Audio power amplifier, referred to as power amplifier. Its function is to amplify the weak audio signal output from the audio source (such as DVD player, CD player, TAPE machine, etc.), and can generate enough power to push the speaker to sound. According to the current demand for audio consumption, civilian power amplifiers have been basically set into two categories, namely pure music amplifiers and home theater AV amplifiers.
Audio power amplifier principleThe audio power amplifier is actually to amplify the smaller audio signal, increase its power, and then output. The pre-amplification mainly completes the amplification of the small signal, and uses a co-amplifier circuit to amplify the voltage of the input audio small signal to obtain the input required by the latter stage. The latter episode focuses on power amplification of the audio so that it can drive the resistors to get the desired audio.
The full name of audio power amplifier is audio power amplifier, which is a power amplifier device used to promote the sound of the speaker to reproduce the sound. It is used in all electronic products that emit sound. The audio power amplifier is actually to amplify the smaller audio signal, increase its power, and then output. The pre-amplification mainly completes the amplification of the small signal, and uses a co-amplifier circuit to amplify the voltage of the input audio small signal to obtain the input required by the latter stage. The latter episode focuses on power amplification of the audio so that it can drive the resistors to get the desired audio.
The dual channel is the stereo sound that is now popular, two speakers or a subwoofer. (Single-channel amplifiers have only one output channel and only one speaker, which has been eliminated).
Important parameters of audio power amplifierThe main performance indicators of audio power amplifiers include output power, frequency response, distortion, signal-to-noise ratio, output impedance, and damping coefficient.
Output Power
Output power: The unit is W. Due to the different measurement methods of various manufacturers, there are some names with different names. For example, rated output power, maximum output power, music output power, peak music output power.
Music power
Music power: refers to the instantaneous maximum output power of the audio power amplifier to the music signal under the condition that the output distortion does not exceed the specified value.
Peak power
Peak power: refers to the maximum music power that the audio power amplifier can output when the volume of the audio power amplifier is adjusted to the maximum without distortion.
Rated output power
Rated output power: the average output power when the degree of harmonic distortion is 10 [%]. Also known as the maximum useful power. Generally speaking, the peak power is larger than the music power, and the music power is greater than the rated power. Generally speaking, the peak power is 5-8 times the rated power.
Frequency response
Frequency response: indicates the frequency range of the audio amplifier and the unevenness within the frequency range. The straightness of the frequency response curve is generally expressed in decibels [db]. The frequency response of the home HI-FI audio power amplifier is generally 20Hz-20KHZ plus or minus 1db. The wider the range, the better. The frequency response of some of the best audio power amplifiers has reached 0--100KHZ.
Distortion
Distortion: The ideal audio amplifier should faithfully restore the input signal after it has been amplified. However, due to various reasons, the signal amplified by the audio power amplifier often has different degrees of distortion compared with the input signal. This distortion is distortion. Expressed as a percentage, the smaller the value, the better. The total distortion of the HI-FI audio amplifier is 0. 03 [%]-0.05 [%]. The distortion of the audio power amplifier includes harmonic distortion, intermodulation distortion, crossover distortion, clipping distortion, transient distortion, transient intermodulation distortion, etc.
Signal to noise ratio
Signal-to-noise ratio: refers to the ratio of the signal level to the various noise levels output by the audio amplifier, expressed in db, the larger the value, the better. The signal-to-noise ratio of general household HI-FI audio power amplifier is above 60db.
Output impedance
Output impedance: The equivalent internal resistance presented to the speaker is called the output impedance. The main parameters of the audio power amplifier currently available in China are: distortion: 1%, efficiency: 90%, power: maximum 20kw, frequency: 100hz-50khz. These indicators are not met at the same time, and different frequency indicators are different.
There are many signal input terminals arranged on the back of the preamplifier or the combined amplifier. They are arranged in pairs of left (L or white) and right (R or red). When using, just connect the corresponding signal source equipment to the corresponding signal input terminal, such as TUNER (tuner), CD (laser player), TAPE (recording base), AUX (spare), PHONO (record player), etc. In fact, except for the PHONO file, the input terminals of other TUNER, CD, AUX, TAPE, etc. have almost the same performance. They are interchangeable and universal, and the effect is exactly the same. But in order to facilitate the selection of different audio sources, we generally adopt the connection corresponding to the audio source.
Common audio power amplifiers:(A) The transformer-coupled Class A amplifier circuit is mainly used in tube amplifiers;
(B) The transformer-coupled push-pull power amplifier circuit is mainly used in some tube amplifiers with large output power;
(C) OTL power amplifier circuit is mainly used in some amplifiers with small output power;
(D) OCL power amplifier is a commonly used amplifier circuit, often used in some power amplifiers with large output power requirements;
(E) The BTL power amplifier circuit is mainly used in occasions requiring higher output power. OTL, OCL and BTL power amplifier circuits are mainly used in transistor amplifiers.
AUdio INPUT is an audio signal input port, all three. The three next to it are 5.1-channel audio input ports. Normally, you can listen to and sing to one of the three groups of AUdio INput. The 5.1-channel stereo effect is good, suitable for watching movies, but it is divided into several groups of signal input. The output is 5 sets of terminal posts (SPEAKERS SYSTEM) on the right, from left to right are right channel, left channel (left and right main channel), center, surround right, surround left. 5 speakers can be connected, red is the positive pole, then the positive pole of the speaker, black is the negative pole, and then the negative pole of the speaker.
The output signal cable of the computer sound card is connected to the AUdio INput of the power amplifier, and the output end of the power amplifier is connected to the speaker. The wireless microphone is connected to the wireless microphone receiver, and the output signal is connected to the power amplifier. If there is a front-level effector, it is more convenient. You can input both the sound card signal and the wireless microphone receiver signal into the front-end effector, and then connect the output of the effector to the power amplifier, which is better. Adjust the sound quality through the effector will be better.
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