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 different frequencies, and compensate and modify various sound sources. Among other special functions, the equalizer on the general mixer can only adjust the three high-frequency, mid-frequency and low-frequency electrical signals separately. In communication systems, inserting an equalizer in the tethered system can reduce the impact of intersymbol interference.
Equalizer (equalizer) Communication system, correct the transmission channel amplitude frequency characteristics and phase frequency characteristics of the components. The sine wave with frequency f is sent to the transmission channel, and the characteristic that the amplitude ratio of the output voltage to the input voltage changes with f is called the amplitude-frequency characteristic, referred to as the amplitude-frequency characteristic; Called the phase frequency characteristic, referred to as the phase frequency characteristic. The signals transmitted by various transmission channels are generally composed of components with different frequencies. Within the range of the signal frequency band, if ①the amplitude-frequency characteristic of the channel is a constant value; ② the characteristic that the phase φ changes with f is a straight line, which can be written as
¢ (f) = 2πft + θ, t is a constant; ③θ (called phase intercept) is equal to nπ, n = 0, ± 2, ± 4, ..., then the signal waveform will not be distorted after transmission. Condition ①makes different frequency components have the same output input amplitude ratio after transmission, and conditions ② and ③ make them have the same time delay. But the actual channel often does not meet the above conditions, so the signal is distorted. If the distortion exceeds the allowable amount, an equalizer must be used to correct the channel characteristics.
The requirements for equalization are related to the nature of the signal. Since the human ear is insensitive to phase, when transmitting analog telephone signals, only the amplitude-frequency characteristics of the channel are required. When transmitting TV signals, the amplitude and phase frequency characteristics of the channel are required, otherwise the image will be distorted. When the digital signal is transmitted in the baseband, the amplitude and phase frequency characteristics are required, because the waveform distortion will generate inter-symbol interference and increase the bit error rate. When the digital signal carrier is transmitted, there is no requirement for the phase cut in the channel phase frequency characteristic, because the phase reference is not needed when receiving the digital frequency modulation signal, and the phase reference can be solved by the carrier recovery circuit when receiving the digital phase modulation signal. In this way, only the amplitude-frequency characteristics and delay-frequency characteristics are required during carrier transmission.
How to adjust the equalizer to achieve the best resultsEqualizer, it is an electronic component, the most common place is our audio. Equalizer It has a full name called Room Equalizer. It plays a vital role in adjusting the sound system, so what specific role does the equalizer have? How can the equalizer be adjusted to achieve the best results? What are the problems with the equalizer? Next, let's introduce it to you.
The role of the equalizer
Conditioning signal
The first function of the equalizer is to adjust the signals of various frequency bands, because we all know that each signal has a different frequency band. And when we use the radio to collect the bands, the signal strength of each band is the same, then it may cause the received sound to be incomplete, so the role of the equalizer here is to simulate each band. Signals, but each signal has different band characteristics and is very diverse, so the analog form of the equalizer can only become digital analog. The digital signals of these bands are converted into analog signals to be processed at home. This is much easier. Therefore, most of the sounds processed by the equalizer have very obvious high and low sounds, and people can easily distinguish them.
High and low bass
There are also equalizers in our computers, which mostly act as a gain. Under normal circumstances, hardware equalizers are generally used, because in addition to this equalizer, other equalizers are difficult to play. To the role of capital increase. However, for some bands with higher power, Xiaobian recommends that you do not use an equalizer here, because it will only make the sound cloudy and have the opposite effect. If it is for some lower or medium bands, then Will bring a kind of effect with half the effort. At the same time, the equalizer can also increase our musical enjoyment, because we all know that the sound is divided into many frequencies. If the sound frequency is too low, many people will not hear it, but it does not mean that this frequency we If you ca n’t hear the equipment, you ca n’t receive it. Some people with super good hearing can hear it. The role of the equalizer here is to effectively adjust the brightness of these bass bands and the overall sense of space.
Beautify the sound
There are some frequencies in the sound that can most affect human speech intelligibility and brightness, but if this part of the frequency is lacking, it will make the timbre extremely flat. After listening, it will feel dull, and if we add With an equalizer, it's different. It can make this sound frequency beautified, and it sounds particularly pleasant.
The above is the introduction of some functions of the equalizer organized by the editor. As an important part of some electrical appliances, the equalizer can play the role of adjusting the sound, so its status is extremely important and indispensable, and a good equalizer It can also play a complementary effect, making the beautiful sound sound more pleasant.
