Which kind of desk do you mix on?
Some steps in this lesson are different on an analogue desk. Choose yours, and the lesson shows the steps for it.
9:52, eight minutes before the service. The pastor says "testing" into his headset, and nothing comes out of the speakers. Somewhere between his mouth and the room, one link has failed or been set wrong, and this lesson is how you find it in a minute, not ten.
Sound starts as vibrations in the air. A microphone turns them into a tiny electrical signal. That signal travels down a cable to the stage box, then on to the desk, where it's boosted, shaped and mixed with everything else. It leaves the desk, an amplifier makes it much stronger, and the speaker turns it back into sound.
Swipe the drawing sideways to see all of it.
Read it from left to right: each box is a link. Many churches today also have a digital stage box: it turns every input into digital audio and sends them all to the desk down one network cable, and the desk's patch page decides which socket feeds which channel. A wireless mic adds two links of its own: the pack or handheld on stage, and its receiver, which plugs in like any other mic.
Every link in that chain can fail or be set wrong. That's good news: when something goes wrong, you only have to find the link.
Cables and connectors
Swipe the drawing sideways to see all of it.
Learn these by sight. Watch the look-alikes: a speaker cable and a guitar cable can have the same jack, but they're not interchangeable. Keep them labelled and apart.
Safety Mute before you plug. Mute the channel before you plug or unplug anything on it, and switch an amplifier or powered speaker off before you touch its cables. A cable pulled from a live channel makes a loud pop that can damage speakers and startle the whole room. Pulling the fader down isn't enough: in-ear sends are taken before the fader (Chapter 4), so the pop still reaches every musician's ears.
Coil over-under, and label both ends. Wrapping a cable around your elbow twists it, and twisted cables kink, tangle and fail early. Coil over-under instead: one normal loop, then one loop with a half-twist the other way, alternating. The cable lies flat, throws out straight and lasts for years. Put a label with the channel number on both ends.
Four signal levels
Swipe the drawing sideways to see all of it.
- Mic level goes into a mic input, where the desk's gain control boosts it.
- Instrument level (passive guitar and bass pickups) is fragile: over a long cable it loses its top end and picks up hum. Send it through a DI box (lesson 3).
- Line level goes into a line input, or through a DI for the long run to the desk. Tracks go in most simply from an iPad into a stereo DI (or two DIs); from a laptop, through an audio interface with balanced outputs (Level 2).
- Speaker level only ever goes from an amplifier to a passive speaker. Never plug it into a desk input.
Check yourself 1 of 3
The bass player has a long guitar cable and wants to plug his bass straight into a stage box socket across the stage. What do you suggest?
A passive bass pickup puts out instrument level, which is fragile: over a long cable it loses its top end and picks up hum, and turning the gain up brings the hum up with it. A DI box turns it into a balanced mic-level signal for the long run. A speaker cable can have the same jack, but it's made for an amplifier's output and has no shield against noise. Plug the bass into a DI beside him, and run a mic cable from the DI to the stage box.
Label everything, front to back
Give every source a number that stays the same all the way through: input 7 is socket 7 is channel 7, on both ends of its cable. Label outputs by where they go (Main L, Sub, IEM 1 Drums: the drummer's in-ear mix), and say stage left and right as the musicians see it, facing the congregation. Name desk channels by role, not by person: Pastor, Lead Vox, Keys.
Then colour-code by family and keep it the same every week. Sanctuary Mix uses yellow for speech, blue for vocals, purple for drums, green for guitars and bass, light blue for keys, tracks and playback, white for effects, and red for anything that must never reach the room: click, cues, talkback and ambient mics. A DCA wears the colour of what it moves. Use ours or your own, but keep it the same, and write each channel's family on your printed channel list. On a digital desk, check the patch page against that list too.
Check yourself 2 of 3
Before rehearsal you notice the lectern mic is plugged into socket 8, and someone has renamed channel 8 "Lectern". Your channel list says the lectern is input 7. It works. What do you do?
One number follows the signal: the socket, both cable ends, the desk channel and the printed list. Channel 7 holds the lectern's saved EQ, compression and in-ear sends, so on channel 8 it's carrying another source's settings, and next week's volunteer follows the list to a silent channel. Changing the list breaks every saved scene instead. Mute both, move the cable to socket 7, give channel 8 its old name back, speak into the lectern to prove it, and tell whoever mixes next.
