The exciter is a kind of harmonic generator, a sound processing device that uses human psychoacoustic characteristics to modify and beautify the sound signal. Various methods such as adding high-frequency harmonic components to the sound can improve the sound quality, timbre, enhance the penetration of the sound, and increase the sense of space of the sound. Modern exciters can not only create high frequency harmonics, but also have functions such as low frequency expansion and music style, making the bass effect more perfect and the music more expressive.
Use exciters to improve the clarity, intelligibility and expressiveness of sound. Make the sound more pleasant and pleasant, reduce listening fatigue and increase the loudness. Although the exciter only adds about 0.5dB of harmonic components to the sound, it actually sounds like the volume has increased by about 10dB. The auditory loudness of the sound is obviously increased, the three-dimensional sense of the sound image, and the separation of the sound are increased; the positioning and layering of the sound are improved, and the sound quality of the replayed sound and the copy rate of the tape are also improved. Because acoustic signals lose high-frequency harmonic components during transmission and recording, high-frequency noise occurs. At this time, the former uses an exciter to compensate the signal first, and the latter can use a filter to filter out high-frequency noise, and then create a high-frequency component to ensure the playback sound quality.
The adjustment of the exciter requires the sound engineer to judge the sound quality and timbre of the system, and then adjust it according to the subjective listening evaluation.
The frequency divider refers to distinguish the sound signals of different frequency bands, respectively amplify them, and then send them to speakers in the corresponding frequency bands for replay. When reproducing high-quality sound, electronic frequency division processing is required. It can be divided into two types:
(1) Power frequency divider: It is located behind the power amplifier and is set in the speaker box. Through the LC filter network, the power audio signal output by the power amplifier is divided into bass, midrange and treble, which are sent to the respective speakers. The connection is simple and easy to use, but it consumes power, the audio valley appears, and cross-distortion occurs. Its parameters have a direct relationship with the impedance of the speaker, and the impedance of the speaker is a function of frequency, which deviates greatly from the nominal value, so the error It is also larger, which is not conducive to adjustment.
(2) Electronic frequency divider: a device that divides the weak audio signal in front of the power amplifier. After the frequency division, each independent frequency amplifier is used to amplify each audio frequency band signal and then send it to the corresponding speaker. unit. Because the current is small, it can be achieved with a lower power electronic active filter. It is easier to adjust, reduce power loss, and interference between speaker units. The signal loss is small and the sound quality is good. However, in this way, an independent power amplifier is used for each channel, which has high cost and complicated circuit structure, and is used in professional sound reinforcement systems.
Equalizer is an electronic device that can adjust the amplification of electrical signals of various frequency components separately. It can compensate for defects of speakers and sound fields by adjusting electrical signals of various frequencies, and compensate and modify various sound sources and other special functions. In general, the equalizer on the mixer can only adjust the high-frequency, intermediate-frequency and low-frequency electrical signals separately. There are three types of equalizers: graphic equalizer, parametric equalizer and room equalizer.
1. Graphic equalizer: also known as graphic equalizer, through the distribution of push-pull keys on the panel, it can intuitively reflect the adjusted equalization compensation curve. The rise and fall of each frequency are clear at a glance. It uses constant Q value technology. There is a push-pull potentiometer at each frequency point. The frequency bandwidth of the filter is always the same no matter whether it raises or attenuates a certain frequency. The commonly used professional graphic equalizer divides the 20Hz ~ 20kHz signal into 10, 15, 27, and 31 bands for adjustment. In this way, people choose different frequency equalizers according to different requirements. Generally speaking, the frequency points of the 10-band equalizer are distributed in octave intervals. In general, the 15-band equalizer is a 2/3 octave equalizer, which is used for professional sound reinforcement. The 31-band equalizer is 1 / 3 octave equalizer, most of the occasions require fine compensation, the graphic equalizer structure is simple, intuitive and clear, so it is widely used in professional audio.
