Sound Reinforcement Tutorial

I plan to give some simple advice here on setting up and running sound reinforcement for a small band. My experience is running sound reinforcement for a small Church Praise Band, but I think the advice should be useful in other venues.

MOBILE SOUND REINFORCEMENT

We are now doing a lot more outdoor portable sound reinforcement events this summer. Digitally controlled wireless mixers and ALL IN ONE compact powered speaker systems with linear tweeter arrays simplify the setup and running of outdoor events.

Tablet Controlled Remote Mixing

    A simplified system for mobile sound reinforcement places a digitally controlled analog mixer on the stage and uses wireless to control the mixer using an iPad or other touch screen computer. Microphone and instrument inputs can be inserted directly into the digitally controlled analog mixer on stage eliminating the need for a snake.

    More expensive rack mounted fully digital mixers are available that can also be controlled over wi-fi and/or ethernet. These fully digital mixers convert the analog signal to digital for processing and then back to analog for output. Some of these units can also be used as a stage box, with a digital snake and a digital console.

All In One Compact Powered Speakers

    ALL IN ONE compact powered systems with a linear array of tweeters and a subwoofer can be used both as speakers as monitors OR as speakers. JBL has its very popular EON ONE and Bose has its F1 FLEXIBLE ARRAY/ Subwoofer system. Both of these systems use multiple tweeters to reduce feedback. As a result of this design, the array/sub-woofer can be placed behind the musician or speaker eliminating the need for a monitor. These systems work well for smaller groups and venues. A limiting factor for larger venues is the prohibitive sound level on stage required to reach the back row. A solution to that limitation is discussed below.

Using a Mixer and All In One Compact Powered Speakers

    We are now experimenting with combining a tablet controlled mixer on stage with multiple ALL IN ONE compact powered speakers. Most analog mixers have at least two main and two aux outputs. In a mono mix a mixer can therefore be used to drive up to four ALL IN ONE compact powered speakers. For instance, one ALL IN ONE powered speaker can be used as a speaker/monitor placed centrally behind the musicians and two ALL IN ONE powered speakers can be used as speakers placed in front and to the sides of the musicians. The combination of a small mixer and multiple ALL IN ONE powered speakers may be able to provide portable sound reinforcement ranging from simple setups (one "speaker" per musician) for small venues to more complex setups (using a mixer and multiple "speakers") for larger venues. In some cases scenes can be stored directly on the rack mounted mixer. Best practice may include using redundant controllers with a wired and AC powered computer on stage and a wireless battery powered tablet at the FOH (Front of the House). 

If you use a digital mixer with Aux 1/2 going to a central "speaker as monitor" consider:

1) Link the main mutes to the aux mutes (eg. Global Aux Mute On) so that when you mute a channel in Main, the same channel is muted in Aux..

2) Set the Aux input to post fader so that effects are included in the center/front musician/audience mix. You may wish to limit the use of compression to minimize feedback.

Outdoor Practice

    With our neighbors blessing, our small Jazz Ensemble has been practicing outdoors using COMPACT sound systems on my driveway. This has now become a regular neighborhood "event" and has been well received.

SOUND REINFORCEMENT

Equipment

All In One Compact Systems

     These systems combine a mixer, amp, woofer and a linear array of tweeters into an easily transportable "speaker as monitor" PA system. They can be described visually as a stick on a box.

They typically have an extended tweeter array that can be mounted low for a small audience, or higher for a larger audience. The use of an array of tweeters minimizes the risk of feedback when a mic is placed in front of the PA. With reasonable expectations these systems can be used as both the main speaker and as the monitor, thus "speakers as monitors." Ideally each musician would have their own PA system. These units are ideal for solo performers and small groups (both indoors and outdoors) as they are easy to transport and simple to use. An example is the JBL EON Portable PA system. In a minority of cases, certain speaking voices may require turning down the treble to avoid "ringing."

Powered Mixers

    The simplest setup combines the functions of the pre-amps, mixers, sub-mixers, equalizers and power amplifiers into a single surface device or rack-type device. This is a common first step, but is less flexible than starting with a separate mixer and power amplifier. If you buy a separate mixer and power amplifier you can replace or upgrade each device separately. More importantly, you can move the power amp to the stage and eliminate a lot of long speaker cable runs. This is more important on a mobile live reinforcement setup. In a permanent setup, the long speaker cable runs can be hidden where they are not visible and not a trip hazard. A rack-type powered mixer is a good fit for a portable PA system with occasional live instrumental/vocal performances.

