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JPH06205495

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DESCRIPTION JPH06205495
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
sound reproducing apparatus used for home audio equipment, theater music reproducing
apparatus, various game machines, videos, movie apparatus and the like.
[0002]
2. Description of the Related Art The regeneration band of a conventional electrodynamic
speaker has been a so-called mass control band above the lowest resonance frequency. In this
band, it is not possible to freely set the balance between the setting of Q0 and the efficiency to
flatten the frequency characteristic of sound pressure, and a speaker using a strong magnetic
circuit has a characteristic that Q0 falls and the frequency response is flat. Reproduction of was
difficult.
[0003]
SUMMARY OF THE INVENTION The present invention is excellent even in a unit with low Q0
using a strong magnetic circuit by actively using a band lower than the lowest resonance
frequency which has not been used in the prior art. An object is to obtain frequency
characteristics and excellent transient characteristics.
[0004]
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1
[Means for Solving the Problems] In order to solve the above problems,
[0005]
(A) One sound reproducing apparatus according to the present invention is a sound reproducing
apparatus combining an electrodynamic speaker housed in a closed cabinet and an amplifier for
driving the speaker. The sound pressure level is made to be the desired characteristics by an
amplifier having a frequency characteristic that corrects the band below the lowest resonance
frequency generated by the cabinet and the cabinet to the characteristics of the sound pressure
level. It is characterized in that the band is regenerated.
[0006]
(B) One speaker system according to the present invention is an audio reproduction apparatus
combining an electrodynamic speaker housed in a closed cabinet and an amplifier for driving the
speaker. The band below the lowest resonance frequency which has not been used in the past
has been actively used by correcting the sound pressure level and making it a characteristic of
various desires by an amplifier that combines the band below the lowest resonance frequency
generated by It is characterized by being used in
[0007]
(C), a reproduction method according to the present invention is characterized in that the band
below the lowest resonance frequency generated by the electrodynamic speaker and the closed
cabinet containing the speaker is characterized by the sound pressure level and the desired
characteristics. Thus, the input signal is corrected to reproduce a band below the lowest
resonance frequency.
[0008]
(D), a correction circuit according to the present invention is characterized in that the sound
pressure level is in the band of the lowest resonance frequency or less generated by the
electrodynamic speaker and the closed cabinet containing the speaker. The input signal is
corrected to be as follows.
[0009]
The characteristics of the speaker system will be described below.
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The sound pressure of the electrodynamic speaker is shown by the following equation.
Pr: Sound pressure at a position rm away from the sound source WE: Input power WN / m2ρ0:
Air density kg / m3 G: Magnetic energy-Wb2 / ma: Diaphragm radius m σ: Voice coil conductor
ratio non-resistance Ω · mMM1 : Weight of cone paper kg Q0: Sharpness of resonance MM2:
Weight of voice coil kgMMA: Additional weight of air kg f0: Minimum resonance frequency Hz
[0010]
The conventional speaker system has used f0 or more as a reproduction | regeneration band.
In the band of f >> f0, the equation 1 becomes
It can be seen that this depends on the mass of the vibrating system to raise the sound pressure
level and requires a light diaphragm to increase the efficiency.
The characteristics in the vicinity of f0 change according to Q0, and in order to obtain a flat
frequency characteristic, it is necessary to design Q0 = 1 as shown in the sound pressure
frequency characteristic diagram of FIG.
[0011]
Q0 is given by the following equation.
RMS: Mechanical resistance of vibration system M · ΩA: Power coefficient = Bl Wb / mRE: DC
resistance of voice coil Ω
[0012]
In general, since A2 / RE >> RMS, Q0 is now reduced to Q0 near f0 as shown in equation 4 when
B1 = A is increased to obtain high efficiency in the conventional speaker system. There was a
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problem that the sound pressure level decreased.
[0013]
The loudspeaker system according to the invention uses less than or equal to f0.
The sound pressure in this case is f << f0, and the equation 1 becomes as follows. When the
frequency decreases, the sound pressure decreases.
[0014]
Moreover, f0 is SMS: stiffness of vibration system N / mSMB: stiffness of cabinet N / m The
equation of number 6 is substituted into the equation 5 and arranged.
[0015]
In the equation (7), it is understood that the sound pressure in the band of f << f0 is not related
to the mass of the vibration system but depends on the compliance of the vibration system.
Also, the fact that it is a quadratic function of the frequency indicates that correction can be
easily performed by the driving amplifier.
[0016]
This brings about the following advantages when operated with f << f0. 1. The sound pressure
is not related to the mass of the vibration system, so a heavy diaphragm with sufficient strength
can be used. 2. The efficiency can be controlled by changing the compliance of the speaker
body and the cabinet. 3. Since a strong magnetic circuit is used, characteristics can be easily
controlled and quality reproduced sound can be obtained simply by changing the characteristic
of the amplifier to be corrected even if Q0 drops.
[0017]
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The present invention has been made based on the above-mentioned viewpoints found by the
applicant.
[0018]
Embodiments of the present invention will be described below with reference to the drawings.
[0019]
FIG. 2 is an embodiment of the present invention.
[0020]
As shown in FIG. 2, a closed cabinet SP containing an electrodynamic speaker, a power amplifier
AMP for driving the speaker, and a minimum resonance frequency f0 generated by the
electrodynamic speaker and the enclosed cabinet. The following band is constituted by a filter FL
having a characteristic that the amplification degree increases as the frequency decreases so that
the sound pressure level emerging from the electrodynamic speaker becomes flat.
[0021]
FIG. 3 shows the respective frequency characteristics. FIG. 3a shows the characteristics of the
closed cabinet SP itself in which the electrodynamic speaker is housed, and FIG. 3b shows the
characteristics of the filter FL.
Here, it should be noted that the left downward characteristic below the lowest resonance
frequency f0 of the closed cabinet SP in which the electrodynamic speaker is accommodated is
compensated by the upward characteristic of the filter FL.
Thereby, the reproduction characteristic of the sound pressure level emitted from the
electrodynamic speaker housed in the closed cabinet through the power amplifier driving the
speaker is the sound signal input to the filter, and the resonance characteristic of the sound
pressure level is the lowest resonance. As shown in FIG. 3C, the band below the frequency f0
becomes flat as shown in FIG.
[0022]
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Further, if the filter FL has a characteristic of horizontal to left-up as shown in FIG. 3d, both high
and low bands separated by f0 can be reproduced flat as shown in FIG. 3e.
In addition, the characteristics of the filter FL may be changed to an active filter which can be
varied according to the desires.
[0023]
Therefore, as in the present invention, actively using the band below the lowest resonance
frequency not used in the prior art has the following advantages.
1. By using a frequency lower than the lowest resonance frequency, mass becomes irrelevant
to efficiency, a strong diaphragm can be used, and good quality reproduction sound can be
obtained. 2. In the conventional system, if the magnetic circuit is strengthened, the level of the
low range is lowered due to the over damping, but according to the present invention, a high
quality sound is obtained so as to strengthen the magnetic circuit, and the level of the low
frequency range You can also raise it.
[0024]
Brief description of the drawings
[0025]
Fig. 1 Sound pressure frequency characteristics
[0026]
Fig. 2 Configuration diagram according to the embodiment
[0027]
Fig. 3 Waveform diagram according to the embodiment
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[0028]
Explanation of sign
[0029]
SP ・ ・ ・ ・ A closed cabinet AMP containing an electrodynamic speaker ・ ・ ・ ・ ・ Power
amplifier FL ... ・ ・ ・ Filter
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