Ceiling Microphone Lifter

1.) Install the mounting plate above the bottom of the finished ceiling so the ceiling bezel will be flush with the bottom surface. Use ½” nuts/bolts/washers. Attach to structural channel or other solid mounting surface. Be sure the plate is level: front-to-back and side-to-side.
2.) Remove the (2) release screws from the lower half of the Limit Switch Cone Assembly.
3.) Install the mounting plate using ½” hardware. Attach to structural channel or a solid mounting surface. Be sure the plate is level front-to-back and side-to-side.
4.) Add a plumb bob to the mounting plate at the indicator hole and hang the bob down to ceiling. This is the center point for the hole cutout location for the microphone assembly.
5.) Cut a 1.75” hole in the ceiling aligned with the plumb bob.
6.) Remove the (2) Release Screws of the lower Limit Switch Cone Assembly. Slide off over microphone cable / weight.
7.) Raise the lift to the mounting plate – insert the lugs into the key holes and slide to narrow side of key hole slot.
8.) Install the locking screws on the side and rear of the unit
9.) Place the ceiling clamp over the drilled hole and thread the microphone cable / mic / weight through the clamp and through the ceiling hole. Slide the microphone cable / mic / weight through the lower Limit Switch Cone Assembly. Now slide the lower-Limit Switch Cone Assembly up through the ceiling hole and ceiling clamp. Tighten the clamp screw to hold in place.
10.) Reinstall the (2) release screws that attach the lower Limit Switch Cone Assembly to the upper portion.
11.) Adjust the ceiling clamp to “sandwich” the ceiling material – tighten the lock down Phillips-head screw.
12.) Replace ceiling bezel – install four screws.

Ceiling Microphone

A ceiling microphone may seem like a perfect idea when it comes to designing a room that needs a microphone, such as a conference room. It may even seem like the only place to put a microphone because is won’t clutter the room, it stays out of sight, and it won’t spoil the overall design of the room itself. But experienced engineers that specialize in audio say that a microphone like this is the last thing you want to add to a room.

The reason you might ask? Well, because it is too far away from the source you want the microphone to pick up. It is also usually too close to undesired noises such as loudspeakers, air conditioning vents, or even buzzing lights. A microphone is sensitive when it comes to noise. It can pick anything up including moving air. A microphone on the ceiling is no exception to this, and cannot determine which sounds are desired and which are not. It will pick them all up.

There are alternatives to using ceiling microphones which will work much better instead. For example, a television anchor uses a microphone on their lapel. You can easily find alternatives to a ceiling mic to place in a room. You can always place a small microphone in the middle of a conference table which will not stick out or become an eye sore. You can also use sets of lapel microphone which shouldn’t bother anyone in using them. If you must use a microphone connected to the ceiling, try using one with a stand that will let it reach down to ear level so you can obtain the best sound quality possible.

JBL - ScreenArray

JBL quality and ScreenArray® performance in a two-way system. The new "next-generation"
Two-Way ScreenArray® speaker systems are now available. The Two-Way ScreenArray® Systems provide smooth and accurate reproduction of cinema soundtracks while being compact and very cost-effective.
Measuring less than 18" deep, each system features screen spreading compenstation and the latest advanced JBL technology. All models offer the low-distortion ScreenArray® horn for clear, accurate reproduction of the mid and high frequencies.

Source:http://www.jblpro.com/

Executive HD

The new Executive HD Wireless Microphone System provides the sound fidelity of wired microphones with the added appeal of a versatile wireless set-up. CD quality 50Hz-20kHz frequency response is a key reason for the improved audio performance. With an optimized speech codec, the new rack mountable Revolabs system handles live sound, voice reinforcement and wideband video- or audio- conferencing applications superbly.

The introduction of the Executive HD System is the latest example of Revolabs drive to deliver state-of-the-art wireless audio products. The audio quality of the HD Wireless Microphones is on par with wired microphones and they are ideal for almost any application.

The Executive HD Wireless System is available in 4 and 8 channel models. In the US, four Executive HD Systems can be linked together to support up to 32 HD Wireless Microphones in High Definition Mode. Five Executive HD Systems can be linked together to support up to 40 microphones in Maximum Density Mode, albeit without two-way audio. The HD System also has a reduced power mode which allows more Executive HD Systems to be used in a given area.

All Revolabs wireless microphones use 128-bit encryption, so no one can listen in. Rechargeable battery that provides up to eight hours of talk time after each full charge. The Executive HD Systems can use any combination of the HD Wireless Microphones.