How to adjust the equalizer to achieve the best results
Subwoofer 20Hz-40Hz, the sound is strong and powerful when appropriate. Can control the sound of thunder, bass drum, pipe organ and bass. Excessive promotion will make the music turbid. Bass 40Hz-150Hz is the basic part of the sound, and its energy accounts for 70% of the entire audio energy, which is an important component of expressing music style. When appropriate, the bass is properly relaxed, the sound is full and soft, when the sound is insufficient, the sound is thin, 150Hz, when excessively boosted, the sound will be dull, the brightness will be reduced, and the nasal sound will be enhanced. The mid-bass 150Hz-500Hz is the structural part of the sound. When the human voice is in this position, the singing voice will be overwhelmed by the music, and the sound is soft and weak. When properly promoted, it will feel thick and powerful, and increase the strength and loudness of the sound. Excessive boost will make the bass sound stiff. Excessive boost at 300Hz is 3-6dB. If reverb is added, it will seriously affect the clarity of the sound.
The midrange 500Hz-2KHz, containing the low harmonics and overtones of most musical instruments, is the characteristic sound of snare drums and percussion instruments. When appropriate, the sound is clear and bright, when insufficient, the sound is dim. Excessive lifting will produce a phone-like sound. The mid-high range 2KHz-5KHz is the characteristic sound of string music (pulling the bow and string of the string music, the sound of the finger of the pull music touching the string). When it is insufficient, the penetration of the sound decreases, and when it is too strong, it will mask the recognition of language syllables. Treble 7KHz-8KHz is the frequency that affects the sound layering. Excessive promotion will make the piccolo and flute sounds prominent, the language's tooth sound will be accentuated and the timbre will be hairy. Very high pitch 8KHz-10KHz, when appropriate, the metal transmission of the triangle iron and stand * is high, and the rhythm of the sand clock is clearly discernible. Excessive boost will make the sound unnatural and easily burn the high frequency unit. Balanced and pleasing sound Below 150Hz (bass) should be full, soft and flexible 150Hz-500Hz (mid-bass) should be thick and powerful and not turbid 500Hz-5KHz (mid-treble) It should be slender, and the garden should be smooth and not sharp.
When the entire frequency response characteristic is flat: the sound is naturally full and flexible, and the level is clear and pleasant. When the frequency response is multiple peaks and valleys: the sound is rough and turbid, the treble is piercing and hairy, and the sound reinforcement without layering is prone to feedback howling. The sound characteristics of the frequency are 30 ~ 60Hz. It is dull. If there is no considerable loudness, it is difficult for the human ear to feel. 60 ~ 100Hz heavy near 80Hz can produce a strong "heavy feeling" effect, high loudness will not give people a comfortable feeling, can give people a strong stimulation. 100 ~ 200Hz, full 200 ~ 500Hz, the intensity is easy to cause the buzzing psychology. 500 ~ 1KHz Mingling 800Hz near 10Hz, will obviously produce a sense of noisy, narrow sense. 1K ~ 2KHz Translucent 2K ~ 4Kz Sharpness around 2800Hz is the most relevant to the sense of brightness, and 3400Hz can easily cause hearing fatigue. 4K ~ 8Kz crisp 6800Hz form a screaming, sharp feeling, "7.5KHz sound is clear and slender. 8K ~ 16Kz slim
Equalizer considerations
Before risking the use of an equalizer to change the audio signal, you should think twice. Excessive use of correction may have advantages and disadvantages for the listener's overall listening performance. The equalizer is not magically incredible, it has many shortcomings, and may have a deeper impact on the sound. The lack of correction equalizer was invented in the 1830s to correct the lack of sound; its main use is in Hollywood film studios. Thanks to the support of an equalizer similar to a fidelity filter, it achieved good results in long-range amplification, which helped to promote its application and also led to subsequent abuse. Since several generations of sound engineers have little or no understanding of the effect of the equalizer on the sound, it is not surprising that the equalizer used in such situations will produce unsatisfactory sound results.
