Article

Thursday, August 18, 2011

The Beginner’s Guide To Taking Charge Of The Sound Check

A look at the essentials of line checks and sound checks for live performances

The sound check 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 sound check: set the levels, EQ and mix, with the goal of everything will sounding great when the performance starts.

I’ll offer some tips to help this procedure go smoothly.

LINE CHECK
Let’s say you have a stage plot and a mic input list. 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.

Note: In situations such as live music festivals, solo each channel and monitor it over headphones to avoid disturbing the audience.

Should you check each mic and DI as it’s 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’re doing the whole thing – mic’ing 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.

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

No Signal
• 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 it.
• The channel is muted, or is not routed to an output bus.
• Make sure the musician’s volume controls are turned up in their entire signal chain.
• Try other guitar cords and mic cables.
• Replace dead batteries.
• Is phantom switched on in the dead channel? Condenser mics and some direct boxes require phantom power.

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. 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
• If the mixer channel is clipping, turn down the input trim until it stops.
• Check the gain staging of the musician’s stomp boxes.
• Replace bad cables.
• Switch in pads in condenser mics (you’ll 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, and so on.

THE SOUND CHECK
Overview
After verifying that all the lines have the right signal and sound clean, you’re ready to begin the sound check itself.

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 sound check 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. For example, “Bass guitar: play for a minute and nod when it’s 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 sound check! 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’s a suggested order of events in a typical sound check:
1. With faders and monitor sends set very low, set the gain trim for each instrument/vocal.
2. With faders up, set the monitor level for musician #1.
3. Set preliminary EQ for musician #1.
4. Repeat steps 2-3 for musician #2, and so on.
5. Set up a drum submix and vocal submix if applicable.
6. Ask the entire band to play, and set up a house mix.
7. 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 sound check. 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 between the soundcheck and the performance.

Set Monitor Levels
Turn up the faders 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, “Terry, play your bass and let me know when it’s loud enough for you.”

Of course, some musicians do not want to be heard in the monitor loudspeakers.

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. It’s 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, and 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.

Then ask the singers to perform at full volume and set up a vocal sub-mix.

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 few different song styles.

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.

Note that 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’s 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. 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.

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 sound checking 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 sound check, 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. 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 sound check?

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:
1. Start with all the gain trims halfway up, 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.
2. Set all faders down.
3. If you haven’t already set the monitor sends, turn them halfway up, or as the band requested during setup. Watch out for feedback.
4. Switch in high-pass filters and set them to a reasonable frequency for each instrument and vocal.
5. Set EQ either to flat or to “typical” values for each instrument and vocal.
6. 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:
1. Touch up the mix.
2. 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.
3. 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.

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 sound check. The talent will thank you!

Bruce Bartlett 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.

{extended}