The basic process of mixer is the best explanation.

Explain first: Please look at the pictures.

Berinda UB 1622FX mixer

As a modern musician, you often see a mixer. It's the kind of equipment that looks scary with countless knobs and various switches. A guy named recording engineer is hiding behind the mixer. He doesn't know what he is busy with. If he is a master, your performance will be great! Maybe you are curious, but you won't mind that you can't use the blender-it's a professional device! No, it's right. But now more and more friends want to record demos for themselves at home and start playing computer music. So always use all kinds of mixers. What analog, digital and audio interfaces may also have built-in mixer interfaces, and those audio software mixers seem to be confusing. In short, you will find the shadow of bartenders everywhere. Many friends think that the mixer is very complicated, and I can't understand it. I haven't heard anything for a long time, depressed! Or don't understand the principle and use the mixer incorrectly, so that it doesn't play its due role.

To learn a thing, you must first know what it can do! What can we do with a blender? There are usually the following items:

1. The mixer can amplify the signal of the input channel, adjust the EQ of the input sound, and even have other effects, such as compression.

2. The mixer can mix many sounds to form a stereo!

3. The mixer can "send back" monitoring for musicians and actors.

4. The mixer assists the effector to add reverberation, delay and other effects to each channel.

5. The mixer sends the sound of each channel to a multi-track recorder or audio interface for track recording.

6. The mixer allows the sound engineer to easily monitor the sound of all channels without disturbing them.

Practice is the best way to learn the mixer. Taking the Berinda UB 1622FX analog mixer as an example, this paper introduces the basic functions and usage of the mixer. UB 1622FX mixer is small in size, but it is fully functional, and it also has a built-in digital effect device. First of all, I am not the "child care" of Berinda Company. I just want to use a concrete example to let you know some basic knowledge of mixers! The same is true of knowledge. As long as you master the basic knowledge of mixers, you can quickly master and use all kinds of mixers, whether analog or digital, or even those virtual mixers.

Let's introduce the functions and usage of the mixer in combination with the actual situation of Berinda UB 1622FX mixer.

Part I: Signal amplification, parameter equalization and insertion effect.

We know that the audio signal produced by the microphone is very weak. The output signals of other devices, such as synthesizers and audio interfaces, are many times stronger than those of microphones, and the signal sizes are different and uneven. We need a device to adjust these large and small sound signals to the same size before mixing. This kind of equipment is the preamplifier, commonly known as the voice amplifier. Please have a look.

UB 1622FX preamplifier part

Look at the picture, the big round socket is called the cannon "cannon" socket, which is used to connect a microphone or some professional equipment that also uses the cannon socket. The jack below the gun socket is TRS jack, which is generally used to connect the signal of line level. Idea, these two sockets can't be used at the same time! And because of the circuit design, on this mixer, you can't plug the line-level equipment into the socket of Canon!

The preamplifier has a control knob, which is called "TRIM" on UB 1622 and "GAIN" or "sensitivity" on some mixers. The Chinese name is fine tuning, gain or sensitivity. Commonly known as "Kouzi". "cut" knob is used to control signal amplification. As for the ground amplification, it depends on the "peak" peak indicator light on the channel. This is normal if the "peak" indicator flashes occasionally. If it flashes fast, it means that your input signal has been distorted! Need to open your mouth a little!

[Low Cut] The bass cut switch can filter out those unnecessary low-frequency sounds.

Another switch associated with the preamplifier is the "phantom power supply" switch. If a condenser microphone is connected, the "Phantom Power" must be turned on! Otherwise, no matter how big your mouth is, there will be no sound.

Phantom power switch

Phantom power switch, on the back of UB 1622FX mixer, can apply phantom power to all cannon sockets.

After the preamplifier, let's look at the parametric equalizer.

Generally speaking, there is a parametric equalizer on the channel of the mixer. In this Belinda UB 1622FX mixer, there is a three-stage semi-parametric equalizer. As shown in the figure.