Mixers

    A standard 16 channel mixer with equalizers and two sub-mixer groups can fit on top of a rolling rack. Larger 24 channel mixers are better suited to a permanent setup in the back of the house sound booth. Don't skimp here. Sliders do not like soda so BE CAREFUL. Use masking tape and label the channels with the performers name and/or instrument.

Digital Mixers

     Newer digital mixers can store performance settings and performer equalization curves for latter recall. Many can be used with a "digital" snake (ethernet cabling) and may be compatible, out of the box, with digital in-ear monitor systems. They often allow a visual "eyes on" adjustment of the equalization curve by providing a graphical view of the eq curve. Consider looking at a model with a full complement of 32 faders. This allows you to look at all 32 input channels, 32 output channels, 32 effects feeds, 32 monitor feeds etc. without switching between "scenes." Newer version support remote control of the board over wireless or ethernet.

Digitally Controlled Analog Mixers

    As discussed earlier, tablet digitally controlled analog mixers can be used to advantage for portable sound reinforcement, eliminating the need for a snake. Wired mixers may be more appropriate for fixed installations.

Rack Mounted Digital Mixers

    Fully digital rack mounted mixers are available without any surface controls. Instead, they can be controlled, for instance using a tablet over wifi or a computer over ethernet. These units can sometimes be used with a digital console mixer of the same brand connected together over ethernet.

Amplifiers

    Get an amplifier that is powerful enough to run at 50-70% so that there is plenty of head room. Some newer amplifiers come with multiple cable input choices such as having both an XLR and a 1/4 inch TRS input on each channel. This can lead to creative wiring including "patching" the two inputs together. You may also want to look for an amplifier with the new combination Speakon/1/4 inch output jack that will accept either a Speakon speaker connector or a standard 1/4 inch speaker cable.

Main Speakers

    These are often 14 inch two way speakers mounted on portable stands placed in front of the stage and any mics.

Array Speakers

    Technology using stacks of multiple speakers for increased dispersion was once reserved for exotic sound reinforcement systems. New designs have now brought array technology to the masses. Small "array sticks on a subwoofer" are now available for "coffee house" sound reinforcement. One of the advantages of these portable speaker arrays is the increased resistance to feedback when the musician is in front of the speaker, obviating the need for a monitor.

Monitor Speakers

    These are often 12 inch two way wedge shaped speakers on the floor pointing toward the performers and in the same general direction of any mic. It is common to use aux 1 and 2 for the monitor mix. You can adjust the gain on aux 1 and aux 2 on each channel to determine how much of that channel goes to the monitors. If the mixer is set to pre-fader, then the signal will remain constant to the monitors even if you slide that channel to zero. If the monitor amplifier is mounted on the stage, you would send the aux 1 and aux 2 output down the snake on one of the 1/4 inch TRS return lines and then to the stage monitor amplifier and then to the monitor speakers.

Powered Speakers

    These combine the on stage amplifier and speakers into one unit. They can be combined with a stand-alone mixer for a portable live reinforcement setup. The downside is that you need to power up each speaker separately as opposed to having the stage electronics on a single rack controlled by a single switch on a power conditioner. The upside is that they can be used as powered monitors in the future if you add a main power amplifier and passive main speakers to your setup at a later date.

Dynamic Microphones

    These are the most common mics like the Shure SM58 and SM57. They do not require 48v phantom power from the mixer and are very resistant to damage. They basically work like speakers in reverse, converting the energy of a singer to electrical power. The SM58 (vocal mic) and SM57 (instrumental mic) have the same innards, but different housings. These mics do not put out as much electrical signal as most condenser mics, but seem to withstand unbelievable abuse.

Condenser Microphones

    These mics require 48v phantom power from the mixer (or some other source). They are more delicate, but are more sensitive and produce more electrical signal. An example would be a Rhode NT5 instrument mic. Some condenser mics are so sensitive they will pick up the hum of the air conditioner. Condenser microphones use a very thin "plate" to capture sound waves and are capable of producing a more accurate signal than a non-powered dynamic microphone. Very little electrical energy is produced by the condenser plate, thus the need for phantom power to strengthen the signal. So, to be clear, the condenser inside a condenser microphone, alone, produces very little electrical energy and the final output of a condenser microphone, through the use of phantom power, is strong.

Balanced vs Unbalanced Cables

    Too much science here. Just figure that balanced equipment with balance cables produce less hum*. So if your equipment outputs both balanced and unbalanced output, try to use the balanced output. Physically the balanced cables have one more wire than the unbalanced cables and the balanced connectors have three contact points. So the XLR three pinned guys and the 1/4 inch plugs with two dark bands of insulation on the tip can be used to send and receive a balanced signal. Unbalanced 1/4 inch plugs only have one band of dark insulation. An instrument cable is an example of an unbalanced cable.