All Revolabs HD Wireless Microphones include the RF Armor™ technology which enables the microphone to operate cleanly even when in direct contact with all wireless electronic devices known to cause unwanted audio interference, such as GSM mobile phones, smart phones, etc.

Source: http://www.revolabs.com/

Video Conferencing

Want a wireless microphone system that plugs directly into the video-conferencing station? Revolabs offers two options that plug directly into video-conferencing stations and give the meeting participants flexibility to move around the room and still be heard! The choice depends on how many wireless microphones you need.

One or two wireless microphones: The Revolabs HD Single Channel System has an analog input and output, and the Revolabs HD Dual Channel System has two of each, plus the ability to mix both outputs into one. The outputs can be set to line level for video-conferencing. All HD Wireless Microphones work with the HD Single and Dual Channel Systems and can be mix and matched, so you have your choice of wearable, tabletop, handheld or Countryman Earset microphones. The Revolabs HD Wireless Microphones can be placed up to 65 feet (20 meters) away from the Revolabs HD Single/Dual Channel System. For detailed instructions on how to configure specific video-conferencing equipment for Revolabs Wireless Microphone Systems, refer to the Technical Documents page.

Four or eight wireless microphones: Revolabs Fusion Wireless Microphone Solution includes all of the necessary cables to plug into any of the major video-conferencing solutions, including Lifesize, Polycom, Sony and Tandberg. It includes a remote control to control the sound volume in your conference room or in the conference room at the far end. Decide on where you want to put the Revolabs Fusion System, whether you want to place it vertically or horizontally, plug in the cables and you are ready to have great wireless audio on your video-conference! The Revolabs Fusion System provides four or eight wireless microphones. The Revolabs Wireless Microphones can be placed up to 65 feet (20 meters) away from the Revolabs Fusion Wireless Microphone System. For detailed instructions on how to configure specific video-conferencing equipment for Revolabs Wireless Microphone Systems.

Source: http://www.revolabs.com/

SPL - What's this mean for my hearing?

Sounds less than 75 dB have no significant effect on our hearing.

Exposure to sounds above 85 dB causes short term hearing losses called temporary threshold shifts. If this occurs, your ear becomes less sensitive, and sounds seem quieter than normal. After some time, normal hearing returns.

Repeated exposure to sounds that cause temporary threshold shifts results in permanent damage to the ear in the form of a permanent threshold shift . The ear loses sensitivity in the frequencies 3,000 Hz through 6,000 Hz, resulting in a "notch" in the hearing range. Time of exposure is important, the louder the sound, the less exposure time before permanent damage sets in.

According to OSHA, the exposure time limits are: (these are A-weighted, most home theater measurements are made with C weighting, which typically gives higer readings for broad spectrum measurements).

If you like to crank it on up during the "good parts" to really feel the action. Look at your results from the Peak SPL Calculator compared with the OSHA guidelines. Most moderate HT systems are capable of 102 to 107 dB peaks at a decent (10+ feet) listening position, at these peak levels the normal dialog is going to be at least 85-90dB, within the range where permanent hearing loss can occur.

SPL - How Loud is That?

Most home theater speakers and ampliers, even modest ones, are quite capable of producing sound pressure levels in excess of 100 dB. So how loud is that? For some analogies, check out this table:

Feedback Destroyer DSP 1100P

*20-bit A/D and D/A converters with 64/128 times oversampling for ultra-high headroom and resolution
*Automatically and “intelligently” searches out and destroys up to 12 frequencies per channel
*24 fully programmable Parametric Filters that can be set manually or via MIDI
*Set-and-forget* default setting enables immediate and super-easy Feedback Destroyer performance
*Single-Shot mode automatically searches and destroys feedback and locks the filter until you reset them manually
*Auto mode continuously monitors the mix, resetting programmed filters automatically
*Manual mode allows for setting up to 2 x 12 fully parametric filters including Frequency, Bandwidth and Gain
*Single-Shot, Auto and Manual modes are assignable for each filter
*Free FEEDBACK DESTROYER software allows for total remote control via PC (download at
www.behringer.de)
*Two software engines give you independent or coupled functions on left and right channels
*Internal 24-bit processing with professional 46 kHz sampling rate
*Servo-balanced Inputs and Outputs on gold-plated XLR and TRS Jack connectors for high signal integrity
*Full MIDI capability and user preset memories to store programs for instant recall
*Accurate eight-segment LED level meters simplify level setting for optimum performance
*Future-proof* software-upgradeable architecture
*High-quality components and exceptionally rugged construction ensures long life and durability
*Internal power supply design for professional applications
*Manufactured under the ISO9000 management system

