JP7282347B1 - Power supply system for cartridge amplifier - Google Patents

Abstract

To reduce noise, reduce the weight of a head shell, and eliminate restrictions on the power supply voltage by not providing a battery for supplying power to a cartridge amplifier in the head shell. A cartridge amplifier comprising a tone arm 3 of a record player 16, a plug-in type head shell 2 detachable from the tone arm, an MC type cartridge 10, and an amplifier near the MC type cartridge. wherein the head shell is provided with the MC cartridge and the amplifier, and power is supplied to the amplifier via the conductive portion of the tone arm and the conductive member of the head shell. is configured to supply a DC voltage 17 of [Selection drawing] Fig. 3

Description

The present invention relates to a power supply system for a cartridge amplifier, and more particularly to a system for supplying power to a cartridge amplifier such as a head amplifier to which a MC (Moving Coil) type cartridge is attached.

MC type cartridges used in record players are popular because of their better sound quality than MM (Moving Magnet) type cartridges. requires a head amplifier in front of the phono equalizer amplifier. In addition, since the output voltage is a very small signal of about 0.3 mmV, there is a disadvantage that it is easily affected by external noise if the transmission line is long.
For this reason, a headshell that integrates an MC cartridge and a head amplifier has been put into practical use.

In Patent Document 1, in FIG. 1, a capacitor-type pickup cartridge is provided with a FET (Field Effect Transistor) for first-stage amplification, and the current amplified by the FET by the power supply of the power supply section is transmitted to an electrostatically shielded tone arm. Then, a configuration is disclosed in which the power supply unit outputs the audio signal to the preamplifier as an audio signal. A similar method is known as a satellite amplifier (Yamaha) for MC type cartridges.
In addition, in the article "The World of Audio Circuits... True/Manufacturing MC Amplifiers" in Non-Patent Document 1, an MC head amplifier is placed on top of the head shell and its power source is a battery (lithium ion battery, button A configuration in which a battery) is also placed together is disclosed.

However, in the method of Patent Document 1, power is supplied from the power supply unit to the FET of the cartridge via the signal line of the tone arm, so there is no need to add a separate wiring for power supply from the power supply unit to the cartridge. However, since the cartridge FET and power supply unit are integrated into one amplifier, a dedicated power supply unit for the cartridge is required, which lacks versatility and is expensive. Also, as the signal from the FET goes through the tone arm, the signal amplification loop becomes larger, making it easier for external noise to affect the connections.
In the method of Non-Patent Document 1, since the signal amplified by the headshell amplifier is transmitted to the tonearm, it is less susceptible to such external noise. Since the lithium-ion battery or button battery is used, the drive voltage is restricted, and the FET (Field Effect Transistor) with a small Idss driven by a voltage of about 3V has poor linearity at the operating point due to its characteristics and the distortion factor. has the disadvantage that it tends to become large, and there is a problem that it is difficult to design a high-performance head amplifier. Also, if you use a button battery, the voltage is about 1.3V, so a booster circuit is required, making noise more likely to occur. There are problems such as an increase as a whole.

JP 2017-41683 A

"Transistor Technology" CQ Publishing, November 2022, pp. 144-151

The problem to be solved is a simple and effective method of supplying the necessary power to the head shell integrated with the head amp as described above, in order to take advantage of the performance of the MC-type cartridge and create a high-performance head amp. It is not

The present invention provides a cartridge amplifier such as a head amplifier through which a power supply required to enhance the performance of the cartridge amplifier such as a head amplifier is supplied via the conductive member (conductive portion) of the tone arm or the conductive main body of the head shell. A main feature is that it is configured to supply the

Since the power supply system for the cartridge amplifier of the present invention supplies necessary power via the conductive member (conductive part) of the tone arm and the conductive main body of the head shell, it can be used with the output line of the existing record player. It can be realized by supplying power from a certain ground wire (shielded wire). In addition, since the power supply for the head amplifier and the like is not mounted on the head shell, there is an advantage that the power supply voltage to be supplied is not restricted and a high-performance amplifier can be realized.

1 is a conceptual diagram showing the overall configuration of a power supply system for a cartridge amplifier according to the present invention; FIG. FIG. 4 is a side view of the head amplifier-integrated head shell according to the present invention; 1 is a diagram showing a circuit configuration of a system for supplying power to a cartridge amplifier according to the present invention; FIG.

