Trouble Shooting Live Sound

Original Live Sound International Piece Here -- w/o my humble additons, found if you read on.

You are in a new venue and the band is setting up. It is your job to get good sound happening quickly. The soundcheck is critical, if well done, it gives the band confidence in you so they can relax and just play. And when you give the band the monitor mixes they need, they perform better. In this process, first you do a line check. Are all the mics and DIs connected to the right inputs and working okay? Then you do a soundcheck: set the levels, EQ and mix. Hopefully, everything will sound great when the performance starts. I will offer some tips to help this procedure go smoothly.

LINE CHECK

Let’s say you have a stage plot and a mic input list. After running the snake, place one copy of your list near the stage box, and another near the mixing console to label the faders. Plug in mics and direct boxes according to the list, and listen to each channel one at a time over the house loudspeakers.

Should you check each mic and DI as it is plugged in?
Or should you connect everything first, then check each channel?

If you check a mic as you plug it in, you know immediately where any problem lies. If you check channels after all the mics are connected, you have to troubleshoot the channels (mute or solo each channel) if you hear a problem. Checking as you plug in works best if you have one technician on stage and one at the mixer. But if you are doing the whole thing – micing and mixing – plug all the mics in and then do a line check. If you hear a noise over the house loudspeakers, mute each channel one at a time and see when the noise stops. Or solo each channel and listen for the noise.

Before the performers arrive on stage, have a helper talk into each mic and identify it. If guitars with pickups are on stage, turn up their volume control and strum each instrument (with the musician's permission). Turn up the channel input trim and fader slowly to avoid feedback. Listen for signals and note any issues.

Note: In festivals, solo each channel and monitor it over headphones to avoid disturbing the audience.

Here are some problems you may hear during a line check, and some fixes to try:

No Signal

Is phantom switched on in the dead channel? Condenser mics and some direct boxes require phantom power.
The mic is plugged into the wrong channel as specified on the input list.
Check the connection.
The snake XLR connector is plugged into the wrong-numbered input.
Check and confirm the number for the cable
The channel is muted.
Un-mute it after checking that the trim and fader is down..
The channel is not routed to an output bus.
Route it to the appropriate submix/buss after checking that the trim & fader are down..
Make sure the musician's volume controls are turned up in their entire signal chain.
BUT not too much in an one or too much cumulatively so as to overload!
Try other guitar cords and mic cables.
Replace dead batteries.
On wireless mic's, acoustic's and some DI's.

Hum or Buzz

Maybe nothing is plugged into the channel input. This creates an open circuit, and that high impedance input picks up lots of hum and buzz.
Make sure the instrument or mic is plugged into the snake.
The mic cable's shield might be broken.
Replace the cable.
Maybe the mic is picking up a humming guitar amp.
Turn up the guitar and turn down the amp.
A guitar with a pickup is plugged in and turned up, but nobody is playing it.
Touch the strings or turn down the pickup volume to see if the hum stops.
A direct box can create hum because of a ground loop.
Be sure it is connected to something if it is ...
Try flipping its ground-lift switch.
A compressor stomp box is raising the gain because there’s no input signal.
Temporarily shut it off and see if the hum goes away.

Distortion

The mixer channel is clipping
Turn down the input trim until it stops.
Check the gain staging of the musician's stomp boxes. Have them turn down and check the level over chain of stomp boxes.
Replace bad cables.
Switch in pads in condenser mics (you will hear this only when the musicians play).

Crackles and Noise

Replace bad cables. There might be a cold solder joint.
Clean cable connectors with a cleaner such as DeoxIT by Caig Labs.
Replace weak batteries.
In some microphones, make sure the mic capsule is screwed fully onto the mic handle.

At this point, you might dial in some levels and EQ based on past experience. You could insert compressors in vocal channels, gates on drums, and so on.

THE SOUNDCHECK

Overview

After verifying that all the lines have the right signal and sound clean, you are ready to begin the soundcheck itself.
By now if you haven't gotten at least a set list ... Ask the band for a set list if possible with as much detail to lead and support vocal specifics and instrument solos or other particulars that will alert you to sudden but temporary changes to the mix.
cmh note: And I quote, "Oh yea in the middle of the current radio single the drummer does a rap for about 3 mintues that isn't on the single. Does he need a mic for that?

It helps to use a talkback mic. At the mixer, plug a mic into a spare channel and turn up its monitor send. Talk to the band through the monitor loudspeakers - it beats yelling instructions across the room or using sign language.

