Transcripts
1. Overview of Mixers: audio mixers come in a number of sizes and designs, but most of them have very similar controls. The two main mixer formats are analog and digital. They each have pros and cons, and the format to use is a matter of preference for each sound engineer. Digital mixers have enormously more features an analog models, but they are also more difficult to learn to use. They usually have lots of built in effects, advanced equalizers, compressors and other sound manipulation tools. Most of them can be operated wirelessly using an iPad or other tablet. Another huge advantage is that a digital mixer can also eliminate the need for many audio components and cables because there is no need for external equalizers, effects units or other devices. Because the interfaces of digital mixers often emulate the controls of analog audio equipment, it is extremely helpful to learn to operate an analog mixer first, and this course you will learn how to use an analog mixer, and that knowledge will help you understand digital mixers as well. Before we get to the actual mixer, let's take a quick look at basic signal flow. The signal starts with source, which is the microphone or instrument. It then goes into the mixers pre al's through the mixers circuitry, and it's sent to the mixers outputs. The signal, then goes to any post mixer audio processors, such as graphic equalizers and active crossovers. The process signal goes to the power amplifiers and finally to the speakers. Keeping this signal flow in mind will help you understand the basics of sound system operation.
2. Mixer Controls Part One : Let's start with a basic mixer. The sound craft model has most of the controls you will find on any small to medium size analog mixing board. Think of a mixer is a group of individual, mostly identical channel strips with the addition of a master section, this mixer has six identical mono channels. Troops plus three stereo channel strips. Let's start with the Mono channels troop. Starting at the top of the mixer, you will see a knob call gain depending on the manufacturer. This control may also be called trim, sensitivity or head out. This control is usually found at the top of each channel, although some mixers may have gang controls in other places, such as on the rear of the mixer. If this control isn't unadjusted properly on East Channel, it is impossible to get a good sound. If it is set too low. You will have lots of operating noise and a weak signal from your microphone or instrument . If it is set too high, the signal will overload the mixer circuitry, and a sound will be distorted next to see the high pass filter. When pressed, it reduces low frequencies by a fixed amount per active. In this mixer, it reduces 100 hertz by 18 db per octave is called a high pass filter. Because all frequencies above that point in this case 100 hertz can pass through unaffected . This is handy to filter out low frequency, booming or stage noise or rumble. One use for high pass filters is to clean up the sound of vocal Mike's on down the channels . Truth. This mixer has the equalization or e que section. This design is similar on many small to medium size mixing boards, and it consists of four knobs. The top nob is the high frequency control. This is a high frequency shelving type equalizer. That means that all frequencies above a certain point will be affected when control is adjusted in the middle position. This equalizer control has no effect at all on the signal. No boost and no cut. When you move the control counterclockwise below the halfway point, the frequencies are reduced or cut. When you move the knob clockwise past the halfway point, the frequencies are boosted. Now let's look down to the low frequency. Control the bottom control in this group of four. It is also a shelving type equalizer and in this case the frequencies below a certain point are affected and again in halfway position. There is no effect on the signal. The mid rise control office more flexibility. It is what is called a semi parametric equaliser. The two knobs work together. The top knob on this mixer's mid rise control allows you to sweep through the frequencies and find the one you wish to either cut or boost. The other knob allows you to either cut or boost that chosen frequency. With this nomine halfway position, there will be no effect on the sound regardless of which frequency you chose. A semi parametric equaliser is a very handy tool for eliminating feedback as well as for fine tuning sounds. The reason this is called a semi parametric equaliser is because in a parametric equaliser a true parametric equaliser, you have 1/3 knob which controls the ban with to be affected. This third control is called Q. Many small to medium mixers have the same set up. You have a fixed high frequency shelving control, a fixed low frequency shelving control and a semi parametric, or sometimes called sweep herbal mid range equaliser
3. Mixer Controls Part Two : moving down the mixer, we see the auxiliary sin section, auxiliary sends or multipurpose controls and ancillary. Send or ox end allows you to feed that channel signal into an individual mix. You can create a mix to use as a feed to stage monitors or in ear monitors, where you can send a signal to an external effects unit or set up a recording mix and many mixers. The ox ends are set up just AUC's 1234 and so forth. And those are the ones that are very flexible and can be used for a variety of purposes. And some mixers you may have dedicated out sends. They may even be labeled as monitor. One monitor, too, affects one affects too, and so forth. It depends on the manufacturer. The most flexible lock sands allow you to choose whether their signal will be taken pre or post fader. A pre fader oxen takes a signal before it reaches the volume fighter. Therefore, with a pre fader oxen, you can set up a monitor mix that is unaffected by the mixers. Main failures. This is desirable because the monitor mix on stage remains unchanged, while the house mix can be changed as needed. The second type of oxen is called post fader. It follows the movements of the channel's volume fader. If you lower the channel's volume fader, the oxen will also lower its output Accordingly, this is handy for effects. Like reverb, this mixer has three ox