When the signal goes missing
No sound? Don't guess. Start where the clue points. One mic silent: look at its channel meter first. Everything silent: start at the other end, with the main meter, the main fader and mute, then the speakers (the no-sound flowchart at the back).
Your desk's meters are your best friend here. Signal on the channel meter means the mic, the cable, the patch and the gain all work, so look after the meter: the channel's mute, its fader, its DCA, its routing, then the main fader. On many desks the meter still moves on a muted channel, so check the mute button too. No signal means look before the meter: the source, the cable and socket, the patch, the gain and phantom power.
On an analogue desk
Most analogue desks have no meter on each channel, only a light or two. To read one channel, press its PFL button and watch the main meter, or watch the channel's signal light. Release PFL when you're done.
Signal, but no sound in the room? As well as the mute (on some desks a button called ON, which must be on) and the fader, check:
- the channel's main button (ST, L-R or Main) is pressed, or, if it goes to a group, the group goes to the main and its fader is up;
- no BREAK or STANDBY button is pressed: it mutes the whole desk;
- no other PFL button is left on: the meter then shows that channel, not the main mix.
Little or no signal? Check the channel's PAD button is off (it's for loud sources, and a voice through it is very quiet), and that nothing is plugged into its line socket, which on some desks takes over from the mic socket.
A wireless receiver tells you about the pack. Signal bars mean the pack and the receiver can hear each other; an audio light that flickers as someone speaks means sound is arriving. Bars but no audio light: the pack is on, but sending silence.
Print: No sound in the room (flowchart, in the guide)
How to use this
Practise: finding a hidden fault in as few looks as you can, by letting the clues tell you where to look.
All three steps, and what to look for
- Read the situation, then choose where to look first. Each look shows what you'd see on a real stage or desk, and costs the time it would take to get there.
- Keep looking until you know what it is, then press "I know what it is" and choose the fix.
- Compare your looks with the quickest path, then press "Next round". Five rounds, from one mic to the whole room.
Look for: the two clues that halve the search. Is it one mic or everything? Is the channel meter moving?
Done when: you've solved all five rounds, each within two looks of the quickest path and with the fault seen before you fixed it (a wrong fix counts as two looks), and the widget says "Done ✓".
Sunday: when a mic goes quiet, ask "one mic or everything?", then look at the desk's meters before you walk anywhere.
Note: A practice desk, simplified. Your desk's buttons and lights look different, but the logic is the same.
This interactive needs JavaScript.
Without JavaScript: A worked example. At 9:50 the pastor's headset is silent in the room. Look 1, ask: another mic works, so the main mix and the speakers are fine, and it's this one mic. Look 2, his channel meter: flat, so the sound stops before the channel. Look 3, the pack: power light green and good batteries, but the mute switch is on. Fix: switch the pack's mute off and show him where the switch is. Had the receiver been your third look, its bars with no audio light would have pointed at the pack too.
Check yourself 3 of 3
The pastor's headset is silent. At the receiver the signal bars are full and the audio light flickers as he talks, but his channel meter is flat. Where do you look next?
The receiver's lights prove the pack, its batteries and the radio link all work: sound is arriving at the receiver. The flat meter says it stops before the channel. What sits between is the receiver's cable, the socket it's plugged into and the patch. The main and the speakers come after the channel, so they can't make its meter flat. Mute the channel, check the cable is in firmly at the right socket, then check the patch page.
Clean power, quiet system
- Power the desk and everything connected to it from the same distribution, away from lighting dimmers, heaters and urns.
- Power order: switch on the desk and sources first and the speakers last. Switch off in reverse, so the speakers never pop. Lesson 8 has the full order.
- Inverters: if your church runs on an inverter during power cuts, it must be a pure sine wave type. Cheaper modified sine wave inverters can make audio gear buzz and may harm some equipment. The label or the manual says which yours is.
- In a power cut: find out what powers the desk, the stage box and the speakers. If the inverter or battery backup feeds the desk but not the stage box, every channel goes silent when the power goes. Level 3 covers the changeover.
Safety Never remove or tape over a mains earth to cure hum. It can make the equipment deadly. Use a DI's ground lift or an isolation transformer on the audio line instead, and ask a qualified electrician to check any circuit you're unsure of.