Transcript BOOK 1: BASIC AUDIO SET-UP

BOOK 1:
BASIC AUDIO SET-UP
Mackie SR24-4
By Mark Langley
Olympia High School Performing Arts Center
March 08
ABOUT THIS MANUAL
BE AWARE: There are many different ways to set
up a system. The methods outlined here are
designed to be quick and simple. Sound techs with
more advanced skills may make different choices
based on specific needs or goals. Pick their
brains! The more methods you know, the better off
you will be.
ABOUT THIS MANUAL
What this manual will cover:
• How to connect a microphone using the Mackie 24/4 mixer and the
house PA system
• How to connect a “playback” device such as a computer, CD player,
iPod, etc.
• Basic troubleshooting
ABOUT THIS MANUAL
What this manual will NOT cover:
• Wireless mics
• Equalization
• Submasters
• How to mix
• Setting up monitor speakers
• Many other fine points of audio system set-up, equipment, and
operation.
While this manual is geared toward the beginner, it is
designed to supplement a hands-on training experience.
CAUTION
ALWAYS TURN DOWN VOLUME BEFORE CONNECTING AUDIO
EQUIPMENT. FAILURE TO DO SO MAY RESULT IN PAINFUL FEEDBACK
WHICH MAY DAMAGE HEARING AND EQUIPMENT
THERE ARE MANY ELECTRONIC FACTORS THAT MAY AFFECT HOW
EQUIPMENT WORKS. NOT ALL EQUIPMENT IS COMPATIBLE. MISUSE MAY
LEAD TO EQUIPMENT AND/OR HEARING DAMAGE.
AUDIO EQUIPMENT CAN BE DELICATE AND EXPENSIVE. PLEASE HANDLE
WITH CARE, AND IF YOU ARE NOT SURE OF SOMETHING, ASK.
BASIC TERMS (grossly simplified)
Signal - The electrical current produced by a device.
Input - 1: The place where a signal enters a piece of equipment; 2: The signal entering
a piece of equipment.
Output - 1: The place where a signal exits a piece of equipment; 2: The signal exiting a
piece of equipment.
Trim/Gain - Typically the amount a signal is amplified relative to its original intensity
expressed in Decibels (dB). The Mackie uses the term “trim,” but many companies and
texts use the term “gain.” They are interchangeable for our purposes. I will use trim in
this manual since that is what is printed on our console.
Fader - A slider that adjusts the signal intensity (volume).
Unity - A setting where the input voltage or intensity equals the output voltage or
intensity.
FOH - Front-of-house; areas in front of the stage, including the control booth, catwalks,
audience seating area, lobby, etc.
Snake - An audio cable consisting of multiple individual lines.
SIGNAL CHAIN: HOW DO WE MAKE IT WORK?
In sound reinforcement, the signal chain is made up of the parts of the
sound system a signal must go through in order to be heard clearly by an
audience. In it’s simplest form it is made up of 4 basic steps:
SOURCE
The origin of the signal. This could be a microphone, CD player,
computer, iPod, electric guitar, record player (what’s that?), cassette
deck, electronic keyboard, etc.
There are typically 2 types of signal sources categorized by the
strength of their output signals.
Mic level, as its name suggests, is typical for microphones. It is very
low voltage, around 2 millivolts (mV), or thousandths of a volt.
Line level, typically from most other sources, is a stronger, though
widely variable signal, typically from 77.5 mV to 24.5 volts
Distribution & Control:
Where the source signal is received, modified, and directed to the
desired output(s). The mixer is the primary tool here. This step may
also include effects processors, equalization, and a variety of other
signal modifications.
Happily, for the purposes of this manual, the final 2 steps
are not anything you will have to work with.
Amplification
The boosting of the signal to a speaker level strength, 24.5 volts or higher,
that can drive a speaker.
Output
In a word, speakers. Output could also end up on tape, CD, or other medium,
but our context, speakers is the most relevant.
The process of setting up an audio system is
merely connecting the links in the chain.
Channel Inputs 1
through 20 Your
source devices plug
in here. (mics, CDs,
FOH snake, etc.)
Only 16 and 17 are
pictured. Inputs 2124 are stereo inputs
that will be covered
in book 2 – Line
Level Devices.
Mono Main Out to
amplifiers. Must be
connected to work!
DO NOT ADJUST
OUTPUT LEVEL!
Power
WHAT’S IMPORTANT ON THE BACK OF THE CONSOLE?
Phantom
Power for
condenser
mics
Trim/Gain
control —
adjusts
incoming signal
strength
WHAT’S IMPORTANT ON THE FRONT OF THE CONSOLE?
Signal Meters
Power Light
Mute — turns off the
channel input signal
(on/off switch).
Output assignment
— directs the signal
to an output (in this
case the Main (L-R)
fader ).
Channel fader —
adjusts output level
(volume) of channel
signal.
Main (L/R)
Fader —acts as
master volume
control for all
faders
ON THE MAIN SOUND RACK IN THE CONTROL BOOTH
TURN THE SYSTEM ON
Push “SYSTEM
POWER” switch should be
lit on main audio rack in
control booth.
