A negative feedback high-low tone circuit made with AD827 / OPA2604 / NE5532, AD827 TONE CIRCUITS
Keywords: negative feedback high-high low tone circuit made by AD827 / OPA2604 / NE5532
Negative feedback high-low tone circuit made with AD827 / OPA2604 / NE5532
The action of the tone control circuit is for timely adjustment of the tone, enabling it in line with a variety of listening requirements, used to compensate for the sound of the sound source, and the frequency response of the sound, and the use of the structure and the use method are relatively simple. Thus, the user is simple and reliable, using the tone controller, its purpose plays an important role in the sound system, in some netizens, the audio system, especially the audio power amplifier circuit is the principle of simplicity Up, reduce the excess function circuit in the signal channel to achieve the original listening effect, the author also in favor of this, the question is if you have enough burn-up high-end speaker unit, its high and low frequency response should reach an ideal More flat curve, this statement is right, and the cabinet cells that most people are in ordinary low-cost market, plus tone circuits to improve its high and low frequency extensions, and have an investment in listening effects A less pleasant way. Be
The species of the audio circuit has the RC attenuation and feedback two-sided, and there is a AA type tone circuit (actually RC attenuation type, but only the AA class in the preampli), the two circuits have advantages and disadvantages. The RC circuit is due to the passive element, the circuit is stable, the phase characteristics are good, but the signal-to-noise ratio is poor, the input and output impedance of the front and rear magnifying circuits is high, and it is easy to be obscene from the external magnetic field. The bass has a small control range. The negative refueling tone circuit has a certain gain, high signal-to-noise ratio, smaller nonlinear distortion, large dynamic range of circuits, but since the circuit is in a depth negative feedback state, if the wiring is unreasonable, it is easy to generate self-integrated, integrated The advantages and disadvantages of the two circuits, this site decides to use the feedback tone circuit to match the SSE01 / SSE02 of this site, the reason is that its disadvantages can be overcome in the carefully reasonable wiring, while the output and inversion input Adding anti-self-excited phase compensation capacitance, adding a power decoupling capacitor in the most recent position of the power supply foot 4, 8 foot, which also uses a high-conversion rate to the circuit design and wiring requirements higher fever operation AD827 / OPA2604 Make a sound-conditioning control Creative condition, do not choose RC circuit, another reason is that the AA tone board for this site is concluded, and the signal to noise is not ideal when it is actually in conjunction with SSE01 / SSE02 board. The magnetic field of the power supply transformer is unfailed, so it is re-designed to replace different op amps by replacing the SSE01 / SSE02 board, which is actually matched with the SSE01 / SSE02 board actually matches the SSE01 / SSE02 board.
The tone control circuit is as shown in the figure above, from W1, W2, W3, W4, which realizes high-stroke, medium sound, bass, balancing control circuit, and volume circuit, which has a volume potentiometer on this site's SSE01 / SSE02 board, so no longer increase The volume potential is between which is 1-5 times the buffer of the pre-stage signal, and the value of R3 / R2 is 1-5 times. The site can be adjusted according to the actual source of sound source. The capacitance C2, C4, C7 in the signal channel have a large influence of the sound quality, with high quality fever, capacitance German red WIMA capacitance, op amp U2 uses high quality fever op amp, AD827 / OPA2604 / NE5532, can, The burnt friends can be selected according to self-propagation, please see if there is a detailed description of the tone of the pre-grade fever, and only the high and low sound control in the pitch control in the above figure and the common power amplifier is added. Control circuitry, in listening, the intermediate frequency portion and music are closely related, the intermediate frequency overlightening or single is thinner will result in a debut distortion, and the W2 incorporation peripheral element constitutes a 6-10 dB of the intermediate frequency signal of 1000 Hz-2000 Hz or Attenuation, achieve the purpose of intermediate frequency control.
In the design of the power supply, the active servo voltage constituted by LM317 / LM337 is used here, which is more than one quantity of power supply and noise than the active servo power source composed of 78/79 series, and the ripple suppression is stronger, and Some relatively complex deposits have the advantages of simple power supply, and the performance stable performance is improved, but the improvement in sound quality is also significantly in actual use. The circuit diagram is as shown in the figure, the input voltage is between the AC double 12V-double 18V, which affects the resistors R14 / RE14, R15 / RE15 of the voltage accuracy, so that the good symmetry of the positive and negative power supply can be achieved. The voltage value of the output is not It must be double 15V, but the positive and negative voltage is consistent (generally output of DC dual 12V-double 15V can work properly) PCB board design graphs
The PCB design sufficiently considers strict requirements with high-rate op amp, and increases the WiMA CBB decoupling capacitor, and the power supply of the circuit is kept from the small signal processing portion, increase the ground isolation measures. And strictly grounded wiring measures, using this board to get the best signal-to-noise ratio. Below is a tall, medium, low, balanced tone control panel, which has been prepared from the manufacturer's custom-made this page, from the manufacturer.
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Component selection: Using the upper fever element on the key components affecting the sound quality, the decoupling capacitance is used in WiMA CBB 0.1U capacitance, and the audio delivery coupling capacitor WiMA 1U capacitance, C14 / CE14 uses genuine ELNA (S) high speed Supported electrolytic capacitors, PCB plates and SSE01 / SSE02 boards, for blue thickening 2MM gold-plated plate power input: AC double 12V-dual 18V can share small voltage output groups on the ring. Mounting Wiring Precautions: The input of the signal is a white needle socket on the board, wherein the socket close to the large electrolytic filter capacitor is the signal output, and the other is the input seat, the signal line is preferably used with a dedicated shield signal line. To avoid obscene from the AC magnetic field. The power input seat is the blue terminal block on the plate, whereby the intermediate standard GND is the ground wire, don't make a mistake.
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