What Are the Different Types of Digital Mixers?

Mixer is also called mixing console. It amplifies, mixes, distributes, modifies sound quality, and processes sound effects of multiple input signals, and then outputs them through the master. The mixer is an important device for broadcasting and recording programs in systems such as modern radio broadcasting, stage amplification, and sound program production. The mixer can be divided into analog mixer and digital mixer according to the signal output method.

Mixer

Mixer (aka Mixer)

Part I: Signal amplification, parameter equalization and insertion effects

We know that the audio signal produced by the microphone is very weak. The output signals of other devices, such as the output of synthesizers and audio interfaces, are many times stronger than the signals of microphones, and their signal sizes are also different and uneven. We need a device to adjust these large and small sound signals to the same size in order to mix. This kind of equipment is a pre-amplifier, commonly known as word amplifier. Please see.

Preamp section of UB1622FX

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

The preamp has control knobs, called "TRIM" on the UB1622, and some consoles called "GAIN" or "sensitivity". The Chinese name is trimming, gain, or sensitivity. Generally known as "mouth". The "mouth" knob is used to control the amount of signal amplification. As for how much zooming in, it depends on the "PEAK" peak indicator on the channel. If the "PEAK" indicator flashes occasionally, it is normal. If it flashes quickly, your input signal is distorted! Need to open your mouth a little bit!

[LOW CUT] The bass cutoff switch filters out unwanted low-frequency sounds.

Another switch associated with the preamp is the "phantom power" switch. If you connect a condenser microphone, you must turn on the "phantom power"! Otherwise, no matter how much "mouth" you open, there will be no sound.

Phantom power switch

The phantom power switch, on the back of the UB1622FX mixer, is capable of applying phantom power to all of the Khanom sockets.

Having said the preamp section, let's look at the parametric equalizer again.

Generally, there are parametric equalizers on the mixer channel. In this Behringer UB1622FX mixer, there is a three-band semi-parametric equalizer. As shown in the figure.

Three-band semi-parametric equalizer

The so-called parametric equalizer is an equalizer that can control the center frequency, Q value (bandwidth), and increase or decrease the frequency amplitude. The three bands of the three-band 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 frequency increase or decrease. Because there is no adjustment of the Q value, it is semi-parametric equalization.

The balanced knowledge is too deep! The important criterion for testing the quality of an audio sound engineer is not IQ, but EQ. Balanced learning Let's delve into it later.

Dynamic processing is only available on very advanced mixers, but this does not prevent the UB1622FX from expanding this capability. How to expand it? The mixer uses a special jack called an Insert to do this.

UB1622FX's Insert jack is on the rear panel of the mixer

Insert has a very special structure. By default, it is connected inside the mixer. When we insert a large three-pin plug. The internal connection is cut off, and the sound will be sent from the head of the large three-pin plug to the input of an effector, and the signal processed by the effector will return to the tuning from the ring of the large three-pin plug. Taichung. For example the compressor can be connected to the mixer in this way!

Please see the diagram

For the Insert jack, we have another way to use it as a Direct OUT socket!

The Direct OUT output is usually taken after the preamplifier circuit. Can be sent directly to a multitrack recorder or audio interface for recording. Advanced mixers have both Insert and Direct OUT jacks on the back. The UB1622 mixer has no Direct OUT output, but we can use the Insert jack for Direct OUT output. It was said that the sound of the input channel can be sent from the TIP of the large three-pin plug to the input of an external device, but if this device is connected to the input of the audio interface, then no sound is returned to the mixer. Then the sound path inside the mixer will be cut off! There will be no sound on this channel! How to do? It's simple! As long as the TIP and RING are connected, the channels of the mixer can continue to be connected! This way we can use the Insert jack as Direct OUT!

The Insert jack is transformed into a Direct OUT output. To connect the "tip" and "ring" of the big three-pin plug directly!

Pan, fader, and stereo buses and groups.

The direction of the sound is set, and we need to control the input sound of each channel. We know that the volume can be controlled with the volume knob. On the mixer, engineers usually design the volume knob into a long bar. Its scientific name is "Attenuator" and its common name is "Fader".

The advantage of using the fader to control the volume is that we can "see" the volume more intuitively. As mentioned earlier, the mixer preamplifier has adjusted the signals 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 the volume of the channel. 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!

With a pan knob and faders, the mixer can control the direction and size of the sound, but this is only a mono situation. How is the sound of multiple channels mixed? Here we must introduce a very important concept of the mixer, which is "bus". Its English is BUS, bus? of course not! This is the common channel for sound signals. The mixer can mix the sound of each channel into a "stereo" because it has a main stereo bus. The stereo bus consists of two single-channel buses-left channel L and right channel R.

