TWI789536B - Vacuum tube bass extraction circuitry - Google Patents

Abstract

A vacuum tube bass extraction circuit system, comprising: a front-end circuit; and a vacuum tube bass extraction circuit connected to the front-end circuit, the vacuum tube bass extraction circuit includes: a small signal amplifying vacuum tube, which receives an input signal from the front-end circuit and outputs An audio signal; and a passive filter circuit, connected to the small signal amplifying vacuum tube, and filtering the audio signal to output a filtered signal; wherein the front-end circuit includes a switching power supply circuit, the switching power supply circuit provides low voltage to The vacuum tube bass extraction circuit; wherein the small signal amplifying vacuum tube has no gain effect on the input signal.

Description

Vacuum tube bass extraction circuitry

The invention relates to a vacuum tube bass extraction circuit system, in particular to a vacuum tube bass extraction circuit system using a switching power supply circuit.

Generally, when a vacuum tube circuit is used, a switching power supply (SWITCH MODE POWER SUPPLY, SMPS) cannot be used. The reason is that the switching power supply contains a pulse (Pulse Width Modulation, PWM) signal, and this signal seriously causes high-frequency noise of the vacuum tube, and the noise becomes serious once it is amplified. In addition, the generally used vacuum tube circuit has a supply voltage between 100VDC and 250VDC, so switching power supply cannot be used. In this case, a single high-voltage power supply will cause design difficulties and cost increases for the subwoofer system, and it is also impossible to use an external switching power supply to reduce power and safety costs. In view of this, there is a need for a vacuum tube bass extraction circuit system that can use a switching power supply circuit and can filter out the generated high-frequency noise.

In order to solve the above problems, one idea of the present invention is to provide a vacuum tube bass extraction circuit system that can use a switching power supply circuit and can filter out the generated high frequency noise.

Based on the idea disclosed above, the present invention provides a vacuum tube bass extraction circuit system, comprising: a front-end circuit; An input signal of the circuit, and output an audio signal; and a passive filter circuit, connected to the small signal amplifying vacuum tube, and filter the audio signal to output a filtered signal; wherein the front-end circuit includes a switching power supply circuit, The switching power supply circuit provides low voltage to the vacuum tube bass extraction circuit; wherein the small signal amplifying vacuum tube has no gain effect on the input signal.

In a preferred embodiment of the present invention, the small-signal amplifying vacuum tube is used as a vacuum tube cathode follower.

In a preferred embodiment of the present invention, the vacuum tube bass extraction circuit includes a second small signal amplifying vacuum tube, the second small signal amplifying vacuum tube is connected after the passive filter circuit, and the second small signal amplifying vacuum tube receives the via Filter the signal and output a second audio signal.

In a preferred embodiment of the present invention, the second small-signal amplifying vacuum tube is used as a vacuum tube cathode follower; wherein the second small-signal amplifying vacuum tube has no gain effect on the filtered signal.

In a preferred embodiment of the present invention, the vacuum tube bass extraction circuit system further includes an amplifier circuit connected to the vacuum tube bass extraction circuit and amplifying the output power of an output signal from the vacuum tube bass extraction circuit.

In a preferred embodiment of the present invention, the amplifier circuit is a bridge-tied load amplifier circuit.

In a preferred embodiment of the present invention, the front-end circuit includes a voltage divider circuit, and the voltage divider circuit divides the voltage provided by the switching power supply circuit to the small signal amplifying vacuum tube and the second small signal amplifying vacuum tube .

The foregoing and other aspects of the invention will become more apparent from the following detailed description of non-limiting specific examples and with reference to the accompanying drawings.

