Wireless Mics New and Old Challenges Dana Taylor Mt. Vernon Senior High School
Wireless Mics New and Old Challenges Dana Taylor Mt. Vernon Senior High School Images Courtesy of
Wireless Mics Tools of Satan!
What we’ll cover… • Wireless mic techniques • Traditional problems • Terminology • Understanding and better using your mixing console • New challenges created by the transition to digital TV. • Using eSET to help with your teaching
Wireless Mics • Two types of wireless transmission • UHF (300 MHz and 3 GHz) • VHF (30 MHz to 300 MHz) • UHF for Mics… 300Mhz-806MHz • VHF for Mics….150MHz-300MHz
Wireless Mics“It is not enough to have the will to win, you must have the will to prepare to win.” Bob Knight 1. Create a mic plot when you cast the show. 2. Do mic tests at least one week before opening. 3. Gain structure does count 4. Everything you do early will minimize the number of things you have to do at final dress. 5. Set and record channel levels for each scene using a template of the console. 6. Make sure you have all needed supplies (batteries, tape, extra mics, etc.)
Wireless Mics • Types of wireless mics • Head worn AT892C Countryman E6
Wireless Mics • Types of wireless mics • Lapel/Lavalier AT MT830CWTH Shure WL93
Wireless Mics OminidirectionalCardioid
Wireless Mics • Types of wireless mics Lapel/Lavalier: Wearing the mic • Ear Rigs • Options: • 14 gauge wire, tape, copper wire, clothes hanger, floral wire, gaffer tape, Hellerman sleeves, surgical tubing, Prisma markers
Wireless Mics • Types of wireless mics Lapel/Lavalier • Clove Hitch
Wireless Mics • Types of wireless mics Lapel/Lavalier: Wearing the mic • Halo • Elastic string • Tie a clove hitch at the base of the mic and at an appropriate length along the cable to secure and fit to the actor. • Doesn’t work as well if actor has little hair
Wireless Mics • Types of wireless mics Lapel/Lavalier: Wearing the mic • Toupee/Wig Clip Method
Wireless Mics • Types of wireless mics Lapel/Lavalier: Wearing the mic In each of the preceding, the cable, elastic cord and even the mic can be colored with makeup, Prisma markers, or other non-permanent markers.
Wireless Mics • Where to put the transmitter? 1. Pouch at waist or under arm 2. Waist Band 3. Bra 4. Pocket of pants or coat (not the best) Hints: • Keep antenna straight • Avoid positions that can damage the transmitter • Keep transmitter dry (Baggies, un-lubricated condoms)
Wireless Mics • Where to put the cable? 1. Keep cable and antenna straight and don’t allow them to touch each other. 2. Attach at base of neck, between base of neck and mic and on the back. 3. Keep extra cable as straight as possible. If looping, do so gently. 4. Hold in place with surgical tape. 5. Prepare skin by using a astringent 6. Provide strain relief at connector
Wireless Mics What ever the method, the best one is the one that works best for you, your actors and the crew. The only rules are… • The mic should be positioned at a reasonable distance from the mouth • The mic is acceptably concealed • You are getting the sound you want
Wireless Mics Traditional Problems: 1. Dropout a. Multipath b. Line of sight Terminology… Dropout: Loss of transmission Multipath: Multiple reflections of the same signal Line of Sight: Unobstructed view between receiver and transmitter
Wireless Mics Traditional Problems: 2. Comb Filtering (phase incoherence) 3. Intermodulation Terminology… Comb Filtering: Phase incoherence produced by one sound hitting more than one mic at nearly the same time. Intermodulation: Result of multiple wireless systems creating “phantom” transmission frequencies
Wireless Mics • Combating multipath 1. minimize distance between transmitters and receivers. 2. Use a diversity system (you probably already do) 3. Change antenna type from ¼ wave to ½ wave or directional. 4. Keep line of sight clear 5. Think about blocking Terminology… Diversity: a receiver with two antennas 1/4 wave/1/2 wave: literally the length of the sound wave
Wireless Mics • Combating Comb Filtering 1. When two mics are near each other, turn the unused mic down…Especially during “love scenes” Terminology… Love Scenes: the icky parts where my daughter shuts her eyes. 3 to 1 Rule: for every 1 unit of distance from two mics, separate the mics by three times that distance
Wireless Mics • Combating Intermodulation 1. If using a complete system (all Shure, all AT, etc.) follow manufacturers guidelines for tuning. 2. If using a mixed system, use manufacturers software for frequency ID and compatibility or an intermodulation software program