    You can also use balanced cables for "stereo" and unbalanced cables for "mono" if you want to think of it that way, but BALANCED STEREO requires two balanced cables with three wires in each balanced cable for a total of six wires. Oh, I have a headache.

    You sometimes can plug a mono or unbalanced 1/4 inch cable into a balanced 1/4 inch system, but you will get unbalanced output, so that is why some 1/4 inch outputs on some mixers are marked balanced/unbalanced. What you get would depend on the type of cable you plug into the mixer output.

    It gets really complicated trying to figure out if a balanced splitter cable is splitting the signal into two balanced outputs or is splitting the signal into two mono (l/r) outputs. You can figure this out by sending a stereo signal down the balanced splitter and listening to the output on each split end using a stereo headset. If sound comes out both sides, then you have a balanced to balanced splitter. If only one ear is getting signal, then you probably have a stereo to mono splitter.

    Finally, some mixers have inserts that are smart so that if you push the 1/4 inch TRS cable all the way in, it acts as an insert and if you push the cable in only one click, it acts as an out. IMHO, this is asking for trouble when someone "helps" you out by pushing the cable all the way in. If you need an extra out and do not need the insert, buy an insert to out cable adapter!

*Science wizards will explain that the balanced cable actually carries two copies of the same signal, 180 degrees out of phase, or inverted. Special circuitry in the sound board is able to convert (sum) the two signals back into one, recreating the original signal at the sound board. "Induced noise" affects both copies equally and 180 degrees out of phase (say -15 in one signal and +15 in the other signal). When summed, the noise cancels out (-15 + +15 = 0), leaving "only" the original signal.

1/4 inch TRS Cables

    These are balanced cables with two bands of dark insulation on the tips and three wires. The TRS stands for tip, ring and sleeve.

    Inserts are special to mixers and expect a tip, ring sleeve setup. Typically, you insert a weird looking adapter with three arms. One arm has a standard 1/4 inch TRS tip that goes into the mixer's insert. The other two arms, one is black and one is red, each have only two wires. One arm is used to send the signal to say a compressor. The other is used to get the compressor output and send it back to the mixer. So this is an UNBALANCED IN-LINE circuit. (You can look at the adapter as a stereo to mono splitter if you want.) The key is that this is an inline circuit so if you turn off say the compressor, you will LOSE the channel. So don't use an insert if you really need an out. It is just one more thing to go wrong and stop the whole show just because someone turned off a device and no one remembered to turn it on. If you need an out and only have an insert left open, buy a insert to out cable adapter. Take my word for it. Been there, done that.

XLR Cables

    These are the weird cables with three pin connectors on each end for use say with microphones. XLR cables are balanced. Instrument cords have a 1/4 inch unbalance plug with only one dark band on on each tip.

Insert to Direct Out Adapter

    Use these if you need an extra out from a channel, but only have an insert left unused.

Speaker Cables

    These run from the amplifier to the speaker. Large cable is good here. The ends can be speakon or 1/4 inch connectors with only one dark band. The speakon is a connector that is less likely to disconnect. You can buy a speakon to 1/4 inch adapter. Newer amplifiers may come with a dual use connector that will accept a speakon OR a 1/4 inch cable. One less adapter to fail!

Snakes

Figure 1. 16X4 Snake. Do NOT send final amplified sound down the 4 TRS returns.

    These are used to run input and output from the stage to the house mixer. A common snake is a 100 foot one with 16 XLR inputs and 4 TRS sends or returns. Inside the snake they both use three wires. The use of TRS for sends to the stage and XLR for input to the mixer may have a historical basis, but it also keeps things simple.  If you segregate input to XLR and send/return to TRS you know what is what when you are in a rush on the stage. You may need an adapter however, if you insist on segregating thing this way on stage. One interesting snake is a 16X4X2 snake, where the snake has an additional two lines of speaker wire.

Digital Snakes

     If you are using a digital mixer, then it is possible to use ethernet cabling as a "snake." Basically ethernet cabling can be used to send the sound inputs in digital form from the stage to a digital mixer. This requires converting the analogue inputs to digital (computer bits) at the stage using a multichannel analogue to digital converter box. The newer digital mixers can used to remotely set the amplification settings for each channel on the analogue to digital conversion box which sits on the stage. Output from the digital mixer can then be sent back "down" the ethernet cabling to the stage where the digital signal is converted back to an analogue signal for amplification. An example of a digital mixer/snake is the Allen Heath GLD-80 digital mixer and AR2412 on stage audio rack (24 in/ 12 out). Tip: Keep your hands off the motorized sliders when switching between setups!