Please refer to the first figure, which illustrates a block diagram of a specific embodiment of the vacuum tube bass extraction circuit system according to the present invention. In the embodiment shown in the first figure, the vacuum tube bass extraction circuit system 100 includes a front-end circuit 110 , a vacuum tube bass extraction circuit 120 and an amplifier circuit 130 . The vacuum tube bass extraction circuit 120 is connected after the front-end circuit 110 , and the amplifier circuit 130 is connected after the vacuum tube bass extraction circuit 120 . Wherein, the front-end circuit 110 further includes a switch mode power supply (Switch Mode Power Supply, SMPS) circuit 112 and a voltage divider circuit 114 . The vacuum tube bass extraction circuit 120 further includes a small signal amplifying vacuum tube 122 , a passive filter circuit 124 and a second small signal amplifying vacuum tube 126 . Wherein, the passive filter circuit 124 is connected after the small signal amplifying vacuum tube 122 , and the second small signal amplifying vacuum tube 126 is connected after the passive filter circuit 124 . In a specific embodiment, the vacuum tube bass extraction circuit only includes a small signal amplifying vacuum tube and a passive filter circuit. The second small signal amplifying vacuum tube can be placed independently in other circuits.

In the embodiment shown in the first figure, the voltage divider circuit 114 of the front-end circuit 110 divides the voltage provided by the switching power supply circuit 112 to the vacuum tube bass extraction circuit 120 to the small signal amplifying vacuum tube 122 and the second small signal amplifying vacuum tube 126 . The small signal amplifying vacuum tube 122 receives an input signal from the front-end circuit 110 and processes the input signal to output an audio signal. The passive filter circuit 124 filters the audio signal to output a filtered signal. The second small signal amplifying vacuum tube 126 receives and processes the filtered signal to output a second audio signal. The amplifier circuit 130 amplifies the output power of an output signal from the vacuum tube bass extraction circuit 120 (in this example, the second audio signal output from the second small signal amplifying vacuum tube 126 ). In a specific embodiment, the voltage provided by the switching power supply circuit 112 to the small signal amplifying vacuum tube 122 and the second small signal amplifying vacuum tube 126 of the vacuum tube bass extraction circuit 120 is a low voltage. For example, the low voltage provided by the switching power supply circuit 112 is a low voltage less than 20V.

In a specific embodiment, the small-signal amplifying vacuum tube 122 and the second small-signal amplifying vacuum tube 126 are three-pole 12AU7 vacuum tubes, but not limited thereto. Wherein, the small-signal amplifying vacuum tube 122 and the second small-signal amplifying vacuum tube 126 only use two poles of them, and have no gain effect. In this way, the vacuum tube bass extracting circuit system 100 can adopt a low-voltage design. In different embodiments, the amplifier circuit 130 uses a TL072 chip, a TDA7375 chip and/or a TDA7377 chip, but not limited thereto. In a specific embodiment, the amplifier circuit 130 is a bridge-tied load (BTL) amplifier circuit, which is driven by a large current to push up the dynamic woofer, so that the vacuum tube bass extraction can use the external switching power supply circuit 112 .

In the embodiment shown in the first figure, the small signal amplifying vacuum tube 122 is used as a vacuum tube cathode follower, and in the vacuum tube bass extraction circuit system 100, the small signal amplifying vacuum tube 122 has no gain effect on the input signal. In addition, the second small signal amplifying vacuum tube 126 is also used as a vacuum tube cathode follower, and in the vacuum tube bass extraction circuit system 100, the second small signal amplifying vacuum tube 126 has no gain effect on the filtered signal. Since the small-signal amplifying vacuum tube 122 and the second small-signal amplifying vacuum tube 126 do not have a gain function in the vacuum tube bass extraction circuit system 100, the required voltage is relatively low, so that the circuit can use the switching power supply circuit 112 as a voltage supply. By. In addition, because the required voltage of the vacuum tube bass extracting circuit system 100 is lower, the cost of safety regulations can be reduced, so as to achieve the advantage of low cost. Moreover, since the small-signal amplifying vacuum tube 122 and the second small-signal amplifying vacuum tube 126 are used as vacuum tube cathode followers, their high input impedance and low output impedance can ensure the design accuracy of the passive filter circuit 124 .

