Multifunctional Hi-Fi preamplifiers

The circuit depicted involves a main amplifier balanced by an electromagnetic pickup, line amplifiers, and a high tone control circuit. It includes components for an electromagnetic player, radio tuner, tape playback, and line input. The preamplifier utilizes an NE5532 integrated operational amplifier, known for its high signal-to-noise ratio and low transient distortion, reflecting superior technical performance. The electromagnetic attenuation employs a phono equalizer amplifier with feedback equalization to meet RIAA standards. The negative feedback mechanism reduces harmonic distortion and enhances the signal-to-noise ratio, although it may introduce transient distortion, affecting high-fidelity performance. The resistive and capacitive attenuation equalizer amplifier comprises a resistor-capacitor network that regulates signals to comply with RIAA specifications. While this approach can lead to significant signal attenuation, necessitating gain compensation after the equalization stage, the circuit integrates features from both designs, using an attenuated feedback phono equalizer amplifier. In the low-frequency range (20Hz to 1kHz), negative feedback is applied effectively, improving distortion and signal-to-noise ratio. For the high-frequency range (1kHz to 20kHz), an attenuation network composed of R6 and C6 ensures compliance with RIAA standards, achieving a total gain of 35 to 40 dB. The line amplifier, utilizing IC3 and associated components, processes input signals from players, tuners, and line inputs, providing necessary amplification to meet post-amplifier input levels while ensuring proper impedance matching. The amplification level is approximately 25 dB. IC4, along with RP3 and related components, forms the attenuated tone control circuit for high and bass adjustments. The tone control circuit can be bypassed via a switch, allowing direct signal flow post-IC3 amplification. High-quality components are recommended for assembly, including metal film resistors with Class I accuracy and polyolefin capacitors. A symmetrical power supply is also advised.

The circuit design integrates multiple functionalities essential for audio signal processing. The NE5532 operational amplifier serves as the core of the preamplifier stage, providing low noise and high fidelity, which is critical in preserving audio quality. The phono equalizer amplifier's feedback mechanism is a crucial aspect, as it ensures that the output closely adheres to the RIAA equalization curve, which is vital for vinyl playback systems. The use of negative feedback in the low-frequency range not only enhances the audio signal's clarity but also minimizes distortion, allowing for a more accurate representation of the original sound.

The tone control circuit, formed by IC4 and associated components, allows for user-friendly adjustments of the audio output, enabling listeners to tailor the sound to their preferences. The inclusion of a switch to bypass the tone control circuit indicates a design consideration for maintaining audio integrity when tone adjustments are not required.

Overall, the circuit is designed for high performance, with attention to component quality and layout to minimize interference and maintain signal integrity. The symmetrical power supply ensures stable performance, further enhancing the reliability of the audio processing capabilities. This comprehensive design approach caters to high-fidelity audio applications, making it suitable for various audio devices, including turntables, tuners, and tape players. Circuit shown in Figure 3 a child opening the main amplifier balanced by the electromagnetic pickup, line amplifiers and high tone control circuit consisting of roads and other parts for electromagnetic player, radio tuner, player, tape playback and line input as before preamplifier is o NE5532 integrated operational amplifier circuit assembly, having a high signal to noise ratio, low transient distortion, etc., it has a high technical performance art. Electromagnetic attenuation using a phono equalizer amplifier feedback equalization amplification clamor, because it has a high technical performance o like negative feedback phono equalizer amplifier by means of a large negative feedback loop to get the RIAA standards prescribed.

The depth of the negative feedback helps reduce harmonic distortion and improve signal to noise ratio, but sometimes increases transient distortion, high fidelity make the circuit is not guaranteed. Resistive and capacitive attenuation equalizer amplifier is a resistor-capacitor network in parallel with the signal path through the attenuation network of regulatory signals to comply with prescribed standards RIAA.

The disadvantage of this approach is balanced after the adoption of a balanced network, signal attenuation is large, and therefore need to increase the network after equalization amplifier stage, to make up for the loss of network signal attenuation gain. This circuit combines the characteristics of the two circuits, using an attenuated feedback phono equalizer amplifier.

In the low moon paragraph (20H ~ lkH) using negative feedback in a balanced manner, due to lower this frequency and the use of an appropriate amount of negative feedback, the electric path at low frequency distortion and signal to noise ratio has greatly improved. For 1kffi- 20kHz high-frequency band by R6.C6 composed by attenuating the attenuation network to eventually meet the standards o RIAA circuit decorated by the late Choi Ilcz make a total magnification so it reaches the desired output level of 35 ~ 40dB.

Line amplifier by the Ic3 and related components. It input signals, including players, tuners, phono, line input, as appropriate amplification to meet the post-amp input level required, and also the front, between the level reached after the output and input impedance reasonable match. The amount of amplification level is about 25dB. IC4, arsenic, RP3 and related components consisting of attenuated tone control circuit, high, bass control, if need sound tone control, a tone circuit I will cut through the switch carp rainbow, directly after the input signal level from the IC3 amplifier circuit.

This circuit should be of high quality components assembled, resistance should use metal film resistors, Class I accuracy. Use electrical capacitance polyol content. Power should use the symmetrical power supply.