JP2000077952A - Amplifier circuit technology and wiring technology in audio - Google Patents

Abstract

(57) [Summary] [Problem] To provide a three-dimensional and high sound quality amplifier for aurally amplifying a weak sound source signal from a sensor or an electric signal from a line without waveform distortion. SOLUTION: The most important auditory problems such as rising and falling of sound are improved by a comprehensive method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit technology including an interface such as a low-level amplifier (a microphone amplifier, an amplifier for a moving coil (MC) cartridge, an equalizer amplifier for a moving magnet (MM) cartridge, and a recore amplifier) for audio equipment. This is a technology for realizing the quality of the sound source (high sound quality) through component modification and wiring technology.

[0002]

2. Description of the Related Art Conventional microphone amplifiers and cartridge interface circuits are unbalanced, and linear amplifiers are generally unbalanced, and no special measures are taken.

[0003]

A method for converting a sound source into an electric signal (microphone, cartridge) is a minute voltage source or a current source, and a method for amplifying the signal without distortion to realize unprecedented quality. In addition, technology for amplifying sound sources with a lively three-dimensional effect, including linear amplifiers.

[0004]

SUMMARY OF THE INVENTION To solve the above problems, the present invention uses a low noise, high frequency operational amplifier. Generally, conventional audio products are relatively low frequency circuits. This is because the human ear is 16Hz-20,000Hz
This is because up to the audible range. However, the sound of music has not only frequency characteristics but also a complicated sound waveform. Therefore, how to transmit this waveform to the speaker faithfully is a major theme. The players, preamplifiers, main amplifiers, and speakers in the audio device can be said to be important in their respective roles, but the distortion of the waveform generated at the input section is transmitted to later, and eventually results in an unnatural sound. Therefore, the present invention focused on the rising and falling edges of the sound, and improved the sound by incorporating a low-noise high-frequency operational amplifier.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The slew rate of a high frequency operational amplifier will be described. The mainstream slew rate of a general operational amplifier used for audio is 30 V / μs or less. The second aspect is a technique of using a high-frequency operational amplifier of 200 V / μs or more, and 1000 V / μs or more in a current feedback type operational amplifier.

[0006]

[Embodiment] As an adverse effect of using an operational amplifier for high frequency,
The wiring itself becomes an antenna and amplifies noise such as the sound of a radio or a radio. Therefore, in this case, noise was removed by using a balanced input [see FIG. 1]. Although this circuit configuration is a classical method, the first contrivance is to use an operational amplifier when normally performing shield drive [Fig.
0]. However, recent amplifiers have low output impedance and have the ability to drive a 50Ω load. Therefore, low impedance resistors 6 and 7 in [Fig. Drive against the copper foil wound resistor. In this way, even if the resistance value used is high, the impedance on the surface of the component is kept low, which is also a countermeasure against oscillation, and can be made strong against noise. Also,
By applying a drive, you can achieve a clear sound. Omission of the operational amplifier for the shield drive not only saves the parts, but also performs the general method [FIG. 10].
Because of the high frequency amplifier, a phase delay occurs, and the input signal cannot be amplified accurately or oscillation occurs.

[0007] When the input is about 1 Vpp and the amplification degree is several times as well, it may be unbalanced [see FIG. 2].

Hereinafter, the present invention will be described in more detail with reference to the drawings. The usage of the high frequency operational amplifier is as follows. First, a copper foil is wound (claim 7), a decoupling capacitor is placed near the IC (claim 5), and the wiring is made as in claim 3. In view of the fourth aspect of the present invention, one-point grounding of the ground (GND) wiring is a commonly used method. However, what is actually wired on the printed board is a solid earth which is equivalently performed. The solid earth is a method of widely filling a ground (GND) on a substrate. In this case, the ground (GND) of the active element does not use a solid earth. It is physically difficult to clearly explain why solid earth is not used, but it is described here as over transients. The meaning of this over transient will be described in detail later in the description of the power supply circuit. The ground (GND) between the resistors 1 and 2 in FIG. 1 is wired from the main power supply. The ground (GND) of the resistor 11 is also wired from the main part. The above wiring method can suppress the oscillation phenomenon that occurs when a circuit having a high amplification degree of the high frequency operational amplifier is configured. In a wiring method other than the fourth aspect, an oscillation phenomenon frequently occurs, which makes it difficult to commercialize the product. The same applies to the ground (GND) wiring of the resistor 15 in FIG. In the above circuit example, although the element ground (GND) is small,
Claim 4 is important when additional circuits are configured.

