JPH067675Y2 - Loudspeaker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the invention: [Industrial field of application] The present invention relates to a loudspeaker, and is particularly used in the field of expanding and enhancing a low frequency range.

[Prior Art] FIG. 4 shows a Japanese Patent Application No. 60-6997 filed by the same applicant.
It is a block circuit diagram of the loudspeaker of No. 3 (application date: May 10, 1985).

[Problems to be Solved by the Invention] The loudspeaker shown in FIG. 4 requires two identical low frequency band amplifiers 1 and 2, and also has two volumes for adjusting the amplification degree of the low frequency band. You need what you let. 2ch
In the case of stereo, four low frequency band amplifiers and four volumes are required, which increases the number of parts and increases the cost. Further, when the frequency bands of the low-frequency band amplifier 1 at the front stage and the low-frequency band amplifier 2 at the rear stage deviate due to variations in component constants or the like, it becomes difficult to obtain the predetermined characteristics in the bass speaker.

The present invention has been made in view of the above points, and was made as an attempt to provide a loudspeaker capable of expanding and enhancing the low frequency range at low cost.

Configuration of the Invention: As shown in the block diagram of FIG. 1, the present invention is a low frequency band amplifier for amplifying a low frequency component of an L channel or R channel input signal (hereinafter referred to as an audio input signal) of a monaural signal or a stereo signal. 10 and a first power amplifier 2 for power-amplifying the output of the low frequency band amplifier
1, a subtractor 23 that subtracts a signal obtained by multiplying the audio input signal by β from a signal obtained by multiplying the output of the low frequency band amplifier 10 by (1 + β), and a phase inverter 24 that inverts the phase of the output of the subtractor 23. A second power amplifier 22 for power amplifying the output of the phase inverter 24 and the first power amplifier 21.
A first output terminal 21h connected to the output, a second output terminal 22h connected to the output of the second power amplifier 22, a low-pitched speaker 32 and a mid / high-pitched speaker 31 are provided. One input end is connected to the first output terminal 21h and the other input end is connected to the ground side terminal 22e of the first power amplifier 21, respectively, and one input end of the bass speaker 32 is connected to the first output. Terminal 21h
The other input terminal is connected to the second output terminal 22h.

[Embodiment] FIG. 2 is a circuit block diagram for explaining an embodiment of the present invention. In Figure 2, the low-frequency band amplifier 10, the feedback resistor of the operational amplifier _{A 1,} resistor _{R 3} and the variable resistor VR ₁
By using an impedance element connected in series between the capacitors C ₁ and R ₄ and the semiconductor inductance L ₁ between the midpoint of the variable resistor VR ₁ and the ground, the amplification factor in a certain low frequency band Is made variable. This low frequency band amplifier 10 sets R ₁ : R ₂ = R ₃ : VR ₁ and at this time, the transfer function T (s) is T (s) = [s ² + k (ω ₀ / Q) s + ω ₀ ² ] / [s ² + (ω ₀ / Q) s + ω ₀ ² ]. Note that k is a coefficient, ω ₀ is a resonance angular frequency, Q is a sharpness, and k = [R ₄ (R ₃ + VR ₁ ) + γ {(1-γ) VR ₁ + R ₃ }] / {R ₄ (R ₃ + VR ₁ ) + γ (1-γ) VR ₁ (R ₃ + VR ₁ )} However, γ indicates the ratio of the resistance value between the midpoint and the ground with respect to the maximum value of the variable resistance VR ₁ .

The subtractor 23 includes a feedback resistor R ₇ between the output terminal and the inverting input terminal of the operational amplifier A ₃ , a leak resistance R ₉ between the non-inverting input terminal and the ground, an input resistor R _{6 at} the inverting input terminal, and a non-inverting input terminal. Since the input resistance R _{8 is} provided and the input signal of the non-inverting input terminal of the subtractor 23 is β · e (t), β = R ₉ (R ₆ + R ₇ ) / R ₆ (R ₈ + R ₉ ), And the input signal at the inverting input terminal is (1 + β) ・ e
Since it is (t), the resistors R ₆ , R ₇ , R ₈ and R ₉ are set as much as 1 + β = R ₇ / R ₆ to obtain an inverted output. That is, the subtractor 23 of the embodiment has a subtracting function of multiplying the input signal by a predetermined constant and then subtracting the both signals, and a phase inverting function of inverting the phase of the signal between the input and the output.