Main sound rack – control booth
SET THE SYSTEM MODE TO
“MANUAL”
Main sound rack – control booth
Manual mode indicator
System Mode switch
Push “System Mode”
switch so “Manual” indicator
light is lit.
IF YOU ARE USING THE MAIN SEATING AREA ONLY, NOT
THE TURNTABLES:
Push “TURNTABLE CONTROL”
buttons so the “LOCAL” indicator
lights are lit.
MAKING IT WORK
STEP 1: POWER ON & PRESET
Make sure all faders and Trim
settings are all the way down!!
(see pictures)
If something is accidentally turned
up the following step can create
horrendous noise and potentially
damage equipment.
TURN ON POWER (SEE PG. 6
FOR SWITCH LOCATION)
MAKING IT WORK
STEP 2: PATCH
Plug input device (source) into
desired channel on the back of the
mixer.
Note: If you have several devices, it
pays to plan out the channels ahead
of time to make operation logical.
Line level inputs here. (CD, DVD, PC,
MP3, etc.)
Line level devices generally have 1/4
inch phone plugs on them (example to
right).
Mic level inputs here. (microphones,
wireless receivers, etc.) Mic level
devices generally have XLR
connectors on them.
FOH snake
XLR cable
MAKING IT WORK
STEP 3: OUTPUT ASSIGNMENT
Assign channel to desired output by
pushing in the appropriate button (in
most cases this will be “L-R”)
MAKING IT WORK
STEP 4: SET FOR UNITY
Set MAIN FADER to “U” (unity gain)
IF you are setting a mic level inputset channel fader at “U”
IF you are setting a line level input
(for example, a CD player) - play device and
fade up to “U”; less if it gets too loud before
Unity.
MAKING IT WORK
STEP 5: SET TRIM LEVELS
IF you are setting a mic level input –
As someone is speaking into the mic,
GRADUALY turn up the trim until you hear a
ringing from the speakers. This is the
beginning of “feedback”. Back off the trim so
that a loud noise into the mic (cough, clap, or
“Pow!”) will not cause painful feedback.
IF you are setting a line level input
(for example, a CD player) –
Turn up the trim until you reach the desired
volume.
You may not need any trim boost at all. For
some recordings or devices you may not
even get to set the fader as high as Unity. For
other recordings, such as a poorly recorded
cassette or a computer with the audio output
turned low, you may need to set the trim quite
high.
Note: The gain on the right is
extraordinarily high for our theatre.
IT ISN’T WORKING! NOW WHAT?
DON’T PANIC; TROUBLESHOOT!
TROUBLESHOOTING
•
The following suggestions include the problems you are most likely to
encounter, and the questions you should ask when trying to isolate a
problem.
•
If you think you have done all of the previous steps correctly, your first step
should be to CHECK AGAIN! Most of the time it is operator error. Don’t
worry, it happens to everyone...frequently
CAUTION
TAKE THE CHANNEL FADER DOWN BEFORE PLUGGING,
UNPLUGGING, UNMUTING, OR SWITCHING ASSIGNMENTS
ON AND OFF. YOU MAY SUDDENLY FIX THE PROBLEM ONLY
TO DEAFEN EVERYONE AROUND WITH FEEDBACK.
IF YOU ARE WORKING AT THE MIXER
ASK THE FOLLOWING QUESTIONS
IS THERE SIGNAL
GETTING TO THE
CONSOLE FROM
THE SOURCE?
Check the input signal light with the trim up.
The green light above the “Mute” button
should blink if there is reasonable signal
level coming in. Turn up the trim gradually
to check.
Are your outputs assigned to L-R?
If YES (the light is
blinking), the
problem is in the
booth. Check the
easy stuff first
Is the main fader up?
Are you bringing up the correct channel
fader?
Is the channel muted?
IF YOU ANSWERED “YES” TO THE PREVIOUS
QUESTIONS, YOU’LL HAVE TO CHECK THE
MORE BASIC STUFF
IS THE SYSTEM TURNED ON AT THE MAIN RACK?
IS THE SYSTEM SET TO “MANUAL” MODE?
IS THE “MAIN OUT” ON THE SNAKE PLUGGED INTO
THE “MONO OUT” ON THE CONSOLE?
DID THE CONSOLE OUTPUT LEVEL GET TURNED
DOWN?
IF YOU ARE NOT GETTING SIGNAL TO THE
CONSOLE, (THE GREEN LIGHT WON’T BLINK)…
IF YOU ARE USING A CONDENSER MIC, IS PHANTOM
POWER ON?
ARE YOU ADJUSTING THE TRIM ON THE CORRECT
CHANNEL?
DID YOU PATCH THE CORRECT SNAKE INPUT?
DID YOU PATCH INTO THE CORRECT CHANNEL?
IF THINGS ARE STILL NOT WORKING, THE
PROBLEM IS MOST LIKELY BETWEEN THE
SOURCE AND THE CONSOLE
IS THE SOURCE
PLUGGED INTO THE
CORRECT INPUT?
Confirm the input # the source is plugged
into matches the input # going into the
channel. For example, you were told to
plug the mic into input 1, but plugged into
input 2 by accident.
IS THE CABLE BAD?
Try the device with a different cable
IS THE INPUT BAD?
Try the device and original cable in a
different input (making the necessary
change at the console, of course!)