2. Parametric equalizer: also known as parametric equalizer. It is an equalizer that can adjust various parameters of equalization. It is mostly attached to the mixer, but there are also independent parametric equalizers. The parameters of adjustment include frequency band, Frequency point, gain and Q value of quality factor, etc., can beautify (including ugly) and modify the sound, so that the sound (or music) style is more distinctive and colorful, to achieve the desired artistic effect.
3. Room equalizer, which is used to adjust the frequency response characteristic curve in the room. Because the decoration materials absorb different frequencies (or reflections) at different frequencies and the effects of normal resonance cause sound staining, the room equalizer must be used. Objectively compensate and adjust the frequency defects due to sound construction.
The finer the frequency band is divided, the sharper the peak of the adjustment, that is, the higher the Q value (quality factor), the finer the compensation during adjustment. The thicker the frequency band is, the wider the adjusted peak is. When the sound field transmission frequency characteristic curve is more complicated Is more difficult to compensate.
Equalizer is an electronic device that can adjust the amplification of electrical signals of various frequency components separately. It can compensate for defects of speakers and sound fields by adjusting electrical signals of various frequencies, and compensate and modify various sound sources and other special functions. In general, the equalizer on the mixer can only adjust the high-frequency, intermediate-frequency and low-frequency electrical signals separately. In communication systems, inserting an equalizer in the tethered system can reduce the impact of intersymbol interference.
Compression limiter is a general term for compressor and limiter. It is a processing device for audio signals, which can compress or limit the dynamics of audio electrical signals. The compressor is a variable gain amplifier, and its amplification factor (gain) can automatically change with the strength of the input signal, which is inversely proportional. When the input signal reaches a certain level (threshold value is also called critical value), the output signal increases with the increase of the input signal. This situation is called Compressor; when it does not increase, it is called Limiter. In the past, the compressor used hard-knee technology, and the input signal reached the threshold as soon as it reached the threshold. The gain is immediately reduced, so that there will be a dynamic mutation of the signal at the inflection point (the turning point of the gain change), which makes the human ear obviously feel the phenomenon that the strong signal is suddenly compressed. In order to solve this problem, the new modern compressor uses soft-knee technology. The compression ratio change before and after the threshold is balanced and gradual, making the compression change difficult to detect, and the sound quality is further improved. .
Compressor can maintain a certain balance between the volume of the instrument and the singer during recording; ensure the balance of various signal strengths. It is sometimes used to eliminate the vocal sound of the singer, or to change the compression and release time to produce the special effect of "reverse sound" from small to large. In broadcast systems, it is used to compress program signals with a relatively large dynamic range and to increase the average emission level on the premise of preventing modulation distortion and preventing transmitter overload. In the sound reinforcement system of the dance hall, the compressor is to compress the signal to maintain the appearance of the original program, reduce the dynamics of the music, and meet the requirements of the sound reinforcement system and artistic activities.
Although the compressor has many uses, modern compressors generally adopt new technologies such as soft knees, which can further reduce the side effects of the compressor of the compressor, but it does not mean that the effect of the compressor on the sound quality is no longer. Re-exist. Therefore, in the sound reinforcement system, do not abuse the compressor, even if it should be used, it should be used with caution to reduce the use of the compressor to process the signal. This is not only the need to protect amplifiers and speakers, but also the need to improve sound quality.
1. The frequency of sound that can be heard by the human ear is generally recognized as 20Hz to 20KHz (Hz Hertz, the unit of frequency).
2. All audio equipment, pickup, mixing, amplification, and loudspeakers will be affected by equipment, materials, etc., which will cause the attenuation or increase of certain frequencies of a sound signal during transmission.
3. The equalizer can be specified to increase or decrease certain frequencies that need to be changed. Usually used to modify the sound frequency curve that has been changed by objective conditions.
4. The exciter is to restore the harmonic components lost in the audio signal, effectively expand the high-frequency bandwidth and improve the signal-to-noise ratio, thereby improving the clarity and expressiveness of sound restoration. Of course, some people think that the exciter is actually creating a distortion, and the harmonic components caused by this distortion will sound very comfortable. Benevolence sees benevolence and wisdom sees wisdom, I generally treat it as MSG.
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