The difference between front and rear power amplifier
Many friends don't understand the difference between the front and back levels of power amplifier. Today, let's explain the difference between the front and back stages of power amplifier. The professional name of the former power amplifier is: the preamplifier is also the most influential part of the whole set of equipment. It is the equipment that provides the appropriate audio level signal and adjusts the sound quality ( Commonly known as preamplifier, connected between sound source and power amplifier). The professional name of the latter power amplifier is: pure latter power amplifier this is the real power amplifier part, which has a great influence on dynamic and low frequency control. It is simply to amplify the 'pre-stage' audio signal to provide sufficient power to drive the speaker to sound (Always connected before the speaker). However, the power amplifier, which is common in ordinary families, should be called a front-end and back-end power amplifier, merging power amplifier. Rear power amplifier ( Pure rear power amplifier) : The input signal of the latter stage is very simple, that is, to undertake the output of the former stage. But the load at the back level is the horn, which is what makes many audio fans and even magazine reviewers uncertain. The latter stage is the front stage load and is a high impedance load; The horn is a rear load and a low impedance load. It looks similar, only one word is missing, but one high and one low impedance makes it easy to push or push. The current stage is connected to a high impedance rear stage, which mainly provides an tangent output voltage because the rear stage expander. The pure rear power amplifier needs a preamplifier to push it. The power of the pure rear power amplifier is generally more than several hundred watts, usually used in some professional places, and multiple speakers work at the same time to push different speakers, since it is not equipped with a front amplifier circuit, there is no low-level input port, and there is no socket for high-resistance input signals such as microphones, this requires adding a preamplifier or mixer in front of him to give a signal to control it. The front amplifier and the pure rear power amplifier are also combined into one, usually with a power of less than 300 watts, and are used in smaller places, homes or KTV. Former power amplifier (Preamplifier) : Preamplifier refers to a circuit or electronic device placed between the source and the amplifier level, which is designed to accept weak voltage signals from the source. The preamplifier is used to amplify the weak signal. Generally, the signal is filtered out by the electrolytic capacitor to filter out the high-frequency noise signal, and then the negative feedback operational amplifier is used to amplify the signal. Power amplifiers generally refer to amplifying the power of AC signals, that is, lowering the current and voltage of large electrical appliances without distortion of the signals. The front release is close to the detector, the transmission line is short, the distribution capacitor Cs is reduced, and the signal-to-noise ratio is improved. The signal is initially amplified by the forward release to reduce the relative influence of external interference. The forward release is designed to achieve impedance conversion and matching with high input impedance and low output impedance. If the technology is discussed alone, the front stage is more precise than the rear stage, and it is more difficult to do well. If you want to add another power cord, you must not use the good line in the rear stage because the rear stage current is large, should be the front level. The front amplifier is generally connected to the pure rear power amplifier. The front output is connected to the input end of the rear stage, and the rear stage is connected to the speaker. The preamplifier is an amplification voltage, the pure rear power amplifier is an amplification current, the preamplifier is a link device between various sound source devices and power amplifiers, and the output signal level of the sound source devices is relatively low, the power amplifier cannot be pushed to work properly, and the preamplifier plays the role of signal amplification. Summary: power amplifier is generally divided into front-level power amplifier, rear-level power amplifier and combined-level power amplifier. The merging machine integrates the front-level and rear-level machines. The front stage is used to initially amplify the signal and adjust the volume; The latter stage is to enlarge the signal from the previous stage to push the speaker.