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The present invention relates to a speaker system capable of simultaneously switching
impedance and band. Generally, in a conventional spilar system, the input impedance is
determined by the impedance of the voice coil of the speaker unit to be used and the impedance
of the noise circuit to L4. Therefore, if the impedance of the speaker system is lower than the
impedance of the combined amplifier (hereinafter referred to as the amplifier), problems such as
heat generation of the amplifier occur. On the other hand, when the impedance of the speaker
system is high, there arises a problem that the maximum power 8 of the amplifier can not be
taken out. Further, in the conventional speaker system, the reproduction frequency band is
constant, and if it is desired to change the reproduction frequency band according to the purpose
of use, it is necessary to correct this on the amplifier side. That is, generally in a small enclosed
space such as a car interior, a low band is easily amplified and reproduced, and an on-vehicle
speaker system needs to have a frequency characteristic matched to such a car interior. However,
when such a speaker system is used in a general room, the low band is obviously insufficient.
Also, the amplifier for vehicle use has an impedance of almost 4Ω, and in order to extract the
maximum power from such an amplifier, the impedance of the speaker system needs to be 4Ω.
However, since many amplifiers for the film chamber have a load impedance of 80 or more,
when a 4Q speaker is connected, the amplifier generates heat, the protection circuit operates
frequently, and in some cases the amplifier Is inconvenient. The speaker system provided by the
present invention can simultaneously switch the impedance 4Q-BQ and switch the low-range
characteristic for vehicle-interior in the case as described above. A conventional speaker system
will be described with reference to FIGS. 1 and 2. In FIG. 1, 1 is an input terminal, 2 is a low pass
filter, 3 is a band pass filter, 4 is a no-pass filter, 6 is a woofer, 6 is a squawker, and 7 is a
tweeter. In such a speaker system, both the sound pressure frequency characteristic shown in
FIG. 2a and the impedance characteristic shown in FIG. 2 are single characteristics, and it is not
possible to switch 1 according to the purpose of use. FIG. 3 shows an embodiment of the present
invention. The parts having the same functions as those in FIG. The reference numeral 8 denotes
a series of impedance elements inserted between the input terminal 1 and the filters 2 to 4 and
the impedance elements 9, and 9 denotes a switch for switching the impedance element 8
between the separation side a and the insertion side.
In each of the speakers shown at 6, 6 ° 7, it is assumed that the voice coil is wound according to
the lower nominal impedance. In the above configuration, when the switch 9 is turned to the a
side, the sound pressure frequency characteristic becomes zero as in FIG. 2 at this time, and the
impedance characteristic becomes as shown in FIG. Here, if the resistance RiR (Zmax (where
Zmax is the impedance at the lowest resonant frequency)) of the resistance of the impedance
element 8 is selected and the switch 9 is turned to the b side, the impedance characteristic
changes as shown in FIG. The sound pressure Pm at is z0 / z. The sound pressure Pf0 at + R * f0
becomes Zmax / Zmax + R, and p, 07 pm= (Z0 + R) / Z0> 1, and the sound pressure in the low
band is apparently increased to widen the band. That is, when the switch 9 is on the b. Side, the
sound pressure frequency characteristics when the same voltage as that applied to obtain the
sound pressure in FIG. 4 a is applied to the input terminal 1 are as shown in FIG. However, when
the switch is in bIIll, the sound pressure frequency characteristics when power equal to the
power applied to obtain the sound pressure in FIG. 4 a is applied to the input terminal 1 is as
shown in FIG. It is understood that it is expanded. As described above, since the present invention
simultaneously switches the impedance characteristic and the reproduction frequency band, it is
possible to realize the impedance matching with the amplifier while realizing a preferable
reproduction band according to the purpose of use of the speaker system. The excellent effect is
Brief description of the drawings
FIG. 1 is a circuit diagram of a conventional speaker system, FIG. 2 is its characteristic diagram,
FIG. 3 is a circuit diagram of one embodiment of the speaker system of the present invention, and
FIG. 4 is its characteristic diagram.
1 @ · · · · · · · · · Input terminal, 2 · · · · · · · · · · · · · · · · · low pass filter, 4 @ @ @ @ own self-panned
pass filter, 4 fist · ell · fist fist pass filter, 6 · 1100. Woofer, 6----+ Skooka, 7----------------------------------
----------------------------------------+ + + + + + + + + + + Name of Agent Attorney Nakao Toshio One other
person First H ψ z z i