All Are Power Amplifiers, The Difference Between The Pre-stage And The Post-stage Is Very Big! Don't Buy It Wrong

- Feb 26, 2020-

Many friends don't understand the difference between preamp and post. Today I will explain the difference between the pre-amplifier and the back-amplifier.


The professional name of the preamp is: preamp. It is also the most influential part of the whole set of equipment. It is a device that provides appropriate audio level signals and adjusts the sound quality (commonly known as preamp, connected between the sound source and the power amplifier).


The professional name of the post power amplifier is: pure post power amplifier. This is the real power amplifier part, which has a great impact on dynamics and low-frequency control. It is a device that simply amplifies the “front-end” audio signal to provide sufficient power to drive the speaker sound (always connected in front of the speaker).


And the common amplifier in the general family should be called the front and rear stage integrated amplifier, right, combined amplifier.

v2-c2bd63925d1a0bc829174587f2d857c5_720w

Rear power amplifier (pure rear power amplifier):

The input signal of the rear stage is very simple, that is, it accepts the output of the previous stage. But the load of the rear stage is the speaker, which is what makes many audio fans and even magazine review writers confused. The rear stage is the front stage load, which is a high impedance load; the speaker is the rear stage load, which is a low impedance load. It looks almost the same, only one word apart, but the high or low impedance makes it easy to push or not move. The current stage is connected to a high-impedance post stage, which mainly provides a suitable output voltage because the post stage amplifier.


Pure back-stage power amplifiers need pre-amplifiers to drive them. The power of pure back-stage power amplifiers is usually a few hundred watts or more. It is usually used in some professional places, and multiple units work at the same time to promote different speakers. Because it does not have pre-amplification The circuit therefore does not have low-level input ports, and there is no jack for high-impedance input signals such as a microphone. This requires a preamp or mixer in front of him to control the signal. Pre-amplifiers and pure rear-stage power amplifiers are also integrated into one, usually with a power of less than 300 watts, which is used in smaller places, such as home use or KTV.


Pre-amplifier (preamplifier):

A preamp is a circuit or electronic device placed between the source and the amplifier stage. It is designed to accept weak voltage signals from the source.


The preamplifier is used to amplify the weak signal. Generally, the signal is passed through the electrolytic capacitor to filter out high-frequency noise signals, and then enters negative feedback to amplify the signal. Power amplifier generally refers to amplifying the power of AC signals, that is, amplifying the current and voltage of electrical appliances without signal distortion. The front is placed close to the detector, the transmission line is short, the distributed capacitance Cs is reduced, and the signal-to-noise ratio is improved. The signal is preliminarily amplified by the preamplifier to reduce the relative influence of external interference. The preamp is designed for high input impedance and low output impedance for impedance conversion and matching.


If you talk about technology alone, the front stage requires more elaborate requirements than the rear stage, and it is more difficult to do well. If you need to add a special power cord, you must not use a good line in the rear stage because the current of the rear stage is large. It should be the front stage. level.


The pre-amplifier is generally connected to a pure rear-stage power amplifier. The front-stage output is connected to the input of the rear stage, and the rear stage is connected to the speaker. The preamp is to amplify the voltage, and the pure rear-stage power amplifier is to amplify the current. The preamp is the linking device between various audio source equipment and power amplifier. The output signal level of the audio source equipment is relatively low, which cannot promote the normal operation of the power amplifier. The preamplifier plays the role of signal amplification.

v2-0eb55d9c2c056279a99acf8fa356297b_720w

to sum up:


Amplifiers are generally divided into front-stage amplifiers, rear-stage amplifiers, and merged-stage amplifiers. The merger machine combines the front-stage and rear-stage machines into one. The front stage is used to preliminarily amplify the signal and adjust the volume; the latter stage is to amplify the signal from the prestage to a large extent to promote the speaker.