JPS6022397Y2 - Expression circuit for electronic musical instruments - Google Patents

Description

[Detailed description of the invention] This invention relates to an expression circuit for an electronic musical instrument that controls the volume of musical tones and rhythm sounds.

2. Description of the Related Art Conventionally, a circuit shown in FIG. 6 has been proposed as an expression circuit for an electronic musical instrument that controls musical tones and rhythm tones so that their volume changes differ in degree.

In this circuit, a variable resistor 4 driven by an expression pedal 3 is connected via a resistor 2 to the output side of a main body section 1 that outputs musical tone signals, and a variable resistor 4 that is driven by an expression pedal 3 is connected to the output side of a rhythm section 5 that outputs rhythm signals. 6, resistor 2 via resistor 7 in series
The resistor 8 is connected to the side connected to the variable resistor 4, and further connected to the resistor 7 side of the resistor 6 and the side connected to the next stage circuit of the variable resistor 4.

The expression circuit configured in this way makes the change in the volume of the rhythm sound more gradual than the change in the volume of the musical sound, so that the volume can be adjusted while maintaining a balance between the volumes of both. Even in the position (when the resistance value of variable resistor 4 is at its maximum), the musical tone signal is guided to the next stage circuit via resistor 2, resistor 7, and resistor 8, so the musical tone cannot be reproduced completely. There were drawbacks.

This idea was made to solve the above-mentioned drawbacks, and it is possible to variably control the volume of musical tones and rhythm sounds so that the amount of change is different, and a certain volume balance can be obtained depending on the volume. Also, when the expression pedal is set to the minimum position (maximum volume resistance),
The object of the present invention is to provide an expression circuit that can completely silence musical tones while producing rhythmic sounds.

Hereinafter, embodiments of this invention will be described based on the drawings.

In the circuit diagram shown in Figure 1, numeral 9 is a main unit that outputs a musical tone signal in response to a keyboard press operation, and the output side is a variable resistor (volume) 10 whose resistance value changes in response to an expression pedal operation. It is connected to the first input terminal A of the differential amplifier 11 via.

On the other hand, the output side of the rhythm section 12 that automatically outputs the rhythm signal is connected to the second human input terminal B of the differential amplifier 11 via a resistor 13.
Further, a resistor 14 is connected between the first and second input terminals A and B of the differential amplifier 11, and the first input terminal A is grounded via the resistor 15.

When a musical tone signal is input from the main body section 9 to the expression circuit configured in this way, a signal controlled by the variable resistor 10 is applied to the first input terminal A of the differential amplifier 11, and further to the second input terminal B. A musical tone signal is applied via a resistor 14.

On the other hand, when the rhythm signal from the rhythm section 12 is input, the resistor 1
This signal is applied to the second input terminal B of the differential amplifier 11 via the resistor 14, and the rhythm signal is applied to the first input terminal A via the resistor 14.

At this time, the voltage V1 of the musical tone signal of the main body section 9, the rhythm section 12
The rhythm signal voltage V2 and the resistance value of the variable resistor 10 are R□
, the resistance value of the resistor 14 is R2, the resistance value of the resistor 13 is R3,
When the resistance value of the resistor 15 is R4, the musical tone signal voltage at the first input terminal A of the differential amplifier 11 8. is, when the influence of R2 is not taken into account, V A 1 = Vl - Moshidori - Similarly, the musical tone signal voltage of the second human power terminal R1 + R2 + R3 3 B is 8° = V1 R1 + R2 + R3, and on the other hand, the first input terminal of the differential amplifier 11 Rhythm signal voltage ■9□ of A can be expressed as VA□1 = V2R1+R2+R3, similarly, R1+R2 rhythm signal voltage VnJ of second human power terminal B, ■8゜=V2R1+R2+R3, if the influence of R4 is not considered. .

When the change in the above voltage is shown in a graph as the resistance value R1 of the variable resistor 10 changes from zero to infinity due to the operation of the expression pedal, the voltage of the musical tone signal V A
1 and ■8□ are as shown in Figure 2, and the rhythm signal voltage ■
9° and VB2 are expressed as shown in FIG.

Here, the voltage at point C on graph V A 1 is ■1, the voltage at point D on graph VB1 is VIR3/ (R2+R3), the voltage at point F on graph VB2 is V2, and the voltage at point E is V
2R2/(R2+R3).

