JPS6035878B2 - fader controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fader controller for a car radio or the like.

The output section of a car radio usually includes a front speaker located at the front of the vehicle interior, for example, near an instrument panel, and a ground speaker located at the rear of the vehicle interior, for example, near a rear seat.

When supplying an output signal from a power amplifier to such front and rear speakers, in addition to driving only one of the front and rear speakers, the output signal is supplied so that the output levels from both speakers are complementary. There is a fader control method that continuously changes the level of an output signal, and a fader controller is a device that controls the distribution of such an output signal to speakers. FIGS. 1a and 1b show an audio signal reproducing apparatus using a conventional fader controller.

In the audio signal reproducing apparatus shown in FIG. 1a, B
TL (Balanced Transfer)
The output from the output terminals 0, 02 of the power amplifier Apn such as ) is distributed and supplied to the two speakers S, , S2 via the sliding terminal of the potentiometer VR.

In the device shown in FIG. 1b, both terminals of the potentiometer VR are connected to the output terminals ○, 02 of the power amplifier, and sliders of the potentiometer VR are connected to the connection points of the speakers S, 02. In the conventional example described above, due to the low impedance of the voice coils of the speakers S, S2, the resistance of the potentiometer VR must also be made small, and the potentiometer VR may consume a large amount of power and generate heat. Since a resistor is inserted in series with the speaker, there are many problems such as deterioration of the frequency characteristics and deterioration of the damping factor, and it is difficult to apply a fader controller with such a configuration to the /fi system. Ta.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a fader controller that does not have the drawbacks of the conventional devices as described above.

Hereinafter, embodiments of the present invention will be described with reference to FIG.

In FIG. 2, a fader controller F according to the present invention is shown.
C is a potentiometer VR whose both terminals are connected to the output ○, 02 of the power amplifier Apw, a buffer amplifier Abf having an input terminal connected to the output terminal of the potentiometer VR, and an output terminal of the buffer amplifier Abf. and a circuit that connects one terminal of the speakers S, , S2, and connects the other terminal of the speaker to both ends of the potentiometer VR.

Note that connection terminals T, -T6 may be provided to connect the inside and outside of the fader controller FC.

In an audio signal reproducing apparatus using the fader controller of the present invention having the above-described configuration, a power amplifier Apw
If it is a BTL amplifier, signal voltages of the same level and opposite phase, such as eo and 1eo, are outputted to the output terminals 0, 02, for example.

The voltage division ratio at the sliding terminal of potentiometer VR is n/
(1-n), a signal voltage of eo·(1-n)-e is applied to the input terminal of the buffer amplifier Abf.
The buffer amplifier Abf needs to be an amplifier with high input impedance and low output impedance, and for example, an operational amplifier, a SEPP amplifier, etc. can be used. Furthermore, although it is necessary for the voltage gain of the buffer amplifier Abf to be 1 in order to function as an original fade controller, the voltage gain should be selected appropriately depending on the positional relationship between the speakers S, S2 and the listener. I can do it. Furthermore, whether the buffer amplifier Abf is a positive phase amplifier or a negative phase amplifier, there is no difference in fade control function, except that the output voltage of the potentiometer and the output of the buffer amplifier differ in phase. Fader controller F mentioned above
It is clear that C can also be manufactured separately as an adapter and coupled to an existing amplifier.

Further, the potentiometer VR in the fader controller according to the present invention does not need to have a signal current flowing therein for driving the speaker, and may be of a large resistance, small power capacity type, and there is no power loss in the potentiometer VR, and the frequency characteristics are There is no harm to it.

Furthermore, it goes without saying that various types of power amplifiers can be used in addition to the BTL amplifier.

Furthermore, even when there are three or more speakers, the present invention can be applied by providing a similar configuration by providing two or more potentiometer sliders and two or more buffer amplifiers.

[Brief explanation of the drawing]

1A and 1B are circuit diagrams showing a conventional example, and FIG. 2 is a circuit diagram showing a fader controller according to the present invention. Explanation of the symbols of the main parts, Apw... Power amplifier 0, Abf... Power amplifier, S,, S2... Speaker power, VR... Potentiometer, FC...
・・Feeder control flow/Figure 2

Claims (1)

[Claims] 1 A fader controller that distributes an audio signal output from a power amplifier to at least two speakers, the potentiometer having both terminals connected between the output terminals of the power amplifier, and a slider of the potentiometer. a buffer amplifier having an input terminal connected to an output terminal of the buffer amplifier and one of each of the speakers;
and a circuit connecting one terminal to the output terminal of the power amplifier and the other terminal to the output terminal of the power amplifier, wherein the buffer amplifier has high input impedance and low output impedance characteristics.