The purpose of improving the performance of amplifiers such as head amps was achieved by supplying the necessary voltage via the conductive members (conductive parts) of the tonearm and the conductive body of the headshell.
BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In the drawings, the same or functionally similar constituent elements are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 1 is a conceptual diagram showing the overall configuration of a power supply system for a cartridge amplifier according to the present invention. Reference numeral 1 in the figure denotes a record disc such as an LP disc or an EP disc, which rotates at a predetermined speed as a turntable provided in the record player rotates. A head shell 2 is integrally attached with a pickup cartridge, a head amplifier, and the like, which will be described later. A tone arm 3 has a head shell 2 detachably attached to one end and a balance weight 5 attached to the other end through a support 6 . Reference numeral 4 denotes a finger hook, which is an insulating member attached to the side surface of the head shell 2 for hooking the finger of the user so that the user can lift and move the stylus from the record disc. The balance weight 5 is configured to be able to adjust the stylus pressure of the record stylus to the record disc. The support 6 regulates movement of the tone arm 3 rotating around the support 6 as a rotation axis. Reference numeral 7 denotes a power supply unit, which will be described later, which shields each output signal line for the left channel reproduction signal and the right channel reproduction signal for reproducing a stereo record, taken out from the support 6 of the record player, and the tone arm 3. A ground wire is connected to 8 is a phono equalizer amplifier (RIAA amplifier) connected to the power supply unit 7 .

Here, the tonearm 3 is an elongated pipe-shaped member, the outside of which is made of a conductive metal (conductive portion) such as aluminum, and the inside of which is filled with a vibration-isolating material to reduce cavity resonance. . In addition, the base portion is supported by the support 6 by means of a pivot structure or the like, so that it can freely swing vertically and horizontally. The tone arm 3 is connected to the head shell 2, and the output signal from the head shell 2 passes through the signal line wired in the anti-vibration material, and the output signal line for each left and right channel from the support 6. It is configured to be taken out as In order to eliminate external noise, the signal lines in the tone arm 3 are equipotentially shielded by a pipe-shaped external metal (conductive portion), in this embodiment, with a DC voltage, which will be described later.

FIG. 2 is a side view of the headshell integrated with a head amplifier according to the present invention. Since the left and right channels of the stereo system have the same structure, FIG. 2 shows an outline of the configuration of one channel. A head shell body 9 of the head shell 2 is connected to the tone arm 3 in a plug-in manner by a connector plug 14 attached thereto. The head shell body 9 is made of a conductive material such as aluminum (conductive member), and is electrically connected to the conductive portion of the tone arm 3 via the connector plug 14 by being joined to the tone arm 3 . will be
At the tip of the head shell body 9, an MC type pickup cartridge (MC type cartridge) 10 having a playback needle (record needle) 11 for tracing the sound source of the record is electrically insulated or non-conductive with the head shell body 9. attached to the contact. The connector plug 14 is mounted by fitting it into a through hole provided in the rear end wall of the head shell body 9. Two output terminals are provided for each of the left and right channels, and a total of four pin terminals are provided in the head shell. It is insulated from the shell body 9 and provided inside the connector plug 14 . When it is joined to the tone arm 3 , it is connected to wiring provided inside the tone arm 3 through each pin terminal 15 .

The head amplifier 12 is located in the vicinity of the pickup cartridge 10 between the pickup cartridge 10 and the connector plug 14, and is composed of an FET 13 and a resistor Rd. A terminal is connected to the source electrode of the FET 13 and one pin terminal of the connector plug 14 . Also, the drain electrode of the FET 13 is connected to one end of the resistor Rd and the other pin terminal of the connector plug 14 . The other end of the resistor Rd is electrically connected to the headshell main body 9 .
With this configuration, when power is supplied to the conductive portion of the tone arm 3 , power to both channels is supplied to the left and right channel head amplifiers 12 via the head shell main body 9 .

FIG. 3 is a diagram showing the circuit configuration of the power supply system for the cartridge amplifier according to the present invention, showing the circuit configuration for one of the left and right channels. Other channels have similar configurations.
In the figure, the power supply unit 7 is provided with a battery 17 that supplies a DC voltage (Vcc), the + (plus) electrode of which is connected to a shield wire taken out from the support 6 of the record player 16 . , and - (minus) electrodes are connected to the substrate (chassis) of the power supply unit 7 and grounded. Therefore, a DC voltage (Vcc) is supplied to the conductive portion of the tone arm 3 and the conductive member of the headshell main body 9 through the shielded wire.