Minimizing Interference • Make certain that the wireless frequencies are not on a local TV channel. • Check all wireless frequencies in use to make certain that no two systems are on the same frequency. • Check to make certain that no two wireless frequencies are too close together. In general, 1 MHz is the recommended minimum spacing between systems. • If a considerable number of systems will be used, operating conditions will be difficult or interference is likely, consider using more sophisticated equipment. Higher-performance systems are better able to reject interference. • Check the squelch control setting on the receiver. A higher squelch setting provides better protection against interference. However, since a high setting also can cause a reduction in operating range, set the control to the lowest position that reliably mutes the interference. • Make certain that all batteries are fresh and new. Weak batteries make a system more susceptible to interference. • Turn off unnecessary electronic equipment, especially computers, CD players, and other digital devices. These are a relatively common cause of wireless interference, especially if they are near the receiver. • If use of computers or digital devices is necessary, keep them at least 3 feet (1 meter) away from the wireless receiver and its antennas. • (From Audio Technica)
Increasing Success • Before you start, have a clear idea of what you want to do. Different applications may require different hardware - a body-pack transmitter as opposed to a handheld transmitter, for example. • Decide if your equipment is appropriate. If interference problems are likely or there will be many wireless systems present, more sophisticated wireless systems might be necessary. • Check to make certain that all necessary supplies and accessories are on hand, such as extra batteries, special microphones, audio cables, power strips, a spare microphone, remote antennas, RF cables, etc. • If using only one wireless system, make certain that its frequency is appropriate to avoid the TV channels operating in the area. • If several wireless systems will be used, special precautions and procedures might be necessary. • Prevention is, by far, the best solution to interference problems. • If there is any doubt about the condition of a battery, replace it. Use only high-quality alkaline batteries and make certain that used batteries are never mixed with new ones. • Take special effort to adjust audio levels properly, otherwise there is an increased risk of audio problems. Consult the user manual included with your wireless system for details. • Always thoroughly check out the wireless equipment - if possible, exactly where the system will be used - well before the actual performance or presentation. Pay particular attention to the possibility of acoustic feedback, interference, and audio level or sound quality problems. • If interference problems should happen to arise, try to take an orderly and systematic approach to finding a solution. (From Audio Technica)
Maximizing Range • For best range, a diversity wireless system should be used. Diversity systems almost always have much better range than similar non-diversity systems. • Make certain that there is an unobstructed line-of-site path between the receiver antennas and the transmitter. Metal objects between the transmitter and receiver, even screens or scaffolds, will usually greatly reduce range. Do not mount receivers behind other equipment, low to the ground, or in back rooms. • A high squelch setting can cause a reduction in operating range. If interference problems require a high squelch setting, eliminate the interference or change frequency to avoid the range loss. . • Keep all transmitters at least 10 feet (3 m) away from the receivers and their antennas. The transmitters can overload the receiver and reduce its sensitivity, as well as possibly cause interference. • Use only high-quality alkaline batteries for transmitters. Other types of batteries might have too low a voltage or inadequate capacity for the transmitter to achieve full power output. • With VHF body-pack transmitters, do not wrap the microphone cable around the transmitter body or bundle it within 18 inches (45 cm) of the audio connector. • For UHF body-pack transmitters, keep the microphone cable well away from the transmitter antenna. • Do not allow receiver