Power Amplifiers

    Put these on the stage if you can. To do this, send the final output of the mixer down two of the 1/4 inch returns to the stage and then to the amplifier on the stage using balanced cables. Alternatively, you can put the amplifier on a rack on the back of the house and send the output to the front of the house using speaker cable. This may work if the run is not too long and in a permanent system. Do not send the powered output down the tiny wires in the snake returns. Some snakes (16X4X2) have an extra two wires specifically for powered output (rare).

Reverbs

    These are often used on vocals. You can assign say aux 3 to the effects and then send the aux 3 output to the reverb. By adjusting the aux 3 knob on each channel you can determine which channel sends signal to the reverb. The reverb output is then sent back to the aux 3 return. This works best when the mixer has a volume control (gain) for sending the aux 3 return to the main mix. Turn up this gain during songs and turn this gain off during talking to vary the amount of reverb on the fly during the performance. If you use the reverb in this way, you only want the artificial effects sent out of the reverb. You do this by setting the reverb to 100% wet, so none of the original signal is output from the reverb. Some more advanced mixers have a stereo return channel that can be used to handle the wet signal from the reverb. This allows you to control the amount of wet reverb signal in the mains using the stereo return sliders.

Direct Boxes

    These guys are used to connect instruments such as guitars to the snake so they take a 1/4 inch unbalanced instrument plug from the guitar and convert it to a balanced XLR plug for connecting to the snake. Unbalanced signal can pick up more hum when it is sent a long distance. So if you want to send the guitar signal down a balanced line in a snake, you must covert the signal to a balanced signal first using a direct box. The balanced signal is much better at surviving the long trip down the snake to the back of the house mixer without picking up hum. Bass players tend to be very particular about the quality and ability of the direct box which needs to properly render the lower bass frequencies. Some direct boxes have a lift button which can reduce hum by "cutting out the ground" when connecting to both an on stage amplifier and a sound board. Passive guitar pick ups may need the ground (no lift) to work properly with a sound board.

Power Conditioner

    We use a lot of these primarily as a power strip so that one switch turns everything on the rack on and off. The are designed to protect the electrical equipment and often have useful lights.

Racks

    These are used to mount electrical equipment, power conditioners, drawers and even mixers on top. They are really useful for organizing your stuff. I use cable ties to clean up the cable clutter. I even use duct tape to secure the power warts to prevent them from unplugging over time.

1/4 Inch TRS Patch Panels

    These are useful if you want to send many different audio signals (Computer/DVD Player/CD Player) to a single input on the mixer OR if you need to send a single output from the mixer to multiple destinations. They are easy to understand much like the old phone operator's patch panel.

Stands

    Well you have speaker stands and music stands.

Ethernet In Ear Monitor Systems

    When you get tired of being asked to put "more of me in my monitor," get one of these babies. The downside is that you need to change your technique, including adding a house mic (mic the audience) into the monitor mix and you need to provide tactile feedback on stage such as a "butt kicker" or powered sub-woofer for the drums and or bass.

Bone Conducting "Headphones"

    Some folks do not like the feel of in ear phones or the isolation of in ear phones. Bone conduction phones use vibration to transfer sound to the skull, leaving the ear canal open.

Subwoofers

    The self powered ones are much better at cutting off the signal at the desired frequency. They are also useful if you are using an in ear system, since you can adjust the volume independent of the mains.

Amplifier Management Systems

    These are sophisticated multipurpose rack units that can be placed between the mixer and multiple amplifiers with options for adding necessary delay. These units simplify the addition of fill speakers (front, mid house, or under balcony). An example would be the DBX DriveRack 260 which also adds whole house auto "eq" and auto feedback reduction capability.

General Principles

1. Choose a lead singer and/or instrumentalist on a given song or even during part of a song and make sure that that feed stands out lest you risk a bland live mix

2. Loud can be good, but you should be able to hear yourself singing --- or maybe not!

3. It is louder up front near the mains than where you are in the back of the house

4. Group the vocals and group the instrumentalist (preferably using the subgroup function on the mixer) and adjust the balance between the two groups (vocals vs instrumentals) during the live mix as needed. So you could send the instrumentals to 1-2 and the vocals to 3-4 and the speaker's mikes to L-R.

5. Adjust the electric drums and bass so that you can feel the beat

6. If you have a vocal performer with a wide vocal volume range during a song, you may need to ride (constantly adjust the volume) that channel during the song or resort to using a compressor on that channel.

7. The mains need to be louder than the monitors, so zero the slider on the mains and listen to the volume produced by the monitors. You will be amazed sometimes.

