JPS6042653B2 - reverberation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION It is already known that a reverberation effect can be produced by combining a low frequency signal such as an audio signal with a delayed signal obtained by delaying the low frequency signal by a predetermined amount of time.

Figure 1 shows an example of this, where 1 is an input terminal for low frequency signals such as audio, 2 is an output terminal, 3 is a delay line (signal delay device) inserted between terminals 1 and 2, and 4 is a The amplifier 5 forming the feedback system is a mixer. In this case, the feedback system (first
In the example shown in the figure, by selecting the gain G of the amplifier 4 to be 1 or less, that is, G<1 (in this case, G represents an absolute value; the same applies hereinafter), this circuit system operates stably without oscillation, and the input For example, when applying a -cycle length signal S to terminal 1,
As shown in FIG. 2 at the output terminal 2, it is possible to obtain a signal that is sequentially repeated while holding the time T and is attenuated. In this case, the reverberation time, that is, the time T until the original signal becomes -60 dB (referred to as reverberation time), is T■ -60T/
It is expressed as 2010gG (where T is the delay time of delay line 3).

For example, if G■0.7 and T=100ms are selected, T=
It will be 2 seconds. In general, in order for sound to be perceived as reverberation, it is necessary to have a large number of output signals per unit time, that is, to have a high density. Incidentally, reverberant sound obtained in the general natural world such as an actual viewing room, a concert hall, or a reverberation room has a property that the reverberation time is long in a low frequency band and short in a high frequency band.

In view of the above-mentioned points, the present invention is designed to generate reverberation effects that approximate the reverberation characteristics of the natural world. An example of the reverberation device according to the present invention will be described with reference to FIG. 3. Parts corresponding to those in FIG. 1 are given the same reference numerals, and their explanation will be omitted.

That is, as is clear from FIG. 3, at least first and second delay lines 3a and 3b having predetermined delay times Ta and D are provided, and these are connected between input terminal 1 and output terminal 2. connected in series, while the first feedback system 7
A is provided between the output side of the first delay line 3a and the input terminal 1, and a second feedback system 7b is provided between the output terminal 2 and the input terminal 1.

Furthermore, the first feedback system 7a is connected to a first amplifier 4a and a first filter having high-pass characteristics. The second feedback system 7b is configured by connecting the second amplifier 4b and the second filter 6b having low-pass characteristics, and the first feedback system 7b is configured by connecting the second amplifier 4b and the second filter 6b having low-pass characteristics.
In case a, a higher gain can be obtained for a higher frequency input than for a lower frequency input, and for the second feedback system 7b, a higher gain can be obtained for a lower frequency input than for a higher frequency input. On the other hand, when a high gain is obtained and the respective gains of the feedback systems 7a and 7b are Ga and Gb, select so that Ga+Gb is 1 or less for each frequency of the signal passing through each feedback system 7a and 7b. This is what I did. As an example, as shown in FIG. 4, the first feedback system 7a has a gain of 0 below the frequency f1.
The gain increases in the range of f1 to F2, and the gain is set to 0.35 above F2, and the second feedback system 7b
Then, the gain is 0.7 below frequency f1, and f1~F2
Each feedback system 7
By setting the gains Ga and Gb of a and 7b,
The configuration is such that the gain of Ga+Gb is 0.7 when viewed from all frequencies. Note that the delay time γa+τb from input terminal 1 to output terminal 2 when feedback systems 7a and 7b are not connected
is equal to the delay time τ in the case of FIG. 1, and therefore τa+
γb=τ, for example, τa=τb=50Tr
L. Second. According to such a configuration, the first delay line 3a - the first amplifier 4a - the first filter 6a - the mixer 5
Considering a system including only the first delay line 3a, the signal (
When one cycle of the frequency F2 or higher is applied to the input terminal 1, the output side of the first delay line C is
A signal Sa shown in is obtained.

In this case, the reverberation time Ta is Ta=-60τa/2010
It becomes gGa. Since τa is selected to be 507n, seconds, the density of this signal Sa is 2 in the case shown in Figure 2.
In addition, the reverberation time Ta becomes approximately 112 times the reverberation time T in the case of FIG. On the other hand, considering a system consisting of only the first delay line 3a, second delay line 3b, second amplifier 4b, second filter 6b, mixer 5, and first delay line 3a, the signal (frequency f1 or lower) When one cycle of the delay line 3b is applied to the input terminal 1, an output Sb shown in FIG. 5B is obtained at the output side (output terminal 2 in this example) of the second delay line 3b.

