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Copy of Introduction to Live Sound

Presentation for Sweetwater

Jeff Barnett

on 19 September 2015

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Transcript of Copy of Introduction to Live Sound

Introduction to Live Sound
Jeff Barnett
So you wanna be a sound guy / girl?
So - a funny thing happened one day at church...
Texas Playhouse Theater

Baylor University

...and a bunch of bands you've never heard of.
Started in 2001
do you love music?
did you ever take apart your toys when you were a kid?
do you want to help other people succeed?
Congratulations, you qualify!
be prepared!
work with performers, venue
assemble input list, stage layout
know how much power you will need and where you'll need it.
schedule load in, soundcheck, load out
have the right gear
wire racks in advance
Duties of a sound engineer
work with the musicians
get to know the director and band.
attend rehearsals and know the music!
be punctual
(that means be early.)
Duties of a sound engineer, continued
take care of the gear
set it up,
strike it,
transport it,
store it,
...like it's yours, even if it's not.
commit to excellence
Learn what a good mix is and practice!
Video operator
Lighting operator
Other duties
Stage Manager
Ticket taker
Public relations
Guitar tech
CD / Merch sales
Levels, connections, & cables
You ready?
Lets dig in...
Speaker signals
amplified signal from amp to speakers - highest voltage of all audio cables
always unbalanced
1/4 Inch TS
Dual Banana
Levels, connections, & cables
audio signals are quantified by:
whether they are balanced or unbalanced
their level (voltage)
the types of connectors commonly used
their impedance
Line level signals
interconnects between equipment
can be balanced or unbalanced
1/4 Inch TS
1/4 Inch
Instrument signals
primarily used by guitars
almost always unbalanced
1/4 Inch TS
Microphone signals
connect mics and DI boxes to preamps - lowest voltage of all audio signals
almost always balanced
Please note:
Connectors can give you clues about the signal level, but don't always tell you what the signal is.

In other words, just because you CAN plug something in, that doesn't mean it's a good idea.
The mixer
the most important thing to understand in the entire system!

fortunately, it's not as complicated as it looks...
Got it?
Moving on...
Direction of
signal flow
The master section
These are important!
A few thoughts on EQ
here's my process for most signals...
set / turn on high pass filter
listen in context of mix and soloed for problem frequencies
use the "add and subtract method" to find offensive frequencies
EQ is all about practice and listening
part art, part science
A few thoughts on EQ
Kick drum
listen for the big three
boom = 50-60 Hz
smack = 3 kHz - 5 kHz
click = 6 kHz - 8 kHz
watch out for mud - 200-500 Hz
use hpf to get rid of sub-sonics, rumble
Here's a starting point...
Lo: +6 dB at 60 Hz
Low mid: -9 dB at 500 Hz
High mid: +6dB at 3.5 kHz
High: +6 dB at 7 kHz
Let's take a tour, shall we?
A few thoughts on EQ
Voices / spoken word
use HPF to cut out everything below 80-120 Hz
ask yourself if that is how the person "really sounds"
turn EQ on and off to hear what you've done
cutting is better than boosting, but both are useful
A few thoughts on EQ
Vocals (singing)
use HPF to cut out everything below 60-120 Hz
pull out a low end to balance proximity effect
ask "is this how I want it to sound?", not "is it good?"
identify and reduce problem frequencies
"add and subtract"
how to get great sounds from your mics?
use the right mic for the source
place it / use it correctly
the secret I probably shouldn't tell you...
you don't need $100,000 worth of esoteric mics.
Directional characteristics
every mic has a polar pattern
Operating principles
dynamic (moving-coil) mics
standard choice for most live sound applications
most durable of all mic types
highest volume handling
most drums
guitar cabinets
any loud instrument that needs to be close-miked
Operating principles
condenser (capacitor) mics
typically most accurate, less coloration
tend to feed back more
require phantom power
drum overheads
acoustic instruments
some vocals
hand percussion
any acoustic instrument that benefits from distance miking
Using mics
close or distance miking?
close - almost always preferred
distance miking applications:
drum overheads
string sections
distance - when a full, natural sound can't be achieved with close miking.
beware feedback!
don't fight it - avoid it!
Avoiding feedback
can be full-blown (self-propagating) or partial (ringing)
mute any mics that aren't being used
place mics BEHIND the speakers
mic as close as possible
increase the distance between mics and speakers
decrease distance between speakers and audience
use the mic's polar pattern to your advantage
cardioid mic aimed away from monitor
hypercardioid mic aimed away from monitor
what if it happens anyway?
step one - kill it before it multiplies
train your ear to recognize ringing before it becomes full-blown feedback
if you're not sure where it's coming from, it's probably the last thing you touched
backing off the main fader just a few dB is usually enough to eliminate ringing
once you've isolated the source, EQ it out
eq is the last resort
Lots more...
digital signals
multipin connectors
cable types
how to wrap and store cables
So much more...
drum overheads
creating sonic space for each element with eq
eq as an effect
Plus how to mic:
guitar amps
3 to 1 rule
stereo miking
ribbon mics
boundary mics
piezo-electric transducers
Wireless mics
why wireless mics?
cleaner stage
allows us to place mics where we couldn't otherwise (lapels, headworn)
performers are free to roam
Wireless mics
why not?
typically 5X the price of a comparable wired mic
sound quality
a $1,000 wireless system still doesn't sound as good as a $25 cable
all the same same problems as wired mics plus a world of new ones
the FCC has LOTS to say about wireless mics
Wireless mics
basics of operation
one transmitter per receiver
just like the FM radio in your car
can be dynamic or condenser, any polar pattern
either handheld or beltpack transmitter
Sept. 15- Oct. 20
10:00am - 11:30am
6 week
Week 1 - Introduction
Week 2 - System Overview
Week 3 - The mixer
Week 4 - Signal processing
Week 5 - Putting it all together
Week 6 - Sound check!
fundamentals of sound
art vs. science
the job of the sound engineer
signal flow
sound system components
connections & cables
microphones & DI boxes