Three-segment semi-parametric equalizer

The so-called parametric equalizer refers to an equalizer that can control the center frequency, Q value (bandwidth) and increase or decrease the frequency amplitude. Three-stage semi-parametric equalizer means that this equalizer can adjust three frequency bands, namely treble, midrange and bass. The midrange part can adjust the center frequency and its increasing and decreasing frequency range. Because the q value is not adjusted, it is semi-parametric equilibrium.

Balanced learning is too deep! The important criterion for testing the level of a sound engineer is not IQ, but EQ. We will learn more about balance later.

Only a very advanced mixer can have the function of dynamic processing, but this does not prevent UB 1622FX from expanding this ability. How to expand? The mixer uses a special jack called a plug-in to do this.

The jack of UB 1622FX is on the back panel of the mixer.

The plug-in jack has a very special structure. By default, it is connected inside the mixer. When we plug in a big three-core plug. The internal connection will be cut off, the sound will be transmitted from the tip of the big three-core plug to the input end of an effector, and the signal processed by the effector will return to the mixer from the "ring" of the big three-core plug. For example, the compressor can be connected to the mixer like this!

Please look at the schematic diagram

For the patch jack, we also have a usage, which is to use it as a direct OUT socket!

The output of Direct OUT is usually obtained after the preamplifier circuit. Can be directly sent to a multi-channel recorder or audio interface for recording. The last advanced mixer had plug-in and direct output jacks. UB 1622 mixer has no direct output, but we can use the plug-in jack for direct output. It is said that the sound of the input channel can be sent from the tip of the big three-pin plug to the input end of an external device, but if this device is connected to the input end of the audio interface, then no sound will return to the mixer. So the sound path inside the mixer will be interrupted! There is no sound in this passage! What shall we do? It's simple! As long as the tip is connected to the ring, the channel of the mixer can continue to be connected! So we can use the jack as the direct output!

draw

The jack is converted to direct output. Connect the "tip" and "ring" of the big three-core plug directly!

In fact, speech playback and equalization are not the core content of the mixer, because they all have special equipment, and the mixer has these functions just for the convenience of work. Some very simple mixers have no words to play with, let alone balance, let alone the interface of the mixer in the software, but we still call them mixers. So what is Andhadhun's most fundamental job?

Part II: Audio-visual, fader and stereo bus and grouping.

If we simplify the MIXER step by step, we will eventually find that its most fundamental job-just like its English name Mixer-is to mix all the input sounds in proportion and become "stereo"! This is the core work of the mixer! Because even the simplest mixer can accomplish this task!

Stereo, connect two speakers or listen to music with headphones? Yes! Listening is of course the easiest thing! But if you want to create stereo with a mixer, it's not that simple! There is a lot of learning here! Let's talk about how the human ear can tell the direction of sound.

Simply put, people can tell the direction of sound because they can tell the intensity and time when a sound reaches two ears respectively. For example, there is a mosquito on our left, and its buzz can enter our left ear without hindrance. Because the head blocks the sound, the sound heard by the right ear is definitely not as loud as that heard by the left ear. So our brains will judge that mosquitoes come from the left! This is the human ear judging the direction of sound according to the difference of sound strength. So what's the time difference? It's simple! Mosquitoes are on our left, so they are closest to our left ear, so the left ear hears the sound first, and the right ear hears it later! Our brains can also distinguish this very subtle difference! ! ! In this way, human beings can judge the direction of sound by feeling the strength difference and time difference of sound with two ears! People can imagine the position of mosquitoes with their eyes closed, just as they can see them. This is called audio-visual, hehe!

So how does the mixer control the direction of sound? In order to create a sense of direction of sound, the mixer must have two left and right channels, corresponding to our left and right ears respectively. As we know above, the human ear uses the difference of sound strength to judge the direction. When the volume output from the left channel of the mixer is greater than the volume output from the right channel, our ears will think that the sound comes from the left. Adjust the audio-visual knob of the mixer (PANPOT in audio-visual English)! When the audio-visual knob is adjusted to the left, more signals will be sent to the left channel. When the human ear hears that the sound of the left channel is stronger than that of the right channel, it will think that the sound comes from the left side. Or conversely, when Dallas arrives in the audience, when the audio-visual knob is set to the middle position of 12, and the sound volume from the left and right channels is the same, then the human ear will think that the sound comes from the front. This is the basic principle of stereo sound produced by audio-visual knob of mixer. Of course, there are other ways to create a three-dimensional sense, such as using the delay effect to create a sense of direction, which will not be discussed in this article.