Please refer to the second figure, which illustrates a block diagram of another specific embodiment of the vacuum tube bass extraction circuit system according to the present invention. In the embodiment shown in the second figure, the vacuum tube bass extraction circuit system 200 is used in a subwoofer system. Wherein, the front-end circuit 210 of the vacuum tube bass extraction circuit system 200 uses a switching power supply circuit 212 to provide voltage. The vacuum tube bass extraction circuit 220 of the vacuum tube bass extraction circuit system 200 adopts a low-voltage power supply to design a 12AU7 vacuum tube. Wherein, the vacuum tube bass extraction circuit 220 includes a small-signal amplifying vacuum tube, a passive RC Low-Pass Filter (Passive RC Low-Pass Filter) and a second small-signal amplifying vacuum tube (the internal configuration of the vacuum tube bass extraction circuit 220 can be, for example, the one shown in the first figure. vacuum tube bass extraction circuit 120).

In a specific embodiment, in order to prevent the high-frequency noise of the vacuum tube caused by the Pulse Width Modulation (PWM) signal contained in the switching power supply circuit 212 from being amplified, the small signal of the vacuum tube bass extraction circuit 220 amplifies the vacuum tube and the first The second small signal amplifying vacuum tube has no gain effect, and the output power of the output signal from the vacuum tube bass extraction circuit 220 is amplified by the amplifier circuit 230 of the vacuum tube bass extraction circuit system 200 . Wherein, the vacuum tube bass extraction circuit 220 performs filter processing through the passive filter circuit between the small signal amplifying vacuum tube and the second small signal amplifying vacuum tube, so as to filter out the high frequency noise of the vacuum tube caused by the pulse signal.

Please refer to Figure 3A, which illustrates a circuit diagram of a specific embodiment of a vacuum tube bass extraction circuit. As shown in the third figure A, the small-signal amplifying vacuum tube 322 and the second small-signal amplifying vacuum tube 326 of the vacuum tube bass extraction circuit 320 only use two poles, and both have no gain effect. Meanwhile, a filter circuit 324 is provided between the small-signal amplifying vacuum tube 322 and the second small-signal amplifying vacuum tube 326 for filtering the audio signal from the small-signal amplifying vacuum tube 322 . Please also refer to the third figure B, which shows pin numbers for each pin of a 12AU7 small signal amplifying vacuum tube 322A. Wherein, the pin numbers marked on the small signal amplifying vacuum tube 322 and the second small signal amplifying vacuum tube 326 in FIG. 3 correspond to the pin numbers marked on the small signal amplifying vacuum tube 322A in FIG. 3 B.

Please refer to Figures 4A to 4C, which illustrate the Bode Plots of different embodiments of the vacuum tube bass extraction circuit. Wherein, it can be found in the Bode diagram 450A shown in the third figure A that the high-frequency signal (greater than 161.406 Hz) has been filtered out. In the Bode diagram 450B shown in FIG. 3B, it can be found that the ultra-low frequency signal (less than 167.423mHz) which is inaudible to the human ear has been filtered out. In the Bode diagram 450C shown in the third figure C, it can be found that the high frequency signal (greater than 100 Hz) has been filtered out. According to the fourth figure A to the fourth figure C, it can be found that the vacuum tube bass extraction circuit in these specific embodiments can indeed greatly reduce the PWM signal of the switching power supply circuit.

So far, the vacuum tube bass extraction circuit system of the present invention has been described by the above description and drawings. However, it should be understood that the various specific embodiments of the present invention are only used for illustration, and various changes can be made without departing from the scope and spirit of the patent application of the present invention, and all should be included in the patent scope of the present invention. Therefore, the specific embodiments described in this specification are not intended to limit the present invention, and the true scope and spirit of the present invention are disclosed in the following claims.

