JPS583240B2 - Electronic reverberation adding device - Google Patents

Description

[Detailed description of the invention] The present invention relates to improvements in electronic reverberation adding devices.

Conventional electronic reverberation adding devices are, for example, charge-coupled devices, as shown in the block diagram of Figure 1.
The output signal of a delay circuit 1 such as a device) is input to an attenuator 2 and attenuated, and the source input signal applied to the input terminal IN and the output signal of the attenuator 2 are added or subtracted and then applied to the delay circuit 1. , delayed by delay circuit 1 and delayed by delay circuit 1
Reverberation was obtained from the output end of the

Note that OUT is the output terminal of the electronic reverberation adding device.

The transfer function of the electronic reverberation addition device described above is given by {exp(− jω
Δt)}/{1±g·exp(−jωΔt)}, and the absolute value of this transfer function is.

As is clear from the above, the absolute value shown by equation (1) is n/2Δt(H
m/2Δω (Hz) when there is negative feedback at the frequency of
It has a maximum value at the frequency of .

That is, the transmission amplitude characteristic of the electronic reverberation adding device shown in FIG. 1 shows equally spaced peak characteristics.

However, m: even number, n: odd number.

This means that if reverberation is added using the above-mentioned electronic reverberation adding device, a characteristic timbre is added, resulting in so-called coloration.

Therefore, as shown in FIG. 2, attenuators 3 and 4 are further added to the electronic reverberation adding device shown in FIG. 1, and the output signal of the electronic reverberation adding device shown in FIG. input, while the source input signal is input to attenuator 4, and attenuator 3
There is an electronic reverberation adding device that subtracts the output signal of the attenuator 4 from the output signal of the electronic reverberation adding device to obtain the output signal of the electronic reverberation adding device, thereby avoiding changes in timbre.

Note that the gain of the attenuator 3 is 1 to g.The gain of the attenuator 4 is g.

1 The transmission amplitude frequency characteristics of this electronic reverberation addition device are flat, and the device is a non-coloration type reverberation addition device as a whole.

In this case, the reverberation time is determined by the gains g of the attenuators 2 and 4 and the delay time Δt of the delay circuit 1, and the reverberation energy density depends only on the gain g.

Therefore, in order to change the reverberation characteristics such as the reverberation time, it is sufficient to change the delay time Δt and the gain g.

However, when changing the gain g, the attenuators 2, 3 and 4
The ratio of the gains (g:1-g2:g) must always be kept constant.

If the gain ratio is disrupted, the transmission amplitude frequency characteristic will no longer be flat, but will have a peak-dip characteristic, and the non-coloration characteristic will collapse.

For example, in the case of gain g=0.71, in order to keep the deviation of the transmission amplitude characteristics within 1 dB, the error in gain g should be set to 0.71.
Must be kept within 0.04dB.

The components of the attenuator are primarily resistors.

Therefore, when considering the size of the variation in resistance values,
The electronic reverberation adding device shown in FIG. 2 has a drawback in that it is extremely difficult to vary the gain g while maintaining desired transmission amplitude frequency characteristics.

The present invention has been made in view of the above, and it is an object of the present invention to provide an electronic reverberation adding device that eliminates the above-mentioned drawbacks.

The present invention will be explained below using examples.

FIG. 3 is a block diagram of an electronic reverberation adding device according to an embodiment of the present invention.

In FIG. 3, 1 is a delay circuit, 2 is an attenuator, and 5 to 8 are adders.

An electronic reverberation adding device according to an embodiment of the present invention has an input terminal I
The source input signal e1 input to N is added to the output signal e3 of the delay circuit 1 in the adder 5, and the output signal e5 of the adder 5 is input to the adder 6 and to the attenuator 2. The output signal e4 is sent to the adder 7 in the adder 7.
The output signal e5 of the adder 5 and the output signal e4 of the attenuator 2 are input to the adder 6. Addition or subtraction is performed, and the adder 8 subtracts the source input signal e1 from the output signal e6 of the adder 6, so that the output signal e7 is obtained from the output end of the adder 8.

Note that OUT is the output terminal of the electronic reverberation adding device.

In the above, when the output signal e4 of the attenuator is subtracted in the adder 7, the adder 6 is added, and when the output signal e4 is added in the adder 7, the adder 6 is subtracted.

Here, the former case is called a negative feedback case.

In the present embodiment shown in FIG. 3, the impulse response of the electronic reverberation adding device in the case of negative feedback is as shown in FIG. 4.

In FIG. 4, the interval between each pulse is the delay time Δt of the delay circuit 1. In FIG.

g is the gain of the attenuator 2 and satisfies 0≦g<1.

Next, between the signals of each part of the electronic reverberation adding device configured as above, e7=e6-e1......(2) e6=e5±e4......(3) e=e1+e3......(4) ) e4=g・e5……(5) e3=A・e2……(6) e2=e1±e4……(7) There is a relationship as follows.

Here, A is exp(-jωΔt).

Therefore, e7=(1±g)(e1+Ae2)-e1...
(8) e2=(1±g)e1/(1±gA)...(9)
Then, the transfer function e7/e1 of this electronic reverberation adding device is
From equations (8) and (9), {±g+exp(-jωΔt)}/{1±g・exp(
−jωΔ1)}.

Therefore, the absolute value of this transfer function is becomes.

That is, the amplitude transfer rate is constant regardless of the frequency of the input signal, the gain of the attenuator 2, and the delay time of the delay circuit 1.

Further, the reverberation time is given by (-3Δ1)/logg.

As explained above, according to the present invention, the transmission amplitude frequency characteristic of the electronic reverberation adding device is flat regardless of the delay time of the delay circuit and the gain of the attenuator, and has non-coloration characteristics, and its configuration is easy.

Furthermore, when changing acoustic characteristics such as reverberation time, there are no components that must be changed while maintaining a constant relationship with each other, and the changes are easy.

Further, in this case, no disturbance occurs in the transmission amplitude frequency characteristics.

[Brief explanation of drawings]

FIGS. 1 and 2 are block diagrams of a conventional electronic reverberation adding device. FIG. 3 is a block diagram of an electronic reverberation adding device according to an embodiment of the present invention. Figure 4 shows the impulse response characteristics of the electronic reverberation addition device shown in Figure 3. 1... Delay circuit, 2, 3 and 4...
Attenuator, 5, 6.7 and 8... Adder.

Claims (1)

[Claims] 1 comprising at least a delay circuit and an attenuator, the source input signal applied to the input terminal is added to the output signal of the delay circuit to obtain a first signal, and the first signal is input to the attenuator. , the output signal of the attenuator is added to or subtracted from the source input signal and input to the delay circuit, and the output signal of the attenuator is subtracted from the fourth signal or the first signal. An electronic reverberation adding device characterized in that the source input signal is subtracted from the second signal, and the source input signal is subtracted from the second signal to obtain an output signal.