Energy-saving mixing amplifier

Abstract

The utility model provides a kind of energy-saving mixing amplifier, including signal input part, signal processing part, power amplification output part;The signal of background music input channel and microphone input channel of signal input part is mixed and early processing after signal processing part, amplification after the power amplification output part drives playing device to play;Power amplification output part includes class D amplifier chip, single-channel coupling output transformer 70 / 100V output and single-channel fixed resistance 4ΩOutput mode, also includes by analog circuit control class D amplifier chip output overheat, overcurrent protection to control class D amplifier chip enters protection mode and resets after fault disappears.The utility model uses class D power amplifier, the whole machine efficiency is improved to 65% or more from 40% or less of previous AB class.

Description

Technical Field

[0001] This utility model relates to the field of mixing amplifiers, and in particular to an energy-saving mixing amplifier. Background Technology

[0002] A mixing amplifier is an electronic device whose main function is to mix multiple audio signals and amplify them before outputting them to speakers or other audio output devices. Mixing amplifiers play a crucial role in music production, live performances, broadcasting, and film and television post-production.

[0003] Existing mixer amplifiers, power amplifiers, and preamplifier circuits are all analog, with scattered components and excessive and complex control circuits. Performance is inevitably inconsistent and unstable, and there are too many wiring connections, resulting in high power consumption and low energy efficiency. Utility Model Content

[0004] This invention addresses the shortcomings of current mixer amplifiers, such as high power consumption and low energy efficiency, by providing an energy-saving mixer amplifier.

[0005] The technical solution adopted by this utility model to achieve its technical objective is as follows: an energy-saving mixing amplifier, including a signal input section, a signal processing section, and a power amplification output section; the signals from the background music input channel and the microphone input channel of the signal input section are mixed and pre-processed by the signal processing section, and then amplified by the power amplification output section to drive the playback device; the power amplification output section includes a Class D amplifier chip, a mono coupling output transformer with 70 / 100V output and a mono constant impedance 4Ω output mode, and also includes overheat and overcurrent protection of the Class D amplifier chip through analog circuit control to control the Class D amplifier chip to enter the protection mode and reset after the fault disappears.

[0006] Furthermore, in the aforementioned energy-saving mixing amplifier: the signal input section includes a 1.5mV TELE / MIC microphone input channel and a 0.5mV MIC2 microphone input channel.

[0007] Furthermore, in the aforementioned energy-saving mixing amplifier: the TELE / MIC microphone input channel is equipped with a voice-activated trigger module and a mute control; the MIC2 microphone input channel is equipped with a phantom power DIP switch for powering condenser microphones.

[0008] Furthermore, in the aforementioned energy-saving mixer amplifier: the signal input section includes a background music input channel that can be switched between auxiliary analog input channels and a flexible external audio channel.

[0009] Furthermore, in the aforementioned energy-saving mixing amplifier, the signal processing section includes a preprocessing module, a mixing module, and a post-processing module.

[0010] Furthermore, in the aforementioned energy-saving mixing amplifier: the preprocessing module includes a module for performing gain and noise reduction processing on the signal input to the signal input section.

[0011] Furthermore, in the aforementioned energy-saving mixing amplifier: the mixing includes a first-stage mixing that mixes the signals from the MIC2 microphone input channel and the background music input channel, and a second-stage mixing that mixes the first-stage mixing with the signals from the TELE / MIC microphone input channel.

[0012] Furthermore, in the aforementioned energy-saving mixing amplifier: the post-processing module includes a timbre control module for adjusting sound quality, a limiter to prevent signal overload distortion, a noise filter, and a balance buffer module to ensure stable signal transmission.

[0013] Furthermore, in the aforementioned energy-saving mixer amplifier, the Class D amplifier chip used is the TPA3251D2DDV Class D amplifier chip.

[0014] Furthermore, in the aforementioned energy-saving mixer amplifier: a switching power supply is used for power supply, and the switching power supply circuit consists of a preamplifier power supply of +28V and a main power supply of +36V.

[0015] This invention uses a Class D power amplifier, which increases the overall efficiency from below 40% for Class AB amplifiers to over 65%.

[0016] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0017] Appendix Figure 1 This is a block diagram of the energy-saving mixer amplifier according to Embodiment 1 of this utility model;

[0018] Appendix Figure 2 This is a circuit diagram of the Class D power amplifier chip connection in Embodiment 1 of this utility model;

[0019] Appendix Figure 3 This is the power supply circuit diagram for Embodiment 1 of this utility model. Detailed Implementation

[0020] Example 1 This example is an energy-saving mixer amplifier, including a signal input section, a signal processing section, and a power amplification output section; as follows Figure 1As shown, the signals from the background music input channel and microphone input channel in the signal input section are mixed and pre-processed by the signal processing section, and then amplified by the power amplifier output section to drive the playback device. The power amplifier output section includes a Class D amplifier chip, a mono coupling output transformer with 70 / 100V output and a mono constant impedance 4Ω output mode. It also includes analog circuitry to control the Class D amplifier chip to enter protection mode and reset after the fault disappears due to overheating and overcurrent protection. "CLASS - D" is a Class D power amplifier, which is highly efficient and suitable for audio driving. Through relays and jumpers, it can be selected to drive directly at 4Ω or output at 70V / 100V constant voltage (suitable for broadcasting and other scenarios); at the same time, "Line Out (1V)" provides line level output for connecting external recording, monitoring and other equipment.

