JPS5926386Y2 - reverberation device - Google Patents

Description

[Detailed description of the invention] The present invention uses a delay element consisting of an analog shift register (BBD or CCD) or a digital shift register (digital shift register, etc.) to delay an input signal and convert the resulting output signal into the input signal. This invention relates to an improvement in a so-called reverberation device that can produce a reverberation effect by mixing.

FIG. 1 is a circuit block diagram showing a conventional example of a reverberation device.

1 is an input signal terminal, 2 is a low-pass filter for removing false signals, 3 is a mixer, 4 is a delay element such as a BBD, CCD, or a digital shift register, and 5 is a feedback signal from the delay element 4 to the mixer 3. 6 is a clock signal oscillator consisting of a variable frequency oscillation circuit, 7 is a clock signal supply line, 8 is an operator of a control means for controlling the oscillation frequency of the clock signal oscillator, 9 is a clock frequency component A low-pass filter for removal, 10 an amplifier, and 11 an output signal terminal.

In such a configuration, the audio signal or musical tone signal input to the input signal terminal 1 passes through the low-pass filter 2 for removing false signals and the mixer 3 and reaches the delay element 4.
The delayed audio signal or musical tone signal appearing as the output signal of the delay element 4 is fed back to the mixer 3 via the signal line 5, and the delayed signal is mixed with the undelayed audio signal or musical tone signal to produce a low frequency signal. By mixing the signal obtained at the output side of the pass filter 9 and the signal separately input to the amplifier 10 from the input signal terminal 1 and obtained at the output side of the amplifier 10, reverberant sound is produced from the output signal terminal 11. It is well known that it is possible to obtain an audio signal or a musical tone signal having the acoustic effect of a voice or musical tone accompanied by a reverberation effect, and to control how the reverberation effect is applied by operating the operator 8.

Now, when a sine wave signal with a frequency close to the frequency of the clock signal as shown in Figure 2A is applied to the input signal terminal 1, the signal waveform obtained as the output of the delay element 4 is as shown in Figure 2A. It is exactly the same as the staircase waveform C obtained as the output of the delay element 4 when the signal shown by the dotted line in A is applied to the input signal terminal 1, and both of the steps applied to the input signal terminal 1 are Unable to distinguish between human signals.

Therefore, in order to prevent the mixing of frequency components such as the sine wave signal, which would cause the result as if a fake signal shown by the dotted line in Fig. 2A had been input, the frequency of the clock signal supplied to the delay element should be changed. A low-pass filter 2 whose cutoff frequency is a specific frequency of approximately % or less is connected to the input signal terminal 1 and the mixer 3.
It is interposed between.

In FIG. 2, the horizontal axis shows time and the vertical axis shows the amplitude of the signal waveform.

Further, the staircase waveform C is a waveform of a voltage to be held in each stage of the analog or digital shift register constituting the delay element 4 by sampling the sine waveform A at every cycle of the clock signal.

On the other hand, on the output side of the delay element 4, when the input signal of the delay element 4, which is indicated by the dotted line in FIG. A waveform appears.

In this figure, the horizontal and vertical axes are the same as in FIG. 2.

Therefore, since the output waveform appearing at the output signal terminal 11 includes a clock frequency component, in order to remove this component and prevent noise from entering other electronic circuits, a specific frequency that is approximately % or less of the clock frequency is set as the cutoff frequency. A low-pass filter 9 for removing clock frequency components is interposed between the delay element 4 and the output signal terminal 11.

In such a conventional configuration, when the operator 8 is operated to change the frequency of the clock signal supplied from the clock signal oscillator 6 to the delay element 4 through the clock signal supply line 7, an input that causes a false signal to the delay element 4 is generated. The frequency of the signal and the frequency of the clock signal component contained in the output signal of the delay element 4 also change accordingly.

Therefore, the cutoff frequencies of the low-pass filter 2 for removing false signals and the low-pass filter 9 for removing clock frequency components must be set to approximately % or less of the lowest clock frequency.

Setting the cutoff frequencies of both filters in the low frequency range as described above is important because when the clock frequency becomes high, the pass frequency band of the entire system is limited by the pass band of both filters, so the audio signal Otherwise, the fidelity of the musical tone signal was compromised, which was a major drawback.

In order to eliminate the above-mentioned drawbacks, this invention has a reverberation system in which the cut-off frequencies of the low-pass filter 2 for removing false signals and the low-pass filter 9 for removing clock frequency components are changed according to the frequency of the clock signal. It provides equipment.

FIG. 4 is a circuit block diagram of a reverberation device showing one embodiment of this invention.

