JPS61125210A - Integrated amplifier - Google Patents

Abstract

PURPOSE:To prevent sound quality degrading due to induction and lowering in price and to improve the quality by providing an equalizer amplifier amplifying an input signal, a selector switch, a variable resistor, an attenuator, an operation switch and a high gain power amplifier. CONSTITUTION:The standard input is fed to an auxiliary input terminal 3 of the high gain power amplifier 16, a low level signal fed to a record player signal input terminal 1 is amplified by the equalizer amplifier 2 to be matched to the input standards of the power amplifier 16 and a high level signal fed to a main input terminal 7 is attanuated by the attenuator 12 to be matched with the input standards of the power amplifier 16. The gain of the power amplifier 16 in this case is 43dB being the addition of the gain 18dB of a flat amplifier and the gain 25dB of the power amplifier to obtain an output of e.g., 60W. Thus, the sound quality is improved because the flat amplifier is eliminated and cost-down is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an integrated amplifier, and particularly to an integrated amplifier with improved sound quality.

[Prior art]

An integrated amplifier is capable of handling signals supplied from various external devices by having multiple types of input terminals with different input sensitivities. A record player signal input terminal, an auxiliary input terminal of 150 mV/20Ω and a main input terminal of 1.23V/20Ω are provided.

FIG. 3 is a circuit diagram showing an example of an integrated amplifier commonly used in the past, in which the signal supplied to the record player signal input terminal 1 is amplified by approximately 36 dB in the equalizer amplifier 2, and is then input to the auxiliary input terminal. Matches the input standard of terminal 3. After the output signal of the equalizer amplifier 2 and the input signal to the auxiliary input terminal 3 are selected by the select switch 4, the level is adjusted by the volume 5, and further amplified by about 18 dB by the flat amplifier 6. By doing so, the input standard of the main input terminal 7 can be met. On the other hand, a signal supplied to the main input terminal 7 from, for example, a graph ink equalizer (not shown) is supplied to the operation switch 9 after its level is variably adjusted by a volume 8 of 20Ω. The operation switch 9 selects and outputs the output signal of the flat amplifier 6 and the output signal of the volume 8. The output signal of the operation switch 9 is
The signal is amplified by, for example, 25 dB in the power amplifier 10, and is supplied as a maximum 21.9 V (60 W) signal to a speaker (not shown) connected to the output terminal 11, where it is converted into a musical tone. Then, the potentials at each point a, b, and c become as shown in diagram 1lfi4.

[Problem that the invention seeks to solve]

However, in the integrated amplifier according to the configuration described in -1-, in order to match the signal standard to the signal system supplied to the main input terminal 7, a volume having a high impedance of 20 Ω must be connected in series to 20. Naturally, when volumes with such high impedance are connected in series, signal distortion increases, and
This has the problem that the sound quality deteriorates because it becomes more susceptible to guidance. In addition, in the above configuration, a flat amplifier is required for the signal system supplied to the record player signal input terminal 3 and the auxiliary input terminal 3, but the sound quality will deteriorate unless this flat amplifier is of high quality. This leads to deterioration, and the problem is that high quality flat amplifiers are difficult to manufacture and expensive.

[Means for solving problems]

Therefore, the integrated amplifier according to the present invention removes the flat amplifier that handles the signals supplied to the record player input terminal and the auxiliary input terminal, increases the amplification of the flat amplifier by removing the amplification of the power amplifier, and The signal supplied to the input terminal is divided by resistance and supplied to the power amplifier, and a low-impedance volume is connected between the resistance division point and ground.

[Effect]

In an integrated amplifier configured in this way, it is possible to use a low-impedance volume as a volume while keeping the impedance seen from the main input terminal side the same as before. Since it is no longer necessary to send the signal to the slider, we can expect an improvement in sound quality. Furthermore, since a flat amplifier is not required, the cost can be reduced by the amount of the flat amplifier, and the deterioration in sound quality caused by the flat amplifier is eliminated.

〔Example〕

FIG. 1 is a circuit diagram showing an embodiment of an integrated amplifier according to the present invention, and the same parts as in FIG. 3 are indicated using the same symbols. In the figure, 12 is an attenuator provided between the main input terminal 7 and the operation switch 9 to lower the signal level, and is connected in series between the main input terminal 7 and the ground to divide the input signal. The voltage dividing point K is constituted by resistors 13 and 14 connected to the operation switch 9, and a volume 15 connected between the voltage dividing point and ground. The volume 15 has a low impedance of 5Ω to 5Ω, and in order to set the impedance seen from the main input terminal 7 to 20Ω as before, the value of the resistors 13 and 14 is set to 18Ω. It is set to Ω and 4.7. 16 is a high-gain power amplifier that amplifies the selected output signal of the operation switch 9 and supplies it to the output terminal 11, which sufficiently compensates for the gain of the flat amplifier conventionally provided between the volume 5 and the operation switch 9. The gain is set.

