JPH0119201Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an audio reproduction device, and particularly to an improvement in a signal transmission path between a record player and a preamplifier.

Conventionally, a record player that reproduces a stereo signal from a record disc and a preamplifier that amplifies this stereo signal are connected, for example, as shown in FIG. That is, the Lch and Rch output terminals 1A, 1 of the stereo cartridge 1
A connecting portion 3A at the base end of the support shaft 3 that supports the tone arm 2 via four internal signal lines 2A, 2B, 2C, and 2D inserted into the hollow part of the tone arm 2.
Derive to. Then, the Lch and Rch signals are led from this connection part 3A to the phono input of a preamplifier (not shown) via the core wires 4A, 5A of the pair of L and R shielded wires 4, 5 and the outer sheath wires 4B, 5B, and separately. A ground wire 6 is provided and connected to the ground terminal of the preamplifier.

Therefore, such a signal transmission path becomes an unbalanced type as shown in FIG. 2, for example. i.e.
In the case of MC type cartridge, each coil 1C,
The 1D output signal is guided to preamplifiers 7A and 7B of preamplifier 7 via shielded wires 4 and 5. The jacket wires 4B and 5B of each shield wire 4 and 5 and the ground wire 6 are connected to a reference potential within the preamplifier 7.

However, in such a device, the outer jacket wires 4B and 5B of the shield wires 4 and 5 are on the reference potential side of the Lch and Rch signals. For this reason, there was a problem in that the outer jacket wires 4B and 5B exposed to the outside were likely to be affected by hum, noise, and the like. And this jacket wire 4B, 5B
When a signal such as hum noise is added to the core wires 4A and 5A, this difference is input to the preamplifiers 7A and 7B, causing a significant decrease in the S/N ratio since the core wires 4A and 5A are less susceptible to this effect.

The present invention was developed in view of the above circumstances, and is an audio system that is not easily affected by hum or noise, and even if it is affected, it can cancel this out and thereby obtain a good S/N ratio. The purpose is to provide a playback device. Hereinafter, one embodiment of the present invention will be described in detail with reference to FIGS. 3 and 4, in which the same parts as in FIGS. 1 and 2 are denoted by the same reference numerals. That is, Lch and Rch signals are guided from the connecting portion 3A of the support shaft 3 of the tone arm 2 to the preamplifier 7 through shielded wires 8 and 9 having two core wires 8A, 8B, 9A, and 9B, respectively.
Also in this case, the outer sheath wire 8 of each shield wire 8, 9
C and 9C are connected to the reference potential on the preamplifier 7 side. Also, one core wire 8A of each shield wire 8, 9,
9A is connected to each non-inverting input of the preamplifiers 7A and 7B, and the other core wires 8B and 9B are connected to the preamplifier 7.
It is connected to the reference potential within the preamplifier 7 along with the inverting inputs of A and 7B.

With such a configuration, the Lch and Rch signals detected by the cartridge 1 are transmitted to the core wires 8A, 8B, 9A, and 9B, which are shielded by the outer sheath wires 8C and 9C, which have the same potential as the reference potential of the preamplifier 7. are led to preamplifiers 7A and 7B via. Therefore,
No signal current flows through the outer sheath wires 8C and 9C, and they are simply held at the reference potential, and each core wire 8 inside these
A, 8B, 9A, and 9B are extremely resistant to external induction such as hum and noise. Also, suppose the core wire 8A,
Even if hum, noise, etc. are induced in 8B, 9A, and 9B, they will be affected to the same extent because they are placed in spaces with approximately the same potential. Here core wire 8
Since the signal currents flow in opposite directions in the pair of core wires A and 8B or the core wires 9A and 9B, the noise components induced here are canceled out and the influence can be significantly reduced.

Note that the present invention is not limited to the above-mentioned embodiment, and for example, as shown in FIG.
Balanced input types may be used for A and 7B. In this case, the outer sheath wire 8 of the shield wires 8 and 9
C, 9C and the ground wire 6 may be connected to a reference potential within the preamplifier 7. In this way, the preamplifiers 7A, 7B themselves are less susceptible to the effects of hum, noise, etc., and an even better S/N ratio can be obtained.

As detailed above, the present invention leads the output of a cartridge for reproducing stereo signals from a record to a preamplifier through the core wires of a pair of shield wires each having two core wires for each channel. The jacket wire is connected to the reference potential of the preamplifier. Therefore, it is not easily affected by hum noise, etc., and even if it is affected, it can be canceled out, resulting in a good S/N.
It is possible to provide an audio playback device that can obtain a high ratio.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of a conventional record player, FIG. 2 is a diagram showing a connection between a conventional record player and a preamplifier, FIG. 3 is a diagram showing a record player according to an embodiment of the present invention, and FIG. This figure shows the connection between the record player and the preamplifier of the above embodiment, and FIG. 5 is a diagram showing another embodiment of the present invention. 1... Cartridge, 2... Tone arm, 3
...Spindle, 6...Ground wire, 7...Preamplifier,
8, 9...shielded wire, 8A, 8B, 9A, 9B
... Core wire, 8C, 9C ... Outer wire.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. A cartridge that reproduces Lch and Rch stereo signals from a record, and the output signal of this cartridge is guided to a preamplifier by two core wires for each channel, and the outer wire is used to preamplify. and a pair of shielded wires connected to a reference potential. 2. The audio reproducing device according to claim 1 of the utility model registration, characterized in that the preamplifier of the preamplifier is of a balanced input type.