ends, one of them dedicated to controlling the built in effects unit. All three Yeltsin's maybe switched to be used either pre or post fader, and the internal effects unit may be bypassed if desired. Oxygen's usually have a master control for each ox mixes. Well, you see here the Alex ends 12 and three, and the selector switches for pre or post as well as their master control knobs, which control the overall volume of each arcs mix. You'll usually find the pre and post fader selector switches either on each channel near the ox ends or in the master section as they are on this mixer. With this mixer, the ox three control on each channel sends a signal to the built in affectionate. The effects Return takes the signal as it comes out of the effects unit and brings it back into the mix. You set the amount of effect you want for each channel using the toxins. Then you control the overall volume of the effect in the mix. With the effects return below the ox section, we find the pan control near the pan control. There are two buttons that work with of hand control. One sense a channel signal either to the left right or to both sides in the main stereo mix . The other button sends the channel signal two Group one When the pan is trying to the left and group to when the pan has turned to the right, the switch is work with the group Master Failures and the Stereo Master Fader, all found in the master section of the mixer. Larger mixers have more groups. These groups or sub mixes allow you to sign several channels to be routed through one fader . For example, you could assign all drum Mike's two Group one and all vocal mice to group to when you adjust Route one. All of the drum mikes would go up and down together. All the vocal mice could be adjusted by moving the group to Fator. It's these channels air assigned on Li to the main stereo fader, then they're controlled by it. Groups must also be assigned to the stereo mix and order for them to be heard in the main mix. This mixture also has an extra mono button to assign the groups to a mono output. Here's an easy one. The mute button. It's simply mutes the channel signal. This is very useful because you can mute microphones or instruments that are not being used at the time. It is a good idea to mute everything before sound check so you can work on the channels one at a time as you bring them into the mix. This mixture has a dual purpose led that illuminates when the channel is muted and also blinks. If the signal is approaching or is at overload level at the bottom of this channel strip, we have the fader, the sliding volume control. This control allows you to adjust the volume in the main mix, often called the house or the front of house mix, this mixer also has to stereo channels. Label 9 10 and 11 12. One channel can be used either with a mono microphone or with a stereo instrument or play back device. The other stereo channel is designed to be primarily used with a stereo playback device, such as a phone, tablet, computer or CD player. Many mixtures include at least one stereo channel. Most of them operate in a similar manner to mono channels but are geared toward use with stereo devices. A very important feature on mixers. This phantom power This power supply, usually 48 votes, provides power for condenser microphones and devices such as active direct boxes. This particular mixer has several added features not commonly found on small mixers. For example, it has a limiter on a couple of channels to prevent overload, and it has a fl or after fader, listen buttons for all auxiliary mixes. You can press thes and listen to each monitor or effects mix on headphones.
4. Mixing Procedures Part One : - Here's how to set the mic channels preempt Gain using the PFL button on this Mackey mixer. First, press the PFL button. Call solo PFL on this mixer, starting with the gain down, while the vocal or instrument is checking at their loudest performance. Volume slowly raised the gang control until the signal shows a maximum of zero DB on the mixers meters. You're at a good starting point, but keep an eye on the channel's overload indicator. It is okay for the light to blink on this particular mixer, but if it glows, that indicates overload and again is set too high. One thing to remember about the gang control. It adjusts the signal coming into the mixer. Therefore, it affects everything in that channel, including monitor mixes. If you have to adjust the gain during a performance, do so carefully and remember to quickly compensate in your monitor ox ends. Otherwise, you could either have feedback or a drop in monitor level. If you increase, the gang simultaneously lowered the monitor levels on that channel. You should never try to mix with the gang controls. Get them set and leave them. Unless there is a problem. You should always mix with the fighters. Another thing to keep an eye on is that the equalizers also affect the gang structure. So if you boost quite a bit on the equalizers, you could also cause overload. Now let's look at the channels equalizers. The best use for equalizers is to cut the frequencies that are too prominent. For example, if the guitar sounds too bright, try cutting the high frequencies first. Once that is done, if you need to add low frequencies or mid range do so slightly excessive boosting of frequencies can create a muddy, unnatural sound. Equalization is best on Lee used, if absolutely needed. In many cases, no equalization at all that's needed a group or some mix is a feature that allows you to route several channels through one fader, for example. All background vocals could be routed to Group one, and this mixer Mackey calls the subs. Here's how to do it. First engaged the group or sub mix button for the channels you wish to assign, Then rotate all of the channels pan controls to the left or odd numbered groups into the right for even number groups in order to include the sub or group in the mix. You press the left and right buttons or stereo mix buttons for that group. Now you can bring all channels assigned a group one up and down with a group or sub one, Fader noted. On many mixers, there is a left fry or stereo mix assignment button on each channel. These need to be disengaged on all the sign channels, Otherwise they will not be controllable by the group fighter alone.
