JPH0794960A - Single amplifier - Google Patents

Abstract

PURPOSE:To reduce the production cost of a single amplifier, to improve its characteristics and to obtain fine reproduced sound from a low frequency band up to a high frequency band by connecting a load to a constant current circuit in parallel equivalently as to AC and allowing the constant current circuit to take charge of a DC component so as to remove the influence of DC upon the load. CONSTITUTION:In order to interrupt DC from a load R (an output transformer or a speaker), a parallel field is constituted by mutually connecting the constant current circuit CRS and the load R in parallel through a capacitor C and allowing the circuit CRS to take charge of a DC component. In order to effectively operate the circuit CRS, the conditions of CRS operation resistance ¦load and CRS operation voltage 2 output voltage of output element should be satisfied and the circuit CRS can be simply assembled from elements such as FETs and beam tubes. Since the DC magnetization of the transformer can be eliminated or the output transformer itself can be omitted, an output drop in a low frequency band can be reduced and a distortion rate also can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single amplifier for amplifying voice.

[0002]

2. Description of the Related Art Conventionally, when a speaker is driven by a single amplifier, an output transformer for blocking direct current is required, but the single output transformer cannot be improved in low frequency characteristics because of its large DC inductance. It was In addition, when trying to improve the low frequency characteristic, the single output transformer becomes abnormally large, heavy and expensive.

[0003]

DISCLOSURE OF THE INVENTION The present invention aims to improve the characteristics and reduce the cost by using a push-pull output transformer without characteristic deterioration due to DC magnetization in a single amplifier or omitting the output transformer of a single amplifier. It is a thing.

[0004]

The present invention uses the following means to cut off direct current from a load (output transformer or speaker). It is a parallel feed in which a constant current circuit and a load are connected in parallel via a capacitor as shown in FIG. 1 and a direct current component is received by the constant current circuit. In order for this circuit to operate well, the operating resistance of the constant current circuit >>> load The operating voltage of the constant current circuit ≥ the output voltage of the output element must be satisfied. The constant current circuit is an element such as FET or beam tube. Easy to assemble.

[0005]

In the single amplifier according to the circuit of the present invention, the DC magnetization of the transformer is eliminated or the output transformer itself is eliminated, so that the decrease in output in the low frequency range is reduced and the distortion rate is also reduced.

[0006]

Embodiments (1) FIG. 2 is a circuit in which FETs are used for the output element and the constant current element to make the DC potential of the output terminal zero, and if the optimum load resistance is almost the same as the impedance of the speaker, the output transformer is eliminated. You can load the speaker directly. (2) In Fig. 3, a triode is used as the output element, a beam tube is used as the constant current element, and a constant current circuit is arranged on the cathode side of the output triode by combining with a push-pull output transformer, and the first stage and the output triode are directly coupled. Circuit. With this circuit configuration, a DC current flows in the primary side of the push-pull output transformer in the direction of canceling the magnetization without an unbalanced current, and there is no DC magnetization. Further, since the ripple component derived from the power source is canceled, the power source filter can be simplified. further,
Since the constant current circuit can be arranged on the cathode side while performing the normal grounded cathode amplification operation, it is easy to directly connect the preceding stage and the output stage, and the voltage consumed by the constant current circuit can be effectively used.

[0007]

The single amplifier according to the circuit of the present invention has a reduced manufacturing cost and improved characteristics so that a beautiful reproduced sound can be obtained from a low range to a high range.

[Brief description of drawings]

FIG. 1 is a circuit diagram which is the basis of the present invention.

FIG. 2 is a circuit diagram of an embodiment (1) of the present invention.

FIG. 3 is a circuit diagram of an embodiment (2) of the present invention.

[Explanation of sign]

CRS: constant current circuit, Q: output element, C: output capacitor, R: load e: input voltage, E: power supply, Eb: bias power supply, T: transformer.

Claims (1)

[Claims] The load and constant current circuit are equivalently connected in parallel for AC,
A single amplifier that eliminates the influence of direct current on the load by allowing the constant current circuit to support the direct current component.