Schematic diagram of controlling sound direction with mixer

The picture above is a schematic diagram of how we control the direction of sound with a mixer! Adjust the audio-visual knob to control the sound "direction"

The direction of sound has been decided, and we need to control the input sound of each channel. We know that the volume can be controlled by the volume knob. On the mixer, engineers usually design the volume knob as a long push rod. Its scientific name is "attenuator" and its common name is "attenuator".

The advantage of controlling the volume with a putter is that we can "see" the volume more intuitively. As I said just now, the preamplifier of the mixer has adjusted the signal of each channel to the same level. If each channel is set to the same standard level value. Then, the position of each fader can also reflect the general situation of channel volume. We can even know the level of this channel according to the scale number next to the fader, which is really clear at a glance!

Through the audio-visual knob and fader, the mixer can control the direction and size of the sound, but this is only the case of mono. How are multi-channel sounds mixed? Here we must introduce a very important concept of the mixer, which is "bus". Whose English is bus, BUS? Of course not! This refers to the sound signal of the common channel. The mixer can mix the sounds of various channels into a "stereo" because it has a main stereo bus. Stereo bus consists of two single-channel buses-left channel L and right channel R.

draw

In this picture, the sound is attenuated by the fader and enters the audio-visual control knob. The sound control knob sends the left signal and the right signal to L and R of the stereo bus respectively. In this way, the sound of multiple input channels can be mixed into "stereo"! This is the basic schematic diagram of the mixer. Even the simplest mixer can accomplish this task! It should be said that this is the most basic concept and application of mixer!

Specifically to UB 1622FX, let's look at one of his input channels!

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[Pan] Audio-visual knobs and faders should be fine! Focus on several switches in the picture: [MUTE] mute switch, [SOLO] solo (or PFL switch), [MAIN] main stereo bus switch and [SUB] sub-packet bus switch.

The first is the mute switch.

[Mute] Mute switch

[Mute] The switch has great power! Because once it is closed, it will close this passage. It can't make any noise anymore! Not much to say about this!

Let's look at the [main] main stereo bus switch.

[MAIN] The sound of the switch control channel is sent to the stereo bus. If the switch is not turned on, there will be no sound when the fader is pushed to the head. This [main] switch is very useful, because sometimes we don't want the sound of the channel to enter the stereo bus directly, so we can turn off the [main] switch.

Auxiliary marshalling bus switch can send channel sound to marshalling bus! Grouping, as the name implies, we can group multiple input channels into a group. The packet signal is taken from the signal after the input channel fader, that is, it is the same as the signal level from the input channel to the stereo bus.

We can control the volume of multiple audio sources at the same time with one fader by grouping. For example, there is a drum group that uses eight microphones. We turn on the switches sent to the marshalling bus by these eight channels respectively. At this time, all the sounds of these eight channels enter the marshalling bus. Next, we can return the sound of these packet buses to the main stereo bus. As shown in the figure, the [left] and [right] switches. You can specify that grouped sounds are sent to the left or right channel of the main stereo bus. Now you can control the sound of eight channels at the same time with a pair! Note: Be sure to turn off the sound sent by these eight channels to the main stereo bus-turn off the [main] switch. Otherwise, we will add the sound of this drum set to the stereo bus!

Send bus faders and switch packets to the main stereo bus.

An important application of marshalling bus is that it is very convenient to send signals of corresponding channels to multi-channel recorder. In the above picture, we only need to press the 【 SUB 】 switch, and then we can send the four-channel sound to the recorder connected to the marshalling bus or the input end of the audio interface for recording!

By the way, if you want to buy a mixer recording, you must choose a bus grouping product! Otherwise, you can only use the auxiliary, which is more troublesome. Some people have neither Dircet OUT direct output nor grouped output on the mixer, and the two poor auxiliary outputs are also responsible for the actor's feedback effect. This mixer cannot record tracks separately. Because if you choose 2TK OUT to connect the audio interface on the mixer, the output signal is only the signal of the main stereo bus, which mixes the sounds of all channels, including the effect sound, so you can't record the audio track separately!