[0021] In this embodiment, the power supply section "AC IN (110 - 220VAC)" is connected to the mains power and converted to DC ("B+", etc.) by the "SMPS switching power supply" to power each module (amplifier, control circuit, etc.).

[0022] This embodiment uses a switching power supply, replacing the traditional linear transformer power supply. The power supply range is upgraded from low-voltage (115 / 230VAC) switching input to a wide power supply voltage input (100V-240VAC), and the overall efficiency is improved from below 40% for Class AB to over 65%.

[0023] A switching power supply with a continuous output power of 1 / 8W and a maximum output power of full power. It can meet a wide power supply voltage range of AC90~263, with a full power efficiency of 89%~90% and a power factor of over 0.8 at full power output.

[0024] The power amplification section of this embodiment is mainly composed of TI's TPA3251D2DDV series integrated Class D amplifier chip, featuring a mono coupled output transformer with 70 / 100V output and a mono constant impedance 4Ω output mode, achieving a full power of up to 120W. Analog circuitry controls the D chip's overheat and overcurrent protection to ensure it enters protection mode and resets after a fault disappears.

[0025] The connection circuit of the TPA3251D2DDV chip is as follows: Figure 2 The diagram shows a Class D power amplifier circuit based on the TPA3251D2DDV chip. The core is built around this Class D amplifier chip to achieve efficient amplification of audio signals. The core chip, TPA3251D2DDV, serves as the core of the Class D amplifier, responsible for pulse width modulation (PWM) and power amplification. Its pinout includes:

[0026] Power supply and power supply: PVDD_AB / PVDD_CD are power supply pins that are connected to high-voltage power supply (such as high-voltage power supply input in the circuit) to ensure high-power output; GVDD_AB / GVDD_CD are low-voltage power supply pins for digital / analog circuits to maintain the operation of chip control logic.

[0027] Signal input: INPUT_A / INPUT_B / INPUT_C / INPUT_D receives audio signals (from the pre-amplifier circuit or signal source) and modulates them inside the chip.

[0028] Output and feedback: OUT_A1 / OUT_A2, etc. are power output terminals, connected to the filter network and the load; OC_ADJ, etc. are used for overcurrent protection regulation; PREQ_ADJ is associated with power supply pre-regulation to ensure stability.

[0029] Signal processing flow:

[0030] Input level:

[0031] Audio signals (such as input interfaces like AMP1) are coupled through capacitors (such as C157 / C110, etc.) and current-limited by resistors (such as R337 / R332, etc.) before entering the TPA3251D2DDV input pin to complete signal preprocessing (DC blocking, impedance matching).

[0032] Class D modulation and amplification:

[0033] The chip internally converts analog audio signals into PWM pulses (high-frequency square waves with a duty cycle corresponding to the audio amplitude), and then amplifies them through a built-in power stage, outputting high-voltage PWM signals from pins such as OUT_A1 / OUT_A2.

[0034] Output filter network:

[0035] The output is connected to an LC filter circuit (inductor L4, capacitor C254, etc.) to restore the PWM pulses to a smooth analog audio signal to drive the load (such as the speaker interface OT-PDA120OUTPUT).

[0036] Power module:

[0037] High-voltage power supplies (such as high-voltage input in the circuit) power PVDD, while low-voltage power supplies (+12V, etc.) power GVDD and the control circuit. Capacitors (C239 / C240, etc.) are used for power supply filtering, suppressing ripple, and ensuring chip stability.

[0038] Protection circuit:

[0039] AMP_RESET resets the power amplifier and restarts it in case of an abnormality; CLIP_OTW monitors clipping / over-temperature and triggers protection actions (such as shutting down the output); overcurrent protection limits the output current through OC_ADJ and external components to prevent device damage.

[0040] Interfaces: BASE JP 3.96 and other interfaces are signal / power expansion interfaces that can be connected to preamplifiers, control circuits or debugging modules; 2EDGRC-5-1 and other interfaces are speaker output interfaces that can be connected to matching loads.

[0041] Auxiliary circuits: Transistors and diodes (such as Q2 / D33, etc.) form switching and clamping circuits to assist in power control, signal switching or protection actions.