5. Mixing Procedures Part Two : most small to medium venues. The front of house engineer has the added task of mixing the monitor or fullback system. Monitor mixes should always be performed using pre fader ox ends, because you do not want the musicians sound changing when you move the house. Mix failures. Assuming that the microphone and instrument gang controls have been set properly, let's look to the master OSS controls. Here we will be using ox one as our monitor sin. Let's set the master all its control. It halfway. That's probably a good starting point. Next, have a musician check his or her microphone or instrument. Start with the channels ox control all the way down and slowly raise it until the musician is happy with their stage Monitor volume. If you need a stronger signal for the monitors, adjust the master ox control to a higher level. Adjust these controls carefully because stage monitors air quick to feedback and in ear monitors are very sensitive. Auxiliary soon's are also used for controlling effects. Most of the time, a post fighter oxen is preferred so that the blend between the effect and the dry signal stays the same as you adjust. The channels fader. If the mixer does not have built in effects, it should have a send in return circuit that allows you to connect an external effects device. Connect the effects Sin Jack to the input of the external device. Then connect the outputs of the external device to the effects. Return shacks on the mixer. You set the amount of effect you want for each channel, usually AUC's ends. Then you control the overall volume of the effect in the mix. With the effects return, engineers often prefer to have their effects returns on failures. To make this work, simply connect your effects. Returns from the external device to either one stereo channel or two mono channels of your mixer used the channels line input. Then you can control the effects just like any other channel of the mixer. You can send them to the monitors using the ox controls, and you can add them to the front of house mix. Using the failures this Mackey mixer has built in effects, and it allows you to send the effect to both the ox one and the ox to mix as well as to the main mix. You can select the type of effect and then find unit. This is a common feature on many mixing boards. Here you see the master effects and for this internal device, and these knobs allow you to add the effect into the main mix. Orange AUC's one monitor mix or rocks to monitor mix.
6. Mixing Procedures Part Three : compressor is an audio device evens out the level between the loudest and softest sounds. Therefore, it reduces the dynamic range of a signal. Compressors are extremely useful in recording and can be effectively used in live sound as well. One such use is keeping a vocal or instrument volume, or even between the soft and loud passages some mixers have built in compressors like this Yamaha model. In this mixer, the compressors are one knob versions that simultaneously adjust several parameters. However, most compressors have several controls. The threshold controls the point at which the compressor starts to affect the signal. The ratio is the amount of compression applied to the signal. A 2 to 1 ratio means that the compressor will attenuate every two db above the threshold down to one db above the threshold. The attack and release knobs control how quickly the compressor affects the signal and how quickly it stops affecting it. The knee control. Adjust how gradual compression will be applied. Some units have gained makeup of control that allows you to boost the compressed signal up to a higher level in life sound. You have to be careful about applying heavy compression to a signal because it can cause microphone feedback. It is best to start with a minimal compression setting and slowly adjust from there. Because he's compressor is unique. It is important to read the particular units manual and to experiment with the compressors effects on the sound limiters or devices designed to stop signals from going past a certain level. You set the limiters threshold for the maximum signal level you wish to allow, and it will keep the signal within that dynamic range. One use for limiters is to protect audio equipment from loud spikes. One way that external audio devices, such as compressors convey connected to a mixer is by inserting them into Jack's call inserts on the mixer. These jacks allow you to use a special insert cable to interrupt the signal and route it through an external device. Here's how to do it. Connect the insert cables, tip ring sleeve or TRS connector into the insert jack of the channel or group that you wish to effect. Then connect the tip sleeve or TS cable label sent into the input of the external device. Finally connect the other TS cable label, return to the output of the device. Commonly equalizers and compressors are connected this way. However, effects devices like reverb units are best connected through the effects. Send and return circuits on your mixer. This will allow you to mix the dry and wet signals. Feedback occurs when a microphone picks up in a signal from a speaker to create a loop. This mixer has two features that are primarily designed to shape sound but can also be used to combat feedback. One is the graphic equaliser and the other is the equalizer found on East Channel. Let's start with a graphic equalizer. Graphic EQ use have frequency controls laid out in a