8. Have the effects on a return to the main mix so that you can turn down the effects with a slider (or gain knob) when the performer wants to just talk to the audience

9. Have the speaker's mic on a channel without effects and going directly to the mains (L/R) so that you can mute the sub-mixers (vocal/instrumental) without muting the speaker and you do not need to worry about turning down the effects when the speaker is using the speaker's mic

10. Mute the sub-mixers when you have a long speech to minimize feedback and setup noises. The risk here is that you are not looking up when the band starts up.

11. Turn on the 60 Hz rumble filters on the vocal mics

12. No effects on the electric guitar who probably has a whole army of effects running anyway

13. Add a talk-back mike on say channel 16 for you to use to talk to the performers. Turn off 1-2, 3-4, and L-R  on the talk-back channel so that the output only goes to the monitors. So you could use aux 1 and aux 2 for the monitors and send the aux1 and aux2 direct outs down the TRS snake returns to the monitor amp and on to the monitors. Now, when you talk, your voice only appears on the monitors. Even better, if you switch to in ear monitors, your voice only appears on the in ear phones.

14. Look behind the rack once in a while so that you can collect those 10 year old donuts :)

Common Analog Mixer Settings

Figure 4. Common 16 Channel Stereo Mixer Setup (I [Instrument] --> 1-2, V [Vocal] --> 3-4, T [Talk-Back Mic] --> L-R)

    I am going to describe a stereo mixer setup. This means that each mono channel might be panned neutral so that equal output goes to say the sub mixer channel 1 or 2. A set of stereo channels might be panned left on the left mic channel and panned right on the right mic channel. If the mixer board has four sub mixer sliders 1-4, then basically you have two sub mixer stereo sub groups: group 1-2 and group 3-4, where 1 and 3 might be left and 2 and 4 might be the right channels. Be aware that it is also possible to do a purely mono mixer board setup. If you do a purely mono mixer board setup then you essentially can have each of the sub mixer sliders be a group. So if you have sub mixer channels 1-4, you can have four mono sub mixer groups, as opposed to two stereo sub mixer groups.

Using Sub Groups for Grouping Instruments and Vocals

    If you are still with me here, then I place the instruments on channels 1-8 and the vocals on channels 9-15. Channel 16 is for the talk back or speaker's mic. Now I would send the channels 1-8 to sub mixers 1-2 and channels 9-15 to sub mixer channels 3-4. The speakers mic is set to L-R, bypassing the sub mixers completely and sending the speaker's mic output directly to the main output sliders. During the performance, if I think the instruments are overpowering the vocals, I would increase the sub mixer sliders 3-4 to boost the vocals or I could decrease the sub mixer sliders 1-2 to decrease the instruments. If you are not yet at this level of live reinforcement, you can greatly simplify your setup by sending all the channels to L-R, bypassing the sub mixer sliders so that they do not affect anything at all!

Using Aux 1 and 2 For Monitors

    Now aux 1 and aux 2 is used for the monitor mix. Each channel is set to pre-fader so that the feed from each channel to aux 1 and aux 2 is not effected by the slider for that channel. So even if I set the channel slider to zero, that channel still shows up in the monitor mix. One way to think about the auxs is that they go left to right or horizontally. You scan the aux 1 pots or gain controls from left to right to see what signal from what channel is going into aux 1. This is in contrast to the channels which go top to bottom or vertically. With each channel you start at the top with the pre-amp pot or gain and go down to the final channel slider to decide what output is going out of the channel to 1-2, 3-4 or L-R.

Using Aux 3 for Effects

    I use aux 3 for the reverb/delay/effects. So the pot or gain on aux 3 determines if that channel's signal gets sent to the effects processor. Usually I set the gain on all the vocal channels on aux 3 to mid position. Again, scan the aux 3 pots going left to right to see which channels are sending signal to the effects.

    Many mixers then have yet another pot or gain that determines the final signal from each aux channel that is sent out to the aux out. 

    One way to start is to set all the gains to mid position or neutral. Then consciously turn off the gains on some channels such as aux 3 (effects) off on the instruments.

    I would then set the effects processor to 100% wet so that only the processed signal leaves the effects processor so that none of the original signal is mixed into the output of the effects processor. On some mixers I would send the effects output back to the same aux channel. On other systems I would send the effects output to a special stereo return. The key is that the amount of effects return is subject to control by a pot or slider before being mixed back into to the main output. This allows me to adjust the amount of effects in the final mix on the fly. For instance, if a performer starts to talk to the audience, I can set the effects return slider to zero so that there is no echo when the performer is just talking.

Speaker's Channel

    The speaker's channel (Channel 16) is set to L-R and the aux 3 (effects) pot or gain is set to zero. So the speaker's channel works even if the sub mixers are muted and the speaker's voice never goes through the effects processor. Consider adding a feedback killer on this channel using the channel insert.

