JPS589440B2 - Electronic musical instrument sound source device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sound source device for an electronic musical instrument that forms harmonic components using frequency modulated sideband waves to produce good performance musical sounds.

The sound source signal in an electronic musical instrument uses an oscillation signal from an oscillator, and by making the sound source signal into, for example, a square wave, a triangular wave, etc., the content of overtones can be set to form an effective musical sound. It is something that exists.

However, with such means, the types of harmonics involved,
There are limits to the states, etc., and even the timbre tends to be in a specified state, making it difficult to produce musical tones that are rich in variety and musicality.

As a means to improve these drawbacks, it is possible to frequency-modulate the sound source signal obtained by key operation with a frequency signal within the audible frequency band, and use the sideband waves generated by this modulation as harmonic components. It is considered.

For example, a pitch signal (KV) with a voltage value corresponding to the pitch of the operated key is generated in the keyboard section as a key is operated, and the level of this pitch signal (KV) is adjusted as shown in Figure 1. The voltage signal (KV) is generated by converting the level in the converter 11.

This voltage signal (KV') drives and controls a voltage-controlled variable frequency oscillator 12 (hereinafter abbreviated as vCO) to generate a frequency signal having a frequency close to the pitch of the operation key,
This frequency signal is supplied to the adder circuit 13 together with the pitch signal (KV) and added.

That is, from this adder circuit 13, the pitch signal (KV)
A voltage signal that oscillates with the frequency signal from the VCO 12 is output based on the VC that generates the sound source signal.
A control drive signal is supplied to O14.

In other words, the VCO 14 generates a sound source signal that is frequency-modulated with the frequency signal in the audible frequency band from the VCO 12 based on the frequency of the pitch signal (KV), and the frequency of this sound source signal is The pitch is the pitch signal (KV
), it is in a state in which a large number of sideband signals generated by frequency modulation by the frequency signal from the VCO 12 are contained as harmonic components.

However, in a sound source device having such a configuration, if the modulation index m of the frequency modulation is increased and the modulation signal amplitude is made larger than the pitch signal (KV), the output from the adder circuit 13 as shown in FIG. Part of the output signal is VCO14
The voltage falls below a specific voltage (for example, Ov) required to drive the VCO 14, during which time the VCO 14 becomes unable to oscillate.

This invention was made in view of the above points, and even when the amplitude of the frequency modulation wave for the vCO that oscillates the sound source signal becomes large, the sound source signal can be effectively modulated and harmonics due to sidebands can be eliminated. The present invention aims to provide a sound source device for an electronic musical instrument that is capable of expressing effective performance musical tones by controlling the signal generation state. The feature is that the signal components below the level of the signal are folded back.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 shows its configuration, in which a keyboard section (not shown) generates a pitch signal Vref of a voltage corresponding to the pitch of the operated key as a key is operated, and this pitch signal Vr
One of the signals ef is applied to the adder circuit 13, and the other signal is appropriately amplified by the amplifier 15, transformed into a voltage signal Vref' corresponding to Vref by the level adjuster 16, and applied to the VCO 12 as a control signal.

The oscillation frequency signal from this VCO 12 is then supplied to the adder circuit 13 and added to the signal V r e f.

In this case, the VCO 12 generates a frequency signal within the audible frequency band that corresponds to the pitch of the operating key, and the adder circuit 13 generates vibrations around the signal V r e f in response to the frequency signal from the VCO 12. A signal is obtained.

The output signal from this adder circuit 13 is supplied to a folding circuit 17, and the output signal from this folding circuit 17 is supplied to a VCO 14, which causes the VCO 14 to oscillate a sound source signal.

In other words, VCO 12 for pitch signal V r e f
When the frequency signals from the OV are added together, the state shown in FIG. 2 is obtained. However, if the folding circuit 17 folds back the signal below OV so that it appears on the positive side, the signal is supplied to the VCO 14. The resulting signal is as shown in FIG.

