HIFI basic knowledge and tuning-related knowledge
Time:April 17, 2018
Views:7097
A speaker is a device that converts electrical signals into sound signals, and the fidelity of the conversion is an important criterion for evaluating the performance of the speaker. An active speaker is a speaker system equipped with a power amplifier (also known as an amplifier). By integrating the power amplifier and the loudspeaker sound system, it can be directly paired with common audio sources (such as portable players, CD players, DVD players, video recorders, etc.) to form a complete audio combination. With an active speaker, there is no need to purchase a separate power amplifier, eliminating the hassle of selecting and matching a suitable amplifier and speaker. It is easy to operate and has a high cost-performance ratio, making it widely accepted by the working class.
Based on different sound generation principles and internal structures, loudspeakers can be categorized into several types, including inverted phase, sealed, flat panel, horn, and maze types, with the most predominant being the sealed and inverted phase types. A sealed loudspeaker simply mounts a speaker on a closed enclosure, resulting in relatively low efficiency. Conversely, an inverted phase loudspeaker differs in that it features a circular phase port on the front or rear panel. It operates based on the principle of a Helmholtz resonator, offering advantages such as high sensitivity, high power handling capacity, and a wide dynamic range. Since the sound waves behind the speaker are also emitted through the phase port, its efficiency surpasses that of a sealed enclosure. Furthermore, when the same speaker is installed in a suitable inverted phase enclosure, it can achieve a 3dB higher low-frequency sound pressure than when installed in a sealed enclosure of the same volume, which benefits the performance of low-frequency components. This is a significant reason for the widespread popularity of inverted phase enclosures.
2. The sound quality of a power speaker is not directly related to its power. Power determines the maximum sound intensity that the speaker can produce, which gives an impression of how powerful the sound emitted by the speaker can be. According to international standards, there are two ways to label power: rated power (RMS: root mean square of sine wave) and peak maximum power output (PMPO power). The former refers to the maximum electrical power that can be used to drive an 8Ω speaker within the rated range, with a specified waveform continuous analog signal, after a certain interval and repeated a certain number of times, without causing any damage to the speaker; the latter refers to the maximum power that the speaker can withstand for a short period of time.
In 1974, the United States Federal Trade Commission established a power rating standard: the effective wattage measured when driving an 8Ω speaker load with two channels and achieving a harmonic distortion of less than 1% within the range of 20-20,000Hz is considered the output power of the amplifier, and its labeled power is the rated output power. Usually, to cater to consumer psychology, businesses label the instantaneous (peak) power, which is generally around 8 times the rated power. Imagine using the same PHILIPS TDA1521 power amplifier chip (with a maximum rated power of 30W and THD=10%), but some products are labeled as 360W or even 480WP.M.P.O. Is this possible? Does it make sense? Therefore, when purchasing multimedia speakers, the rated power should be the criterion. The power of the speaker is mainly determined by the power of the power amplifier chip and the power of the power transformer. Considering other factors, it can be calculated that if the rated power of the transformer is 100W, the power of the power amplifier chip it can actually drive smoothly should be below 45W. Therefore, by calculating the power relationship between the speaker transformer and the power amplifier, it can also be verified whether the actual rated power of the speaker can reach the labeled value. The power of the speaker is not necessarily the greater the better; it's best to choose one that is suitable. For ordinary household users in a room of about 20 square meters, a true 60W power (referring to the effective output power of the speaker 30W x 2)
It is sufficient, but the greater the reserve power of the power amplifier, the better. Ideally, it should be more than twice the actual output power. For example, if the speaker output is 30W, the power amplifier's capacity should preferably be greater than 60W. For HiFi systems, the power amplifier driving the speakers has a very high capacity.
Based on different sound generation principles and internal structures, loudspeakers can be categorized into several types, including inverted phase, sealed, flat panel, horn, and maze types, with the most predominant being the sealed and inverted phase types. A sealed loudspeaker simply mounts a speaker on a closed enclosure, resulting in relatively low efficiency. Conversely, an inverted phase loudspeaker differs in that it features a circular phase port on the front or rear panel. It operates based on the principle of a Helmholtz resonator, offering advantages such as high sensitivity, high power handling capacity, and a wide dynamic range. Since the sound waves behind the speaker are also emitted through the phase port, its efficiency surpasses that of a sealed enclosure. Furthermore, when the same speaker is installed in a suitable inverted phase enclosure, it can achieve a 3dB higher low-frequency sound pressure than when installed in a sealed enclosure of the same volume, which benefits the performance of low-frequency components. This is a significant reason for the widespread popularity of inverted phase enclosures.
2. The sound quality of a power speaker is not directly related to its power. Power determines the maximum sound intensity that the speaker can produce, which gives an impression of how powerful the sound emitted by the speaker can be. According to international standards, there are two ways to label power: rated power (RMS: root mean square of sine wave) and peak maximum power output (PMPO power). The former refers to the maximum electrical power that can be used to drive an 8Ω speaker within the rated range, with a specified waveform continuous analog signal, after a certain interval and repeated a certain number of times, without causing any damage to the speaker; the latter refers to the maximum power that the speaker can withstand for a short period of time.
In 1974, the United States Federal Trade Commission established a power rating standard: the effective wattage measured when driving an 8Ω speaker load with two channels and achieving a harmonic distortion of less than 1% within the range of 20-20,000Hz is considered the output power of the amplifier, and its labeled power is the rated output power. Usually, to cater to consumer psychology, businesses label the instantaneous (peak) power, which is generally around 8 times the rated power. Imagine using the same PHILIPS TDA1521 power amplifier chip (with a maximum rated power of 30W and THD=10%), but some products are labeled as 360W or even 480WP.M.P.O. Is this possible? Does it make sense? Therefore, when purchasing multimedia speakers, the rated power should be the criterion. The power of the speaker is mainly determined by the power of the power amplifier chip and the power of the power transformer. Considering other factors, it can be calculated that if the rated power of the transformer is 100W, the power of the power amplifier chip it can actually drive smoothly should be below 45W. Therefore, by calculating the power relationship between the speaker transformer and the power amplifier, it can also be verified whether the actual rated power of the speaker can reach the labeled value. The power of the speaker is not necessarily the greater the better; it's best to choose one that is suitable. For ordinary household users in a room of about 20 square meters, a true 60W power (referring to the effective output power of the speaker 30W x 2)
It is sufficient, but the greater the reserve power of the power amplifier, the better. Ideally, it should be more than twice the actual output power. For example, if the speaker output is 30W, the power amplifier's capacity should preferably be greater than 60W. For HiFi systems, the power amplifier driving the speakers has a very high capacity.
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