In this figure, the sound is faded into the panning control through the fader, which sends the left and right signals to L and R of the stereo bus, respectively. This way we can mix the sound of multiple input channels into "stereo"! This is a working diagram of the most basic mixer. Even the simplest mixer can accomplish this task! It should be said that this is the most basic concept and application of the mixer!

Specific to UB1622FX, we look at the situation of one of his input channels!

[PAN] The pan and fader should be fine! Focus on a few switches in the picture: [MUTE] mute switch, [SOLO] solo (or PFL switch), [MAIN] main stereo bus switch, [SUB] sub-group bus switch.

The first is the [MUTE] mute switch

[MUTE] Mute switch

[MUTE] The power of the switch is great! Because once it is closed, this channel will be closed. It can no longer make any sound! I wo nt say more about this!

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

The [MAIN] switch controls the sound of the channel to the stereo bus. If you do not turn on this switch, there will be no sound when you push the fader to the head. This [MAIN] switch is useful because sometimes we do nt want the sound of the channel to go directly to the stereo bus. At this time we can turn off the [MAIN] switch.

[SUB] Sub-group bus switch can send the sound of the channel to the group bus! Grouping, as the name implies, we can group multiple input channels into a group. The grouped signal is taken from the input channel fader signal, which means that it is the same level as the input channel to the stereo bus.

We can use grouping to control the volume of multiple sound sources at the same time with one fader. For example, there is a drum kit that uses 8 microphones. We turn on these 8 channels to send to the group bus. At this time, the sounds of these 8 channels all enter the group bus. Next we can let the sound of these grouped buses return to the main stereo bus. [LEFT] and [RIGHT] switches as shown in the figure. You can specify the grouped sound to be sent to the left or right channel of the main stereo bus. We can use a pair of groups to control the sound of 8 channels at the same time! Note: Be sure to turn off the sound sent by these 8 channels to the main stereo bus-turn off the [MAIN] switch. Otherwise we just superimpose the sound of this drum kit on the stereo bus!

Group bus faders and switches to the main stereo bus

An important application of marshalling buses is that they can easily send the signals of the corresponding channels to a multitrack recorder. In the above picture, we can send the sound of the 4th channel to the input of the recorder or audio interface connected to the group bus by pressing the [SUB] switch to record!

By the way, if you want to buy a mixer for recording production, be sure to choose a product with a marshalling bus! Otherwise, you can only use auxiliary, which is more troublesome. Some people do nt have direct Dircet OUT or group output on their mixers. Two poor auxiliary outputs are also responsible for the return and sending effects of the actors. This kind of mixer can't make split track recording. Because if you choose 2TK OUT on the mixer to connect to the audio interface, this output signal is only the signal from the main stereo bus. It is a mix of the sound of all channels, including the effect sound, so it is impossible to perform track recording operation at all!

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

[SOLO] Switch and monitor the bus.

Guitarists love guitar solo, only then did he feel like he was being noticed! During recording and live sound reinforcement, the sound engineer also hopes to pay attention to the sound of a certain channel. At this time we need to monitor the bus!

The monitor bus is a bus specifically designed for monitoring! It has a set of listening system, which can directly select all input and output channels of monitor input channels, main stereo bus, group bus and auxiliary bus. And he does not interfere with any channels. It is connected to the main stereo bus by default. When we press the [SOLO] switch of the corresponding channel, the sound will automatically switch to this channel! The monitoring bus includes monitoring the PFL before attenuation and the AFL after attenuation (referred to as solo in UB1622FX). The monitor bus has its own independent output interface (Ctrl Room OUT) to control the room monitor output. This is where we should connect the monitor speakers. In fact, the headphone output is also from the monitor bus!

The monitor bus allows the tuner to work very freely. The Behringer UB series mixers are perfect for monitoring. This is its advantage!

Let's take a look at the system block diagram of this part. Hope it helps everyone understand the above

Part III: Auxiliary Sending and Sending Back Effects

Here we are how to demodulate a console to add returns to an actor and add effects to the sound. This part of the content is always complicated for beginners! In fact, it is not difficult! Let's talk about returns first.

It's hard to imagine someone playing without the accompaniment and their own instruments! Many friends have such experiences. When performing on the stage, there is a huge speaker at the mouth of the stage, but the people on the stage cannot hear their performance or singing. The return is to solve such problems!

Would it be okay to copy the signal from the main stereo bus directly to the actors? The direct use of the signal from the main stereo bus to the actor to return the monitor is only suitable for small personal recording studios, where there is generally only one actor and there is no concern about feedback howling, and the flexibility of such monitoring is poor. If there are a lot of actors, this is obviously not possible, because the requirements of the actors and the audience are different! Every actor wants their singing or performance volume to be greater than the accompaniment volume, but the sound returned from the main stereo bus is definitely not the case. Maybe some actors feel OK but some actors can't hear it. In this case it is impossible for you to satisfy all the actors. We need auxiliary sound buses to mix backing music for each actor separately!