More of Me in the Mix :)

    If a performer complains that they cannot hear themselves in the mix, you can then turn up the pot or gain on aux 1 or aux 2 on their channel depending on the speaker nearest to that performer. What usually happens of course is that everyone complains and all the aux1 and aux 2 channels or set near to max anyway :) You really need to go to in ear monitors. Really. That way each performer is responsible for their own personal mix and they will stop bugging you!

Common Digital Mixer Settings

The basic setup for a digital mixer is similar to an analogue mixer with a few significant differences. For instance, digital mixers use more of a horizontal view of controls than analog mixers. The mute lights on some digital mixer boards are opposite of those on analog boards. Digital mixers are very intolerant of hot signals from the preamp, resulting in "clipping." Analog mixers are much more forgiving of hot signals from the preamp.

Mute Buttons: Newer units have a button labeled "Mute" with turns red when activated.

FX: There are usually multiple FX Groups. FX A may be a delay and FX C may reverb. Unlike an analog mixer where there is a knob on each vertical channel for FX sends, on a digital mixer FX levels are controlled in a horizontal "FX" view. For instance, to add effect A to channel one you select the FX A horizontal view and raise the slider on channel one. A master fader in the FX view then controls the overall FX levels.

Scenes: You can save and load board settings in memory. These settings are called "scenes." Scenes are usually stored in the mixer itself.

Monitor Feeds: Again you can use say Aux 1 and Aux 2 for monitor feeds. Unlike an analog mixer with a knob on each vertical channel for setting the aux send level, on a digital mixer Aux levels are controlled in a separate horizontal "Aux" view. For instance, to add Channel 1 to Aux 1, you select the Aux 1 horizontal view and raise the slider for Channel 1. A master fader in the Aux 1 view then controls the overall Aux 1 level.

Sub Groups: You can select to send a specific Channel to a specific Sub Group instead of directly to the Mains. For instance, you can send all of the singing vocal mics to Sub Group A and all of the instruments to Sub Group B instead of to the mains. In turn, the output of the Sub Groups is sent to the mains as long as the Sub Group Fader is at unity. If you select the Sub Group view, then only the channels in that group appear in a horizontal layout and the sub group master fader only affects the output of the selected channels to main. You can then adjust the Group Fader to control say the level of the vocals only going to the mains. This allows you to control the overall levels of the vocals in contrast to the instrumentalist on the fly with only one slider. If you select the Group Mains view then you can control the overall level from say both sub groups (Vocal vs Instrumentals) from a single horizontal view.

DCAs: Digitally Controlled Amplifiers. You can create DCA Groups, which are filters for what is displayed and controlled by the DCA view. For instance, you would navigate to DCA 1 and edit the group by selecting every Channel except the speaker's mic inputs. This allows you to navigate to the DCA 1 horizontal view and mute the DCA 1 master fader, muting all of the board channels except the speakers mics. This allows you to reduce feedback when the speakers are talking or to reduce popping when instruments are being plugged in or unplugged. 

Mute Groups: Some mixers have a Quick Panel view that allows you to mute All outputs or specific Mute Groups on the fly.

Connectivity: This can be problematic. On some mixers you must wait for the board to completely power up before you try to connect over wireless. Wired connections, of course, tend to be more reliable. 

Common Problems

1. The monitors are so loud that you have no control over the house volume with the main sliders. Solution: Turn off the mains and see if the house volume changes.

2. No one is happy with the on stage monitor mix. There is no solution to this age old problem. Just kidding. Use in ear monitors.

3. Feedback because a mic is aimed at a loudspeaker or there is a non-directional mic on the stage. Solution: Aim the monitors and mics to the rear. Place the mains in front of the stage. Remove the non-directional mics.

4. The singer's/speaker's mouth is miles away from the mic and there is no way you can get the volume up. Solution: Use a wireless mic attached to their head!

5. The singer/speaker uses the mic as a prop and half the time they are not being mic'd. Solution: ask them to use a mic stand and get close to the mic.

6. The singer/speaker is too close to the mic and "pop's". Solution: use a mic screen or teach them to sign over and past the mic

7. The drummer plays so loud, no one on stage can hear the monitors. Solution: Use an electric drum kit and headphones for the drummer. Then place a butt kicker on the drummers seat.

8. It is too loud in the front and too quiet in the back of the house. Solution: Fly the main speakers, angled slightly downward. Some popular speakers come in versions with built in suspension points.

9. No signal on the condenser mic. Solution: Turn on the 48v to that channel.

10. Hum. Solution: Try to use balanced cables whenever possible. Set the lift switch to on on the direct boxes. Move the power cables away from the sound cables.