Hands-on: assemble a portable PA system
layout & common sections
signal flow
channel strip
inputs and outputs
digital vs. analog mixers

Hands-on: use analog and digital mixers to experiment with routing and EQ
compression / limiting
speaker processing
live recording

Hands-on: try each type of processing discussed and hear what it does to the signal
power up / down sequence
gain structure
mic technique for vocals, guitars, and drums
how to run a sound check
building a mix

Hands-on: Set up proper gain structure on our system, and mic up a band
Hands-on: using a recorded band, each participant will run a sound check and set up a mix on the VENUE console in Sweetwater's performance theatre
tip #1: don't cover up the antenna
tip #2: don't wrap the cable around the beltpack
Choosing a wireless mic
where am I?
not just now, but in the future
avoid interference from TV stations
how many channels will I need?
unless you want to replace it in a few years, buy for what you'll need in the future, not what you need now.
Choosing a wireless mic
features to look for
true diversity
more than one antenna
frequency agility
ability to change channels
remote-mountable antennas
The big
Line level source
connected directly
through DI boxes
What's a DI Box?
reduces the level and impedance of a signal to mic level
balances an unbalanced signal
to connect instrument or line-level gear to a mic input on a mixer
to make long cable runs possible
The mixer
back panel / jack field
digital mixers
built-in effects
mute groups
reverb / effects
speaker processing /
feedback suppression
system eq
line array
floor monitors
in-ear monitors
all speakers need an amplifier
takes line-level signals up to speaker level
one of the few things in a sound system that can hurt you!
high current
can overheat if used improperly
buy good ones, don't overload them, and you'll be fine.
wattage ratings are important, but don't choose an amp based on that alone
in essence, a speaker is a dynamic microphone in reverse
turns electrical current into acoustic vibration
multiple drivers dedicated to different frequency ranges - 2-way, 3-way, etc.
Passive speaker
most common type
requires an external amplifier
Active speaker
amplifier is built in to speaker
requires AC power
often has customized signal processing to make the speaker / amp combo sound as good as possible
less stuff to carry to the gig!
Line array
consists of multiple speakers arrayed vertically
more even volume from front to back of audience
better control over where the sound goes (and where it doesn't)
the problem
give them a dedicated mix, separate from the mains.
musicians need to hear themselves and each other, but are behind the main speakers
place a small speaker on the stage aimed at them
'nuther problem
what the musicians need to hear isn't the same as what the audience wants to hear
'nuther solution
new problem
speakers on the stage? won't that cause feedback?
new solution
in-ear monitors eliminate the chance of feedback from the monitors *
*...but come with a whole bunch of challenges of their own. no magic bullets here.
can be passive or active
Full transcript