It should be noted that never turn on the [SUB] grouping switch from the sound card to the channel of the mixer. Otherwise it may cause howling, at least the input sound will be recorded together with the accompaniment from the sound card! This is not a track recording!

Switch and monitoring bus.

Guitarists like guitar solo, and only in this way will he feel concerned! When recording and live sound reinforcement, the sound engineer also hopes to pay attention to the sound of a certain channel. At this time, you need to monitor the bus!

The monitoring bus is a bus specially used for monitoring! It has a set of listening and selecting system, which can directly select all input and output channels of monitoring input channel, main stereo bus, marshalling bus and auxiliary bus. And he doesn't interfere in any channels. By default, it is connected to the main stereo bus. When we press the [SOLO] switch of the corresponding channel, the sound will automatically switch to this channel! The monitoring bus includes the monitoring PFL before attenuation and the monitoring AFL after attenuation (called SOLO solo in UB 1622FX). The monitoring bus has its own independent output interface (Ctrl Room OUT), and the control room monitors the output. This is where we should connect the monitor speakers. In fact, the headphone output is also from the monitoring bus!

Monitoring the bus allows Andhadhun to work very freely. The monitoring of Berinda UB series mixer is perfect. This is its advantage!

Let's take a look at the system block diagram of this part. I hope it will help you understand the above content.

system chart

Part III: Auxiliary sending and sending back effects.

Now let's learn how the mixer adds feedback to the actors and effects to the sound. This part of the content is always complicated for beginners of mixer! In fact, it is not difficult! Let's talk about the return of goods first.

It's hard to imagine someone playing without listening to the accompaniment and their own instruments! Many friends have the experience of performing on stage. There is a huge loudspeaker at the entrance to the stage, but the people on the stage can't hear their own voices clearly. Return is to solve such a problem!

Can you directly copy the signal of the main stereo bus for the actors to listen to? Directly using the signal of the main stereo bus to send the monitor back to the actor is only suitable for small personal recording studios, generally there is only one actor, and there is no concern about feedback howling. This kind of monitoring has poor flexibility. If there are many actors, this is obviously not possible, because the requirements of actors and audiences are different! Every actor wants his singing or playing volume to be higher than the accompaniment volume, but the sound returned by the main audio bus is definitely not like this. Some actors may think so, but some actors can't hear it. In this case, you can't please all the actors. We need an auxiliary sound bus to mix accompaniment music for each actor separately!

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The auxiliary sound bus is independent of the main stereo bus! Its English abbreviation is [AUX]. Each input channel has a knob to send sound to the auxiliary bus! Please look at the picture above. This is the volume control sent to the auxiliary bus.

There are two kinds of auxiliary channels, one is that the channel fader takes the signal before, which we call "pre-attenuation assistance", and the other is that the channel fader takes the signal after, which we call "post-attenuation assistance". UB 1622FX mixer has two auxiliary buses. Auxiliary 1 can be switched to two states: before attenuation or after attenuation. Pay attention to the [PRE] switch next to the auxiliary 1. We have to press it to get pre-attenuation assistance. Pre-attenuation assistance is usually used to send back actors. Because we don't have to worry about whether the actor's feedback will become louder or louder when adjusting the fader.

Some advanced mixers have many auxiliary buses, so you can mix a mix for each musician and actor. Generally speaking, the auxiliary is a single channel! Of course, we can do a stereo foldback with two assistants, but only if we have two pre-attenuation assistants available!

Another purpose of the auxiliary is to add effects to the sound of each channel! Let's first understand a concept: the "echo" effect.

To put it simply, sending the echo effect is to send the sound to the input end of the effector, and the effect sound output by the effector is mixed with the original signal, so that we get the added effect sound!

Please look at the schematic diagram

Some guitar speakers have "send" and "return" jacks on the back. This is used to connect chorus, delay and reverberation effects. These three effects are generally not connected to the distortion channel of the guitar speaker, otherwise the sound will be hard to hear. Add effects by sending and returning, and the sound will be better!