100: Vacuum tube bass extraction circuit system

110: front-end circuit

112: Switching power supply circuit

114: Voltage divider circuit

120: Vacuum tube bass extraction circuit

122: small signal amplification vacuum tube

124: Passive filter circuit

126: The second small signal amplification vacuum tube

130: Amplifier circuit

200: Vacuum tube bass extraction circuit system

210: front-end circuit

212: Switching power supply circuit

220: Vacuum tube bass extraction circuit

230: Amplifier circuit

320: Vacuum Tube Bass Extraction Circuit

322: small signal amplification vacuum tube

322A: small signal amplifier vacuum tube

324: filter circuit

326: The second small signal amplification vacuum tube

450A: Bode plot

450B: Bode plot

450C: Bode diagram

The first figure is a block diagram of a specific embodiment of the vacuum tube bass extracting circuit system of the present invention.

The second figure is a block diagram of another specific embodiment of the vacuum tube bass extraction circuit system of the present invention.

The third figure A is a circuit diagram of a specific embodiment of the vacuum tube bass extraction circuit.

The third figure B is a schematic diagram of a specific embodiment of the small signal amplifying vacuum tube with pin numbers marked.

The fourth figure A is a Bode diagram of a specific embodiment of the vacuum tube bass extraction circuit.

The fourth figure B is a Bode diagram of another specific embodiment of the vacuum tube bass extraction circuit.

The fourth figure C is a Bode diagram of another specific embodiment of the vacuum tube bass extraction circuit.

none

100: Vacuum tube bass extraction circuit system

110: front-end circuit

112: Switching power supply circuit

114: Voltage divider circuit

120: Vacuum tube bass extraction circuit

122: small signal amplification vacuum tube

124: Passive filter circuit

126: The second small signal amplification vacuum tube

130: Amplifier circuit

Claims (7)

A vacuum tube bass extraction circuit system comprising: a front-end circuit; and a vacuum tube bass extraction circuit connected to the front-end circuit, the vacuum tube bass extraction circuit comprising: a small signal amplifying vacuum tube receiving an input signal from the front-end circuit and outputting An audio signal; and a passive filter circuit, connected to the small signal amplifying vacuum tube, and filtering the audio signal to output a filtered signal; wherein the front-end circuit includes a switching power supply circuit, the switching power supply circuit provides low voltage to The vacuum tube bass extraction circuit; wherein the small signal amplifying vacuum tube has no gain effect on the input signal. The vacuum tube bass extraction circuit system described in item 1 of the scope of the patent application, wherein the small signal amplifying vacuum tube is used as a vacuum tube cathode follower. As the vacuum tube bass extraction circuit system described in item 1 of the scope of patent application, wherein the vacuum tube bass extraction circuit includes a second small signal amplifying vacuum tube, the second small signal amplifying vacuum tube is connected after the passive filter circuit, the second small signal amplifying vacuum tube The signal amplifying vacuum tube receives the filtered signal and outputs a second audio signal. The vacuum tube bass extraction circuit system described in item 3 of the scope of the patent application, wherein the second small signal amplifying vacuum tube is used as a vacuum tube cathode follower; wherein the second small signal amplifying vacuum tube has no gain to the filtered signal Effect. The vacuum tube bass extraction circuit system described in item 1 of the scope of the patent application further includes an amplifier circuit connected to the vacuum tube bass extraction circuit and amplifying the output power of an output signal from the vacuum tube bass extraction circuit. As the vacuum tube bass extraction circuit system described in item 5 of the scope of patent application, the amplifier circuit is a bridge-connected load amplifier circuit. The vacuum tube bass extraction circuit system described in item 1 of the scope of patent application, wherein the front-end circuit includes a voltage divider circuit, and the voltage divider circuit divides the voltage provided by the switching power supply circuit to the small signal amplifying vacuum tube and the The second small signal amplifies the vacuum tube.

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