidth
independently, the switching operation of setting the output power level ratio ? and ? of the
two attenuators in the device to specific values respectively is necessary. Because of this, the
actual operation has to be somewhat complicated. Although some of the commercially available
graphic equalizers can change the position, level and bandwidth of the center frequency of peak
and dip independently, they are too expensive to be used as a correction device for transmission
frequency characteristics in a general writing room, which makes them practical Lack of sex. In
view of these points, the present invention is a transmission frequency characteristic correction
apparatus capable of independently and independently changing the position, level and
bandwidth of peak-dip mid-D frequency in a constant frequency band of a bass region. Intended
to provide. An embodiment of the present invention will be described below. FIG. 3 shows an
embodiment of the present invention. 1 is a sound source device such as a record player, a tape
recorder, or an FM tuner, 2 is a glowing including old KA characteristic equalizers, 3 is a
transmission frequency characteristic correction device according to the present invention, 4 is a
main amplifier, and 5 is a loudspeaker. The transmission frequency characteristic correction
device 3 in the above configuration operates as a peak dissoge filter in a constant frequency
band (for example, 1oo to 400 Hz) of the bass range, and further, the position, level and
bandwidth of the center frequency of the peak dissoge In the case of having each peak, the peak
can be deleted by using the transmission frequency characteristic correction device 3 as a
dissoge filter which approximates the inverse characteristic of the peak. In the case where a noise
occurs as in the installation position S3 of the speaker, the transmission frequency characteristic
correction device 3 may be used as a peak filter.
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Therefore, by using the transmission frequency characteristic correction device 3 of the present
invention, the transmission frequency characteristic can be corrected without using an expensive
graphic equalizer as in the prior art. Further, in the transmission frequency characteristic
correction device 3, the bandwidth can also be varied. EndPage: 2 Next, the transmission
frequency characteristic correction device 3 will be specifically described. The transmission
frequency characteristic correction device 3 is configured using a peak-dip filter. This peak-dip
filter is based on the principle that a peak dip is generated by adding a signal whose phase
changes monotonously (0 to ?2? radians depending on frequency and a signal having no phase
change). Based on. FIG. 4 shows a block circuit of the peak-dip filter. 11.20 is a switch, 12 to
15.17 to 21 ░ 24 is an adder, 16, 21.23 is an attenuator-122 monotonously changes the phase
of the signal of the input signal along with the increase of the frequency to O to -2? lanoan Is an
all-pass filter circuit. These are connected between the input terminal IN and the output terminal
OUT in the order shown in the figure. Each filter circuit 22 is easily constructed by cascading two
CR bridge circuits as shown in FIG. 5, for example. This CR bridge circuit is positive. The resistors
& having the same resistance value on the negative signal lines 261 and 262, and the input and
output sides of R2 are connected by connecting the capacitors C1 and C2 having the same
capacitance value. Hereinafter, an embodiment of a peak-dip filter configured using this CR
bridge will be described. The peak-dip filter thus configured becomes a dip filter if the switch 11
is turned on and the switch 20 is turned off and the peak filter ? is turned off, and the switch 11
is turned off and the switch 20 is turned on. First, the transfer function P (?) of the peak filter
and its amplitude term IP (?) 1 ? are respectively shown by the following equations. IP (?) 1 =
и и и (2) T; time constant ? of CR bridge circuit; input / output level ratio ? of attenuators -21, 23;
attenuator-160 input / output level ratio transfer function of data filter and its amplitude The
terms are indicated by the inverse of the function of the equations (1) and (2), respectively. The
characteristics of this peak-dip filter are as follows. (1) When the amplitude characteristic is
taken on the log 'axis, it becomes symmetrical and has maximum value / minimum value at ?-I /
T (that is, center frequency f).
?????? (2) When ? is changed, the levels of peak and deep extreme values and minimum
values change in the range of ▒ 9.5 dB. That is, when ? is large, the peak (dip depth) is high
(deep) and 9.5 dB (?9, 5 dB) at ??1. (3) The bandwidth changes when ? is changed. In other
words, the larger the ?, the narrower the bandwidth 9, the sharper the shape of the peak dip. In
principle, the bandwidth can be arbitrarily varied. That is, this peak-dip filter is capable of
independently changing the position of the center frequency of peak-dip, the level, and the
bandwidth of each of the three types of paradoxes, and changing the level by changing + of ?.