line. The lower frequencies are on the left, and the higher frequencies are on the right. They are controlled by sliding failures called bands. In the center position. The ban has no effect. When pushed above the halfway point, the frequency is increased. When dropped below the halfway point, the frequency is reduced. If your sound system is not bright enough, you can increase the bands in the high frequency side a bit. If the system sounds bumi or bass heavy, you can reduce the lower frequencies to clean it up. Equalization should be done in small amounts, and it is always better to cut the annoying frequencies down a bit rather than to start boosting other frequencies to compensate. Here's how you can use a graphic equalizer to control feedback. If you hear feedback in the main speakers first, poorly overall volume down a little with the master fader. In order to stop the feedback, knicks slowly raise the master fader until you just start to hear the feed bag. If it is a low roar, you will know to focus on the left side of the e que. If it is a how it is likely in the middle section. If it is a squeal, it is in the upper mid to high frequency bands. When you first hear the return of the feedback hunt for the offending frequency by pulling down one frequency band at a time, reduce it to minus 12 DB or so. When the feedback stops, slowly raise the band back up, but not enough for the feedback to return. This keeps you from over equalizing, the sound making unnatural. The channel equalizers, although laid out differently, work much in the same way you have a fixed high frequency in a fixed low frequency, but you have a sweep herbal mid range control so you can reduce the high frequency if you hear a squeal or the low frequency. If you hear a low roar, but you can cut back the mid range control and then sweep through the frequencies with the second mid rise control until you find the offending frequency, then raise the mid range control up a bit so it sounds more natural but not high enough to allow the feedback to return.
7. How to Sound Check a Band: do an imaginary sound check for a three piece band with a drummer, guitarist and a bass player. The guitarist and basis also sing there to monitor mixes on Stage one, mix across the front of the stage and one mix for the drummer. In this small venue, we only need three drum Mike's kick, snare and overhead. First, prepare the mixing board, turn all gain knobs and AUC's ends completely down. Pull all theaters down and set the equalizers at halfway mute all channels. Now we are ready to start. Set the master Monitor sins at halfway as a starting point. But leave all channel ox ends down. You can change this master auction level later if needed. Set the main mix. Fator at zero db Unmoved the vocal Mike's Next have East vocalists. Check his or her microphone one at a time and set the gang control for these mikes. Now let's bring up the vocal mike failures to a good performance level and listen for any problems. Now let's start checking the instruments as the drummer to play the kick drum first. Set the channels gang control. I didn't bring up the fader and listen for noise or any other problems. If the kick drum is okay, move on to the snare. Finally asked the drummer to play the whole drum kit and check the overhead. Micah's Well, now check the guitar and bass channels one at a time, first set to gain control, then bring up the fader to check the sound. You can see what we're doing here. We're setting the gang control for each mike or instrument, and then we're listening to each micro instrument for two reasons. One to adjust the sound to to make sure that there are no noises or problems. Let's had a bit of reverb to the vocal Mike's to prepare the effects unit. Let's set the master effects in at halfway and the effects return to the main mix of halfway these air starting points and may need adjusting later for this venue. Let's select the medium plate reverb setting now have each focal has checked the microphone and turn up the effects sand for that channel until you hear the correct amount of reverb. Keep an eye on the clip light on the effects unit. If it illuminates back down the effects in a bit and raise the effects return to the main mix level. The goal is to get plenty of effect without overloading the effects units. Circuitry is the band once effects and the monitors. You can use the ox one and ox two effects. Return knobs to send a bit of reverb to them and the monitors. Now let's get a good starting point for both monitor mixes for the ban. Slowly bring up the vocal mic channels Ox INGE, one at a time until the vocalist tells you it is a good monitor level starting point. Check with each man member to make sure they have all the instruments and vocals they need in the monitors. And let's do a full band check because this is a small venue. Let's pull everything down except for the vocal Marks asked the band to play a song and mix all instruments to their proper levels relative to the vocals. After sound checking, the first song asked the band what changes that needed in the monitors and adjust accordingly. If everything is too loud, you can pull the vocal volume down a little bit and adjust everything else to mash that you can also pull the main mix fighter down a bit as well. When you are happy with the front of house mix and the band is happy with the monitor mixes , the sound check is finished.
Rick Fowler, Musician and Audio Engineer/producer