In the inch gray tent amplifier configured in this way, the signal supplied to the record player Shinzuki λ power terminal 1 is amplified by, for example, 36 dB in the equalizer amplifier 2, and then supplied to the select switch 4. , the standard matching with the signal supplied to the auxiliary terminal 3 is performed. The output signal of the equalizer amplifier 2 selected by this select switch 4 and the auxiliary input terminal 3
Either one of the signals supplied to the controller is supplied to the operation switch 9 via the volume 5.

- On the other hand, the signal supplied to the main input terminal 7 is attenuated by -18 dB at the attenuator 12 and then supplied to the operation switch 9, whereby the standard for the high gain power amplifier 16 is adjusted. Then, either the output signal of the volume 5 or the output signal of the attenuator 12 selected by the operation switch 9 is amplified by, for example, 43 dB in the high gain power amplifier 16 and then sent to a speaker (not shown) via the output terminal 11. Supplied. In other words.

The signal supplied to the auxiliary input terminal 3 is set as the input standard for the high-gain power amplifier 16, and the low-level signal supplied to the record player signal input terminal 71 is amplified in the equalizer amplifier 2 to be input to the high-gain power amplifier 16. In addition to conforming to the input JJI rating, the high level signal supplied to the main input terminal 7 is attenuated by the attenuator 12 to conform to the input standard of the high gain power amplifier 16. In this case, the gain of the high-gain power amplifier 16 is 43 dB, which is the sum of the 18 dB gain of the conventionally used flat amplifier and the 1125 dB gain of the power amplifier, in order to obtain the desired output of, for example, 60 W. It has a gain of . Therefore, the sound quality improves by the amount that the flat amplifier is removed, and the cost town can be measured.As a result, the signal levels at points A, B, and C in Figure 1 become as shown in Figure 2. become.

On the other hand, the attenuator 12 connects the signal supplied to the main input terminal 7 to the resistor 13 of Ω to 18, and the resistors 4 and 7 connected in parallel.
The input impedance seen from the main input terminal 7 is adjusted to the standard 20Ω by dividing the voltage using a resistor 14 of 5Ω and a volume 15 of 5Ω. In this case, since the configuration is such that the volume 15 is connected between the divided voltage output terminal of the resistors 13 and 14 and the ground, the volume 15 has a resistance value of 5Ω, which is sufficiently small compared to the conventional one. 15, the input impedance of the main input terminal 7 can be adjusted to 20Ω.

As a result, since the impedance of the volume 15 is reduced, noise signals are prevented from being induced, and the sound quality can be improved. Also, since the volume 15 is connected in parallel to the signal system, the volume 15
The signal will no longer flow to the slider No. 5, and the resulting deterioration in sound quality will be prevented. It goes without saying that the resistance value constituting the attenuator 12 must be selected appropriately in relation to the high gain power amplifier 16 used.

〔Effect of the invention〕

As explained above, in the integrated amplifier according to the present invention, it is possible to reduce costs by eliminating the flat amplifier that requires high quality, and also to reduce the volume that handles the signal supplied to the main input terminal. Since the impedance can be lowered, deterioration in sound quality due to induction of noise signals etc. can be prevented. Also, since the volume that handles the signal supplied to the main input terminal is connected in parallel to the signal system,
It has various excellent effects, such as significantly improving the sound quality because the signal does not waver on the volume slider.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an embodiment of an integrated amplifier according to the present invention, Fig. 2 is a characteristic diagram showing signal levels of each part in Fig. 1, and Fig. 3 is an example of a conventional integrated amplifier. The circuit diagram shown in FIG. 4 is a characteristic diagram showing the signal level of each part in FIG. 3. l...Record player signal input terminal, 2...Equalizer amplifier, 3...Auxiliary input terminal, 4...Selector switch, 5...Volume, 7...Main input terminal, 9... Operation switch, 11.
...Output terminal, 12...Attenuator, 13.14.
...Resistance, 15...Volume.

Claims (2)

[Claims] (1) An equalizer amplifier that amplifies the signal supplied to the record player signal input terminal, a select switch that selects the output signal of this equalizer amplifier and a signal supplied to the auxiliary input terminal, and an output signal level of this select switch. A variable volume, an attenuator that attenuates the signal supplied to the main input terminal, an operation switch that selects the output signal of the volume and the output signal of the attenuator, and a high gain that amplifies the output signal of the operation switch. An integrated amplifier characterized by providing a power amplifier. (2) The attenuator is connected between the first and second resistors that are connected in series between the main input terminal and the ground and whose divided voltage output is used as the output signal, and between the voltage dividing point of the first and second resistors and the ground. 2. The integrated amplifier according to claim 1, further comprising a connected low-impedance volume.