JPS6015198B2 - equalizer amplifier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an equalizer amplifier, and more specifically, the present invention relates to an equalizer amplifier. This invention relates to an equalizer amplifier that can be used for both.

The moving coil type cartridge has a small mass of the vibrating part and can have a large conformance, so it has excellent followability of the cord groove, and the vibration system is supported at one end, so the vibration mode is simple and theoretical. Although there are fewer problems and it is easy to make the vertical angle close to 150 due to the structure, the output voltage is low, so as shown in Figure 1a, a moping magnet type cartridge amplifier MMA with cartridge terminal CT and RIAA equalizer characteristics is used. A step-up transformer SUT is provided between the moving magnet type cartridge amplifier MMA and the step-up transformer SUT is selectively connected to the input of the moving magnet type cartridge amplifier MMA using switches SI and SI' to obtain the sensitivity. Moving magnet type cartridge amplifier MMA with termina'VCT and RIAA equalizer characteristics
A dedicated amplifier MCA is installed between the switches S1 and SI'
A method was used in which the amplifier was selectively connected to the input of a moving magnet type cartridge amplifier MMA to obtain sensitivity.

However, when using the former step-up transformer, there are limits to power supply hum, frequency characteristics, and transformer-specific distortion, and it is expensive, and when using the latter, the circuit configuration becomes complicated. I also didn't like that it was expensive.

The purpose of this invention is to solve the above-mentioned conventional drawbacks in using a moving coil type cartridge.
Its feature is that it uses a differential input type amplifier with RIAA equalizer characteristics, and by using this as an inverting or non-inverting amplifier, it can be used as an output amplifier that matches moving coil type and moving magnet type cartridges, and is common to both cartridges. It is used for.

Hereinafter, an embodiment of the present invention shown in the drawings will be described in detail.

FIG. 2 is a configuration diagram of an equalizer amplifier for moving coil type and moving magnet type cartridges according to the present invention. This amplifier consists of a positive input terminal (non-inverting input terminal) INI and a negative input terminal ( Inverting input terminal) Movable contacts c, c of the switch SI, SI' for switching the gourd 2
', a resistor Rg is connected between the positive input terminal INI and the ground terminal (reference potential point) E, a resistor RE is connected between the input terminal m2 and the ground terminal E, and a resistor RE is connected between the output terminal OUT and the ground terminal E. The negative input terminal...2 and RIAA in the dark
A negative feedback circuit element (equalizer element) Zf for reproduction curve is connected, and the fixed contacts a,
b' is connected to the cartridge terminal CT, and the fixed contact b of the changeover switch SI is connected to the ground terminal E, respectively.

Next, the operation of this equalizer amplifier will be explained using FIGS. 3 and 4.

As shown in Fig. 3, when the movable contacts c and c' of the changeover switches SI and SI' are connected to the fixed contacts a and a', respectively, it is equivalent to a conventional equalizer amplifier (for moving magnet type). This circuit configuration is advantageous for an inductive signal source that has a high input impedance and is easily matched to a moving magnet type cartridge.

In this case, the signals from the signal sources es and Rs are sent to the amplifier OPA.
Transistors Q1 and Q2 that constitute the first stage differential amplifier of
and a loop passing through the resistor RE, and the transfer characteristic G in this case is G=.10. A reference characteristic is obtained by using a RIAA regeneration curve element in the negative feedback circuit Zf.

Next, as shown in Figure 4, when the movable contacts c and c' of the changeover switches SI and SI' are connected to the fixed contacts b and b', the positive input terminal INI is connected to the ground terminal E, and the negative input terminal IN
2 is connected to the cartridge terminal CT, which becomes an inverting amplifier in this case, so the signals from the signal sources es and Rs flow into a loop passing only through the transistors Q1 and Q2 that constitute the first stage differential amplifier of the amplifier OPA. The transfer characteristic G is Zf G:RS〆〆RE, and the circuit configuration is suitable for a moving coil type cartridge.

In other words, the moving coil type cartridge has a low internal resistance (several Q to several tens of Q), and the audio band is almost purely resistive, and unlike the moving magnet type, there are very few inductive elements, so this current drive type There is no harm in configuring this.

