Transcript
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.
Page 1
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.
Page 2
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. Page 3
Picture Not Available
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.
Page 4
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.
Page 5
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 Page 6
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. Page 7
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. Page 8
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.
Page 9
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 Page 10
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
Page 11
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.
Page 12