[0042] Characteristics of Class D power amplifiers

[0043] High efficiency: By using PWM modulation and switching amplification, power loss is reduced (compared to analog power amplifiers), making it suitable for high-power, energy-saving scenarios.

[0044] Compact design: The chip has a high degree of integration and relatively simple peripheral circuitry (relying on LC filtering rather than complex analog amplifier circuitry), which is conducive to miniaturization.

[0045] In short, this embodiment is a typical Class D power amplifier with TPA3251D2DDV as its core, covering the entire process of "signal input → Class D modulation amplification → filtering output". With the help of power supply and protection circuits, it can achieve high-efficiency audio power amplification and drive speakers to output audio.

[0046] The switching power supply circuit consists of a pre-amplifier power supply of +28V and a main power supply of +36V, such as... Figure 3 As shown.

[0047] This is a switching power supply circuit, built around the core principles of "AC / DC conversion → power transformation → voltage regulation and control → output filtering". The circuit is described below by functional modules:

[0048] Input and rectification / filtering (AC to DC preamp)

[0049] AC input: Connect to AC power or AC power supply through a socket (such as the 2-pin interface in the lower right corner). Electromagnetic interference (EMI) is suppressed through a fuse (which may contain a fuse element) and a common mode inductor (such as L1 / L2), and noise in the AC power supply is filtered out.

[0050] Rectifier bridge: Converts AC voltage into pulsating DC voltage through diode bridge rectifier (such as D1), and then filters it through capacitors (C1 / C2, etc.) to obtain a preliminary smooth DC voltage, which powers the subsequent switching circuit.

[0051] Switching power conversion (core high-frequency conversion)

[0052] Switching transistor and controller: A MOSFET (such as Q1) serves as the core of the switch, paired with a PWM control chip to generate a high-frequency pulse signal (kHz level). The control chip adjusts the pulse duty cycle to control the on / off time of the switching transistor, achieving "chopping" transfer of energy.

[0053] Transformer / Inductor: A high-frequency transformer (or inductor) serves as the core of energy transfer. It uses the principle of electromagnetic induction to convert the DC voltage of the preceding stage into high-frequency AC voltage, thereby achieving voltage transformation (to adapt to output requirements) and electrical isolation (to ensure safety).

[0054] Voltage regulation and feedback control (ensuring output accuracy)

[0055] Feedback loop: The output voltage signal is acquired through optocouplers (such as U1) and voltage divider resistors (Rxx), and the voltage change at the output terminal is fed back to the control chip. The optocoupler achieves strong and weak current isolation, ensuring the safety of the control circuit.

[0056] PWM regulation: The control chip dynamically adjusts the PWM pulse duty cycle based on the feedback signal: if the output voltage is too high, the duty cycle is reduced (shortening the on-time of the switching transistor); if it is too low, the duty cycle is increased, eventually stabilizing the output voltage.

[0057] Output filtering and protection (stable power supply + safety redundancy)

[0058] Output filtering: High-frequency AC is rectified by diodes (D2, etc.) and filtered by capacitors (C3 / C4, etc.) + inductors (L3, etc.) to restore it to a smooth DC voltage (such as 3.3V / 5V / 12V, etc., which needs to be confirmed with circuit parameters) to power the load.

[0059] Protection circuit: Includes overcurrent protection (monitors current through sampling resistor and shuts off the switching transistor in case of abnormality), overvoltage protection (triggered by Zener diode or comparator), and undervoltage protection (ensuring operation stops when the input voltage is too low) to prevent circuit damage.

[0060] Auxiliary circuits and functional expansion

[0061] Soft start: Through a charging and discharging circuit composed of capacitors and resistors, the output voltage is slowly increased when the device is turned on to avoid surge current impact.

[0062] Standby and Control: Some circuits (such as the upper left corner) may enable standby power supply and enable control (starting and stopping the power supply via ON / OFF signals) to meet the device's sleep / wake-up requirements.

[0063] Summary of switching power supply characteristics

[0064] High efficiency: High-frequency switching + transformer isolation significantly reduces power loss compared to linear power supplies (especially in high-power scenarios).

[0065] Flexible: It can adapt to a wide range of input voltages through PWM adjustment and output multiple sets of voltages to meet the needs of complex loads.

[0066] Compact: The high-frequency design reduces the size of magnetic components, which is conducive to miniaturized layout.

[0067] In short, this embodiment is a typical isolated switching power supply. Through the process of "AC rectification → high-frequency chopping → transformer → feedback regulation → DC output", it achieves efficient and stable power conversion, and is suitable for the power supply needs of industrial equipment, consumer electronics and other scenarios.

[0068] The signal input section mainly consists of microphone inputs MIC and MIC2, as well as auxiliary inputs.