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 see the picture above. This is the volume control sent to the auxiliary bus.

There are two types of auxiliary channels. One is before the signal is taken from the channel fader, which we call "pre-fading auxiliary", and the other is that the signal is from the channel fader, which we call "post-fading auxiliary". There are two auxiliary buses on the UB1622FX mixer. Auxiliary 1 can be switched to two states before attenuation or after attenuation. Pay attention to the [PRE] switch next to Auxiliary 1, we have to press it to get a pre-fading auxiliary. Pre-fading assistance is often used to return actors. Because we don't have to worry about the sound of the actors returning louder or smaller when adjusting the faders.

Some advanced mixers have many auxiliary buses, so he can mix a mix for each musician actor individually. Generally, the auxiliary is single channel! We can certainly make a stereo return with two assistants, but only if we have two pre-fading assistants available!

Another use of assist is to add effects to the sound of each channel! Let's first understand a concept: the "send back" effect.

In simple terms, sending a return effect is sending sound to the input of the effector, and the effect sound output by the effector is then mixed with the original signal, so we have the effect-added sound!

Some guitar amps have a "SEND" and a "RETURN" jack behind it. This is used to link the Chorus, Delay, and Reverb effects. These three effects are generally not connected to the distortion channel of the guitar speaker, otherwise the sound will be difficult to hear. Add effects by sending back, the sound will be better!

A little digression, let's go back to the mixer. What if we want to add reverberation to a channel? Very easy to do! Remember the insertion point effect mentioned earlier? We can use the insertion point to add reverb or delay effects to a channel. But if you want to add effects to multiple channels at the same time, you need to insert a reverb effector for each channel? This is obviously difficult. And even with so many reverberators, it's hard to create a sense of overall space!

Not so troublesome. We still use the auxiliary bus to complete this work, for example, we want to add effects to the sound of channel 1. First let the sound of channel 1 enter the main stereo bus. What we hear is the original sound without any effect. Then we use the auxiliary send knob to send the sound signal of channel 1 to the auxiliary bus, and the signal output from the auxiliary bus is input to the effector. The effect signal produced by the effector is then returned to the mixer and the main stereo bus is superimposed with the original signal. Then we can hear the sound of adding effects! This is the case for one channel! So what if multiple channels need to add effects? Don't forget that the auxiliary bus can be used for any channel that needs to add effects. We turn on the auxiliary knob of each channel in order to add the same effect to all channels! And as long as you control the volume sent to the auxiliary bus, you can add a different amount of effect to each channel! By the same token, the effect sound returned to the mixer can also be sent to the auxiliary bus used by the actor to return. Then the actors can hear the sound with effects!

Post-fader is usually used to send sound to the effector. The advantage of this is that when the channel fader is changed, the volume sent to the effector will also change, so that the ratio of the original signal to the effect signal is always the same. !!

There is a channel on the UB1622FX mixer dedicated to assisting send back, English is AUX RETURN. In fact, this AUX RETURN input is a very simplified input channel. It has no gain control, no equalization, and only an auxiliary send function. We generally do not use her, but directly return the effect to the ordinary input channel of the mixer. Get the strongest control ability. but! It is important to note that the sound of the effect return channel must not be sent to the auxiliary bus used for effect sending, otherwise it will cause feedback howling and damage the equipment! !! !!

We use the following figure to illustrate the application of send and return effects on the mixer.

Application of send and return effects on the mixer

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

The fourth part: the main control part, the main stereo output fader, monitoring status selection and auxiliary send return

Let's take a look at the main part of the UB1622FX mixer first! Please see the picture below

Main control part

The so-called main control part actually controls the main stereo bus, group bus, auxiliary bus, and monitor bus introduced earlier.

Volume control of SUB group bus. This section has already been mentioned before, and MAIN MIX is no longer repeated. This is the attenuator that controls the overall volume of the main stereo bus, commonly known as the "master fader". The sound of all channels is finally collected here and output from the mixer MAIN OUT. MAIN OUT should be connected to the final mixing result, such as a tape drive, or a live sound box for the audience.

The CTRL ROOM & PHONE knob is used to control the monitor bus volume output. Note that there are three switches on the left side of this knob, which are [TAPE], [SUB], [MAIN]. When the [TAPE] switch is pressed, the monitor bus selects the sound from the tape return port, which is used to check the tape return sound. Some advanced decks support "post-monitoring", in this way we can check the sound that the monitor has recorded on the tape! If the [SUB] switch is pressed, the sound of the sub group is monitored. If [MAIN] is pressed, the control room monitors the sound from the MAIN MIX master stereo bus! Generally we open this [MAIN] by default.

