If we look at this signal from a waveform, this original signal has many spikes, and their energy is not large, but the peak is sharp and very high. These spikes contribute little to loudness, but have a great impact on sound quality. If clipping occurs, the amplified sound may sound dry and hard. This has something to do with the details of the subjective listening that we usually say. If the power is amplified, only pay attention to the transmission of energy (the corresponding amount is loudness), and not pay attention to the waveform change (causing distortion) during transmission, then we may hear the sound can be very loud, but not good. For active speakers, the amplifier part is built inside the speaker, and the work it does is also to drive the speaker to bring enough output power to the speaker. The nominal writing method we see about speaker power is not very standard. Generally, the power of the speaker that indicates "speaker" refers to the "output power (RMS)" of the power amplifier (power amplifier circuit part of the active speaker). , RMS (rootmeansquare) refers to the root mean square, currently in the multimedia speaker annotation, mostly rms power. The rms power is different from the average power and rated power. The specific algorithm is to take the average value of the square of the power value of each point of the sample and then open the square. How to calculate the root mean square? We will not go deep into the future. The next thing we need to discuss is the relationship between the power amplifier and the rated power and the speaker power. . Home theater network shopping guide
Exploring the charm of sound, the secret behind the power amplifier
The amplified signal of the power amplifier is a complex signal. According to the investigation results of various instruments and different types of program signals in acoustic engineering, the maximum rms power of most program signals (ie, the peak-to-peak value of the program signal is on the load). The ratio of the power to the average rms power (ie, the average power of the program signal on the load) is 3 to 10, up to 12.7. If the power amplifier's rated power corresponds to the average rms power of the program signal, then the maximum output power of the power amplifier should be 3 to 10 times to ensure that the output signal does not clip. This is why we choose the power of the power amplifier to be much larger than the average rms power of the amplified program signal, which is what we usually call the power reserve. From the current low-end products, the maximum output power of the power amplifier should not be 10 times the power reserve of the signal rms power. The power reserve of the design is definitely different. This is one of the reasons why we encounter distortion problems at different volume or volume when testing in peacetime. On the other hand, multimedia speakers rarely indicate when the power is rated power, maximum output power, output RMS power or even speaker power. This is a very confusing parameter.
In addition, if we pay attention to the nameplate on some speakers, there is also a power-related value. What does this value have to do with the output of the power amplifier? In the design document, we can see the following statement: "In order to ensure the safety of the speaker system to which the amplifier is connected, the rated output power of the amplifier is required to be equivalent to the nominal power of the connected speaker system", "to ensure sufficient The power reserve is usually 1.2 to 2 times the power amplifier of the speaker power. This kind of formulation is actually incorrect. The power of the power amplifier is not the same concept as the power of the speaker. The output power of a power amplifier generally refers to the sinusoidal output power at a certain distortion limit. The manufacturer we usually see after power is marked with a specified total harmonic distortion of 0.1%. When the output signal of the power amplifier on the rated load reaches the distortion, the output voltage is called the maximum output voltage, and the voltage is used to calculate the power amplifier. The output power is the nominal output power of the power amplifier, which can also be understood as the maximum output power of the amplifier.
The nominal power of the speaker, the manufacturer often provides the powder noise power, which refers to the power in the rated frequency range of the speaker, which is fed with the specified analog program signal for 100 hours without heat and mechanical damage. Obviously, these two powers are specified and tested from a completely different perspective, and the two are incomparable. If the manufacturer can provide the sinusoidal power of the speaker (referring to the power fed with the sinusoidal signal as the test signal), then the two are comparable. However, manufacturers generally do not provide this data. So, for the speaker, does the noise power of the speaker have a certain correspondence with the sinusoidal power? The answer is - no! The speaker's pink noise power and sinusoidal power are completely different for different structures, different materials and different sizes of speakers, the latter also related to frequency. Therefore, it is not advisable to compare the power of the power amplifier with the nominal power of the loudspeaker to characterize its power reserve in the design of the loudspeaker and power amplifier.
Obviously, comparing the power of the speaker to the power of the power amplifier does not make any sense. From the above, we can also understand that the topic of whether the power is sufficient and the power reserve is sufficient is basically based on the feeling of subjective listening. It is meaningless to look at the label on the speaker because Everyone's method of labeling is not standardized, and the standards are different. Naturally, there is no comparability.
Displacement sensor, also known as linear sensor, is a linear device belonging to metal induction. The function of the sensor is to convert various measured physical quantities into electricity. In the production process, the measurement of displacement is generally divided into measuring the physical size and mechanical displacement. According to the different forms of the measured variable, the displacement sensor can be divided into two types: analog and digital. The analog type can be divided into two types: physical property type and structural type. Commonly used displacement sensors are mostly analog structures, including potentiometer-type displacement sensors, inductive displacement sensors, self-aligning machines, capacitive displacement sensors, eddy current displacement sensors, Hall-type displacement sensors, etc. An important advantage of the digital displacement sensor is that it is convenient to send the signal directly into the computer system. This kind of sensor is developing rapidly, and its application is increasingly widespread.
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