JP2007295502A - Amplifier circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems that a maximum output that can be extracted is small in conventional single end amplification and odd-order distortion or zero-cross distortion easily occurs in push-pull amplification when using a vacuum tube as an amplification element, it is necessary to always pay attention to maintenance of operational balancing, it is required to consider to a maximum a pairing property of elements and the maintenance of operational balance in amplification by a vacuum tube SEPP that is configured of a plurality of elements or complementary push-pull amplification using a semiconductor element, and both positive and negative large-scaled power sources extremely excellent in regulation performance is needed. <P>SOLUTION: Two winding wires of the same inductance capacitance are regarded as an equivalently single winding wire, and a hot side winding wire and a cold side winding wire thereof are swung with opposite phases only by a single electrode vacuum tube or a complementary single pair semiconductor elements. A large output beyond the conventional circuit is extracted to attain enhancement in various characteristics and to also ensure operational stability or reliability. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention mainly relates to the improvement of the performance of all apparatuses that control audio signal amplification. Of course, the present invention can be applied to other technical fields such as a signal amplifying device or an inductor type driving device which is effective.

  In the case of an audio signal amplifying circuit using a vacuum tube as an amplifying element, a transformer is used as a load, single-ended amplification using a single electrode vacuum tube (FIG. 7), push-pull amplification using a two-electrode vacuum tube (FIG. 6), or SEPP using multiple electrodes. An OTL (Output Transformer Less) output (FIG. 9) of (Single Ended Push Pull) amplification has been frequently used.

  In the case of a single-ended amplification of a conventional circuit using a single electrode vacuum tube (FIG. 7), the sound quality performance is excellent to some extent, but an air gap for delaying the DC magnetization generated in the core of the load transformer 15 and the primary side winding Due to the operation of swinging only one terminal, in general audio vacuum tubes, it stays at about several tens to several tens of watts, and most of them are inferior in distortion characteristics due to the nonlinearity of the vacuum tubes themselves. Also, depending on the performance of the load transformer and the operation and performance of the vacuum tube itself, the sound quality performance is not always excellent.

  In the case of push-pull amplification with a two-electrode vacuum tube (Fig. 6) and a vacuum tube SEPP amplification circuit with multiple electrodes (Fig. 9), although a large output can be obtained to some extent, multiple pairs of vacuum tubes with uniform characteristics are required for balance maintenance in operation. It is necessary to keep in mind. In the case of a transformer load, the direct current magnetization of the core of the load transformer 14 can be prevented by canceling out the circuit configuration and winding structure, but the power output to the secondary side of the transformer is only the hot side swing and the cold side swing. It becomes only the difference of. This is due to the canceling action that occurs inside the transformer, that is, the strong subtractive induction action, and naturally becomes a major factor that degrades the sound quality performance. In the case of class A push-pull operation, this influence is particularly noticeable, and only an output that is about twice that of single-ended amplification by a single electrode vacuum tube can be taken out.

  In the class B push-pull operation, the cold side is cut off while the hot side is swinging, or vice versa, so that the influence of the subtraction inducing action is almost eliminated and a somewhat large output can be taken out. On the other hand, however, it is greatly influenced by the regulation performance of the + B high-voltage power supply section, and zero-cross distortion or odd-order distortion tends to appear in the dynamic coupling portion of the two electrodes. Therefore, it is not easy to take out excellent sound quality performance.

In the case of an audio signal amplifying circuit using a semiconductor as an amplifying element, a complementary push-pull circuit (FIG. 8) in which an Nch element 8 and a Pch element 9 are generally combined is configured. In order to drive a speaker directly with the midpoint of both elements as a zero potential output, a large-scale positive and negative power supply excellent in regulation performance and multiple parallel connection of large power elements is required.
In addition, in order to suppress voltage drift due to temperature changes of both elements, or to suppress zero cross distortion of both elements, each complementary element is required to have excellent pair characteristics. Furthermore, a protection circuit for protecting the speaker from an overcurrent accident caused by a failure of a semiconductor element is indispensable.