Feedback Destroyer PRO FBQ2496

*Ultra-Fast 24-Bit/96 kHz Feedback Suppressor/Parametric EQ
*Automatically and "intelligently" locates and destroys up to 20 frequencies per channel
*Ultra-fast feedback detection (>0.2 sec) due to patented* FFT signal analysis
*Ultra-narrow notch-filters (up to 1/60th octave) for very effective feedback suppression, while keeping highest sonic quality
"Set-and-forget" default setting plus Panic button enable immediate and super-easy Feedback Destroyer performance
*Auto mode continuously monitors the mix, resetting programmed filters automatically
*Single-shot mode automatically detects and destroys feedback and locks the filter until you reset it manually
*Manual mode allows individual setting of up to 40 fully parametric filters with frequency, bandwidth and gain adjustment
*Ultra-high resolution 24-bit/96 kHz A/D and D/A converter powered by a 32-bit DSP for ultimate audio performance
*Open MIDI architecture for future software updates and flexible communication with digital equipment
*Balanced inputs and servo-balanced outputs with gold-plated XLR and ¼'' TRS connectors
*Internal switch-mode power supply for maximum flexibility (100 - 240 V~), noise-free audio,
*superior transient response plus lowest possible power consumption for energy savings
*High-quality components and exceptionally rugged construction ensure long life
*Conceived and designed by BEHRINGER Germany

Wireless Microphone Problems

ATTACK OF THE BLACKBERRY

We've all heard it — that angry buzzing sound whenever a BlackBerry gets close to a car stereo, computer speaker, or speaker-phone. In most situations, it's just annoying, but when the interference is picked up by the P.A. system during the CEO's speech, it's a big deal. Here's how it happens.

BlackBerrys, like all phones that use the GSM transmission standard, transmit on frequencies in either the 800 to 900 MHz or 1,800 to 1,900 MHz range, depending on the country and the carrier. They transmit data in RF energy bursts that are short but powerful. These bursts occur 217 times per second at power levels as high as 2 watts (depending on how far the phone is from the nearest cell tower). This 217 Hz “lightning bolt” can easily induce a ragged-sounding noise (the now-familiar “dit di-dit di-dit di-dit”) into most audio equipment. The noise can invade at almost any point — at inputs or outputs, through a cable, or directly into a component on the circuit board.

Most of the time, GSM interference occurs when the phone is within just a few feet of an audio device. Audio equipment manufacturers are quickly finding that protecting their products from GSM noise requires extensive design changes — not just the addition of a component or two at the connector. Until such protection is universal, AV technicians need to keep GSM phones away from unbalanced audio lines, including lavalier and headworn mics, hanging choir/ audience mics, and interconnect cables between equipment. The only instant sure-fire solution: Make presenters turn off their phones.

Digital Extras 
Learn about the science of radio waves, refer to a chart showing how the type of cable you use can cause signal loss at 200 MHz and 800 MHz, and get links to online scanner and frequency finders.

Wireless Microphone Problems

SETTING AND FORGETTING

PROBLEM: Probably the most frustrating problem with wireless is that the airwaves themselves keep changing. The list of analog and digital TV channel assignments has been changing regularly since the DTV transition began years ago. Rights to the UHF TV spectrum above channel 51 is in the process of being auctioned. Some of it (like channel 55) is already being used by the new owners, while the rest may remain unused until 2009.

As if that weren't enough, the FCC is trying to figure out a way to allow a new strain of consumer products (PDAs, smartphones, or home equipment) to use the unoccupied TV channels (also known as “white spaces”) to deliver wireless Internet access.

SOLUTION: It used to be enough to know whether your city had odd-numbered or even-numbered TV channels in the VHF band. Today, however, the people who set up and use wireless microphones (as well as in-ear monitors and intercom systems) need to regularly check local spectrum conditions, even when working at venues they know well.

Wireless Microphone Problems

WRONG OUTPUT LEVEL SET ON RECEIVER

PROBLEM: After so much discussion of frequency, wavelength, and antennas, it's easy to overlook the most fundamental requirement of a wireless microphone system: to replace the connecting cable between the source and the sound system as transparently as possible.The receiver will usually have an output level control, while most wired microphones do not. This provides the opportunity to more precisely match the output of the receiver to the input to which it is connected.

SOLUTION: Whether microphone level or line level, the output level should be set to the highest practical level while not exceeding the limits of the sound system input. This might be indicated by the peak light on a mixer input channel, or simply by listening for audible distortion.