antennas to touch each other. For best results, keep antennas from different receivers as far apart as possible. • Mount receiver antennas as high as feasible, if possible at least 8 to 10 feet (2.5 to 3 m) above the floor or stage. Keep antennas away from metal objects, including cables, pipes, cabinets, scaffolds and the supports for acoustic ceiling tile. Make certain that there is an unobstructed line-of-site path between the receiver antennas and the transmitter. • Make certain that wireless equipment is well maintained. After a long period of use, wireless receivers can lose sensitivity and the power from transmitters can drop. If range is not what it once was and there is no other obvious cause, consider having the system serviced. (From Audio Technica)
Wearing the Mic • Don't coil the microphone cable around the case of VHF body-pack transmitters. Don't coil or bundle the microphone cable. (Doing so could reduce operating range because the cable on some transmitters also functions as the antenna.) • On UHF body-pack transmitters, keep the microphone cable away from the antenna. • Don't bend the microphone cable sharply, especially at the microphone capsule or the connector. This can cause premature failure of the cable. For the same reason, try to avoid repeated flexing of the cable where it enters the connector or capsule. • For high-stress applications, fasten the microphone cable to clothing so that the repeated flexing is distributed over smooth loops near the middle of the cable. • When using clip-on microphones, position them reasonably close to the mouth. This is especially important in noisy surroundings or where feedback could become a problem. • In high-noise situations, consider using a headworn microphone instead of a clip-on microphone. Alternately, a handheld transmitter can be used if the hands do not need to be free. • Always make certain that a new, fresh alkaline battery is installed just before every important performance or presentation. Always have additional fresh batteries available. • When wearing a body-pack transmitter under clothing, make certain that it can be reached quickly to mute the microphone and replace the battery. • If the wireless user is likely to perspire heavily, it is advisable to wrap body-pack transmitters in clear kitchen food wrap, with the microphone cable opening pointed downwards. This will keep the transmitter relatively dry, avoiding performance problems and possible damage. After use, always unwrap transmitters and mics to let them fully air-dry.
It Don’t Work • Make certain that the transmitter battery is in good condition. • Make certain that the transmitter control switch is all the way to the "on" position and not still in the "standby" position. • Double-check that the wireless transmitter and receiver are on the same frequency. It is easy to accidentally mix up transmitters when more than one system of the same type are in use. • Turn on the receiver and make certain that its power indicator is illuminated. Also make certain that the antennas are installed and not touching each other or another object. • Turn the transmitter on and bring it to a position about 10 feet (3 m) from the receiver antennas. Observe the receiver "RF," "Tuner" or "RF Level" indicator and verify that it is illuminated. • If the receiver RF indicator is not on, try replacing the transmitter battery with a brand new, fresh alkaline battery. If the receiver RF indicator still does not illuminate, the system is most likely defective and should be serviced. • If you have another transmitter on the same frequency, try these tests again with the receiver. • If the RF indicator is on, try speaking loudly into the microphone while observing the "AF," "AF Peak" or "AF Level" indicator on the receiver. • Make certain that the receiver AF level control is set at maximum. • If the AF indicator still does not illuminate, and the transmitter is a body-pack unit with a plug-in microphone, make certain that the microphone connectors are undamaged and secure. • If the AF indicator still does not illuminate and the transmitter is a body-pack unit, the microphone could be defective. If a spare mic is available, substitute it for the original microphone and again speak loudly while observing the AF indicator. • If the transmitter is a handheld unit or there is still no audio indication with the test microphone connected, the system is most likely defective and should be serviced.
