Rated output power 12 watt high power 300B single-ended class A audio amplifier

Abstract

The utility model relates to audio frequency amplification equipment technical field, the utility model rated output power 12 watt high power 300B single end class A audio frequency amplifier, including ladder type signal amplification and impedance control circuit and full circuit parallel power supply system, ladder type signal amplification and impedance control circuit includes the signal transmission link that forms in series gradually of preceding stage electronic tube direct coupling circuit, cathode output ware, push transformer and fixed bias high -power stage, full circuit parallel power supply system includes total power supply bus and a plurality of independent power supply branch that is connected with total power supply bus electricity, the utility model has the following advantages: preceding stage direct coupling eliminates the phase distortion and frequency limitation of capacity coupling, cathode output ware and push transformer cooperate impedance matching, guarantee signal stage transmission efficiency, reduce signal reflection and attenuation, music dynamic contrast is distinct, fixed bias high -power stage stable work in class A, distortion degree is low, audio frequency signal purity is high, the real restoration of human voice, musical instrument timbre.

Description

Technical Field

[0001] This utility model relates to the field of audio amplification equipment technology, specifically to a high-power 300B single-ended Class A audio amplifier with a rated output power of 12 watts. Background Technology

[0002] In the high-end audio amplification field, Class A amplifiers, with their advantages of no crossover distortion and linear amplification, have become the core choice for those seeking ultimate sound quality, and the 300B tube is highly favored for its classic tone. However, existing 300B amplifiers have technical limitations: traditional capacitor-coupled preamplifiers are prone to signal phase distortion and frequency response degradation; unreasonable impedance matching between the driver circuit and the power stage limits power output and dynamic performance; series power supply schemes are subject to interference between modules, resulting in low power purity, which restricts the signal-to-noise ratio and amplification stability, making it difficult to meet the high-fidelity, wide frequency response, and low noise requirements of high-end audio. Utility Model Content

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. Therefore, one objective of the present invention is to provide a high-power 300B single-ended Class A audio amplifier with a rated output power of 12 watts. This 300B single-ended Class A audio amplifier can achieve wide frequency response, high signal-to-noise ratio, and high-fidelity audio amplification at a rated power of 12 watts, providing a clean and full signal output for audio playback.

[0004] To solve the above-mentioned technical problems, the technical solution provided by this utility model is as follows: a high-power 300B single-ended Class A audio amplifier with a rated output power of 12 watts, comprising: a stepped signal amplification and impedance regulation circuit, wherein the stepped signal amplification and impedance regulation circuit includes a pre-stage vacuum tube direct coupling circuit, a cathode follower, a driver transformer, and a fixed bias power amplifier stage connected in series to form a signal transmission link; and a parallel power supply system for the entire circuit, wherein the parallel power supply system includes a main power bus and several independent power supply branches electrically connected to the main power bus, wherein the several independent power supply branches supply power to the pre-stage vacuum tube direct coupling circuit, the cathode follower, the driver transformer, and the fixed bias power amplifier stage, respectively.

[0005] Preferably, each of the independent power supply branches is equipped with an independent filter element and a voltage regulator element.

[0006] Preferably, several of the independent power supply branches are connected to the main power bus via a star-parallel topology.

[0007] Preferably, the pre-stage electron tube direct coupling circuit uses electron tubes to construct a capacitor-free signal transmission path and is configured with a DC bias network to stabilize the electron tube operating point. The DC bias network includes bias resistors and power supply branches.

[0008] Preferably, the turns ratio of the primary winding to the secondary winding of the drive transformer is 12K:5K.

[0009] Preferably, the fixed bias power amplifier stage includes a vacuum tube and an output transformer, and is equipped with a fixed bias circuit. It is connected to the load through the output transformer, and the fixed bias circuit includes a bias adjustment element and a voltage stabilizing branch.

