Use Skills of Professional Audio Equipment IV-Electronic F
发布日期：2019-07-15 15:31] 共阅次
In my last few articles, I briefly introduced the use of mixers, equalizers and pressure limiters. In this article, I would like to share with you the use of electronic frequency dividers.
In a set of audio systems, the frequency divider generally refers to an audio peripheral device that can divide the audio signal from 20Hz to 20000Hz into suitable and different frequency bands, and then send them to the corresponding power amplifier to drive the corresponding speaker. Because it is an electronic device used to process and distribute audio frequency signals, we usually call it electronic frequency divider. I will not say much about the detailed functions and working principles of the electronic frequency divider. Here I just focus on some aspects that we attach importance to or often feel confused to do some easy-to-understand introduction, hoping to help you all!
1. Why do we use electronic frequency divider
Our acousticians study electroacoustics and the continuous development of Electroacoustics equipment and technology for one purpose: to reproduce all kinds of sound sources faithfully as possible. Of course, it is unrealistic and almost impossible to reproduce all kinds of strange and strange sounds in nature completely by using the present electroacoustics technology. As you know, the frequency range of sound is between 20Hz and 20000Hz. Now the frequency range of most of the front-end audio processing equipment can reach this width, but the current speaker has become a bottleneck part. We want to use one or a few speakers to send out nearly 20Hz-20000Hz broadband. Rate sound is difficult to achieve, because the effective frequency range of a single speaker is not very wide. In view of this, electroacoustic engineers have designed speakers working in different frequency bands, such as:
1. Bass speaker: Let it work in the frequency range of about 30-200 Hz.
2. Bass-to-bass speaker: Let it work in the frequency range of about 200-2000 Hz.
3. Treble speaker: Let it work in the frequency range of about 2000-20000Hz.
So we can use different kinds of speakers working in different frequency bands to configure a sound system that can be as close as possible to the real frequency of sound (20Hz - 20000Hz). Of course, the composition and parameters of different speaker equipment are different. What I mentioned above is taking a three-frequency system as an example. In practice, there are other systems such as two-frequency or four-frequency systems. Moreover, because the speakers used in different sound systems will be different, the working frequencies of these speakers can not be fixed. Yes, but the general principles and ideas are the same.
So there's a question: how can we flexibly allocate audio frequencies to these different types of speakers working in different frequency bands? In order to solve this problem, electronic frequency divider came into being. It can provide appropriate frequency bands according to the needs of different speaker frequencies, such as:
1. We can use electronic frequency divider to transmit high frequency signal to high-pitch loudspeaker through power amplifier.
2. An electronic frequency divider can be used to transmit the IF signal to the middle-tone loudspeaker through the power amplifier.
3. Electronic frequency divider can be used to transmit the low frequency signal to the bass speaker through power amplifier.
In this way, the high, medium and low frequency signals can be output independently and do not interfere with each other. Therefore, the advantages of different loudspeakers'working frequency bands can be brought into play as far as possible, so that the sound reproduction of each frequency band in the audio system becomes more balanced, the sound has a more hierarchical sense, and the timbre is more perfect. That's why we use electronic frequency dividers.
2. The Function and Characteristics of Electronic Frequency Divider
Through the above introduction, you should have a general understanding of the electronic frequency divider, then what are the functions and characteristics of the use of frequency divider, and even shortcomings? Based on years of work experience, I summarize the following points:
(1) Role and characteristics
1. Fundamental frequency division tasks: Because there are many kinds of speakers, the electronic frequency divider of which function and frequency division should be used in the system still needs to be flexibly configured. Now the commonly used electronic frequency divider is divided into 2, 3 and 4 frequency division, which is too complex and meaningless to exceed 4 frequency division. Of course, the electro-acoustic technology is changing with each passing day. At present, there are some dividers which can process audio signals in some other ways while dividing frequency, but the main functions and tasks of any type of electronic divider are still dividing frequency.
2. Protecting speaker equipment: We know that the working frequencies of different loudspeakers are different. Generally speaking, loudspeakers with larger aperture have better low frequency characteristics and lower frequency dive. As if in the same case, the bass effect of 18-inch speakers is generally better than that of 15-inch speakers; on the contrary, the baritone part should adopt smaller-caliber speakers, because the smaller the caliber of the present paper basin vibration speaker, the higher the sound frequency; and so on. Vibration diaphragms should also be very small to produce high frequency sounds. Since loudspeakers are so complex and diverse, it is important to ensure that they can work safely and effectively. Electronic frequency divider can provide the best working frequency for different loudspeakers, so that all kinds of loudspeakers can work more reasonably and safely. Imagine: If the medium and high frequency speakers in the system do not pass through the electronic frequency divider, but directly use the full frequency band audio signal, then these medium and high frequency speakers will be easily damaged under the impact of low frequency signal. Therefore, besides the frequency dividing task, the normal use of electronic frequency divider has more important functions. Protect speaker equipment.
3. Increase the hierarchical sense of sound: If there are many different types of speakers in a sound system, and indeed no electronic frequency divider is used, and different types of speakers use full-frequency signals without frequency division, there will be many frequency overlap and repetition parts between different speakers, and sound interference will become very serious. The sound will become blurred, the sound field will be poor, and the microphone will be prone to sound feedback. If the electronic frequency divider is used to divide the frequency reasonably so that different speakers are in the best working condition, the range of sound frequency produced between different speakers will hardly be repeated, thus reducing the interference between sound waves, the sound will become more clear, and the timbre will be better and more hierarchical. Now!