11. No signal on a mic. Solution: Check the connections. Assume you have a bad connection or bad cable. Check for phantom power if you are using a condenser mic.

12. Signal on a mic channel, but no sound on the mains. Solution: Check to see if the channel is muted, the SUB MIXER strip is muted, the correct button 1-2, 3-4, L-R is down or enabled, or if an insert effects device is turned off. Finally, look for a cable disconnect.

13. OK. I "flew" the main speakers, but now it is "dead" in the front rows. Solution: Consider adding MONO front fill speakers on sticks, or on the "stage" lip, running off a second amp. Adjust the volume of the front fills to just cover the front rows. Consider adding a delay to the front fills so that the sound from the mains and fills reach the front rows at the same time. 

14. Poor sound under the balcony in the back of the house. Solution: The balcony may be blocking the sound path from the mains. Consider adding under the balcony fills, aimed below the balcony, with the appropriate delay times. This may require an "amplifier management unit" with adequate delay capabilities. Remember, sound travels about one foot per mill-second. I know, that was probably more than you wanted to know!

15. The wireless mics dies at the worst times. Solution: Check the battery charge at the beginning and if it is not showing a full charge, replace the batteries. Really!

16. I get feedback when I try to amplify the speaker's mike. Solution: Try muting all of the vocal mics. Adjust treble downward.

Other Stuff

Stereo Miking    

    This is too big a topic.. If you are doing a stereo recording, it may just be easier to place both mics in the center and cross them at a 90 degree angle.

Cab Miking    

    Some electric guitar or bass players like to use their on stage cabinets to tune their sound. Place the cabinet behind the player and aim a mic on a low "table" mic stand at the cab opening. 

Talk Back

    Basically a mic for you to talk to the performers without going out the mains. Just turn off 1-2, 3-4, and L-R. Put yourself into the monitor mix on aux 1 and aux 2.

General Technical Philosophy

1. Green signal is good. Occasional yellow is normal. Red is not good. Then use the sliders to control the output volume of that channel.

2. If anything can go wrong or break, it will happen!

General Aesthetic Philosophy

1. Choose a lead singer and/or instrumentalist on a given song or even during part of a song and make sure that that feed stands out lest you risk a bland live mix.

2. Loud can be good, but you should be able to hear yourself singing while, perhaps, not being able to hear your neighbor singing.

3. Adjust the electric drums and bass so that you can feel the beat.

4. Turn down the effects slider when a performer is talking.

5. Ride the lead vocalist or speaker if they have a wide dynamic range and you do not have a compressor on that channel.

6. Adjust the relative mix of the vocals and instrumentals using sub mixer groups.

7. Crank up the volume of the lead guitarist on the exit song!

Per Channel EQ to Reduce Feedback

     A more advanced technique to avoid feedback is to use per channel equalization. This is doable on a digital board with per channel graphical EQ. Each singer, speaker and instrument is eq'd against feedback and the eq stored in digital memory for reuse. In a nutshell, each eq "pot" is pushed and narrowed to cause feedback, then the EQ "pot" is inverted to decrease feedback. This is best done with a digital board with a graphical EQ display. My apologies that I cannot real explain this well. The technique is much more obvious with a hands on, visual demonstration.

Separate Sub Woofer Feed/Mix

A more advanced technique is to run a separate feed to a powered subwoofer. By running a separate "mix" for the subwoofer, you can customize the low end of the house sound. For instance, you may only want to run the drum kit and bass input to the subwoofer mix. The advantage is better control at the cost of complexity: a separate mix and a new gotcha. Since the sub woofer volume is on a separate mix not controlled by the master fader, it is possible to "mute" the master fader and still hear sound output (coming from the subwoofer!).

Drum Kit Mix

If you are running in ear personal monitors you may want to run a separate mix to a single "drum" channel.  For instance, you may assign "Mix 12" to the "Personal Monitor Channel 12." In turn, "Mix 12" will control the volumes for the four drum mics. Each performer will then have a single feed on their personal mixer for the "drums."

Micing a Diva

If you are blessed with a vocalist with an amazing volume range and not possessing the same level of mic technique (moving the mic closer or farther to even out the house volume) consider adding a compressor and limiter onto that channel. Although "riding" the mic fader is preferred, adjusting the volume on the fly requires anticipation and concentration. Occasionally things will just too complicated and a mild amount of compression can save the mix.