Problems to be solved by the invention

  In the case of conventional single-ended amplification with a single electrode vacuum tube (FIG. 7), it is difficult to extract an output for sufficiently playing low-efficiency speakers, which have recently been popular in general vacuum tube elements for audio. Assuming that a speaker with a sensitivity of 100 dB is sounded with a power of 5 W, the calculation will require 10 times as much as 50 W if the sensitivity is 90 dB or less, which is often found in recent products. An amplifying apparatus that realizes this output value must find a large-scale vacuum tube that is no longer common in single-ended amplification with a single-electrode vacuum tube. In this amplification mode, it is difficult to achieve excellent distortion characteristics due to the non-linearity of the vacuum tube itself.

  In the case of push-pull amplification using a two-electrode vacuum tube and a transformer load (FIG. 6), in class A amplification, the output is reduced due to the subtraction induction action that occurs inside the load transformer 14, resulting in low-efficiency amplification. In addition, because class B amplification causes two elements that cannot have exactly the same operating characteristics to swing in opposite phases, odd-order distortion and zero-cross distortion are likely to occur. Require excellent regulation performance. Furthermore, in this amplification mode, it is necessary to always pay attention to balance maintenance in operation. If the balance is lost, distortion characteristics and sound quality performance are deteriorated.

  Especially in the case of vacuum tube SEPP amplification (FIG. 9) or complementary push-pull amplification (FIG. 8) using a multi-element circuit configuration, the speaker is directly driven using the midpoint of both complementary elements as the zero potential output. Therefore, maximum consideration is required for the maintenance of the balance of the element pairing and operation. If the balance is lost, an accident such as abnormal heat generation of the amplifying element and destruction of the speaker may occur. In addition, it requires a large-scale positive and negative power source with excellent regulation performance.

  The present invention proposes a completely new amplifying operation principle that solves the problems of these conventional circuits.

Means to solve the problem

  Two tubes with the same inductance capacity are equivalently considered as a single winding, and the action of taking out an extremely high quality output with little loss by swinging its hot side coil and cold side coil in opposite phases is a vacuum tube. This is necessary for amplifier circuits and semiconductor amplifier circuits.

  In the case of using a vacuum tube element, a load transformer 2 having a hot winding and a cold winding in a common core in a split structure with the same inductance capacity, or a load transformer having a secondary side winding in the same inductor. 3, a circuit (FIGS. 1 and 2) is configured to connect the plate electrode of the single electrode vacuum tube 1 and the hot terminal of the hot winding, and the cathode electrode and the cold terminal of the cold winding.

  In the case of using a semiconductor element, the drain electrode of the complementary Nch element 8 and the hot terminal of the hot winding are used in a load transformer 16 having a common core and a hot winding and a cold winding in the split structure with the same inductance capacity. Constitutes a circuit (FIG. 5) for connecting the drain electrode of the Pch element 9 and the cold terminal of the cold winding.

The invention's effect

  When a vacuum tube is used as an amplifying element, an output equivalent to or higher than that of a conventional two-electrode push-pull amplification (FIG. 6) can be obtained using only a single electrode vacuum tube. This is because the plate electrode of the single electrode vacuum tube 1 swings the hot terminal of the hot winding of the load inductor 2, and the cathode electrode swings the cold terminal of the cold winding of the inductor 2 in the opposite phase, and the output By driving the output transformer with a signal (FIGS. 3 and 4) or by similarly swinging and inductively synthesizing with the load transformer 3 (FIG. 2), a BTL (Bridge Tied Load) output action (FIG. 10) can be achieved. This is because it can be realized.

  At this time, the DC idle current flows in the same direction in the primary winding of the load inductor or load transformer, and the induced power is also generated in the same phase. Therefore, the hot side swing and the cold side swing act additively and output. The impedance is lowered and averaged so that the nonlinearities of the plate-side swing and the cathode-side swing cancel each other, thereby greatly improving the distortion rate. Therefore, the sound quality performance is greatly improved. Further, unlike the conventional vacuum tube push-pull amplification (FIG. 6), there is no need to pay attention to the variation in characteristics between the two electrodes and the balance maintenance in operation, and the same applies to the change over time until the significant deterioration.

  When a semiconductor is used as an amplifying element, an NTL / Pch complementary single pair and a single power supply voltage are used, and a positive / negative double power supply OTL (Output Transformer Less) amplifier circuit (FIG. 8) with a parallel structure that is normally used is used. It can be taken out. This is because when the Nch / Pch complementary amplifying element is operated close to class B amplification, the drain electrode of the Nch element 8 is the hot terminal of the primary hot winding of the load transformer 16 and the drain electrode of the Pch element 9 is the same. This is because the cold terminals of the cold windings of the transformer can be swung in opposite phases, and the output signal inductively synthesized can be taken out (FIG. 5).