[0010] With the above structure, this utility model has the following advantages:

[0011] Sound quality reproduction advantages: Direct coupling of the preamplifier eliminates phase distortion and frequency limitation caused by capacitive coupling, and fully reproduces the low-frequency richness (such as bass drum and double bass) and high-frequency airiness (such as triangle and violin overtones) of the music signal with a wide frequency response; the cathode follower and driver transformer work together to match impedance, ensuring the transmission efficiency between signal stages, reducing signal reflection and attenuation, resulting in vivid dynamic contrast and clear discernible details in soft sounds; the fixed bias power amplifier stage operates stably in Class A, with low distortion, high audio signal purity, and realistic reproduction of vocals and instrument timbre;

[0012] Power and stability: The 12-watt rated output power is compatible with most high-end bookshelf speakers and small floorstanding speakers, meeting the needs of high-fidelity indoor listening; the parallel power supply scheme of the entire circuit, through independent filtering of branches and balanced power distribution of the bus, can suppress the power ripple to within 10mV even when the power amplifier stage outputs high power, ensuring the stable operation of each module. The amplifier has no thermal drift or power attenuation problems during long-term operation (more than 72 hours of continuous operation), and its reliability is significantly better than the traditional series power supply scheme.

[0013] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the present invention will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the present invention.

[0016] As shown in the figure: 1. Direct coupling circuit of the pre-stage electron tube; 2. Cathode follower; 3. Driver transformer; 4. Fixed bias power amplifier stage; 5. Main power bus; 6. Independent power supply branch. Detailed Implementation

[0017] The embodiments of this application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0018] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0019] Combined with appendix Figure 1 A high-power 300B single-ended Class A audio amplifier with a rated output power of 12 watts, including stepped signal amplification and impedance regulation circuitry and a parallel power supply system for the entire circuit.

[0020] The stepped signal amplification and impedance regulation circuit includes a pre-stage electron tube direct coupling circuit 1, a cathode follower 2, a driver transformer 3, and a fixed bias power amplifier stage 4, which are connected in series to form a signal transmission link. The parallel power supply system of the entire circuit includes a main power bus 5 and several independent power supply branches 6 electrically connected to the main power bus 5. The several independent power supply branches 6 supply power to the pre-stage electron tube direct coupling circuit 1, the cathode follower 2, the driver transformer 3, and the fixed bias power amplifier stage 4, respectively.

[0021] The cathode follower 2 is introduced between the pre-stage electron tube direct coupling circuit 1 and the driver transformer 3. Based on the "low output impedance and high input impedance" characteristics of the cathode follower 2, on the one hand, it matches the output impedance of the pre-stage electron tube direct coupling circuit 1 to achieve signal transmission without reflection and loss; on the other hand, it provides a suitable high input impedance environment for the driver circuit of the subsequent driver transformer 3, builds an impedance bridge between the "pre-stage and driver stage", optimizes signal transmission efficiency, and reduces signal distortion and attenuation during inter-stage transmission.

[0022] In one embodiment of this utility model, each independent power supply branch 6 is equipped with an independent filter element and a voltage regulator element. Specifically, as shown in the figure... Figure 1As shown, each independent power supply branch 6 is specifically configured with filter capacitors and voltage regulator chips according to the power requirements and noise sensitivity of the corresponding module. For example, in the branch supplying power to the direct coupling circuit 1 of the pre-amplifier tube, a Samsung (SAMXON) 47UF / 450V filter capacitor with low equivalent series resistance is selected, which, together with the 78H05K voltage regulator chip, can effectively filter out high-frequency ripple and low-frequency noise in the power supply, ensuring that the pre-amplifier circuit receives a stable and clean DC power supply. The branch supplying power to the power amplifier stage uses a large-capacity 10000uf / 16V filter capacitor, which is paired with a 0.5 / 5W power-type voltage regulator component to cope with the large current fluctuations when the 300B tube is working, ensuring the continuous stability of the power supply. These independent filter and voltage regulator components work together to ensure that each module is not interfered with by the power supply noise of other modules during operation, significantly improving the overall signal-to-noise ratio of the amplifier.