It Don’t Work • If the AF indicator does illuminate when speaking into the microphone, but there is no sound in the audio system, check the receiver audio with headphones (if the receiver has a headphone output). • If the headphone audio is working, or the audio cannot be tested with a headphone, try turning up the mixer or amplifier input control. • If there is still no audio in the system and your wireless is plugged into a mic-level input, try replacing the wireless with a wired microphone. If the wired microphone also does not work, the problem is not in the wireless system. • If the wired microphone does work, reconnect the wireless and retest. • If there is still no system audio, the wireless system is probably defective and should be serviced. • For body-pack systems: If the audio is intermittent or noisy when the wearer moves, the problem might be a bad microphone cable. Try a spare microphone or a working microphone from another wireless system. • If no spare microphone is available, try carefully and gently flexing the microphone cable where it enters the microphone capsule and at the connector. If the audio cuts in and out, or is noisy when the cable is flexed, the microphone cable probably is bad. • Bad batteries are a common cause of wireless problems. Always make certain to have fresh, new alkaline batteries on hand, and always check the transmitter battery first if there are problems with a system. • Ensure that the transmitter battery is secure and making good contact. • If the receiver audio is noisy, the problem might be interference.. • (From Audio Technica)
It Don’t Work/Scientific Method • Isolate problem: Is it on? • What could be wrong: Is it the mic, the receiver, the transmitter, the cable, the battery • Write down everything you do
Trusting the Teenager • In the Booth • Be certain that the script is clearly marked • Have two crew members at the board • Create a spreadsheet for cues which includes mics on and off as well as aural and visual cues • Rehearse the show without the actors • Train them for emergencies.
Trusting the Teenager • On the Stage • Have an additional audio person on the stage. They should have all equipment needed including: batteries, tape, additional cables, mics, transmitters (yeah, right)
Preshow Routine • 1 ½ hours: Replace all batteries and turn on all mics. Check with headphones the output of the mics • 1 hour: Mic check with actors • Remember, it will sound louder and brighter during sound check with no audience present • Leave mics on!
Mixing Desk • Standard Features • Channel Faders • Master Fader • Gain/Trim/Sensitivity/Head Amp • Sends/Returns • Monitor • Pan • Equalization (3 or 4 band) • Phantom Power • HiZ, LoZ inputs (Mic/Line) • Other (not always standard) Features • VCA/DCA • Mute Groups • On board effects
Mixing Desk • Standard Features • Channel Faders: control the overall output of an individual channel • Master Fader: control of the overall output of the board. • Gain/Trim/Sensitivity/Head Amp: Individual channel sensitivity control • Sends/Returns: route taken by audio signal • Monitor: stage or booth speakers • Pan: left, right center…pseudo stereo • Equalization (3 or 4 band): manipulation of frequencies • Phantom Power: additional power required to run condenser mics (48 volts) • HiZ, LoZ inputs (Mic/Line): Mics are usually LoZ, guitars, CD’s are HiZ • Other (not always standard) Features • VCA/DCA: Voltage control amps. Means of grouping channels • Mute Groups: Means of turning off groups of channels simultaneously • On board effects: built in sound effects (reverb, echo, etc.)
EqualizationHe who uses EQ least uses it best (Audio Proverb) • EQ out problems • Reduce frequencies to gain others: if you want more highs, reduce the lows. • Every time you increase a frequency, you increase the likelihood of further problems • There are no standard settings other than flat.
EqualizationHe who uses EQ least uses it best (Audio Proverb) • Almost all desks will have High, Mid and Low controls. (3 Band EQ) • Higher end desks will have High, High Mid, Low Mid and Low (4 Band EQ) • Some higher end desks will have Q (or width control) allows you to narrow or broaden effected range. • Additional EQ types are Parametric and Graphic.
EqualizationHe who uses EQ least uses it best (Audio Proverb)Graphic EQ
EqualizationHe who uses EQ least uses it best(AudioProverb)Parametric EQ
Increasing System OutputPotential Acoustic Gain • Minimize number of mics in use • Decrease distance from sound source to mic • Use zones for mics (turning off unused zones) • Examine scenic design and blocking Terminology… Number of mics: everytime you double the number of mics, you lose 3dB. Inverse Square Law: Doulbling the distance from the mic will cause a loss of 6dB, halving it will increase by 6dB
Wireless MicsGain Structure 1. Start with the channel fader at 0dB 2. Gain at 0 (all the way to the left) 3. EQ at 0 4. Press PFL or Solo and start talking, singing, yelling into the mic 5. Slowly bring up Gain control until the LED meter reaches a range of -3 to -6dB. 6. Repeat with the rest of the mics