It's a little off topic. Let's go back to the mixer. What if we want to add reverberation to a channel? Very easy to handle! Remember the insertion point effect mentioned earlier? We can use the insertion point to add reverberation or delay to the channel. But if you want to add effects to multiple channels at the same time, you need to insert a reverb effector in each channel? This is obviously difficult. And even if there are so many reverberators, it is difficult to create an overall sense of space!

It's not that troublesome. We still use the auxiliary bus to complete this work. For example, we want to add an effect to the sound of channel 1. First, let the sound of 1 channel enter the main stereo bus. Now what we hear is the original sound that has no effect. Then we use the auxiliary sending knob to send the sound signal of 1 channel to the auxiliary bus, and the signal output by the auxiliary bus is input to the effector, which generates the effect signal, and then returns to the mixer and enters the main stereo bus to be superimposed with the original signal. So we can hear the sound of special effects! This is the channel situation! What if so many channels need to add effects? Don't forget that the auxiliary bus can be used for any channel that needs to add effects. We can add the same effect to all channels by turning on the auxiliary knob of each channel in turn! And as long as you control the volume sent to the auxiliary bus, you can add different effects to each channel! Similarly, the effect sound returned to the mixer can also be sent to the auxiliary bus used by the actors. So actors can also hear effective voices!

Usually, faders are used to send sounds to effectors. The advantage of this is that when the channel fader changes, the volume sent to the effector will also change, so the ratio of the original signal to the effect signal will always remain the same!

On the UB 1622FX mixer, there is a dedicated channel for auxiliary sending and returning, which is AUX RETURN in English. In fact, this AUX return input is a very simplified input channel. It has no gain control and equalization, only auxiliary transmission function. Generally, we don't need her, and directly send the effect back to the ordinary input channel connected to the mixer. The strongest control ability can be obtained. But! It should be noted that the sound of the effector's return channel must not be sent to the auxiliary bus for sending the effect again, otherwise it will cause feedback howling and damage to the equipment! ! !

We use the following figure to illustrate the application of send and return effectors in the mixer.

Application of return effector in mixer

Schematic diagram of the effect of using auxiliary bus to send back and send back. Use pictures to illustrate contrast images.

The fourth part: main control part, main stereo output fader, listening state selection, auxiliary transmission and return.

Let's take a look at the main control part of UB 1622FX mixer first! Please look at the picture below

Main control part

The so-called main control part is actually to control the main stereo bus, marshalling bus, auxiliary bus and monitoring bus introduced earlier.

Volume control of grouped buses. This part has been mentioned before, so the main collocation will not be repeated. This is an attenuator that controls the total volume of the main stereo bus, commonly known as the "main fader". The sounds of all channels are finally gathered here and output from the main output end of the mixer. The main output should be connected to the final mixing effect, such as a tape drive or a final live speaker for the audience.

Control Room & The telephone knob is used to control the volume output of the monitoring bus. Note that there are three switches on the left side of this knob, namely [tape], [sub] and [main]. When the [TAPE] switch is pressed, the monitoring bus selects a sound from the tape return port for checking the tape return sound. Some advanced card stands support "after-band monitoring", so that we can check and monitor the sound that has been recorded on the tape! If you press the [SUB] switch, please listen to the sound of grouping. If you press [MAIN], the control room will listen to the sound from the main stereo bus of MAIN MIX! Normally, we open this [MAIN] by default.

Control room & There is a [MODE] mode switch under the knob of the mobile phone, which has two states-PFL and SOLO. This PFL means listening before the fader and listening before the fader. It is used to monitor the original state of the input signal. SOLO is actually listening to the signal from the channel fader. After hearing the fader, some solos on the mixer are also called AFL. The advantage of SOLO is that it can monitor stereo signals.

AUX send auxiliary send and output control knob. Needless to say, of course, it is to control the total output of the auxiliary bus. As for stereoaux return stereo auxiliary return input control. I don't want to go into details, because I have already talked about the principle of effect sending back! Through our understanding of the blender, can we understand its mystery? I hope you can study it.