101 is a human input signal terminal, and 102 is a voltage-controlled low-pass filter for removing false signals, the cut-off frequency of which changes according to the voltage value supplied to the filter.

103 is a mixer, 104 is a delay element, and 105 is a signal line, which correspond to 3, 4, and 5 in FIG. 1, respectively.

106 is a variable frequency clock signal oscillator; 107 is a clock signal supply line that supplies the output signal of the variable frequency clock signal oscillator 106 to the delay element 104; 108
109 is a voltage-controlled low-pass filter for removing clock frequency components, and 109 is a voltage-controlled low-pass filter for removing clock frequency components.
Its cutoff frequency changes according to the voltage value supplied to the filter 109.

110 is an amplifier, and 111 is an output terminal.

112 is a variable resistor configured to operate in conjunction with the operator 108, and is connected to the voltage-controlled low-pass filter 10.
2 and 109. 113 and 114 supply the control voltage set by the variable resistor 112 to the voltage-controlled low-pass filters 102 and 109, respectively. This is a control voltage supply line.

For example, if we adjust and control the operator 108 to obtain a clock signal as shown in Figure 5 as the output signal of the variable frequency clock signal oscillator 106, the variable resistor 112 is linked to the operator 108, The variable resistor 112
A control voltage as shown in FIG. and a voltage-controlled low-pass filter 109.

Therefore, depending on the frequency change of the clock signal supplied to the delay element 104, the cutoff frequencies of the voltage-controlled low-pass filter 102 for removing spurious signals and the voltage-controlled low-pass filter 109 for removing clock frequency components simultaneously change as shown in FIG. It changes as shown below.

In FIG. 5, the horizontal axis is time.

Normally, it is effective to set the frequency of the clock signal supplied to the delay element 104 to 5KH2 to 10KH2, but if the frequency of the clock signal is 5KH2, the voltage control low frequency band for removing false signals It is clear from the function of the conventional low-pass filter for removing false signals that the cutoff frequency of the pass filter 102 should be 2.5KH2 or less.

Therefore, the cutoff frequency of the low-pass filter 102 is set to be less than % of the frequency of the clock signal by the control voltage set by the variable resistor 112.

At the same time, the cutoff frequency of the low-pass filter 109 is also less than % of the frequency of the clock signal.

Furthermore, since it is easy to set the control voltage of the low-pass filter 109 to a different value from the control voltage of the low-pass filter 102, it is possible to make the cut-off frequencies of both the low-pass filters 102 and 109 different from each other. is possible.

Therefore, if the frequency of the clock signal supplied to the delay element 104 becomes higher than 5KH2 by operating the operator 108 to change the delay time of the delay element 104, the low-pass filters 102 and 109 As mentioned above, each cut-off frequency of is also increased.

As described above, the reverberation device according to this invention consists of a voltage-controlled low-pass filter for removing spurious signals connected to the input side of a delay element such as an analog or digital shift register, and a clock connected to the output side of the delay element. Since the cut-off frequency of the voltage-controlled low-pass filter for frequency component removal can be changed according to the frequency of the clock signal supplied to the delay element, even if the frequency of the clock signal becomes high, it can still pass through the entire system. Since a sufficient passband width is secured for the signal to be transmitted, the fidelity of the audio signal or musical tone signal can be maintained at a good level.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram showing a conventional example of a reverberation device. ]...Input signal terminal, 2...Low pass filter for removing false signals, 3...Mixer, 4...Delay element, 5...
- Signal line, 6... Clock signal oscillator, 7... Clock signal supply line, 8... Operator, 9... Low pass filter for removing clock frequency component, 10... Amplifier,
11...Output signal terminal. FIG. 2 shows the relationship between input signals and false signals. FIG. 3 shows the relationship between the output signal and the clock frequency component, and FIG. 4 is a circuit block diagram of a reverberation device showing an embodiment of this invention. 101 to 111 correspond to 1 to 11 in FIG. 1, respectively. 112... Variable resistor, 113.114... Control voltage supply line. FIG. 5 shows the relationship between clock signal frequency versus control voltage and cutoff frequency of a voltage controlled low pass filter.

Claims (1)

[Scope of utility model registration request] A voltage-controlled low-pass filter for removing false signals is connected to the input side of a delay element extracted from an analog or digital shift register, etc., and a voltage-controlled low-pass filter for removing clock frequency components is connected to the output side of the delay element, An operator of a control means for controlling the frequency of a clock signal supplied to the delay element, and a variable resistor interlocked with the operator,
A reverberation device characterized in that a control voltage supplied to each of the voltage-controlled low-pass filters is adjusted and controlled by the variable resistor.