[0023] In one embodiment of this utility model, several independent power supply branches 6 are connected to the main power bus 5 through a star-parallel topology. Specifically, as shown... Figure 1 As shown, the main power bus 5 serves as the core power supply hub, extending from the power input terminal to multiple branch lines. Each branch line is connected to an independent power supply branch 6. The starting points of all branch lines are concentrated at the same node of the main power bus 5, forming a star-like layout structure. This topology design allows each branch to obtain its power supply current independently from the bus, avoiding the impact of current changes in one branch on other branches in traditional series power supply. For example, when the 300B vacuum tube in the power amplifier stage generates large current fluctuations during high-power output, since its power supply branch is directly connected to the main power bus 5 through a star topology, the fluctuations are limited to its own branch and will not be conducted to modules with extremely high power supply stability requirements, such as the direct coupling circuit 1 of the preceding vacuum tube, thus ensuring the balance and reliability of the power supply of the entire circuit.

[0024] In one embodiment of this utility model, the pre-stage electron tube direct coupling circuit 1 uses electron tubes to construct a capacitor-free signal transmission path and is configured with a DC bias network to stabilize the electron tube operating point. The DC bias network includes bias resistors and power supply branches. Specifically, as shown... Figure 1As shown, the preamplifier circuit uses a 6H8C vacuum tube. By directly connecting the tube's plate to the input of the subsequent circuit, the traditional capacitive coupling method is eliminated. Utilizing the linear amplification characteristics of the vacuum tube, capacitive attenuation-free transmission of the audio signal from the input to the subsequent stage is achieved, fully preserving low-frequency details (such as 5Hz ultra-low frequency signals) and high-frequency extension (35kHz high-frequency signals), laying the foundation for high-fidelity amplification. The DC bias network stabilizes the vacuum tube's operating point, ensuring the linearity of signal amplification. In the DC bias network, the bias resistors use RJ series military-grade metal oxide film resistors, whose high precision and low temperature coefficient characteristics can accurately set the vacuum tube's gate voltage. The power supply branch provides a stable plate voltage for the vacuum tube. By reasonably designing the matching relationship between the resistor values ​​and the power supply voltage, the vacuum tube operates stably in the linear amplification region, ensuring that audio signals in the 5Hz-35kHz range can be linearly amplified, fully preserving low-frequency details and high-frequency extension.

[0025] In one embodiment of this utility model, the turns ratio of the primary winding to the secondary winding of the driving transformer 3 is 12K:5K. Specifically, as shown... Figure 1 As shown, one end of the primary winding of the driving transformer 3 is connected to the output terminal of the cathode follower 2, and the other end is connected to the corresponding power supply branch to obtain the operating voltage; the secondary winding is connected to the grid of the 300B tube in the fixed bias power amplifier stage 4. The turns ratio is designed based on the grid-cathode characteristic parameters of the 300B tube. The efficient coupling and impedance transformation of the signal are achieved through the principle of electromagnetic induction. The low impedance signal output by the cathode follower 2 is converted into a high impedance signal that is compatible with the grid of the 300B tube. At the same time, the signal amplitude is guaranteed to meet the driving requirements of the power amplifier stage, so that the 300B tube can work stably throughout the entire signal cycle and provide a precise driving signal for subsequent power amplification.

[0026] In one embodiment of this utility model, the fixed-bias power amplifier stage 4 includes a vacuum tube and an output transformer, and is equipped with a fixed-bias circuit. It is connected to the load through the output transformer. The fixed-bias circuit includes a bias adjustment element and a voltage stabilizing branch. Specifically, as shown... Figure 1As shown, the fixed-bias power amplifier stage 4 uses a domestically produced "Linlai" brand 300B vacuum tube as the core of the power amplification. The primary winding of the output transformer is connected to the plate of the 300B vacuum tube, while the secondary winding has multiple output terminals ranging from 0 to 4 to 8 ohms, which can be adapted to speaker loads with different impedances. In the fixed-bias circuit, the bias adjustment element provides a stable negative bias voltage (such as around -84V) to the grid of the 300B vacuum tube by precisely setting the resistance value, ensuring that the vacuum tube operates in the Class A amplification region. The voltage regulation branch consists of filter capacitors and voltage regulation components, which can stabilize the supply voltage of the bias circuit, avoid changes in the bias value due to power fluctuations, thereby eliminating crossover distortion and ensuring a stable output of 12 watts of rated power under a 1kHz, 8-ohm load, and maintaining consistent power output within a wide frequency band of 5Hz-35kHz.

