In the field of professional sound, there are many aspects involved in the configuration of power amplifiers and speakers, such as power matching, power reserve matching, impedance matching, damping coefficient matching, etc. Recognizing the above points during assembly can fully utilize the performance of the equipment used and achieve the desired effect.

1. Power matching
In order to achieve high fidelity listening requirements, the rated power should be determined based on the optimal listening sound pressure. Everyone has this feeling: when the volume is low, the sound is weak, thin, the dynamics are small, there is no luster, the low frequency is significantly lacking, and the fullness is poor; When the volume is appropriate, the sound is natural, clear, round, soft, full, powerful, and dynamic; When the volume is too loud, the sound is stiff, not soft, rough, and has a harsh feeling. Therefore, there is a significant relationship between the sound pressure level and sound quality. It is recommended that the sound pressure level in the listening area be 80-85dB (weighted by A). The rated power of the speaker and the rated power of the amplifier can be calculated based on the distance from the listening area to the speaker and the sensitivity of the speaker's characteristics.
As we all know, when designing the acoustics of a hall, it is necessary to determine the power of the speakers based on a series of calculations, and then determine the power of the amplifier from the power of the speakers. Firstly, typically within the range of 20Hz-20kHz of the human ear, music signals that concentrate a large amount of energy are usually in the mid to low frequency bands, with high frequency band energy only equivalent to 1/10 of the energy in the mid to low frequency bands. Generally, speakers lose much less power at high frequencies than at low frequencies. And the power amplifier is like a current modulator. Under the control of the input audio signal, it outputs currents of different sizes to the speaker, causing it to produce sounds of different sizes. Under a certain impedance, a power amplifier with a nominal power of 200W can achieve 400W or several times the output. However, the distortion (THD) of the power amplifier will be greatly increased. This distortion mainly occurs in the high-frequency harmonics in the middle and low frequency signals. The larger the distortion, the greater the energy of the high-frequency harmonics. These high-frequency distortion signals will enter the high pitched head together with the high-frequency music signal. This is why small power amplifiers can cause the speaker to burn the high pitched head when they are pushed up. Secondly, the power configuration of the amplifier and speaker is also related to the target loudness and the usage scenario. At a certain target loudness, the dynamics of the music signal should be fully guaranteed on each piece of equipment. If the power amplifier is too high and the gain setting is very small, the loudness has reached the required level, but at this time, the gain of the amplifier limits the dynamic range of the signal. So, the power of the amplifier should not be too high, otherwise it will not only waste expenses, but also bring the trouble of inability to balance loudness and music dynamics, as well as excessive load on the speaker.
In short, the selection of power amplifier must be determined by the speaker. Under a certain target loudness, the speaker can be larger than the design value for different purposes, and the power of the power amplifier should be strictly determined by the speaker, without much flexibility. The specific standard for power configuration of amplifiers and speakers should be: under certain impedance conditions, the power of the amplifier should be greater than that of the speaker, but not too large. In general applications, the undistorted power of the amplifier should be 1.2-1.5 times the rated power of the speaker; In large dynamic situations, it should be 1.5-2 times. By configuring according to this standard, it is possible to ensure that the amplifier operates at its optimal state while also ensuring the safety of the speaker. Even for inexperienced operators, as long as it is not a serious operational error or improper calibration of the front-end peripheral equipment, the speaker and amplifier can operate in a stable state.

