JPS59105708A - Loudness control device - Google Patents

Abstract

PURPOSE:To reproduce the sounds of high quality with compensated low and high bands by inserting an equalizer between a preamplifier and a main amplifier and compensating automatically the loudness with mutual function between the equalizer and a loudness variable filter circuit provided at the output side of the main amplifier in accordance with the signal level. CONSTITUTION:For an equalizer 2, the equalizer characteristics is set at a differential between an equal loudness curve of the minimum control level and a reference equal loudness curve on the basis of a certain sound pressure level of a Fletcher-Munson loudness contour together with the speaker characteristics taken into consideration. A loudness variable high-pass filter 5a for low band is provided along with a loudness variable resonance circuit for high band consisting of a resistance element R having its value varying by the current, a capacitor C and a coil L connected in parallel to each other. In such a constitution, the loudness is automatically compensated in accordance with the level of the signal.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a loudness control device used in audio equipment such as stereos.

Conventional configuration and problems There is a flexure-Munson curve that expresses the loudness auditory characteristics of humans. This means that when the loudness level is high, the difference in the sense of volume depending on frequency is relatively small and flat, but as the loudness level decreases,
This indicates that it becomes difficult to hear low and high frequencies. There is a loudness control circuit to compensate for this, and FIG. 1 shows a circuit that has been commonly used in the past. In addition, the loudness compensation characteristics of this circuit are
It is shown in the figure.

According to this conventional circuit, the loudness compensation characteristic is fixed even though the reproduced sound constantly fluctuates, and there is a problem in that it cannot cope with transient sound level fluctuations. In addition, the loudness compensation characteristic is close to a loudness curve such as a flexure curve, and because it does not take into account the relationship between the sound pressure level during recording and the sound pressure level during playback, the loudness compensation characteristic may be overemphasized. There was a problem that good cloudiness compensation could not be achieved.

OBJECTS OF THE INVENTION The object of the present invention is to provide a loudness control device that can automatically perform loudness control that matches the auditory characteristics of 8mj.

Structure of the Invention For this reason, the present invention creates an equalizer characteristic between a preamplifier and a main amplifier with an equal loudness curve at a minimum control level and a reference equal loudness curve, based on a sound pressure level that has a certain level of equal loudness. In addition, we inserted an equalizer that takes into account the characteristics of the speaker, and installed a resistor element whose resistance value changes continuously depending on the magnitude of the market value in a part of the network circuit on the output side of the main amplifier. A circuit consisting of a capacitor is provided so that the reproduction output is equalized by the difference between the equal loudness curve of the reproduction level and the reference loudness curve, and when the input pressure is small, the equalizer characteristics are obtained as is, and the input To provide a loudness control device in which as the voltage increases, the low frequency range is cut and the boost amount in the high frequency range is gradually reduced, thereby automatically changing the loudness characteristic to a target characteristic according to the input voltage.

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 6 and 7. In Figure 3, (1) is a preamplifier, (2) is
7. An equalizer that takes into account the sound pressure level with a loudness curve such as 7-retscher-mannnn, so that the equalizer characteristic is the difference between the equal loudness curve of the minimum control level and this standard equal loudness curve, and also takes into account the characteristics of the speaker. The equalizer characteristic here is u, 100(]
, B as the standard, and the characteristics are the difference between the shield loudness curve at a level 33 dB lower than the standard loudness curve. (3) is the main amplifier,
(4a) is a network circuit for low frequencies, and (41)) is a network circuit for high frequencies. (5a) is a variable loudness bypass filter for low frequencies, which is composed of a circuit in which a resistor collector C) whose resistance value changes depending on the current shown in Fig. 4 and a capacitor (C) are connected in parallel. ing.

Therefore, when the input pressure is small, the resistance value of the resistor collector (c) is small, and the color source flows toward the resistor element CR), so #1 hardly acts as a filter, and the equalizer (2)
) can be obtained as is, and as the input pressure increases, the current flows through the resistor ().In fact, the current flows through the capacitor (C) because the resistance value increases. Similarly, it acts as a bypass filter. Therefore, the characteristic is that the low range is cut from around the cutoff frequency. (No. 5 is a variable loudness resonant circuit for high-temperature sound. As shown in Figure 5, the resistor element whose resistance value changes depending on the current is 0), the capacitor (C), and the coil (L) are connected in parallel. Consists of connected circuits. The function of the resistance element (c) is similar. (6a) and (6b) are speakers for bass and treble, respectively.

Incidentally, examples of resistance elements (c) whose resistance changes continuously include regular thermistors, thermistors, varistors, pilot lamps, etc.

FIG. 6 shows the characteristics of the bypass filter (5a).

Furthermore, FIG. 7 shows the characteristics of the loudness control device. Due to this characteristic, loudness correction can be automatically performed depending on the signal level, and sound with corrected image area and high range is reproduced. As is clear from the above explanation, the signal level is determined by the interaction between the equalizer inserted between the preamplifier and the main amplifier and the loudness variable filter circuit on the output side of the main amplifier. The loudness can be corrected automatically according to the size of the sound, and rich sound with corrected high frequencies can be reproduced.

[Brief explanation of the drawing]

Figures 1 and 2 show conventional examples, Figure 1 is a loudness control circuit diagram, Figure 2 is a diagram of four erections, and Figures 6 to 7 are examples of the present invention. , Figure 6 is the hydrofluoric acid Pr of the loudness control device, Figure 4 is the circuit diagram of the bypass filter, Figure 5 is the high resonance circuit diagram, and Figure 6 is the circuit diagram of the bypass filter.
The figure is an inertia diagram of the bypass filter, and FIG. 7 is an inertia diagram of the loudness control device. (1) is a 7゛ reamp, (21Fi, equalizer, (3
) is the main amplifier, (4aX4b) is the network circuit, (58) is the loudness variable bypass filter, (5b
) iJ loudness variable resonant circuit. Figure 1 Figure 2 訃γK (/”/F) Figure 3 Figure 4 Figure 6 Figure 7

Claims (1)

[Claims] Insert an equalizer between the preamp and main amp.
A loudness control device in which a circuit consisting of a resistor element and a capacitor whose resistance value continuously changes depending on the magnitude of the current value is installed as part of the network circuit on the output side of the main amplifier.