Wireless Microphone Problems

UNADJUSTED TRANSMITTERS

PROBLEM: As good as it is, analog wireless audio transmission has limitations imposed by the inherent noise and limited dynamic range (about 50 dB) of FM transmission. To overcome this, most wireless microphone systems typically employ two kinds of audio processing to improve sound quality. Pre-emphasis is applied in the transmitter (with corresponding de-emphasis in the receiver) to improve the signal-to-noise ratio. A compressor in the transmitter and expander in the receiver can increase the dynamic range to more than 100 dB. This makes it important for audio levels to be set carefully. If the audio level is too low, hiss will be audible. If it's too high, distortion may result.

SOLUTION: To get the best sound quality, the transmitter's input gain should be adjusted so that the loudest sound level that will occur produces full modulation but not distortion.

Wireless Microphone Problems

NOT ENOUGH JUICE

PROBLEM: Despite the fact that transmitter battery life is a top concern with wireless mics, users continue to try and cut operating costs by using inexpensive batteries. Most wireless manufacturers specify alkaline or lithium single-use batteries because their output voltage is very stable over the life of the battery. This is important because most transmitters will exhibit audible distortion or signal dropouts when supplied with low voltage. Rechargeable batteries often seem like the ideal solution, but most rechargeables provide about 20 percent less voltage than a single-use battery — even when they are fully charged.

SOLUTION: To combat battery problems, carefully compare the transmitter's voltage requirements with the battery's output voltage over time to make sure that the battery will last through a full performance. Lithium-ion and rechargeable alkalines usually work well, while Ni-Mh and Ni-Cad batteries may last only a couple of hours. This issue is specific to 9-volt batteries; AA rechargeables offer similar performance to single-use AA batteries.

 

Wireless Microphone Problems

UNINTENTIONAL SIGNAL BLOCKAGE

PROBLEM: The human body can also interfere with wireless signals. Largely composed of water, our bodies absorb RF energy. In addition, if a user cups his or her hands around the external antenna on a handheld transmitter, its effective output can be reduced by 50 percent or more. Similarly, if the flexible antenna on a bodypack transmitter is coiled or folded, the signal suffers.

SOLUTION: Keep the transmitter antenna fully extended and unobstructed to achieve maximum range and performance.

Wireless Microphone Problems

NON-DIVERSE RECEIVER ANTENNAS

PROBLEM: Receiver antennas are one of the most misunderstood areas of wireless microphone operation. Mistakes in antenna selection, placement, or cabling can cause short range, dead spots in the performance area or low signal strength at the receiver that leads to frequent dropouts. Modern diversity receivers offer much better performance than single-antenna types, but the right antennas must still be put in the right place to maximize the performance and reliability of the system.

SOLUTION: To ensure good diversity performance, space antennas apart by at least one-half of a wavelength (about 9 inches at 700 MHz). The receiver antennas should be angled apart in a wide “V” configuration, which provides better pickup when the transmitter is moving around and being held at different angles.

If the receiver will be located away from the performance area (in an equipment closet or a closed rack, for example), ½-wave antennas or directional antennas should be remotely mounted (ideally above the audience) in order to have a clear line of sight to the transmitters. (Short ¼-wave antennas should never be remotely mounted, however, because they use the receiver chassis as a ground plane.) Extra distance between the antennas will not significantly improve diversity performance, but may allow better coverage of a large stage, church, or meeting room. If the antennas will be far from the stage, use directional antennas to improve reception by picking up more signal from that direction and less from other angles. If the antennas will be connected to the receiver with a length of coaxial cable, in-line antenna amplifiers may be required to overcome the inherent signal loss in the cable.

The amount of loss depends on the exact length and type of cable used, so follow the manufacturer's recommendations. Total net loss should be limited to no more than 5 dB.

Wireless Microphone Problems

OTHER DIGITAL DEVICES

PROBLEM: Other wireless audio devices that operate in the TV band — in-ear monitors, intercom systems, etc. — as well as non-wireless devices can also cause interference problems. Digital devices (CD players, computers, and digital audio processors) often emit strong RF noise and can cause interference if they are located within a few feet of the wireless microphone receiver. For transmitters, the most common sources of interference are GSM mobile phones and PDAs worn by presenters.  

SOLUTION: Be aware of other wireless audio equipment when selecting wireless microphones frequencies. Keep digital equipment at least a few feet away from wireless microphone receivers. Use an AM radio as a cheap RF noise detector; you might be surprised at what the gear in your rack is emitting. 