2. Power reserve matching
The so-called "power reserve" refers to speakers. According to the AES standard, a typical speaker can withstand an instantaneous peak input power that is 4 times (6dB) higher than its rated input power in a short period of time. That is, a speaker with a nominal power of 300W can withstand an input power of 1200W in a short period of time. According to the standards of the FTC laboratory in the United States, with sufficient power supply capacity, a power amplifier can instantly output a peak output power 3dB higher than its rated output power. In other words, a power amplifier with a rated output power of 300W can provide twice the peak output power (600W) in a short period of time. If a power amplifier that can provide a peak output power of 1200W is required, the rated output power of this amplifier needs to reach 600W. In order for both the amplifier and the speaker to fully represent various music peak signals, the rated output power of the amplifier should be equal to twice the input power of the speaker.
However, in this configuration, it is required that you cannot fully add the rated power of the amplifier to the speaker. If you do, the speaker will actually be subjected to an input power that exceeds its rated input power by more than 1 times, which means that the speaker will always be in an overloaded working state. This is very dangerous for the speaker. Therefore, according to the ratio of amplifier output power to speaker input power of 2:1, the purpose is only to allow the speaker to display its peak output capability, but the control of the amplifier input level is relatively strict. Under normal circumstances, the rated input level of the power amplifier is 0dB. At this time, the input level of the power amplifier is set 3dB lower than the rated power input level. That is to say, when a 600W power amplifier only operates at 300W, when a signal with a 4x (6dB) peak characteristic enters the power amplifier, the actual input level of the power amplifier reaches 6+(-3):+ 3dB, and at this point, the instantaneous output power of the amplifier reaches l times the rated output power, which matches the peak input power of the speaker. If the power level is not controlled in this way, for example, if a 600W rated power amplifier pushes a 300W speaker, and the amplifier still inputs 600W power according to its rated input level, the amplifier will normally input 600W power. The speaker has l times the input power. When a+6dB (4 times) peak signal enters, the amplifier's peak output power needs to reach 2400W, but its peak output capacity is only 2 times, and it cannot emit 4 times the undistorted power. At this time, the audio signal is clipped, turning the sine wave audio signal into a square wave signal, and the speaker is easily damaged.
There are two ways to set the control level: the first is to set the normal operating level of the system to OdB, and when the output level of the equipment in the front stage of the power amplifier indicates OdB, reduce the volume potentiometer of the power amplifier by 3dB; The second method is to set the normal operating level of the system to OdB. and then reduce the output level of the mixing console by 3dB under normal conditions.

3. Impedance matching
Impedance matching refers to the rated output impedance of the power amplifier, which should be consistent with the rated impedance of the speaker. At this point, the power is in the optimal design load state and can output the maximum undistorted power. If the rated impedance of the speaker is greater than the rated output impedance of the amplifier, the actual output power of the amplifier will be less than the rated output power; If the rated impedance of the speaker is lower than the rated output impedance of the amplifier, there is a risk of overload in the amplifier, and it is required that the amplifier has complete overcurrent protection measures to solve it. For electronic tube amplifiers, impedance matching requirements are more stringent.

4. Matching of damping coefficients
The damping coefficient KD is defined as: KD=rated output impedance of the power amplifier (equal to the rated impedance of the speaker)/internal resistance of the power amplifier output+line resistance. Due to the fact that the internal resistance of the amplifier output has become the electrical damping device of the speaker, the KD value determines the amount of resistance experienced by the speaker. The larger the KD value, the heavier the resistance. Of course, the KD value of the power amplifier is not necessarily better. If the KD value is too high, it will cause excessive electrical damping in the speaker, resulting in an increase in the establishment time of the pulse front and a decrease in the transient response index. The basic condition for ensuring good steady-state and transient characteristics of playback is to pay attention to the coordination between the equivalent mechanical quality factor (Qm) of the speaker and the amplifier damping coefficient (KD). This kind of coordination requires considering the feeder of the speaker as a part of the overall sound system. The equivalent resistance of the feeder of the speaker should be small enough to be negligible compared to the rated impedance of the speaker. In fact, the power loss of the speaker feeder should be less than 0.5dB (about 12%) to achieve this coordination.

5、summarize/strong>
In summary, only by fully considering several important factors that affect the matching between power amplifiers and speakers, such as power matching, power reserve matching, impedance matching, damping coefficient matching, etc., can the performance of the equipment be fully utilized, achieving the desired sound amplification effect while protecting the safety of the equipment.