Before the gig, make sure the talkback mic and its cable sound clean. I recently did a soundcheck in which I heard crackles and noise, and wasted time tracking it down ... until I found it was the talkback mic’s cable!

Musicians want clear directions from the sound mixer.

"Bass guitar: play for a minute and nod when it is loud enough."
"Lead singer, please get closer to your mic."
"Mr. guitar, please move your mic a little more toward the neck."

Never allow feedback during a soundcheck! Not only is it annoying and painful, it can damage hearing and cause tinnitus. Some studio engineers, placed in a live situation without prior live sound experience, can inadvertently create feedback when they turn a knob too quickly, or un-mute a channel when its gain is way up. They are used to turning knobs with no harmful consequences. Slow and deliberate is the key.

Here is a suggested order of events in a typical soundcheck:

With faders set to UNITY and monitor sends set low (9 o'clock), set the gain trim for each channel
With faders up, set the monitor level for musician #1.
Set preliminary EQ for musician #1.
cmh note: I like the following order: drums, bass, guitar(s), key(s), support vox, front vox.
If there are horns do those in mic groups.
Repeat steps 2 and 3 for the rest of the musicians.
Set up a drum submix, instrument submix, and vocal submix(es).
Ask the entire band to play, and set up a house mix.
Touch up the monitor mixes as requested by the band members.

We’ll go over each step. Let’s say the lines are checked and the band is on stage.

Set Gain Trims

First, set the faders and monitor sends very low to prevent feedback as you are adjusting the gain trims.
You might say to the band, “Okay we’re ready for the soundcheck. I’m just setting levels now, not monitors.” Ask musician #1 to play or sing as loud as he/she will during the performance. Slowly turn up the gain trim until clipping occurs, then back off about 10 dB to create some headroom. (There are other methods).
Repeat for each musician.
Important: Remind the musicians not to change their volume-control settings on amps and instruments between the soundcheck and the performance.

Set Monitor Levels

Turn up the faders/knobs to design center (but watch out for feedback). Use full-volume house levels if possible so the monitors don’t need to be turned up so much. Ask musician #1 to play. Slowly bring up that channel’s monitor send until the musician says the level is okay.
Say something like, “Bass player, play and let me know when it’s loud enough for you.”
Of course, some musicians do not want to be heard in the monitors.
cmh note: the soundman is a servant first and an advisor second.
One may not want to be heard when others really need to hear that musician.
Suggest that while needed in other monitor mixes they will be kept out of their own.

Set EQ

Now ask musician #1 to play or sing non-stop as you set preliminary EQ for that channel. Make sure it sounds reasonably accurate.

If an acoustic guitar is boom-y, move the mic away from the sound hole or turn down the low-frequency EQ.
If an acoustic guitar pickup is too bright or electric sounding, turn down 2 kHz and/or 12 kHz.
If you hear vocal pops, switch in a high-pass filter at 100 Hz or so.
If you know the frequency of the standing waves, Q those down now.
In fact it is a good idea to high-pass everything except maybe the bass, kick and synth.

Set the monitor level and EQ for each musician.
A typical checking order is:

drums (each part of the kit)
bass
backup instruments
lead instruments
vocals

Do The House Mix

Once all the instruments and vocals are set individually:

Ask the drummer (if any) to play. Set up a drum sub-mix.
cmh note: I like the bass in with the drum mix so after getting the drums set have the bass join in.
Ask the entire band to play and set the submix for the rest of the instruments.
cmh note: You might want the drums and bass to stop for a bit even,
for a real fine-tune on the mix OR sub that buss and do so.
Ask the singers to perform at full volume. Set up a vocal sub-mix.
cmh note: If you have enough buss room, do this in two steps and sub mix's,
first support vox and then lead vox.
Ask the band to play a song all together as you set up a house mix.
Then ask them to play a short section of a song representing the volumes and styles they plan on using in that nights set(s).
cmh note :This gives you a feel for general volume and dynamics for the gig. KEEP NOTES.

Touch Up The Monitor Mixes

You, or the monitor mixer, will set each performer’s monitor mix so they can hear themselves and any other parts they need to hear. That’s not necessarily the same as the house mix.
Ask each player what they want in their monitor. If the monitors seem “hot” overall and are starting to ring, turn down the master monitor send a little.
Some musicians comment on the monitor tonal balance. They may want less bass, less mids, more highs, or whatever. If your monitor sends do not have EQ, you can tweak the graphic EQ that is feeding the monitor power amp.
cmh note: just be careful you don't undo the settings you made when you rang the system before anyone else showed up!!!
ALSO: see of you can get some EQ from the channel into the monitor send using pre and post switches for the sends.
Remember the musicians are hearing the bass-y sound off the back of the house loudspeakers, so they may not need much bass in the monitors. That is great – then you can roll off or filter out the lows in the monitors, which also reduces rumble and feedback.