The bandwidths can be easily changed by changing ?, ?, respectively. FIG. 6 shows the
characteristics at the time of bandwidth change, and FIG. 7 shows the characteristics at the time
of level change. FIG. 8 shows a block circuit of another embodiment of the peak-dip filter
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constructed using a cascade connection of CR and Brythno. Reference numeral 31.43 is a switch,
33 to 36.36 to 42, 44, 47.48 is an adder, 45 to 46. 49 to 51 is an attenuator-137, 38 is the CR
bridge circuit described above. These are thus connected in the order as shown in the figure
between the input terminal IN and the output terminal OUT. The peak-dip filter configured as
described above becomes a dip filter when the switch 31 is turned off and the switch 43 is
turned on, and becomes a dip filter when the switch 31 is turned on and the switch 43 is turned
off. The transfer function P (?) of the dip filter and its amplitude term IP (?) 1 are respectively
shown by the following equations. EndPage: 3
иииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииии
ииииииииииииииии иии And their amplitude terms are shown by the inverse numbers of the functions of Eqs.
(3) and (41), respectively. The features of this peak-dip filter are as follows. (If the 11 amplitude
characteristic is taken on the logarithmic axis, the local maximum and the local minimum are at
the place where it becomes symmetrical with ? = 1 / T, respectively. (2) When ? is changed, the
levels of the local maximum and the local minimum change in the infinite range. That is, as ?
decreases, the height of the peak (dip) increases. (3) The bandwidth changes when ? is changed.
That is, as ? increases, the bandwidth narrows and the shape of peak dip becomes sharp.
That is, also in this peak / dip filter, the three parameters of the position of the center frequency
of peak / dip, the level of maximum value / minimum value, and the bandwidth can be varied
independently, and by changing only ?. The bandwidth can be easily varied by changing only
the level ?. FIG. 9 shows the amplitude characteristics when the bandwidth is changed with the
level of the minimum value of the dip being fixed. As described above in detail, in the apparatus
of the present invention, the position, level and bandwidth of the peak dip center frequency can
be varied independently within a constant frequency band of the bass range. Moreover, in actual
use, operability can be extremely improved since two types of attenuators for leveling and
bandwidth can be adjusted independently. Therefore, by using the device of the present
invention, it is possible to correct the peak / dip of the low frequency band of the transmission
frequency characteristic in the listening room accurately and simply. Further, the device of the
present invention can be manufactured inexpensively as compared to the graphic equalizer, and
can be incorporated without increasing the cost of the audio equipment itself, which is practical.
Also, as a single product, it can be used as a practical and effective low-pitched sound quality
adjustment device. ??????? By independently applying them to both R channels, it is
possible to easily correct the difference in level of R between both channels of the bass region
caused by the difference in the condition of the reflection surface around both the L and R
speakers. In addition, by selecting and changing the circuit constants appropriately, the
midrange. The present invention is applicable to a tone control device for high frequency range
and has such a great effect.
4. Brief description of the drawings. FIG. 1 is an illustrative view showing a change in
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transmission frequency characteristics according to the installation position of a speaker, FIG. 2
is a characteristic view of a tone control device, and FIG. 3 is a transmission frequency
characteristic according to the present invention. FIG. 4 is a block diagram showing one
embodiment of the correction device, FIG. 4 is a block diagram showing one embodiment of the
present invention device, FIG. 5 is a block diagram of a CR bridge circuit, and FIG. Characteristic
diagram, Fig. 7 is characteristic diagram at the time of level change, Fig. 8 is a block diagram
showing another embodiment of the device according to the present invention, and Fig. 9 shows
another embodiment in which bandwidth is changed with constant level. It is a characteristic
view which shows the example of a change of the amplitude characteristic of a dip when it is
made to make it go. 3 и и Transmission frequency characteristic correction device, 16. 21 и и и
Attenuator, 37. 38 и CR bridge circuit, 49 to 51 и и и Attenuator. Patent Assignee Name EndPage: ?
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