[0009] Claim 5 is an audio product, so it can be said that it is a necessary condition for hearing. Ceramic (including multilayer ceramic) capacitors, metallized film capacitors, and aluminum electrolytic capacitors are audible at all and result in little sense of using high frequency op amps. General tantalum capacitors must not be turned on. This is because when the capacitor is destroyed, the power is short-circuited and the system goes down. The capacitor according to claim 5 has a built-in fuse. It is important to select the material of the components in audio products.

The contents of claim 6 will be described by taking the processing of a resistor as a sample. When you want to suppress the diffusion of sound, wrap copper foil as shown in [Fig. 4], and connect the copper foil itself to nowhere. To improve the sound quality, connect a shield drive signal to the copper foil shown in Fig.4. To avoid noise at high impedance, connect the copper foil to a nearby ground (GND) [Fig. 5]. When a circuit using a resistor and a capacitor is configured between the ADF elements (ICs, transistors, FETs, electron tubes, etc.), a method for improving the rise of sound as shown in FIG. 6 is used. That is, one of the copper foils is connected to a resistor and connected to the output side of an IC or the like. The same applies to the condenser.

According to the present invention, the electric charge on the surface of the IC becomes uniform, noise is reduced, and self-oscillation becomes difficult.

A power supply circuit is important as a source of energy. This is because the sound source is greatly changed depending on how the circuit is assembled. Hereinafter, claims 8 and 9 will be described in detail.

As shown in FIG. 7, in the capacitor smoothing circuit, a bipolar-connected electrolytic capacitor is inserted on the power supply side. The capacity of the bipolar connection capacitor is preferably in the range of + 40% and -50% of 1/20 of the capacity of the main capacitor. For example, if the capacity of the main condenser is 1000
At μF, the bipolar connection capacitor is 70μF
２５25 μF.

As shown in FIG. 8, there is a case where an electrolytic capacitor is inserted in parallel with the constant voltage diode only on the power supply side. Use when you want to add thickness to the sound.

As shown in FIG. 7, a coil of a toroidal core is inserted after the constant voltage power supply. The above is the feature of the power supply circuit. By inserting this coil, the three-dimensional effect and sound separation of the sound source are improved in terms of hearing.

The above-mentioned device for the power supply circuit is necessary because the product is audio. To put it flatter, it is the human hearing that ultimately feels the sound, and it is the speakers (or headphones) that provide the sound. The loudspeaker has a certain mass, and at the same time, has an air resistance, which is a transmission medium. No matter how fast or accurate the electrical signal is, the loudspeaker does not work as expected. For example, it is assumed that a signal for pushing the speaker forward is input, and then there is an input to be pulled later before the speaker is sufficiently moved. Extremely speaking at that time,
The speakers do not move. The electric signal is turned into heat by the voice coil of the speaker. This state is expressed as an over-transient (a state in which the transient characteristic is too fast to keep up with the transient characteristics). Claims 8 and 9 devised not to create the above state. Generally-large capacity aluminum electrolytic capacitors for power supply are not made by the manufacturer. Therefore, claim 8 is required. Configuring all capacitors with no polarity will result in over-transients. Claim 8 provides a method for creating a suitable transient characteristic of the power supply, which is finely adjustable and convenient.

Claim 9 can also be said to be generally difficult to electrically consider. This is because the regulation of the constant voltage power supply becomes worse by inserting the coil. However, by actually inserting the coil of the toroidal core, the sound source resounds openly and can be heard as comfortable music by people. This can also be said to be the optimization of the transient characteristics.

According to a tenth aspect, the amplifier is properly used depending on the type of the amplifier. This is effective when the input is a minute voltage (or current) source, and is not necessary when the input is large and the amplification is low, such as a line driver.

[0019]

The rise and fall of sound in music are still being pursued in the audio industry. Experiments using high frequency IC operational amplifiers have probably been tried and tested. However, when actually used, it seems that the sound was slightly faded and suffered from noise and self-oscillation, and it could not be realized in a very good state. Since sound is a matter of auditory sensitivity, I would like to elevate the effect of expressing powerful music with a sense of speed as intended.

[Brief description of the drawings]

FIG. 1 A balanced receiver circuit of a line amplifier or an amplifier of a moving magnet (MM) cartridge or an amplifier of a moving magnet (MC) cartridge

Fig. 2 Line driver amplifier or line receiver amplifier

FIG. 3 is a wiring method using a high frequency IC operational amplifier.

Fig. 4 Modified drawing with additional resistance

Fig. 5 Modified drawing with additional resistance

FIG. 6 is a remodeled diagram with additional resistance added.

FIG. 7: Power supply balance circuit

FIG. 8-Power supply constant voltage circuit

FIG. 9 is a circuit diagram in which a coil is inserted between a power supply circuit and a load.