This figure shows a case where the amplitude m of the modulation signal with respect to the sound source signal generated by the VCO 14 is made sufficiently large, and the part of the added output signal from the adder circuit 13 that is lower than Ov is folded back to the positive side. The signal shown by the solid line is supplied to the VCO 14 as an oscillation control signal.

Here, there is no output signal from VCO 12 and the VCO
Output musical tone signal f from 14.

When no modulation is applied to (1), if Q(t) = ω1 = K-vref, then (Ω(t)... instantaneous angular frequency, K... proportionality constant) fo (t) - A1 cos ω11 ・・
...(1) (A1 . . . amplitude of output musical tone signal).

Moreover, in a state with no folding and modulation, Ω(t
) − K−Vre f + K−A2 COSω2t(
ω2...Modulation signal angular frequency, A2...Modulation signal amplitude).

However, m is a modulation index. Furthermore, when there is a turnaround, fo(t)=Atcos(fot(K-Vref
K-A2Cos(cJ2t)dt}= A 1COS
(1(ω1t+mSinω2t)) =-(3
).

Comparing the time when equation (2) is not folded and the time when equation (3) is folded in the above modulated state, we get
Equation (3) is exactly the same as the negative angular frequency defined in Equation (2).

In other words, the spectral distribution is folded around "0", and the generated sound, which is composed of harmonic components due to sideband waves, can be perceived as unchanged audibly, with only a simple phase shift.

Therefore, it is possible to make the modulation index m sufficiently large by increasing A2.

In other words, a sound source signal with a sufficiently high harmonic content is generated, and a performance musical sound with rich timbre can be effectively expressed.

FIG. 5 shows the above-mentioned embodiment in further detail, in which the pitch signal Vref is generated from the keyboard circuit 18 in correspondence with the pitch of the operated key, and from this keyboard circuit 18, the pitch signal Vref is further generated in accordance with the pitch of the operated key. Keying signal KON related to key release key action
is generated.

The output frequency signal from the VCO 12 driven by the voltage signal Vref' formed based on the pitch signal Vref is applied to the waveform conversion circuit 19, and is converted into a sine wave, a square wave, and a sawtooth wave signal, respectively. The resulting sinusoidal frequency signal is used as the above-mentioned frequency modulation signal.

This sinusoidal frequency signal is guided to a voltage-controlled variable gain amplifier 20 (hereinafter abbreviated as VCA).

This VCA 20 is gain-controlled by the voltage signal Vref', and increases the amplitude of the frequency signal as the pitch increases.

This is because the frequency of the modulated sound source signal increases exponentially as the scale rises, so the amplitude of the modulated signal is increased accordingly, so that the same modulation is performed in different key ranges.

The frequency signal obtained from the VCA 20 in this way is
It is supplied to the desymmetrization circuit 21.

This circuit 21 transforms the waveform of the vertically symmetrical sine wave signal obtained from the VCA 20 so that it becomes larger on the upper side and smaller on the lower side.

This is because when the VCO 14 generates a sound source signal, the input control voltage is set to change exponentially in response to changes in the pitch of the output sound source signal, so the modulation signal that vibrates up and down also changes accordingly. The top and bottom are not symmetrical.

In this case, if the VCO 14 is configured so that the oscillation frequency changes exponentially with respect to the input voltage, and the input voltage changes linearly with respect to changes in pitch, this asymmetry circuit 21 is necessary. I don't.

The frequency signal obtained from this asymmetry circuit 21 is supplied to the adder circuit 13 via the VCA 22.

The gain of the VCA 22 is controlled by an envelope signal from an envelope generation circuit 23 which is controlled by the keying signal KON.

The envelope generating circuit 23 generates a waveform signal whose voltage value changes over time, rising when a key is pressed and decaying and falling when a key is released. Condition signals such as level and decay time constant are set as voltage signals by a control waveform setting section (not shown), and the condition signals are applied to the VCA 22 as indicated by the arrow.