Wireless Microphone Problems

TV STATIONS

PROBLEM: Wireless microphones are also subject to interference from other sources transmitting in the same spectrum. The most significant culprits are typically TV stations. FCC rules require wireless microphone users to avoid frequencies in TV channels occupied by a broadcast TV station in the same geographic area.

SOLUTION: When indoors, avoid TV channels active within 40 to 50 miles. Outdoors, a 50- to 60-mile radius should be used. Because active channels vary from city to city, the appropriate frequencies for wireless microphone operation depend on location. Manufacturers usually offer guidance as to which frequencies to use in different cities.

According to FCC mandates, all analog TV stations will cease operations in February 2009. At the same time, the spectrum above TV channel 51 will be repurposed for use by new services. Wireless microphones operating above 698 MHz may need to be tuned to a lower frequency in order to avoid experiencing interference once new services become active. As the transition continues, the occupied TV channels in a given location may change, so it's wise to regularly check published information.

Wireless Microphone Problems

COMPATIBLE, BUT NOT QUITE ENOUGH

PROBLEM: There are different degrees of frequency compatibility. If you know exactly what the operating situation is, you might be able to be a bit more aggressive and squeeze a few more systems into the space. The key is understanding the trade-offs.

One important assumption that is made by most frequency compatibility software is that all receivers will be turned on and unmuted all the time (even though some transmitters will occasionally be turned off), making it important that none of the receivers is picking up an intermodulation signal that might be heard as noise.

Therefore, the software needs to leave ample space between the intermodulation signals and the wireless mics themselves.

If you assume that the sound system operator will take a more active role, however, you may find that more systems are actually compatible. In this scenario, it's assumed that the operator will mute any receiver that's not actually in use at the moment — and that all transmitters will be left on at all times during the show. The distance between each transmitter and the receiving antennas is also assumed to be similar. These assumptions would make sense in a Broadway theater installation; however, the same performance might not reasonably be expected in a school auditorium operated by volunteers with little or no training.

Interference symptoms are much worse when the transmitters are located very close to the receiving antennas or to each other — or when high-powered transmitters are being used. This is why it's much more difficult to get 40 wireless systems to work in a theater (many transmitters very close together at various distances from the receiver) than it is to get them to work in a school with one system in each classroom (transmitters far apart from each other but fairly close to its own receiver).

SOLUTION: To get a balance of high performance with the maximum number of systems, make sure that the level of compatibility between frequencies is appropriate to the expected use of the systems. Keep transmitters at least 10 feet from the receiver antennas. If the transmitter's RF output power is adjustable, use the lowest transmitter power that is necessary to cover the expected distance between the transmitter and receiver.

Wireless Microphone Problems

WE'VE ALL FELT IT — THAT UGLY, sinking feeling you get when a simple AV job mutates into an unpredictable nightmare. For many systems integrators and technicians, the addition of wireless microphones to the list of AV gear causes just such a reaction.

Getting wireless mics to work reliably sometimes seems to require equal parts rocket science and black magic. One day you can pull off a trouble-free show or presentation with dozens of wireless mics; on another, you can't even get one bodypack to behave for a two-hour sales meeting. That's why knowing how these devices work is so critical to make them work.

Let's take a closer look at 10 of the most common problems that seem to pop up in most wireless mic applications — and what you can do to avoid them.

INCOMPATIBILITY

PROBLEM: When using multiple wireless microphones, interference between the systems themselves always seems to crop up. Even if each system is on its own frequency and spaced several megahertz apart, the mics can still interfere with each other through a phenomenon called intermodulation distortion (IMD), which occurs because radio transmitters interact with each other to create intermodulation signals.

If there is not enough space (in megahertz) between these intermodulation signals and the operating frequencies of the units themselves, the receiver has a hard time picking up the signal from its transmitter. Typical symptoms include crosstalk between systems, frequent signal dropouts, poor range, or excessive noise and distortion.

The minimum separation between frequencies depends on the design of the system's receiver. An entry-level receiver may require a 1 MHz interval between the nearest adjacent system or intermodulation frequency. A more expensive receiver typically has a narrower tuning “window,” allowing for closer spacing between each system or intermodulation frequency.

SOLUTION: To avoid intermodulation distortion, select only frequencies that have been calculated to be compatible with each other. Because it requires knowledge of the design characteristics of the transmitter and receiver, the wireless system manufacturers provide these calculations.

For example, when just eight wireless microphones are used together, thousands of calculations must be performed to ensure compatibility. As a result, most manufacturers publish lists of compatible frequencies for their systems. In addition, software is available that can help identify compatible frequencies in some cases.