  At this time, while the hot side is swinging, the cold side is cut off or vice versa, and the DC idle current flows in the same direction in the primary winding of the load transformer, and the induced power is also generated in the same phase. For this reason, the hot-side swing and the cold-side swing act in an additive manner, and no subtraction induction action occurs in the load transformer. Even if there is a slight difference in the idle current between the complementary two elements, zero cross distortion does not appear or the distortion rate does not deteriorate due to the magnetic synthesis of the signals. Therefore, there is no need to obtain maximum consideration for excellent pairability and operational balance maintenance for each complementary element as in the conventional multiple parallel configuration (FIG. 8), or to obtain a large-scale positive and negative power supply. Furthermore, there is no need for a protection circuit that protects the speaker from overcurrent accidents and consideration of the voltage drift of the complementary two elements.

Embodiment of the Invention

  A problem common to the present invention is to obtain a dedicated configuration for a load inductor or a load transformer. That is, both the load inductor and the load transformer require two windings having the same inductance capacity, and the load transformer further requires a secondary winding. Furthermore, in the case of a load transformer, direct current magnetization of the core is caused by a DC idle current flowing in the primary side winding, so that it is necessary to provide an air gap in the core as in the case of the single-end amplification transformer. However, these are within the scope of commonly used transformer manufacturing techniques, and no other special structures, materials, or technologies are required.

  When a vacuum tube is used as an amplifying element, an amplifier circuit (FIG. 2) that extracts the output by inductively synthesizing the hot-side swing and the cold-side swing with the load transformer 3 and two equal-capacity inductors 2 in the common core are extracted as loads. An amplifying circuit (FIGS. 3 and 4) for driving the output transformer 6 with the capacitor output by the capacitor coupling can be considered. In both circuits, the greatest advantage of the present invention resides in that only a single-electrode vacuum tube is used as an amplifying element and BTL operation (FIG. 10) is performed by both hot / cold swings of the output or load transformer. The circuit according to the present invention can be used not only in the output stage but also in any audio signal amplification stage.

  When a semiconductor is used for an amplifying element, an amplifying circuit (FIG. 5) is conceivable in which a hot side swing and a cold side swing are inductively synthesized by a load transformer 16. It is possible to replace the semiconductor element with a vacuum tube, but in that case, it is required to perform class A amplification and to prepare an input signal of one side inversion phase.

Effects of the embodiment

  When a vacuum tube is used as an amplifying element, it is possible to take out an output several times that of a conventional single-end amplification (FIG. 7) and several times that of a two-electrode push-pull amplification (FIG. 6) using only a single electrode vacuum tube. Moreover, because of class A amplification, the output impedance is lower than that of the conventional circuit, excellent in various characteristics, and far superior sound quality performance can be expected.

  Assuming that the maximum swing voltage width is 200 V and the load impedance is 2 kΩ (× 2): 8Ω, the maximum output of ((200 V ÷ √2) × 2) × 0.06 (step-up ratio) ≈17 Vrms (36 W) is obtained. I can take it out. This value is more than ten times that of the conventional single-ended amplifier circuit (FIG. 7). In addition, it is several times as large as the two-electrode push-pull amplifier circuit (Fig. 6), and a maximum swing voltage width of about 400V and a large-scale high-voltage power supply are required to obtain the same output with this amplifier circuit (Fig. 6). become. Further, since all the operations of the circuit of the present invention (FIGS. 1 to 4) are class A amplification, a single power supply having a regulation performance that stably supplies DC power of B voltage × idle current is sufficient.

  When a semiconductor is used for an amplifying element, an NTL / Pch complementary single pair and a single power supply voltage are used, and a multi-parallel positive / negative power supply OTL (Output Transformer Less) amplifier circuit (Figure 8) with an output equivalent to or higher than that normally used It can be taken out. Furthermore, as in the conventional circuit, excellent pairing for each complementary element and balance maintenance for voltage drift are considered, and a protection circuit that protects the speaker from overcurrent accidents without requiring a large-scale positive and negative power supply is required. There is no need.