The first power amplifier 21 and the second power amplifier 22 are adapted to mutually perform power amplification in phase with the same amplification degree A.

The speaker device 30 includes a mid-high range speaker 31 and a low-range speaker 32. Then, one input end (+) of the mid-high range speaker 31 is connected to the first output terminal 21h (hot side terminal), and the other input end (-) is connected to the ground side terminal 21e of the first power amplifier 21, respectively. And one input end (+) of the bass speaker 32 is the first output terminal 21h.
The other input terminal (−) is connected to the (hot side terminal) and the second output terminal 22h (hot side terminal), respectively.

Now, assuming that the audio input signal is e (t), the low frequency band amplifier 10 amplifies a predetermined frequency band of the audio input signal e (t), and at the point a, T (s) · e ( t), and the power is further amplified by the first power amplifier 21. At point b, the output of T (s) · A · e (t) is obtained to drive the mid-high range speaker 31. Subtractor 23 calculates T (s) · (β + 1) · e (t) to β · e
(T) is subtracted and inverted output is made, and at point c, an output of {β-T (s) · (β + 1)} × e (t) is obtained, and the second power amplifier 22 further amplifies the power in phase. At the point d, A {β-T (s) (β + 1)} e (t) is obtained, and the first output terminal 21h of the first power amplifier 21 and the second output terminal of the second power amplifier 22 are obtained. During 22h, 2A × [s ² + {k (β + 2) −β} / 2 × (ω ₀ / Q) s + ω ₀ ² ] / {s ² + (ω ₀ / Q) s + ω ₀ ² } × e ( The signal t) is obtained to drive the bass speaker 32 at the angular frequency ω ₀ with {k (β + 2) −β} / 2 times enhanced.

As described above, the loudspeaker according to the embodiment of the present invention can extend and enhance the low frequency band. In the embodiment, the subtractor 23 is configured so that the input and output phases are inverted, so that the action of the phase inverter 24 is also provided. Needless to say, when the outputs are in-phase, a well-known phase inverter may be connected to the outputs.

Effect of the Invention: The loudspeaker of the present invention can extend and enhance the low frequency band, and instead of using two low frequency band amplifiers 1 and 2,
By providing the individual low-frequency band amplifiers 10 and the subtractor 23, which is cheaper than the low-frequency band amplifiers 10, the cost becomes low.

[Brief description of drawings]

FIG. 1 is a circuit block diagram for explaining the present invention, FIG. 2 is a circuit block diagram characteristic diagram of an embodiment of the present invention, FIG. 3 is a characteristic diagram of a low frequency band amplifier 10, and FIG. 4 is a conventional example. FIG. 10 ... Low frequency band amplifier, 21 ... First power amplifier,
22 ...... second power amplifier, 23 ...... subtractor, 24 ...... phase inverter, 30 ...... speaker device, 31 ...... in a tweeter, 32 ...... _woofer, A _1, A 2, _{A 3} …
... Operational amplifiers, C ₁ , C ₂ , C ₃ ... Capacitors, L ₁ ... Semiconductor inductances, R ₁ , R
₂ , R ₃ ..., R ₉ ... Resistors, VR ₁ ... Variable resistors, respectively.

Claims (1)

[Scope of utility model registration request] 1. A low-frequency band amplifier (10) for amplifying a low-frequency component of an audio input signal, a first power amplifier (21) for power-amplifying the output of the low-frequency band amplifier, and the audio input signal β A subtractor (23) for subtracting the multiplied signal from the signal obtained by multiplying the output of the low frequency band amplifier (10) by (1 + β), and a phase inverter (24) for inverting the phase of the output of the subtractor (23), The phase inverter (24)
A second power amplifier (22) for power amplifying the output and the first power amplifier.
A first output terminal (2 connected to the output of the power amplifier (21)
1h) and a second output terminal (22h) connected to the output of the second power amplifier (22), a bass speaker (32) and a mid-high range speaker (31), and the mid-high range speaker ( 31) has one input end connected to the first output terminal (2
1h) has the other input terminal connected to the ground, and one input terminal of the bass speaker (32) has the first output terminal (21h) and the other input terminal has the second output terminal (22h). ) Each of which is connected to a loudspeaker.