HIFI basic knowledge and tuning related knowledge

HIFI Audio Basic Knowledge Manual
1. Speaker
A speaker is a device that restores an electrical signal to a sound signal, and the authenticity of the restoration will be an important criterion for evaluating the performance of the speaker. Active speakers are
A speaker system with a power amplifier (ie, power amplifier). The power amplifier and the speaker sound system are integrated, which can be directly connected with the general sound source (such as
Walkman, CD player, DVD player, video recorder, etc.) to form a complete sound combination. With active speakers, there is no need to purchase additional power amplifiers
Daqi, no longer worry about the reasonable selection of power amplifiers and speakers, easy to operate, and its extremely high performance-to-price ratio is generally accepted by the working class.
According to different sounding principles and internal structures, speakers can be divided into phase-inverted, closed, flat, horn, labyrinth and other types.
The most important forms are the closed type and the inverted type. A closed speaker is to install a speaker on a closed cabinet, which has relatively low efficiency; while the inverted sound
The difference between the box and it is that a circular phase hole is installed on the front or back panel. It works according to the principle of Helmholtz resonator, excellent
The point is that the sensitivity is high, the power that can withstand is large, and the dynamic range is wide. Because the sound wave on the back of the speaker is also emitted from the phase guide hole, its efficiency
It is also higher than the airtight box. And the same loudspeaker installed in a suitable inverter box will get higher low-frequency sound pressure than installed in a closed box of the same volume.
The output of 3dB is beneficial to the performance of the low frequency part, so this is also an important reason why the inverter box is widely popular.
2. Power
The sound quality of speakers has no direct relationship with power. The power determines the maximum sound intensity that the speaker can emit, and it feels like it is emitted by the speaker
How powerful the sound can be. According to international standards, there are two labeling methods for power: rated power (RMS: sine wave root mean square) and instantaneous peak
Value power (PMPO power). The former refers to driving an 8Ω loudspeaker within the rated range. The waveform is a continuous analog signal, and there is a certain interval.

After repeating a certain number of times, the loudspeaker does not cause any damage to the maximum electric power; the latter refers to the maximum power that the loudspeaker can withstand in a short time.

The U.S. Federal Trade Commission stipulated the power calibration standard in 1974: drive an 8Ω speaker load with two channels at 20~
The effective wattage measured when the harmonic distortion is less than 1% in the range of 20000Hz is the output power of the amplifier, and its marked power is the rated output
power. In order to cater to consumers' psychology, businesses usually mark the instantaneous (peak) power, which is generally about 8 times the rated power. Imagine being the same
Use PHILIPS tda1521 power amplifier chip (maximum rated power 30W, when THD=10%), and some products have a nominal 360W, even
To 480WP.M.P.O., is this possible? Does it make sense? So when purchasing multimedia speakers, the rated power shall prevail. The power of the speaker is amplified by the power
The power of the amplifier chip and the power of the power transformer are mainly determined. Taking into account other factors, it can be calculated if the rated power of the transformer is
If the power rate is 100W, the power of the power amplifier chip that it can actually drive smoothly must be below 45W, so the power of the speaker transformer and the power amplifier is calculated.
The rate relationship can also verify whether the actual rated power of the speaker can reach the nominal value. The power of the speaker is not the bigger the better, the application is the best,
For an ordinary home user's room of about 20 square meters, the real power of 60W (refers to the effective output power of the speaker 30W x 2)
It is enough, but the larger the reserve power of the power amplifier, the better, preferably more than 2 times the actual output power. For example, the speaker output is 30W, then the power
The power amplifier is preferably greater than 60W. For HiFi systems, the power amplifier power driving the speakers is very large.
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How to adjust the equalizer
1. How to adjust the equalizer:
Subwoofer: 20Hz-40Hz, strong and powerful sound when appropriate. Can control the sound of thunder, bass drum, organ and bass.
Excessive boost will make the music become muddy.
Bass: 40Hz-150Hz, is the basic part of the sound, its energy accounts for 70% of the entire audio energy, is the expression of music style
Important ingredient.
When appropriate, the bass is relaxed, the sound is full and soft, the sound is thin when it is not enough, 150Hz, and the sound is too loud when it is raised too much.
Muffled, decreased brightness and increased nasal sound.
Mid-bass: 150Hz-500Hz, is the structural part of the sound, the human voice is located in this position, when it is not enough, the singing will be music
Submerged, the sound is soft and weak, and it will feel thick and powerful when properly raised, increasing the strength and loudness of the sound. Over-lifting will make it low
The sound becomes stiff, with an excessive increase of 3-6dB at 300Hz. If reverberation is added, it will seriously affect the clarity of the sound.
Midrange: 500Hz-2KHz, contains the low-order harmonics and overtones of most instruments, and is the characteristic sound of snare drums and percussion instruments. suitable
At that time, the sound was transparent and bright, but when it was insufficient, the sound was dim. Excessive boosting will produce a phone-like sound.
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