Live Sound Basics

Main PA (FOH Speakers):

Point toward audience

Full-range or with separate subs

Often flown (hung) or on stands

Subwoofers:

Handle frequencies below 100Hz

Positioned on floor (coupling)

Provide physical impact

Stage Monitors (Wedges):

Angled speakers on stage floor

Let performers hear themselves

Each musician may have different mix

In-Ear Monitors (IEMs):

Earphones fed by wireless transmitter

Eliminate stage volume/bleed

Require separate monitor mix

Delay Speakers:

For large venues

Placed further back, time-aligned

Extend coverage area

Live mixer signal flow per channel:

Preamp/Gain → Set input level (-10 to +60dB)

HPF → High-pass filter removes rumble

EQ → Usually 3-4 band parametric

Dynamics → Compression/gate (if available)

Aux Sends → Monitor mixes, effects

Pan → Stereo position

Fader → Final level to main mix

Aux Sends Explained:

Pre-fader: Signal unaffected by fader (monitors)

Post-fader: Follows fader (effects sends)

Groups/Buses:

Combine multiple channels

Process drums as group, all vocals together

VCAs link faders without combining audio

Complete signal flow visualization showing the path from sources through stage box, FOH mixer, amplifiers, to main PA and monitors. Key positions: FOH (Front of House) controls the audience mix, MON engineer handles stage monitors, and backstage manages tech and power.

Microphone Positioning:

Keep mics behind main speakers (never in front)

Point rejection null toward monitors

Minimize mic-to-source distance

Use directional mics (cardioid, hypercardioid)

Monitor Positioning:

Angle monitors correctly toward performer

Position in mic's rejection zone

Maintain consistent distance

Volume Management:

Only as loud as necessary

Turn down unused channels

Mute between songs

Room Considerations:

Hard surfaces reflect more

Empty rooms feedback easier than full

Low ceilings problematic

Performer Habits:

Don't cup the mic (destroys polar pattern)

Consistent mic distance

Don't point mic at monitors

Ringing Out Monitors:

Process to identify and notch feedback frequencies:

Start with flat EQ on monitor send

Slowly raise gain until feedback begins

Identify frequency (by ear or analyzer)

Cut that frequency with narrow Q (around -3dB)

Raise gain again until next feedback

Repeat 3-6 times per monitor

Common Feedback Frequencies:

250Hz: Boxy, hollow tone

400Hz: Cardboard, nasal

1kHz: Honky, telephone

2-4kHz: Harsh, presence

8kHz+: Whistle, piercing

Tools:

Graphic EQ (31-band common)

Parametric EQ with narrow Q

Automatic feedback suppressors

Important: Ring out with the performer's mic technique—they should be present if possible.

Visualization showing the feedback loop mechanism (mic → amplifier → speaker → back to mic) and the correct monitor positioning to prevent feedback. Position the monitor in the mic's rejection zone, ensure performers don't cup the mic, and keep stage volume controlled.

Example Input List Format:

Ch	Source	Mic/DI	Stand	Notes
1	Kick In	Beta 52	Short	Inside shell
2	Kick Out	D112	Short	6" from head
3	Snare Top	SM57	Clip	1" from rim
4	Snare Bot	SM57	Clip	Phase flip
5	Hi-Hat	SM81	Boom
6	Rack Tom	e604	Clip
7	Floor Tom	e604	Clip
8	OH L	C414	Tall	XY pair
9	OH R	C414	Tall
10	Bass DI	Active DI	-	Post-EQ
11	Bass Amp	MD421	Short	4x10 cab
12	GTR L	SM57	Short
13	GTR R	e609	Hang
14	Keys L	DI	-	Stereo
15	Keys R	DI	-
16	Lead Vox	SM58	Tall	Wireless
17	BV 1	SM58	Tall
18	BV 2	SM58	Tall

Efficient Soundcheck Order:

Line Check (no playing)

- Verify all inputs work - Label channels - Set rough gains

Drums First

- Kick (check phase if two mics) - Snare (top then bottom, phase) - Toms, hi-hat - Overheads (check phase) - Full kit together

Bass

- DI and amp together - Check phase between them - With kick drum for pocket

Guitars/Keys

- One at a time - Check all sounds they'll use - Balance with rhythm section

Vocals

- Lead vocal against full band - Backing vocals

Monitors

- Each performer's needs - Ring out as needed

Full Song

- Play representative song - Check transitions/dynamics - Final balance tweaks

Example stage plot showing typical band positioning: drums at rear center, bass and keys on opposite sides, guitars at outer front, lead vocal center front with backing vocals flanking. Monitor wedges positioned for each performer. Color-coded legend shows instrument types.