Furthermore, since the signal loop does not include the resistor RE, the overall noise is reduced by the amount of noise generated in the resistor RE, compared to the case of the non-inverting amplifier shown in FIG.

Moreover, since the internal resistance and output voltage of a moving coil type cartridge have a relatively proportional relationship, when the cartridge is driven by current, the change in the output signal eo due to variations in the cartridge output voltage is reduced, so sensitivity switching due to this is practically unnecessary. It is versatile.

Fig. 5 shows an example in which the present invention is applied to an amplifier other than a differential amplifier, in which the cartridge terminal CT is connected to the fixed contacts a and b'' of the changeover switches S1 and SI', and the other fixed contact b is connected to the cartridge terminal CT. is grounded, and the fixed contact a' is not connected to anything so that the movable contact c' is disconnected.The movable contact c is connected to the base of the transistor QI and grounded via the resistor Rg, and this base is connected to the base of the transistor QI. Resistance R2
The emitter of transistor Q2 is connected to the emitter of transistor Q2 through resistor R4, and this emitter is grounded through resistor R4.

The collector of the transistor QI is connected to the base of the transistor Q2 and connected to the power supply Vcc via a resistor RI, the collector of the transistor Q2 is connected to the power supply Vcc via a resistor R3, and the collector of the transistor Q2 is connected to the output terminal OUT. Further, the output terminal OUT is connected to the emitter of the transistor QI via the negative feedback circuit element Zf, and this emitter is grounded via the resistor RE and connected to the movable contact c' of the changeover switch SI'.
In this case, the operation can be switched to a moving coil type or a moving magnet type cartridge in the same manner as in FIGS. 2 to 4.

As described above, the present invention includes interposing an equalizer element between the inverting input terminal and the output terminal of an amplifier having a non-inverting input terminal, an inverting input terminal, and an output terminal, and also inserting an equalizer element between the inverting input terminal and the reference potential. a resistor is inserted between the non-inverting input terminal and the inverting input terminal of the amplifier and the cartridge input terminal, and a switching switch for selectively connecting these is inserted between the non-inverting input terminal and the inverting input terminal of the amplifier and the cartridge input terminal. is a sliding position for a moving magnet type cartridge in which the terminal output is supplied to the non-inverting input terminal of the amplifier, and a position in which the terminal output is supplied to the inverting input terminal of the amplifier and the non-inverting input terminal is in the reference position. Since the structure has a switching position for the moving coil type cartridge connected to the potential point, a step-up transformer and a dedicated amplifier for the moving coil type cartridge, which were required when using the moving coil type cartridge, are no longer required, and a single equalizer amplifier can be used. It can be used for both purposes, simplifying the circuit configuration, and when using an inverting amplifier, the impedance on the non-inverting input terminal side is directly grounded, so the noise source in this system is only the internal elements of the obeamp, reducing noise. Moreover, it has the advantage of having a circuit configuration that passes through both cartridges.

[Brief explanation of the drawings] Figures 1a and b are configuration diagrams of a conventional equalizer amplifier;
4 to 4 each show an embodiment of the present invention. FIG. 2 is a configuration diagram of the equalizer amplifier, FIGS. 3 and 4 are explanatory diagrams of two types of operation of the equalizer amplifier, and FIG. FIG. 2 is a configuration diagram of an amplifier other than an inset amplifier. CT...Cartridge terminal, OPA...
．． ...Amplifier, S1, SI'...Cut switch, Rg, RE...Resistor, Zf...Feedback circuit element, OUT...Output terminal, E...
・Earth terminal. Figure 1 (Mountain) Figure 1 (Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. An equalizer element is inserted between the inverting input terminal and the output terminal of an amplifier having a non-inverting input terminal, an inverting input terminal, and an output terminal, and a resistor is inserted between the inverting input terminal and a reference potential point. A changeover switch is inserted between the non-inverting input terminal and inverting input terminal of the amplifier and the cartridge input terminal to selectively connect them, and this changeover switch is configured so that the terminal output is connected to the cartridge input terminal. a switching position for a moving magnet type cartridge which is supplied to a non-inverting input terminal; a moving coil type cartridge in which the terminal output is supplied to an inverting input terminal of the amplifier and the non-inverting input terminal is connected to the reference potential point; An equalizer amplifier characterized in that the equalizer amplifier is configured to have a switching position.