Common Types House, Stage Setups (Mixer, Main Amp, Main Speaker, Monitor Speaker)

Powered house mixer and stage main speakers

House mixer and stage powered speakers

House mixer and power amp(s), stage main speakers and stage monitors

House mixer, stage main amp, monitor amp, main and monitor speakers (See below)

House mixer and analog to digital (Ethernet) converter, stage main amp, digital (Ethernet) to analog in ear mixers, and stage pounding sub woofer (See below)

Common Standard House Mixer, Stage Power Amplifier Setup

Figure 2. House Mixer, Stage Amplifiers

Common House Rack Setup

16 Channel Non Powered Mixer on surface rack

Power conditioner with master on/off and lights

Digital Reverb/Delay

100 Foot 16 XLR in (Mics, Electronic Drums, Bass, Guitars), 4 TRS out snake (2 balanced TRS to main amp, 2 balanced TRS to monitor amp)

Wireless microphone receiver for speakers wireless headset mic

Optional feedback killer for speaker's mic using the insert of the speaker's mic channel

Common Stage Rack Setup

Power conditioner with master on/off

Main power amplifier

Monitor power amplifier

Short speaker cable runs to passive main and monitor speakers

Common Stage Speakers

14 inch 2 way Main speakers

12 inch 2 way wedge Monitor speakers

Common Stage Mics

Shure SM58 Vocal Mics

Shure SM57 Instrument Mics

Dynamic Mic for Lead Vocal

Wireless headset mic for speaker or podium mic

Common Mistakes/Problems

Placing power amps on remote mixer rack and trying to run powered output down the tiny wires in the four TRS snake returns to the stage. If you want to place the power amps on the remote house rack, use large gauge speaker wires and run them all the way to the stage.

Not using balanced 1/4 TRS connectors from the snake going to the power amplifiers

Not have speaker cables that connect to the special secure speakon connectors on the back of many amplifiers or not having the necessary speakon to 1/4 mono adaptors

Having the monitors up so loud that they over power the main speakers

Having the mics aimed in the direction of the monitor speakers resulting in feedback

Having any mic in front of the main speakers resulting in feedback

Advanced House Setup with Three In Ear Monitors

Figure 3. House Mixer, Stage Amplifiers, 3 Digital Personal In Ear Mixers as Monitors

House Rack Setup

16 Channel Non Powered Mixer on surface rack

Power conditioner with master on/off and lights

Digital Reverb/Delay

16 channel analog to digital Ethernet converter for in ear mix

100 Foot 16 XLR in (Mics, Electronic Drums, Bass, Guitars), 4 TRS out snake (2 balanced TRS to main amp, 1 TRS drum return, 1 TRS bass return)

Ethernet cable run from back of house to front of house for in ear monitoring

Wireless microphone receiver for speakers wireless headset mic

Optional feedback killer for speaker's mic

Stage Rack Setup

Power conditioner with master on/off

Main power amplifier

16 channel digital Ethernet distributor with 16 channel personal mixers for in ear monitors

Short speaker cable runs to passive main speakers

Common Stage Speakers

14 inch 2 way Main speakers

12 powered sub-woofer to provide tactile feedback from drums and bass to performers on the stage

Common Stage Mics

Shure SM58 Vocal Mics

Shure SM57 Instrument Mics

House mic aimed at audience for environment feedback into in ear monitor mix (aux 1 and aux 2), NOT into main mix (No 1-2, 3-4, R-L)

Dynamic Mic for Lead Vocal

Wireless headset mic for speaker or use a podium mic

Common Mistakes/Problems

Not understanding that in ear phones block the sound of the audience and failing to provide a house mic for the in ear mix

Not understanding the need to provide tactile feedback from electric drums and bass to performers on the stage with a powered sub-woofer or butt kicker

Failing to pad the input to the digital in ear system so that the signal clips and is degraded

Failing to insure that the inputs to the digital in ear system are pre fader

Advanced Digital Setup with Three In Ear Monitors

Figure 4. House Digital Mixer, Stage Amplifiers, Stage "Audio Rack", 3 Digital Personal In Ear Mixers as Monitors

An advanced digital system can use ethernet cabling as a "digital snake." In this setup, there are 32 (24 + 8) analogue to digital channel "pre amps" on the stage which can be remotely controlled from the digital mixer at the back of the house. Some digital boards have built in graphical frequency cutoffs, equalization and digital effects. Having the analog to digital converters at the Front of the House, shortens the distance that the signal needs to travel before being digitized. The house mix can be sent back down the digital snake and converted to an analogue signal at the the Front of the House. This analogue signal can then be sent to a powered floor monitor if desired.

Common Mistakes/Problems

Light on means the channel on a digital mixer is hot, the opposite of what you see on an analogue mixer where light on means the channel is muted! Grrrr.

Be much more wary of clipping on a digital pre-amp compared to an analogue pre-amp.

Have fun,

JAL