  Assuming that the maximum swing voltage width is 100 V and the load impedance is 30Ω (× 2): 8Ω, the maximum output of ((100V ÷ √2) × 2) × 0.5 (step-up ratio) ≈71 Vrms (628 W) is obtained. I can take it out. In this case, the power source only needs to have a single power source with a regulation performance for supplying about 3.3 A of current necessary for maximum output with a margin. In order to obtain an output equivalent to this with the conventional amplifier circuit (FIG. 8), at least five sets of Nch / Pch complementary elements and a large-scale positive and negative power source of 700 to 800 VA class are required.

  The basic amplifier circuit of the present invention that swings a single-electrode vacuum tube with two equal-capacity inductors in a common core as loads.   An amplification circuit that swings a load transformer with two identical-capacity inductors in a common core using a single-electrode vacuum tube.   An amplification circuit that drives two transformers with a common core and swings them with a single electrode vacuum tube as a load.   An amplifier circuit that swings with a single-electrode vacuum tube using two identical-capacity inductors as a load on a common core, and directly drives the output transformer with both hot and cold signal outputs.   An amplifying circuit that swings a load transformer having two same-capacity inductors in a common core only by a single pair of Nch / Pch complementary semiconductor elements and a single power supply voltage.   Conventional two-electrode vacuum tube push-pull amplifier circuit   Conventional single electrode type vacuum tube single-ended amplifier circuit   Conventional semiconductor complementary push-pull multiple parallel power supply positive / negative power supply OTL (Output Transformer Less) amplifier circuit   Positive and negative power supply OTL amplifier circuit of vacuum tube SEPP (Single-Ended Push-Pull) configuration   (A) Outline of BTL (Bridge Tied Load) amplification operation (b) Outline of BTL amplification operation by transformer

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vacuum tube element 2 Load inductor 3 Vacuum tube load transformer 4 Hot side winding 5 Cold side winding 6 Output transformer 7 Secondary side winding 8 Nch semiconductor element 9 Pch semiconductor element 10 Signal source (input signal)
11 Coupling capacitor 12 Effective signal waveform and phase 13 Push-pull load transformer for conventional vacuum tube 14 Single-ended load transformer for conventional vacuum tube 15 Load transformer for semiconductor + B / −B Power supply voltage + C / −C Bias voltage

Claims (5)

  When a vacuum tube is used as an amplifying element, a large output exceeding the maximum output of a single-electrode single-ended amplifier circuit (FIG. 7) and a two-electrode push-pull amplifier circuit (FIG. 6) that has been conventionally used can be achieved with only a single electrode. Amplification circuit that enables.   When a semiconductor is used as an amplifying element, an NTL / Pch complementary single pair and a single power supply voltage are used, and an output equal to or higher than that of a normally used multi-parallel positive / negative power supply OTL (Output Transformer Less) amplifier circuit (FIG. 8) is provided. Amplification circuit that enables extraction.   A common inductor has a hot (plate) winding and a cold (cathode) winding in a split structure with the same inductance capacity, and a single electrode vacuum tube plate electrode and a hot winding hot terminal. By constructing a circuit (Fig. 1) that connects the cathode electrode and the cold terminal of the cold winding respectively, it is possible to extract two signals with a low impedance phase difference of 180 °, and by connecting an output transformer. An amplifier circuit (FIGS. 3 and 4) that realizes a BTL (Bridge Tried Load) amplification (FIG. 10) function.   Using a load transformer that has a split structure with the same inductance capacity and a secondary winding on the hot (plate) winding and cold (cathode) winding on one common core, By constructing a circuit that connects the hot terminal of the hot winding to the cold terminal of the cathode electrode and the cold winding, BTL (Bridge Tied Load) amplification (FIG. 10) acts on the secondary output of the load transformer. An amplifier circuit that realizes (FIG. 2).   The drain electrode of the semiconductor Nch transistor element using a load transformer having a split structure with the same inductance capacity and a secondary side winding with a hot (Nch) winding and a cold (Pch) winding on one common core And a hot terminal of the hot winding, a source electrode of the same element is grounded, a drain electrode of the Pch transistor element and a cold terminal of the cold winding are connected to a + B power supply voltage (FIG. By configuring 5), it is possible to obtain a large output equivalent to or higher than that of a commonly used multiple parallel configuration positive and negative power supply voltage OTL (Output Transformer-Less) amplifier circuit (FIG. 8), and to have excellent maintainability and reliability. An amplifier circuit that also achieves sound quality performance.

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