A signal output from the drain electrode and the source electrode of the FET 13 is output as an audio signal to the power supply unit 7 via wiring inside the tone arm 3 . The output signal connected to the drain electrode is connected to a capacitor C provided in the power supply section 7 to remove the DC component and becomes the output signal of the power supply section 7 (+signal line). Also, the output signal connected to the source electrode becomes the output signal of the power supply unit 7 as it is (-signal line).

In the phono equalizer amplifier 8, a ground line connected to the negative electrode of the battery 17 provided in the power supply unit 7 is connected to the ground terminal (G terminal), which is connected to the substrate (chassis) of the phono equalizer amplifier 8, and the voltage is supplied. It is connected to the output signal (-signal line) input from the unit 7 .
As a result, a power supply loop to the head amplifier 12 is composed of the power supply section 7, the tone arm 3, the head shell main body 9, the head amplifier 12, the tone arm 3, the power supply section 7, the phono equalizer amplifier 8, and the power supply section 7. is formed with one closed circuit loop. In consideration of the so-called ground loop problem that causes noise such as hum generated by connecting multiple devices, - the signal line is not connected or grounded to the board in the power supply section 7 , and one closed circuit is formed only when it is connected to the phono equalizer amplifier 8 .

Here, the DC voltage (Vcc) can be set to an appropriate voltage (in this embodiment, it is set to 15 V) so as to drive the FET 13 at an operating point with good linearity due to its characteristics. Therefore, there is no mounting restriction on the voltage as in the case where the battery is mounted on the head shell 2, and no booster circuit is required.
In this embodiment, the capacitor C for removing the direct current component is provided in the power supply unit 7, but it is not limited to this, and can be provided in the head amplifier 12 as well. Moreover, it can replace with FET13 and an operational amplifier (operational amplifier) can also be used.
Although the tonearm is shielded with a constant voltage (15V), it has the same shielding effect as the conventional case where it is shielded with a ground voltage (zero volts).

By supplying a constant voltage using the ground wire that shields the tone arm, which has been used in the past, power can be supplied to the head amplifier installed in the head shell without the need for additional wiring. . Therefore, the output terminal can be used as it is without modifying the existing record player, and only the head amplifier needs to be mounted on the headshell, so that the structure can be made lightweight. Also, since the optimum voltage can be supplied from the power supply unit to the head amplifier, the performance of the record player can be improved.
In this embodiment, the headshell and the power supply section are configured as separate options, but the record player and the power supply section can be integrated, or the power supply section and the phono equalizer amplifier can be integrated. can. Also, the head shell can be integrated with the tone arm so that the tone arm has the function of the head shell. The output signal (±) of the power supply unit can be connected to an existing phono equalizer amplifier to reproduce the audio signal.

In this embodiment, by connecting the power supply voltage to the shield line (ground line) of the tone arm, it is possible to maintain the shield effect for the signal line and supply a desired voltage to the head amplifier. Thus, when using a circuit capable of supplying a power supply voltage between the shield line and the output signal line, for example, when using an MM type cartridge, a phono equalizer amplifier (RIAA amplifier) is used instead of the head amplifier in this embodiment. is provided in the vicinity of the cartridge, a similar effect can be obtained in the power supply required for the phono equalizer amplifier. In this case, for example, the power supply loop can be constructed by grounding the - signal line in the power supply unit.

1 record 2 head shell 3 tone arm 4 finger hook 5 balance weight
6 support 7 power supply unit 8 phono equalizer amplifier 9 head shell body 10 pickup cartridge 11 playback needle 12 head amplifier 13 FET
14 connector plug 15 pin terminal 16 record player 17 battery

Claims (5)

In a system for supplying power to an amplifier comprising a tone arm of a record player, a cartridge, and an amplifier installed near the cartridge,
A power supply system for a cartridge amplifier, wherein the power supply to the amplifier is configured to supply a constant voltage via the conductive portion of the tone arm. The amplifier is characterized by comprising an FET to which an output signal from the cartridge is connected, and a resistor having one end connected to the FET and the other end connected to the conductive portion of the tone arm. 2. A power supply system for a cartridge amplifier according to claim 1. 2. A power supply system for a cartridge amplifier according to claim 1, wherein said amplifier comprises an operational amplifier. 2. A power supply system for a cartridge amplifier according to claim 1, wherein said amplifier is a phono equalizer amplifier. A plug-in type head shell detachable from the tone arm is further provided, and the head shell is provided with an MC type cartridge as the cartridge and the amplifier, and the power supply to the amplifier is performed by the conductive portion of the tone arm and the amplifier. 2. A system for supplying power to an amplifier for a cartridge according to claim 1, wherein power is supplied via the conductive member of said head shell.

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