In this case, the reverberation time n is Tb'. −60(τa+τb)
/2010gGb. And τa+γb is 100r
Since rL, seconds is selected, the reverberation time of this signal Sb is the same as in FIG. Therefore, high frequency signals have a high density and a relatively short reverberation time, while low frequency signals have a relatively long reverberation time, resulting in a reverberation effect close to that of the natural world. . The closed loop including the low-pass filter (second filter) 6b has two delay lines 3a and 3b, and as is clear from FIG. teeth,
Since the gain Gb of the feedback system 7b is larger than the gain Ga of the feedback system 7a in a high frequency band (band higher than F2), the reverberation time Tb becomes large, while the high-pass filter (
The closed loop including the first filter 6a has only one delay line 3a, and as is clear from FIG. 4, in the high frequency band (band higher than F2), the gain Ga of the feedback system 7a is a low frequency band (f is a low band)
Since the gain Gb of the feedback system 7b is smaller than the gain Gb of the feedback system 7b in
).

Note that since two feedback systems are connected between the input and output terminals, as the reverberation time becomes longer, the number of signals per unit time increases. Note that the first and second delay lines 3a and 3b are packet precade devices or charge devices, respectively.
A charge transfer device called a coupled device can be used, and in reality, the first and second delay lines 3a and 3b are formed as one piece, and by drawing out a lead line from the middle part of the first and second delay lines 3a and 3b, as shown in FIG. The equivalent circuit is shown in .

It is well known that when a charge transfer device is used, the delay times τa and τb are determined by the repetition frequency of the clock pulse that drives the charge transfer device and the number of unit circuits (bits) constituting the device. The example shown in Figure 3 is the case where two feedback systems are provided, but if three feedback systems are similarly provided, the characteristics 6a and 6b as shown in Figure 6 will be obtained.
It will be obvious that a filter (not shown) having a filter and a filter 6c may be used.

Note that the illustrated numerical values are just examples, and the present invention is not limited thereto. FIG. 7 shows another embodiment of the present invention. In the embodiment described above, the first feedback system 7a is provided between the output side of the first delay line 3a and the input terminal 1. On the other hand, in this example, the first feedback system 7a is provided between the output terminal 2 and the input side of the second delay line 3b, and the effect is the same as in the above case. From here on, corresponding parts are given the same reference numerals and their explanations will be omitted.

According to the present invention described above, since the signals applied to the input terminal 1 can be sequentially delayed by a predetermined period of time and sequentially attenuated to be obtained at the output terminal 2, it is of course possible to obtain a reverberation effect. However, in this case, according to the present invention, it is possible to include a large number of signals per unit time in a high frequency band in the signal obtained at the output terminal 2, and to shorten the reverberation time. , the reverberation time can be lengthened in a low frequency band, that is, the reverberation effect can be made to approximate that of the natural world.

[Brief explanation of drawings]

Figure 1 is a block diagram showing an example of a conventional reverberation device;
3 is a block diagram showing an example of a reverberation device according to the present invention, FIG. 4 is a characteristic curve diagram of the filter, and FIG. 5 is a waveform diagram for explaining its operation.
FIG. 6 is a characteristic curve diagram of a filter according to another embodiment, and FIG. 7 is a block diagram showing still another embodiment of the reverberation device according to the present invention. 1 is a signal input terminal, 2 is an output terminal, 3a, 3 and b are delay lines, and 6a, 6b are filters.

Claims (1)

[Claims] 1 At least first and second delay lines each having a predetermined delay amount are connected in series between the input terminal and the output terminal,
A first feedback system is provided between the output side of the first delay line and the input terminal, or between the output terminal and the input side of the second delay line, and a first feedback system is provided between the output side of the first delay line and the input terminal. A feedback system is provided between the output terminal and the input terminal, the first feedback system is configured by connecting a first amplifier and a first filter having high-pass characteristics, and the first feedback system is configured by connecting a first amplifier and a first filter having high-pass characteristics. The second feedback system is configured by connecting a second amplifier and a second filter having low-pass characteristics, and the first feedback system receives a high frequency input as compared to a low frequency input. The second feedback system can obtain a higher gain for low frequency input than for high frequency input, and the sum of the absolute values of the gains of each feedback system can be calculated as follows: A reverberation device characterized in that the reverberation frequency is selected to be 1 or less for each frequency of a signal passing through each feedback loop.