There is a [MODE] mode switch under the CTRL ROOM & PHONE knob, which has two states-PFL and SOLO. This PFL means PRE FADER LISTEN, monitoring before the fader. It is used to monitor the original state of the input signal. Solo actually monitors the signal from the channel fader. SOLO is also called AFL, AFTER FADER LISTEN on some mixers. The benefit of SOLO is that it can monitor stereo signals.

AUX SENDS auxiliary send output control knob. It goes without saying that the total output of the auxiliary bus is controlled. As for the STERO AUX RETURN input control.

English abbreviation Chinese meaning

ACTIVITY indicator

BALANCE OUTPUT

CUE selection switch

DISPLAY level indicator

ECHO

A simple and complete sound system, from the beginning to the end, it includes at least four units: a microphone, a mixer, an amplifier, and a speaker. Of course, the actual sound system used by the tuner is much more complicated than this. When multi-channel signal is input, in addition to the microphone, there will also be a DVD player (or CD player), recording and playback

Digital Mixer as

Mixers can be classified from a variety of perspectives.
1. Classification according to the use form (1) Portable mixers Portable mixers have 2-4 channels. They are equipped with simple high and low compensators, and have input, output, and mixing circuits. Mostly used for sound reinforcement or live recording, the advantage is that it is easy to carry and easy to operate.
(2) Semi-mobile mixer has 4-6 channels. The platform is equipped with high, medium and low frequency compensators, and some are equipped with high and low pass filters and automatic volume control. Output The circuits are mostly two-channel. It is mainly used for language recording, and is most used by movie studios.
(3) Fixed mixers There are two types of fixed mixers: large and medium. Large mixers have more than 24 channels, even hundreds of channels. Medium-sized mixers generally have 12-24 channels and are fully functional. And attached peripheral equipment such as reverberator, limiter. It is widely used in radio stations, movie studios, audio and video production departments, etc. It can record music and perform mixed recording. There are many output channels. With multi-track recorders, it can perform multi-channel recording. In large theaters and concert halls, stationary mixers are also used for amplification.
2. Classification by structure (1) Integrated mixer integrates the functions of the mixer, power amplifier, graphic equalizer, and effects into one chassis. The appearance basically keeps the style of the mixer unchanged. Such mixers are sometimes referred to as "four-in-one" mixers. The output power of this type of mixer is small (generally no more than 2X250W) and easy to operate, especially suitable for fluid performances.
(2) The most prominent feature of non-integrated mixers is that they do not have power amplifiers. 3. Classified by purpose. The computer system with optional functions or configuration is the highest grade in the mixer. Mostly used in radio, television, film studios, record companies' recording studios for high-quality multitrack recordings.
(2) Amplifying mixer

After adjusting the appropriate influence balance, frequency compensation, effect configuration and sound image localization of each sound source, they are mixed into a set of stereo signals and sent to the power amplifier for sound reinforcement. It is used for stage performance, broadcasting, and other occasions. Higher-grade ones can also be used in recording studios.

(3) Disco mixer (DJ mixer)

This is a dedicated small mixer, which is special in:
ADJ mixers are usually small, no more than eight, but each is a stereo input.
B has a control switch that can easily switch the sound source, a "cross fader" that moves left and right, commonly known as a horizontal fader. The cross attenuator controls two sets of stereo signals in the opposite direction. When the fader is pushed to the far left, the first group of stereo signals is the strongest, the second group of attenuation is , completely silent; as the fader moves to the right, the first group of stereo signals gradually decreases, and the second stage of stereo signals continues Enhancement; When the rightmost end is reached, the first stereo signal is completely attenuated, and the second stereo signal is the strongest. By using the horizontal fader, the two sound sources can be switched continuously without any trace.
CDJ mixers have at least two turntable input ports, which can accept signals from two stereo turntables. With the corresponding RIAA and RIAA equalization network required for electromagnetic pickups, ordinary mixers cannot directly receive the signals from the turntable of electromagnetic pickups.
DJ mixers are mainly used in disco dance halls.
4. Classification by signal processing method (1) Digital mixer The audio signal in the mixer is a digital signal, which can be easily realized fully automated, and the total harmonic distortion and equivalent input noise are low. Often used in demanding audio systems.
(2) The analog mixer adopts the traditional analog method for signal processing. The technology is mature and the cost is low.
5. According to the number of input channels, the mixer can be divided into 6, 8, 12, 16, 24, etc. according to the number of input channels (usually called the number of input channels). The performance and structure of each input channel Similarly, each input channel can accept one microphone or line level signal. If it is a stereo signal, it will occupy two upper channels. ^[1]