JPS6133410B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a tone control circuit that can adjust the treble and bass levels as desired relative to the midrange level with a single operating knob. The simplest tone control circuit is one that raises and lowers the treble level by changing the direction of rotation of a single operating knob to the left and right, thereby achieving the frequency characteristics of tone L or tone H. In this type of tone control circuit, when emphasizing high tones (tone H), the high tones are raised higher than other levels as shown in Figure 1b, but when emphasizing low tones (tone H), the high tones are raised higher than the other levels. Since setting the level lower than other levels only makes the bass level appear relatively high, tone control that simultaneously changes bass and treble, for example, tone H and tone L, is impossible. In contrast,
The tone control circuit is equipped with operation knobs (volumes) for adjusting bass and treble, allowing tone control to independently set the bass and treble levels above and below the intermediate level, as shown in Figure 2. It is possible to realize the frequency characteristics of tone H and tone L that simultaneously emphasize bass and treble as shown in FIG. However, in this case, it is necessary to use two independent operation knobs for bass and treble adjustment, so when applying to small, multifunctional audio equipment such as an autoradio that is integrated with a tape deck, it is necessary to use two operation knobs. There are often design issues regarding installation space and operability. By the way, when we examine the actual state of tone control operation, we find that people who like treble will raise the treble, people who like bass will raise the bass, and people who want to produce both treble and bass will emphasize these. They can be broadly categorized, and if they are equipped with these functions, they can almost satisfy the tone control requirements. The present invention has been made focusing on such points,
This provides a tone control circuit that can emphasize bass, treble, and high-bass sounds with a single operation knob. The present invention provides a first resistor connected between an input end and an output end, a variable resistor whose both ends are grounded via a low frequency capacitor, and whose sliding end is directly grounded, and the variable resistor. a second resistor connected between one end and the output end; a third resistor connected between the input end and an intermediate tap of the variable resistor; and a third resistor connected between the intermediate tap and the output end. and a treble range capacitor connected between the variable resistor, and the frequency characteristics of the treble range and the bass range are changed by changing the sliding end position of the variable resistor. However, this will be explained in detail below with reference to the illustrated embodiment. When the variable resistor is a rotary type and its rotation angle is changed, the tone control circuit changes the bass range L, middle range M, and high range H at the same time.
If each level becomes as shown in the characteristic curve of FIG. 3, the frequency characteristics at rotation angles A, B, and C become as shown in FIG. 4, a, b, and c, respectively. All of these exhibit typical characteristics, and of course there are intermediate characteristics between them. As shown in Figure 3, while changing the rotation angle from A to B, the midrange M remains constant.
The bass range L is made to drop slightly, the treble range H is made to drop significantly, and while the rotation angle is changed from B to C, the middle range M is kept constant, and the bass range L is further reduced.
If the treble range H rises rapidly again, it becomes clear from Figure 4 that the characteristics L, H, and M at each point A, B, and C in Figure 3 are plotted on the frequency vs. level coordinate plane. Characteristics a, b, and c can be obtained, and almost all tone control requirements can be satisfied. FIG. 5 shows an embodiment of the tone control circuit of the present invention exhibiting such characteristics, and shows an input terminal E _i (this symbol E _i will also be used as an input voltage below) and an output terminal E _p (same as above). (This symbol is also used as the output voltage) A first resistor R ₁ is connected between the output voltage and the output voltage. R _y is a rotary type (or slide type) variable resistor, and both ends thereof are grounded via capacitors C _l and C _l for low frequency range. One end of the variable resistor R _v is connected to the output end E _p via the second resistor R ₂ , and the sliding end S is grounded. The intermediate tap T of the variable resistor R _v is connected on the one hand to the input end E _i via the third resistor R ₃ and on the other hand to the output end E _p via the treble range capacitor _Ch . Both end positions A and C of variable resistor R _v and intermediate tap T
The positions B corresponding to 1 and 2 correspond to the rotation angles shown in FIG. Capacitor C _h has an effect in the high frequency range,
Furthermore, the capacitor C _l has an influence on the low frequency range, and is selected to have a value that satisfies the conditions of the following formulas. However, ω _n is an angular frequency in the middle and high range.

[Table] 〓……(1)
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Claims (1)

[Claims] 1. A first resistor connected between the input end and the output end, a variable resistor whose both ends are grounded via a low frequency capacitor, and whose sliding end is directly grounded, and one end of the variable resistor. a second resistor connected between the output terminal and a third resistor connected between the input terminal and an intermediate tap of the variable resistor;
A treble range capacitor is connected between the intermediate tap and the output end, and the frequency characteristics of the treble and bass ranges are adjusted by changing the sliding end position of the variable resistor. A tone control circuit characterized by: