Concourse Sound System Handbook

Handbook for the Operation
Of the Mix Wiz Sound System
At the AACTMAD Concourse Facility
The Mix Wiz system installed at the Concourse Hall consists of three parts
a) The console or the “mixer” position
b) The snake which is a bundle of wires running from the console to the speaker
module and is buried in a trough under the floor
c) The amplifier module which takes the signal from the mixer or console, amplifies the
signal and sends it to the speakers
The Mix Wiz Console
The mix wiz console is where the individual inputs to the audio system are mixed together into
a pleasant listening experience. Inputs include wired microphones, computers, MP3 players,
and wireless microphones. There are 16 inputs to the mix wiz, each handles ONLY one input.
These are views of the Allen and Heath Mix Wizard, also called the mixer or console. This is the
brains of the sound system and how you’ll get sound out of the system.
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The AFS 224, AntiFeedback Unit
The antifeedback unit detects feedback occurring in the main speakers (called the Front-OfHouse speakers) or the monitor speakers (the wedge shaped speakers on the stage that the
musicians listen to). The idea here is that if feedback is detected, these units determine the
frequency of the feedback and then cut it out using something called a notch filter. As currently
configured, the top AFS unit is used for the Font-Of-House speakers and the bottom AFS unit is
used for the monitors on stage for the musicians.
Front View of AFS 224, AntiFeedback Unit
Rear View of the AFS 224, AntiFeedback Unit
1/3rd Octave Band Graphic Level Equalizer, dBX 1231
The graphic equalizer is used to change the aural characteristic of the sound produced by the
FOH (Front-Of-House) speakers or monitor speakers. This is done to make the speakers sound
“better” for the music or sound being listened to or to eliminate sounds that are causing
feedback. You should adjust these levels only if you KNOW WHAT YOU ARE DOING. If you think
things aren’t sounding optimal, tell a sound tech and they will make adjustments.
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Front View Of dBX 1231 31-Band Graphic Level Equalizer
Rear View of dBX 1231 31-Band Graphic Level Equalizer
As currently configured, the top Equalizer is used for the FOH speakers and the bottom unit is
used to equalize the monitor speakers.
The Compressor/Limiter, dBX 166 XL
The compressor/limiter is a multifaceted unit that a) gates the sound so that the microphone
will “hear” sound after the level get above the turn-on level, b) attenuates the sound level if the
level gets above a threshold level (think about a quiet voice going through the unit without any
attenuation or compression, but a sudden loud noise would be reduced in volume to avoid
saturating the amplifiers), and c) provides a limit to the amount of sound that will be passed.
This limiter is set so that no damage can occur to either the speakers or the audience. The
166XL is a stereo unit, meaning there are two channels, each acting independently. One
channel is dedicated to the caller’s voice. The other channel is open. This is a specialized unit.
If you DON’T KNOW HOW TO USE IT, THEN DON’T USE IT.
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The Snake, The Bundle of Wires Running From the Stage To The
Console
The snake is the conduit that connects the sources of sound on the stage to the console and
then provides the amplifiers and speakers with the combined sounds that you hear from the
speakers. The snake consists of a stage head or box that is under the front part of the stage,
the “wire bundle” or snake running from the stage to the console along the room’s perimeter
and the fan-out or tails which connects to the rear of the MixWiz console. There is no reason
to disconnect the fan-out from the console. You will “plug-in” microphone cables in the stage
head.
For the most part, and at the Concourse in particular, all audio cables have a Canon connector
called an XLR. The XLR comes in two genders, a male and a female. The male connector has
three pins and the female connector has three sockets. The audio standard is that “sound”
flows out of a male connector and into a female connection. If you look at the stage head,
you’ll see 16 female sockets and 4 male plugs. Microphone cables, also abbreviated as XLRs,
also have the male/female pairing. The male end goes into the stage head sockets, 1 through
16. The female end of the cable then plugs into either a microphone or a DI which we’ll discuss
shortly. The four male plugs in the stage head are what we call “returns” and the speaker or
monitor signals come out of these. There is no reason to change the cabling in the returns. If
you think something is wrong, contact an audio technician.
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Stage Head, found under or on the stage
Snake Fanout, these are the male ends, note the channel numbers
on the white shrink tubing. The numbers for the Concourse Snake go
from 1 through 16. The male XLRs plug into the back of the MixWiz
console.
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Returns XLR Ends on the Snake Fanout. Notice the returns have RED
bands and the plugs are Female. The white shrink wrap also are
marked with numbers, for the Concourse, the numbers are 17 through
20
The Amplifiers, DriveRack, FOH Speakers and Monitors
Other than turning this unit on, you should not have to adjust anything in this rack.
The return signal from the MixWiz consists of a Left and Right signal for FOH speakers. Actually,
in the Concourse, the sound is not a stereo mix. Instead the “Left and Right” are really signals
and signal levels for the front fill speakers, i.e. the center cluster of speakers, and the side fill
speakers, the speakers on the left and right hand side of the stage. On the MixWiz console, you
can adjust the level for the center cluster and the side fills using the Left and Right Faders.
We’ll discuss these terms when talking about the operation of the system. The other two
Return Signals are for the on-stage monitors. These two signals go directly into a stereo
amplifier and from there to the wedge shaped monitors on the stage. Again, the amplifier is
pre-set and you should not mess with the settings unless YOU KNOW WHAT YOU ARE DOING.
Also in the “Amplifier Rack” is the dBX 260 DriveRack. This rack “massages” the FOH signal
from the console to set a graphic level equalizer for a pre-determined mix which optimizes the
sound from the speakers. It also sets the levels going to the speakers so the sound is balanced
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in the room. The only thing you need to do to the DriveRack is un-mute the speakers. The
reason for this is during turning on the system, an electrical spike can be generated which can
damage the speaker. In the operations section of this manual, an explanation for turning off
the mute will be provided.
Other than un-muting the speakers, DON’T MESS WITH THIS UNIT. IT REQUIRES A SPECIAL
MICROPHONE TO SET THE EQ AND KNOWLEDGE OF HOW TO PROGRAM THE RACK!
Front Panel of the dBX 260 Drive Rack. The Mute Switchs are on
the Right Hand Side of the Panel as are LED columns that indicate the
level of signal going to the speakers. The Center LED columns are to
indicate input levels.
A Rear View of the dBX 260 DriveRack. Note the 6 XLR output sockets
(i.e. they have male pins). The three female XLR sockets are the inputs
for the left and right signal from the MixWiz console and an input for an
RTA (Real Time Analyzer microphone). Do Not Mess With The Cables
plugged into these sockets.
The Front-of-House speakers are RCF’s ART 312-A speakers. They are self-powered and have a
12 inch woofer (the main, or big speaker) and a 1” constant directivity horn for higher
frequencies. The sound dispersion is 900 horizontally and 600 vertically. Two of the speakers
are mounted as a center cluster and two are mounted at either end of the stage as side-fill
speakers. The amps in the speakers are set at 3/4ths of full volume. Speaker volume is
controlled at the mixing console.
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Front and Back View of the RCF ART 312-A Front-of-House Speakers
The monitors are either CGM or Horizon wedge monitors. They are used by the band to hear
themselves. The monitors have a 12” woofer and a 1” horn. They are not self powered and use
an amplifier to drive them. The small podium sound system does not work with the monitors.
Only the MixWiz console can supply a signal for them. The signal for the monitors are from the
AUX 1 and 2 outputs on the MixWiz. Aux’s 1 and 2 feed the lower AFS 224 Anti-Feedback unit
and the lower 1231 Graphic Level Equalizer. From the mixing console the monitor signals go
down the snake and are fed directly to the amplifier. Speaker cables go from the amp, a QSC
2402, to the monitors.
The speaker cables have “Speakon” connectors on their ends. These are twist and lock type
connectors. If you will be using the monitors, have an audio tech demonstrate how to use
these cables. Once you’ve seen them demonstrated you won’t have any trouble using them.
They do LOCK into the amp and monitor sockets so trying to just pull the cables free like you
can do with ¼” speaker cables will result with a badly damaged monitor or amp. Get a
demonstration on how to use the cables and this won’t be an issue.
The QSC amps are set at half power which will provide enough speaker sound for most
applications at the Concourse. If you feel you will need additional sound, ask a sound tech to
make the adjustments. The Concourse is acoustically live enough that too much monitor sound
on stage will severely impact the sound in the hall. The level of sound at the monitors is
controlled at the MIXWiz console. Get input from the musicians when adjusting these levels.
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Front and Rear Views of the PLX 3402. The Concourse Amplifiers Are
the PLX 2402 Which Are Similar In Appearance But Don’t Provide As
Much Speaker Power
The switches in the rear of the amplifier are adjusted so that the QSC amplifiers work as two
separate amplifiers. Do Not mess with the DIP switches on the rear of the amp.
Microphones and DI’s
The Concourse Hall has SM-58 and SM-57 microphones and passive Direct Input boxes. The
SM-58 and SM-57 microphones are called dynamic microphones. A sound wave striking the
diaphragm of the microphone is converted into a current by causing the diaphragm (a very thin
metallic plate to vibrate in a magnetic field from a magnet fixed in the microphone. As you
might guess, the current level is very tiny. A microphone that you might see is a condenser
microphone. Here the sound wave is turned into a current by changing the distance between
two plates in the microphone, making the microphone into a variable capacitor. Unlike the
dynamic microphones, an external voltage must be provided to the microphone to get it to
work. This power or voltage source is called phantom power. If you look at the top edge of the
MixWiz mixing console, you will see a button called +48 V. Pushing the button in, will cause a
red light to be illuminated indicating that a voltage is being supplied to that circuit. If a
musician supplies you with a microphone, ask if it is a condenser microphone. If they say yes,
you’ll need to provide phantom power. Always mute the channel that has phantom power
before plugging the microphone in or out.
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SM-57 Microphone
SM-58 Microphone
Some instruments have their microphone or “pick-up” installed in the instrument. These pickups differ from a microphone by having a different output resistance. You can tell immediately
that you have a high impedance device (i.e. a pick-up in the instrument) if the cable having the
signal is a ¼” mono cable. For example, look at an electric guitar and notice the cable the
musician plugs into the guitar. You need to plug this cable into a DI or Direct Box before
sending the signal to the console. The output of the DI is the standard XLR cable. Once the
instrument is plugged into a DI, you can treat the channel as if it is just a microphone. Electric
keyboards will require a DI. If in doubt about what to do, ask the musician. They have probably
plugged into a mixer and can help you get them connected.
DI – Top View
DI – Input Side View
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DI – Output Side View
Notice on the INPUT SIDE View picture of the DI. On the right hand side there is a switch that
says Ground Lift. When connecting instruments to the MixWiz mixing console, you can get a
condition known as Ground Looping. You’ll know it because you’ll hear a buzzing in the
speakers. Lifting the ground often takes care of the problem and the buzz will disappear.
Below are some pictures showing a ¼” instrument cable, also called a ¼” mono cable, and a ¼”
stereo cable, also called a TRS. Notice that on the mono cable there is a tip on the plug and the
sleeve and they are separated by a piece of non-conducting material. On the TRS (for tip, ring,
sleeve) view you see the tip, a piece of non-conducting material, a ring, another piece of nonconducting material, and finally the sleeve. When plugging into a DI from an instrument, you
want to use the ¼”mono plug.
¼” Mono or Instrument
Cable
¼” Stereo or TRS Cable.
Also known As A Balanced Cable
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Operating the Concourse Hall Audio System
The audio system at the Concourse Hall will eventually have two audio systems. There will be a
“small” system for with inputs for a microphone and an MP3, CD player, etc. which will be used
when the hall is rented to outside events. The larger system is the MixWiz system which has
been described earlier. This “how to” manual will concentrate on using the MixWiz system.
The first thing you do when you want to use the system is to turn on the console. There is a
Power Conditioner rack just below the mixer console. On the right hand side there is a switch.
Turn it on and the pieces of the rack will light up. If nothing happens, check to see that the rack
is plugged in.
After turning on the console rack, go to the AMP rack. There is another power conditioner unit
in the top of the amp case. Turn it on. The front screen of the DriveRack will light up. On top
of the amp case there should be a white power strip. Turn it on. You have now turned on the
DriveRack and the Front-of-House speakers. On the front face of the DriveRack there are 6 LED
columns and at the bottom of these LED strip are buttons that say MUTE. The buttons should
be glowing red. Push each button and the red light should go off. The speakers are now getting
an audio signal.
Go back to the console and plug a microphone or other sound source into a channel. Make
noise. You should hear it from the FOH Speakers.
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