(2) Disadvantages and shortcomings
1. Too many choices of frequency division will lead to confusion: as the saying goes, there are advantages and disadvantages. Like other professional audio peripheral equipment, electronic frequency divider is not perfect. Sometimes the system needs more audio dividers will be very complex, because different speakers need different frequency division points, different workers. As for the frequency band, for the average sound engineer, in this case, the use of electronic frequency divider will make them feel helpless. Therefore, careful adjustment is very important. At the same time, we can use as little as possible 4-frequency, 2-frequency or 3-frequency method, which can be simpler, but also let our adjustment ideas become clearer.
2. The use of electronic frequency divider will lead to a decline in sound efficiency: although the use of electronic frequency divider has many advantages, but because it rigidly defines the working frequency range of different speakers, so the efficiency of these speakers is limited, not fully played out, and a large part of resources are wasted. For example, a double 15-inch full-frequency speaker can make a normal and loud sound without passing through the electronic frequency divider, but if it works at frequencies above 200 Hz after passing through the electronic frequency divider, the speaker's fullness and shock force will be all gone, because the bass of the speaker is cut off by the electronic frequency divider at this time. Now. In the same case, we use electronic frequency divider to cut off the high part of most bass speakers, although the timbre may be pleasant, but it is undeniable that the bass speakers also waste a lot of energy. It doesn't matter for a sound system that has a large number of speakers and pays attention to timbre, but if the number of speakers in a sound system is small and the timbre is only louder, then it's more realistic to not use an electronic frequency divider at this time.
3. The unreasonable frequency distribution will lead to equipment damage: the above said that the rational use of electronic frequency divider can protect equipment, the same electronic frequency divider is a double-edged sword, if used improperly, it will damage equipment: for example, we send the high-pitched signal from the electronic frequency divider to the bass speaker, because the bass are pronounced. Not so high frequency sound, so the phenomenon at this time is: the high-pitched speakers and bass speakers will not have sound. If some acousticians don't look at the reason, just blindly increase the volume of the front signal and the rear amplifier, then the result is that it's useless to increase the volume even more. At this time, it is easy to damage the amplifier, and if the level signal is too large to be distorted, it is easy to burn the speaker. Don't think that the speaker will be okay without sound. After all, there is already a large current passing through the coil of the speaker. The same is true of other speakers, so improper use of electronic frequency divider will damage the equipment, there will be an example in the following space for your reference.
ntroduction and Adjustment of Functional Key of Electronic Frequency Divider
Introduction of Functional Knobs in Electronic Frequency Divider
Different electronic frequency dividers will have different adjusting knobs and parameters. The following is a brief introduction: RANE (Ryan) AC22 electronic frequency divider as an example:
RANE (Ryan) AC22 electronic frequency divider is a stereo frequency divider, each single channel from left to right has six buttons or knobs, in turn:
1. MASTER-LEVEL: Channel signal input level. It can adjust the level of input signal.
2. LOW-LEVEL: Volume adjustment knob for bass output. It can adjust the bass output signal level.
3. LOW-MUTE: Bass mute button. Press this button to cut off the volume of LOW-LEVEL bass output.
4. LOW-DELAY: Bass Delay Knob. It can delay the bass signal and make the low frequency fuller.
5. LOW/HIGH-FREQUENCY: Frequency dividing knob. The frequency dividing point of the electronic frequency divider can be adjusted.
6. HIGH-LEVEL: Volume adjustment knob for high-pitch output. The tweeter output signal level can be adjusted.
(2) Adjustment method of electronic frequency divider
1. MASTER-LEVEL: It is very important to adjust the input level of the channel signal, just like adjusting the channel gain of the mixer, the volume of the first step is very important. Generally, it is more appropriate to adjust the position of the clock at 12 o'clock, which does not require a big adjustment.
2. LOW-LEVEL: The adjustment of bass output volume depends on the frequency division point and the number of bass speakers in the system. Generally, it is adjusted at 12 and 14 points of similar clock. When adjusting, we should also pay attention to whether the LOW-MUTE bass mute button is pressed or not, otherwise there will be no bass signal sent out.
3. LOW-MUTE: Bass mute button. Press this button to cut off the volume of LOW-LEVEL bass output. This is mainly to compare the effect of bass and treble. Of course, don't press it in normal use.
4. LOW-DELAY: The adjustment of the bass delay knob should be flexible. It should be adjusted according to the effect of the scene. Sometimes the bass sounds too hard and too thin, we can turn it on, let the bass add a sense of delay, so as to increase the fusing and fullness of the bass. On the contrary, if you think the bass are suitable, don't turn it on. Otherwise the bass would be cloudy and muddy. It is generally adjusted at 8 and 11 o'clock-like locations.
5. LOW/HIGH-FREQUENCY: Frequency dividing knob. The frequency dividing point of the electronic frequency divider should be adjusted according to the type and characteristics of the speakers used in the audio system. In the mode of 2 frequency dividing, the frequency dividing point of the electronic frequency divider should be adjusted in the range of 180 Hz-250 Hz. That is to say, adjust the position of the clock at 10:00 and 11:00.
6. HIGH-LEVEL: Volume adjustment knob for high-pitch output. Adjustment of the output volume of tweeter depends on the number of frequency dividing points and tweeters in the system. Generally, it is adjusted at the position of 12 and 14 points similar to the clock. At the same time, attention should be paid to the integration of high and low tones when adjusting: if the high tone is too small to surround the low tone, it will appear dim; if the high tone is too big and too prominent, it will appear that it is out of touch with the low tone and does not mix. Moderate is good.