Controlling Stage Volume

If you turn up a vocalist’s mic in the monitors, and the instruments are very loud at that mic, you also turn up those instruments in the monitors. You need to get more vocals and less instruments at the singer’s mic. So ask the vocalist to sing with lips touching the mic’s foam pop filter, and don’t place the vocal mic right in front of a guitar amp or drum kit.
cmh note: if you are clever with the gate and/or comp you can minimize this as well.
Turn down the instruments if possible. If the guitar amps' stage volume is too high, suggest that the guitar players place their amps to their side, aiming up at their ears so the amps will sound louder to them. Then you can turn down the amps. Other tools for reducing stage volume are in-ear monitors, clear plastic drum baffles, and electronic drums.

Muting

Make sure that musicians with DI’s alert you when they want to unplug or plug in. Mute their channel when they signal in order to avoid loud pops in the sound system. Caution: some mixing consoles do not mute the monitors when the channel is muted. In that case, temporarily turn down the monitor send for that channel, then reset it where it was. (see pre and post note above)

Warm-Up Acts

If there’s a warm-up band (support act), put them on different faders or a different mixer than the main act if possible.
Note which channels the monitor mix cables are plugged into. If you shift the monitor mix cables from one mixer to the other, you’ll need to put them back where they were. After soundchecking the headline act, do the same for the support act. The concert starts with the support act, and when they finish, it’s time for changeover. Remove the support act’s gear and set up again for the headline act. Do another line check to make sure nothing has changed.

No Soundcheck?

What to do If you have no soundcheck, say at a festival or “open mike” with short changeovers?

First, it helps to dedicate each snake channel and mixer channel to a specific instrument.
Don’t change that assignment during the festival.
Suppose input 2 and snake channel 2 are always kick drum.
The kick-drum settings that worked for band #1 might be in the ballpark for band #2.
For that matter, the guitar and bass settings already there will be a good starting point if the musical styles are similar.
So when band #2 comes on stage, you’ll already have them roughly dialed in.
Allow some extra channel assignments for larger groups.
Now, how can you get a quick monitor mix and house mix for the first band with no soundcheck?
At small festivals or open mics, you can set monitor levels ahead of time as you talk into each mic on stage. Listen to the monitors on stage and make sure they are loud enough and sound good.
As the band is setting up and you are placing the mics, ask them what they want in their monitors so you can pre-set that.
Do a line check over headphones.
Even if an audience is present, see if you can set the monitor level quickly for each instrument and vocal before the band starts.
The band members need to hear themselves clearly just to play, and you don’t want them to sound incompetent!

You’ll need to set up a mix quickly during the first song. Some engineers employ the following method.

Before the band plays:

Start with all the gain trims halfway up (midnight or 12 o'clock)
maybe lower for condenser mics and loud instruments,
higher for dynamic mics and vocals.
Or set them based on your experiences at previous gigs (take notes).
If you have a digital console, just recall a preset.
Set all faders to UNITY.
If you haven’t already set the monitor sends, turn them between 9 and 11 o'clock, or as the band requested during setup. Watch out for feedback.
Switch in high-pass filters and set them to a reasonable frequency for each instrument and vocal.
Set EQ either to flat or to “typical” values for each instrument and vocal.
Bring up the faders for the vocals or quiet instruments – slowly to prevent feedback. If there are no lead vocals, you might bring up all the faders equally.

When the band starts:

Touch up the mix.
If any channel is clipping, turn down its gain trim until clipping stops, and simultaneously turn up that channel’s monitor send by the same amount in dB.
Watch for the performers’ cues on stage, and touch up the monitor levels.

Some engineers prefer to set all the faders to design center (or up to 12 dB lower for large mixes), then mix with the gain trims.
cmh note: see I told you
Note: adjusting the gain trims will affect the monitor mix, making it similar to the house mix. Watch out for monitor feedback. The claimed advantage of this method is that it tends to create optimum gain staging in the mixer. Good luck in running a professional soundcheck. The talent will thank you!

Perfection (IMHO): Trim at midnight, Q sounds 'natural', faders@unity.
Mixing the busses and tweeking the comp thresholds!

Stolen from: Bruce Bartlett.
He has mixed sound for concerts, jazz festivals and folk festivals. Bruce and Jenny Bartlett are the authors of Practical Recording Techniques 5th Ed. and Recording Music On Location