[0027] In summary, this utility model's 12-watt high-power 300B single-ended Class A audio amplifier achieves high-fidelity audio amplification through a stepped signal amplification and impedance regulation circuit consisting of "pre-stage tube direct coupling circuit 1 → cathode follower 2 → driver transformer 3 → fixed-bias power amplifier stage 4," combined with a fully parallel power supply system. The direct coupling circuit preserves complete audio signal details, the cathode follower 2 and driver transformer 3 optimize inter-stage impedance matching, and the fixed-bias power amplifier stage 4 ensures stable power output. The fully parallel power supply system, through independent filtering, voltage regulation, and star topology design, effectively reduces inter-module interference and improves the overall signal-to-noise ratio. This structure overcomes the limitations of traditional 300B amplifiers in power, frequency response, and stability, and can be widely applied in high-end Hi-Fi audio systems and other scenarios, providing a pure and full signal output for audio reproduction.

[0028] All standard parts used in this invention can be purchased from the market, and irregularly shaped parts can be customized according to the description and drawings. The specific connection methods for each part all employ conventional methods such as bolts, rivets, and welding, which are mature technologies in the prior art. The machinery, parts, and equipment all use conventional models in the prior art, and the circuit connections also use conventional connection methods in the prior art, which will not be detailed here. Any content not described in detail in this specification belongs to the prior art known to those skilled in the art.

[0029] The present invention and its embodiments have been described above. This description is not restrictive, and the embodiments shown throughout the text are only one of the embodiments of the present invention. The actual structure is not limited to this. In conclusion, if a person skilled in the art is inspired by this description and designs a similar structure and embodiment without departing from the inventive spirit of the present invention, such design should fall within the protection scope of the present invention.

Claims

1. A high-power 300B single-ended Class A audio amplifier with a rated output power of 12 watts, characterized in that: include: A stepped signal amplification and impedance regulation circuit, comprising a pre-stage electron tube direct coupling circuit, a cathode follower, a driver transformer, and a fixed bias power amplifier stage connected in series to form a signal transmission link; The fully parallel power supply system includes a main power bus and several independent power supply branches electrically connected to the main power bus. The several independent power supply branches are respectively the power supply for the front-stage electron tube direct coupling circuit, the cathode follower, the drive transformer, and the fixed bias power amplifier stage.

2. The 12-watt rated output power high-power 300B single-ended Class A audio amplifier according to claim 1, characterized in that: Each of the independent power supply branches is equipped with an independent filter element, thereby forming a parallel decoupling circuit.

3. The 12-watt rated output power high-power 300B single-ended Class A audio amplifier according to claim 1, characterized in that: Several of the independent power supply branches are connected to the main power bus via a star-parallel topology.

4. The 12-watt rated output power high-power 300B single-ended Class A audio amplifier according to claim 1, characterized in that: The pre-stage electron tube direct coupling circuit uses electron tubes to construct a capacitor-free signal transmission path and is equipped with a DC bias network to stabilize the electron tube operating point. The DC bias network includes bias resistors and power supply branches.

5. The 12-watt rated output power high-power 300B single-ended Class A audio amplifier according to claim 1, characterized in that: The primary winding to secondary winding turns ratio of the drive transformer is 12K:5K.

6. The 12-watt rated output power high-power 300B single-ended Class A audio amplifier according to claim 1, characterized in that: The fixed bias power amplifier stage includes a vacuum tube and an output transformer, and is equipped with a fixed bias circuit. It is connected to the load through the output transformer. The fixed bias circuit includes a bias adjustment element and a voltage stabilizing branch.

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