In this VCA 22, the amplitude envelope of the modulation frequency signal applied to the adder circuit 13 is set in response to key operations, the degree of modulation is variably set over time, and the state of the timbre of the performance musical sound is adjusted at the rise of the musical sound. , it is made to change according to the state of attenuation, making it rich in expressiveness.

The signal obtained by the adder circuit 13 is supplied to an absolute value circuit 24.

This absolute value circuit 24 corresponds to the folding circuit 17, and is configured as shown in FIG.

In FIG. 6, the input signal Vin is given from the adder circuit 13, and when Vin≧0, the diode D
1 is on and D2 is off.

Therefore, VA-Vin becomes.

On the other hand, in the state of Vin≦0, the diode D1
is turned off and D2 is turned on, so that vA=o, and as shown in FIG. 4, an output signal Vout in which the signal components below Ov are folded back can be obtained.

Then, with the output signal from this absolute value circuit 24, the VCO1
4 is controlled and driven to obtain a sound source signal output which is frequency modulated with an audio frequency band signal from the VCO 12 and sufficiently contains harmonic components due to sideband waves thereof.

One of the square wave and sawtooth wave output frequency signals from the waveform conversion circuit 19 is taken out as a sound source signal of another series by a switch 30, and a voltage-controlled variable filter 25 (hereinafter abbreviated as VCF) is used. to form the tone.

In this case, the VCF 25 is controlled by an envelope waveform signal generated based on the key-on signal KON from the envelope generation circuit 26, and effectively modulates the timbre to form the tone, and the musical tone signal obtained from the VCF 25 is Mixing the signal generated by the VCO 14 with the mixing circuit 27,
Supplied to VCA28.

This VCA 28 is gain-controlled by an envelope signal from an envelope generating circuit 29 corresponding to the key-on signal KON, performs open/close envelope control on the mixed musical tone signal from the mixing circuit 27 in response to key operations, takes it out as an output signal, and outputs the output musical tone. The signal is led to a speaker unit (not shown) and is produced as a performance sound.

Furthermore, all the folding circuits described above have been described so as to invert a negative input signal to the positive side.

However, if it is preferable to output a negative signal from the folding circuit due to a circuit design problem, the positive signal may be folded back to the negative side.

As described above, according to the present invention, by frequency modulating the sound wave signal generated by the vCO with a signal within the audio frequency band corresponding to other pitches, a performance containing harmonic components can be effectively achieved. It enables musical tones to be obtained, and in particular, even when the degree of modulation is increased to increase harmonic components, musical tones can be effectively formed, and it improves the performance of musical tones of electronic musical instruments. This has an extremely large effect on improvement.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining a conventional sound source device, FIG. 2 is a diagram for explaining an example of a modulation state in the conventional example, and FIG. 3 is a diagram for explaining a sound source device according to an embodiment of the present invention. FIG. 4 is a diagram showing the state of the modulation signal of the above embodiment, FIG. 5 is a diagram showing a further embodiment of the above embodiment, and FIG. 6 is a diagram showing a specific example of the absolute value circuit of the apparatus shown in FIG. be. 12, 14...variable frequency oscillator, 17...folding circuit, 24...absolute value circuit.

Claims (1)

[Claims] 1 means for generating a pitch signal with a voltage value corresponding to the pitch of the operating key; a variable frequency oscillator for generating a frequency signal for modulation in the audible frequency band driven by a signal with a voltage value corresponding to the pitch signal; an adder circuit that adds the frequency signal from the oscillator and the pitch signal; a folding circuit that supplies the output signal from the adder circuit and folds back the output signal from the adder circuit based on a specified level; A sound source device for an electronic musical instrument, comprising a voltage-controlled variable frequency oscillator driven by an output signal from a circuit, and a sound source signal is extracted from the oscillator.