Differential amplifier 1 for each musical tone signal and rhythm signal
The difference voltage between the first and second human power signals of 1 becomes the output of the differential amplifier 11.

Therefore, the output voltage of the differential amplifier 11 in the musical tone signal is ■.

1 becomes ■1-V2R3/ (R2+R3), and the fourth
In addition, the rhythm signal output voltage of the differential amplifier 11 is as shown in the graph shown in the figure.

2 becomes V2 V2R2/ (R2+R3),
The graph shown in FIG. 5 is obtained.

The above is an examination of the musical tone signal and rhythm signal voltage without considering the influence of the resistance value R4 of the resistor 15. However, as shown in Figure 5, when the expression pedal is set to the minimum (resistance value R1 is infinite) ), the result is that the rhythm sound also disappears.

Next, when considering the influence of the resistor 15 connected to the first input terminal A of the differential amplifier 11, musical tone signal voltages VAI, VM 'J rhythm signal voltages ■9□, ■ shown in FIGS. 2 to 5 are taken into consideration.
8□, and their differential amplifier output voltage V o 1g
The graphs of V o2 change as shown by the dashed lines.

In particular, in the rhythm signal voltage graphs of ■8□ and ■A□ in Figure 3, when the expression pedal is at its minimum, that is, when the resistance value R□ of the variable resistor 10 is infinite, there is no difference if the resistor 15 is not considered. Since the internal impedance of the dynamic amplifier 11 is considered to be almost infinite, there is no voltage drop due to the resistor 14, and ■8□=■8°, but the resistor 15
When R1 is infinite, ■6° becomes smaller than VB2 due to the voltage drop caused by R2.

Therefore, ■8□−■9° shown in Fig. 5, that is, ■
.

As shown in the broken line graph of 2, when the resistance value R□ is infinite, a residual signal voltage 8 occurs, and even when the expression pedal is set to the minimum, the rhythm signal of the voltage 8 is output from the differential amplifier 11. Can make rhythmic sounds.

As described above, according to the expression circuit of the electronic musical instrument according to this invention, the musical tone signal from the main body is outputted to the first input terminal of the differential amplifier via the volume whose resistance value changes according to the operation of the expression pedal. , the rhythm signal from the rhythm section is output to the second input terminal of the differential amplifier via a resistor, both input terminals are connected via a resistor, and the first input terminal is grounded via the resistor. Therefore, the volume of musical tones and rhythm sounds of electronic musical instruments can be variably controlled so that the amount of change is different, and a certain volume balance is obtained depending on the volume. When set to the maximum value, it has the effect of completely erasing musical sounds while still producing rhythm sounds.

[Brief explanation of the drawing]

Figures 1 to 5 show an embodiment of this invention, Figure 1 is a circuit diagram of an expression circuit, and Figure 2 is a variable resistor 1.
The first musical tone signal of the differential amplifier for the resistance value R1 of 0,
FIG. 3 is a graph showing changes in the second human power terminal voltages vAl and VBl, and FIG.
□! A graph showing changes in VB2, Figure 4 is variable resistor 1
Differential amplifier output voltage of musical tone signal with respect to resistance value R1 of 0. FIG. 5 is a graph showing changes in the rhythm signal differential amplifier output voltage V o with respect to the resistance value R1 of the variable resistor 10.
6 is a conventional expression circuit diagram. 9...Main unit, 10...Variable resistor (volume), 11...Differential amplifier, 12...
...Rhythm section, 13, 14. 15...Resistor, A...First input terminal, B...Second human power terminal.

Claims (1)

[Scope of utility model registration request] a main unit that outputs a musical tone signal in response to a pressing operation on a keyboard;
It is equipped with a rhythm section that automatically outputs a rhythm signal, a volume whose resistance value changes according to the operation of an expression pedal, and a differential amplifier, and the musical tone signal from the main body is transmitted through the volume to the differential amplifier. outputting the amplifier to the first input terminal, outputting the rhythm signal from the rhythm section to the second input terminal of the differential amplifier via the resistor, and connecting both input terminals via the resistor; An expression circuit for an electronic musical instrument, characterized in that the first input terminal is grounded via a resistor.