The equalizer is used for mixing the input channels and wiring devices of the mixing console, for example, on an output line to the speaker. Although the use of an equalizer in the microphone input channel allows us to recall its method of shaping speaker sounds or instrument sounds, the often overlooked question is whether the need for an equalizer may be a sign of error in the rest of the link. Equalization may be used to compensate for problems within the audio characteristics of the audio link or loudspeaker, microphone selection, or studio acoustics. It may even appear in studios with perfect acoustic characteristics, the latest speakers and the best microphones.
The use of an equalizer in the output channel to the speaker is a particularly interesting situation, because people are easily mistaken to solve all the problems of improper room acoustics and speaker sound reproduction. Two equalizers are used for parametric and graphic: parametric and graphic equalizer. Measurement and correction characteristic curve of double frequency equalizer. The upper curve is the total response of 3 filters set at + 6dB, center frequency is 630, 1250 and 2500Hz;
The lower curve is the same frequency doubling filter set at + 2dB. The parametric equalizer can correct the sound signal while independently controlling the filtering frequency, bandwidth, and amplitude gain or attenuation. The frequency and peak amplitude or trough in each frequency range can be adjusted continuously or in steps using potentiometers and switches. The operator can adjust in the 20: 1 frequency range, and adjust the sharpness or peak bandwidth at the same time, which is the well-known quality factor (Q value), and the value is 0.29 to 5.0. Generally, the highest and lowest frequency ranges can be switched from peak to flat.
The illustrated equalizer can usually correct the shape of the sound signal in 8, 12, or more fixed frequency bands. Each band has its active filter, and the center frequency of the filter is specified near the potentiometer used to adjust the correction amount (in dB). If the frequency band is divided into octave bands, then this equalizer is a multiplier type, which uses a smaller number of frequency bands (filters). 1/3 frequency multiplier equalizer has more frequency bands, for example, 31 filters (center frequency 20Hz ~ 20kHz), allowing more accurate but more complex correction than frequency multiplier equalizer. The amount of correction available is usually ± 15dB in one channel, or ± 15dB in both channels. When the sliding calibrator is set, they form a certain graph curve whose shape corresponds to the selected calibration curve. This is where the name "graphical equalizer" comes from. When such an equalizer is used to correct insufficient acoustic characteristics or speaker return characteristics, the operator may set the calibrator subjectively "through the human ear" or objectively using an audio analyzer.
The microphone of the analyzer acts on the sound wave at the measurement position, and the shape of the calibration pattern of the calibrator is set to be opposite to the shape of the measurement, so that the resulting characteristic curve is as linear as possible. But all this applies only to one point in space. Since the operator's ear and the microphone of the analyzer record the response characteristic curve of the speaker at a certain position, this may be a problem when the operator moves to another position. All settings of the equalizer at a certain position are not suitable for any place except where the microphone is placed. In addition, considering the complexity of the sound field in terms of standing acoustic waves and indoor resonance modes, and the ratio of direct to reflected sound waves in a more or less diffuse acoustic space, it is easy to understand that a slightly improved response is produced at a location, The equilibrium that produces problematic results at all other nearby locations is not as good as the non-equilibrium.
The human ear (average distance 19cm) separated by the skull is very sensitive to the sound diffraction around the head, so that we can feel the direction, intensity and time difference of the direct and reflected arrival of the sound wave. This is "binaural" hearing. Undesirable effects In all cases except the use of an artificial head (the microphone is placed at the precise position of the left and right ears), due to the subjective nature of hearing, monophonic microphones or even coincident pairs of stereo microphones will feed the analyzer to what the listener hears Completely different objective data. The measurement correction characteristic curves of the 1/3 frequency doubling equalizers set at +2, +4, +6, +8, +10, and + 12dB respectively. However, even with a simulation head and a measurement method with good subjective sensory correction, it is worth remembering that, depending on the type of equalizer, any correction in a frequency range may be in a more or less large range Leading to undesirable effects. Figures 1 and 2 illustrate this situation. Obviously, the multiplier equalizer (Figure 1) has much wider correction characteristics than the 1/3 multiplier equalizer. This is determined by the characteristics of the equalizer. However, even if 1/3 octave equalizers have fairly narrow characteristics when the trimmer is set to the highest position (+12 or + 10dB), they will have wider characteristics at + 4dB. As for "narrowband" 1/6 octave and 1/10 octave equalizers, the greater the potential of the equalizer, the greater the number of ways to achieve unusual, exaggerated and artificial sound effects. Therefore, it is very important to balance with a calm mind, as rationally and logically as possible.
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