[0069] Here, the auxiliary input is BGM (Background Music), which refers to music used as background music in various media formats. It is widely used in movies, TV dramas, video games, animations, and public places such as bars and shopping malls to adjust the atmosphere, enhance emotional expression, and give the audience or participants a more immersive experience. In this embodiment, the BGM mainly consists of "AUX 1 (233mV)" as an auxiliary analog input and "SOURCE MODULE" for flexible access to external audio sources. After switching between the two and "MUTE", they are used in the mixing.

[0070] Microphone inputs: There are TELE / MIC (1.5mV) and MIC 2 (0.5mV) microphone input channels. After amplification, TELE / MIC can be controlled via VOX (voice-triggered) and MUTE (mute control, which is also controlled by the ALL Mute button, etc.); MIC 2 has a Dipswitch for Phantom power (powering the condenser microphone), which is amplified and then used for subsequent mixing, and is also associated with the "MC2 Mute" control.

[0071] Preprocessing and Mixing: The preprocessing module preprocesses the input signal (e.g., gain, noise reduction, etc.), and the multi-channel signal (after being controlled by mute, etc.) is fed into the "Mixing" mixing module to achieve signal mixing. "CHIME" (with volume control, corresponding to 'Volume control for chime') can be overlaid with prompts to enrich the mix content.

[0072] After mixing, the tone is adjusted by "Tone Control"; then optimized by "Limiter" and "FILTER"; and finally sent to power amplification by "Balance Buffer".

[0073] In this embodiment, the preamp inputs include: BGM (AUX input), microphone input, and line input (LINE and UNITS are specifically PREC prioritized). The preamp signal is amplified and processed by volume / priority analog processing before entering the power amplification stage.

[0074] A switching power supply with a continuous output power of 1 / 8W and a maximum output power of full power. It can meet a wide power supply voltage range of AC90~263, with a full power efficiency of 89%~90% and a power factor of over 0.8 at full power output.

[0075] The power amplification section is mainly composed of TI's TPA3251D2DDV series integrated Class D amplifier chip, with a mono coupled output transformer for 70 / 100V output and a mono constant impedance 4Ω output mode (120W full power). Analog circuits control the D chip output overheat and overcurrent protection to control the D chip to enter protection mode and reset after the fault disappears.

[0076] In this embodiment, after the preamplifier, the preamplifier signal is processed by analog circuitry for volume / priority / mixing digitization, filtering control, limiting control, and other functions before being output to the power amplifier stage and then to the output terminal.

Claims

1. An energy-saving mixing amplifier, comprising a signal input section, a signal processing section, and a power amplification output section; the signals from the background music input channel and the microphone input channel of the signal input section are mixed and pre-processed by the signal processing section, and then amplified by the power amplification output section to drive a playback device for playback; characterized in that: The power amplification output section includes a Class D amplifier chip, a mono coupling output transformer with 70 / 100V output and a mono constant impedance 4Ω output mode. It also includes analog circuit control of the Class D amplifier chip output overheat and overcurrent protection to control the Class D amplifier chip to enter protection mode and reset after the fault disappears.

2. The energy-saving mixer amplifier according to claim 1, characterized in that: The signal input section includes a 1.5mV TELE / MIC microphone input channel and a 0.5mV MIC2 microphone input channel.

3. The energy-saving mixing amplifier according to claim 2, characterized in that: The TELE / MIC microphone input channel is equipped with a voice-activated trigger module and a mute control; the MIC2 microphone input channel is equipped with a phantom power DIP switch for powering condenser microphones.

4. The energy-saving mixer amplifier according to claim 3, characterized in that: In the signal input section, the background music input channel includes an auxiliary analog input channel that can be switched between each other and a flexible external audio channel.

5. The energy-saving mixer amplifier according to claim 4, characterized in that: The signal processing section includes a preprocessing module, a mixing module, and a post-processing module.

6. The energy-saving mixing amplifier according to claim 5, characterized in that: The preprocessing module includes a module that performs gain and noise reduction processing on the signal input from the signal input section.

7. The energy-saving mixer amplifier according to claim 5, characterized in that: The mixing includes a first-level mix that mixes the signals from the MIC2 microphone input channel and the background music input channel, and a second-level mix that mixes the first-level mix with the signals from the TELE / MIC microphone input channel.

8. The energy-saving mixer amplifier according to claim 5, characterized in that: The post-processing module includes a timbre control module for adjusting sound quality, a limiter to prevent signal overload distortion, a noise filter, and a balance buffer module to ensure stable signal transmission.

9. The energy-saving mixing amplifier according to any one of claims 1 to 8, characterized in that: The Class D amplifier chip used is the TPA3251D2DDV.

10. The energy-saving mixer amplifier according to claim 9, characterized in that: Power is supplied by a switching power supply, which consists of a pre-amplifier +28V and a main power supply +36V.

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