FIG. 10 is a shield drive circuit diagram.

[Explanation of symbols]

1 A circuit diagram in which a resistor is soldered to a copper foil wound as shown in FIG. 4 2 A circuit diagram in which a resistor is soldered to a copper foil wound as shown in FIG. 4 3 A resistor as shown in FIG. 4 Circuit diagram soldered to a rolled copper foil 4 Circuit diagram soldered a resistor to a copper foil rolled as shown in [Figure 4] 5 Circuit diagram soldered a resistor to a copper foil rolled as shown in [Figure 4] 6 A circuit diagram in which a resistor is soldered to a copper foil wound as shown in FIG. 4 7 A circuit diagram in which a resistor is soldered to a copper foil wound as shown in FIG. 4 8 A resistor as shown in FIG. 6 Circuit diagram treated with rolled copper foil 9 Circuit diagram treated with copper foil wound as shown in FIG. 6 10 Circuit diagram treated with copper foil rolled as shown in FIG. 6 11 Resistor Circuit diagram of processing copper foil wound as shown in FIG. 6 12 2-core shielded wire 13 Copper foil wound as shown in FIG. 6 14 Circuit diagram in which copper foil is wound with a resistor as shown in FIG. 6 15 Resistance of general parts 16 Shield wire 17-Power supply decoupling tantalum capacitor 18 + Power supply decoupling tantalum capacitor 19 IC Copper foil spread over 20 Power supply connection point + power supply connection point 21 Power supply connection point-Power supply connection point 22 Power supply connection + ground (GND) connection point 23 Power supply connection point Wiring-Ground (GND) connection point 24 High frequency IC operational amplifier 25 Resistance 26 Copper foil wound figure 27 Resistance 28 Copper foil wound, and the copper foil connected to ground (GND) 29 Resistance 30 Copper foil wound Fig. 31 Solder on one side with lead wire 31 Solder 32 Lead wire 33 + Power supply smoothing circuit 34-Power supply smoothing circuit 35 Main electrolytic Capacitor 36 bipolar connected capacitor 37 ceramic capacitor for high frequency improvement, 38 constant voltage diode 39 electrolytic capacitor 40 ceramic capacitor for high frequency improvement 41 constant voltage power supply circuit 42 coil of toroidal core 43 load circuit including IC 44 high frequency for shield drive Operational amplifier 45 Input balanced receiving high frequency operational amplifier 46 Input balanced receiving high frequency operational amplifier 47 General component resistance 48 General component resistance 49 General component resistance 50 General component resistance 51 Two-core shielded wire

Claims (10)

[Claims] The present invention is a technology that enables the production of a high-quality sound product by making various improvements described below. Microphone amplifier, moving coil (M
C) Preamplifier for cartridge, Preamplifier for moving magnet (MM) cartridge (Equalizer AM
P) Use technical innovations depending on the characteristics of the amplifier, such as a linear amplifier and a mixing amplifier. 2. An amplifier uses a low-noise high-frequency operational amplifier. 3. A return line (GND) sandwiching the + power supply and the decoupling capacitor is wired with a single line. Similarly, the return ground (GND) sandwiching the power supply and the decoupling capacitor is wired with a single line. In this way, wiring is performed in the same manner even when a large number of operational amplifiers are used. 4. A power supply and a ground (GN) on a circuit.
About D). All of them are wired one by one radially so as not to have a common impedance. Combine power grounds in one place as much as possible. The power supply (+
The wiring of (power supply, -power supply) is also radiated and put in one place. When wired as above, ground, + power,-
It becomes a power source, and if they are put together in one place, they will be put together in a total of three places. 5. An ultra-high speed digital noise limiter tantalum capacitor is used as a decoupling capacitor of an IC. 6. Processing of a resistor and a capacitor to be used. Spread copper foil on the insulation of the component. The copper foil is connected to the ground (GND). Connected to the output of the operational amplifier. Connected by connecting a resistor in series. Nowhere can be connected. The above four states are used properly depending on the characteristics of the circuit. This copper foil may be another metal as long as it is a conductor metal. In addition, general parts other than the processed parts as described above are used in combination. 7. An operational amplifier is sowed with copper foil. This copper foil may be another metal as long as it is a conductor metal. 8. A smoothing capacitor for a power supply unit. -Insert a bipolar connected electrolytic capacitor in parallel with the power supply. 9. A trocar core coil is inserted between a constant voltage circuit and a load circuit. 10. An electrolytic capacitor is connected in parallel with a constant voltage diode to a power source of a constant voltage circuit.