Wireless microphones are quickly becoming more popular with their usage now expanding beyond TV broadcasts into multiple other areas.

The microphones industry of India in 2009-2010 has been estimated to be in the vicinity of Rs. 90-Rs. 100 crore, with broadcast mics constituting Rs. 25 crore.

2009-10 saw slower sales than last year. With major requirements for the Commonwealth Games (albeit mostly for rentals), and increasing popularity of TV programs such as Big Boss, 2010-2011 promises to be a better year for the microphone industry.

These include dynamic, condenser and ribbon microphones. Dynamic mics are dominant with 60 to 70 percent market share, whereas ribbon mics are barely at 2 to 3 percent, leaving condenser mics (which are considered to be premium and very sensitive) to hold the remaining 30 to 40 percent.

The major market players of this segment in India are Shure, Sennheiser (and Neumann), and AKG by Harman Microphones. Other brands maintaining some presence are Sanken, Coles, Beyerdynamics, Audio Technica, DPA, and Sony. The Rode brand is a leader in radio mics, alongwith a small presence of ElectroVoice. In addition, some Chinese brands, with very aggressive pricing, are also finding limited success.

Wireless microphones are quickly becoming more popular with their usage now expanding beyond TV broadcasts into multiple other areas such as radio broadcasts, live theatre, and other live events such as political and business conventions, and music concert tours.

Major Players in India

Shure Communications is one of the leading manufacturers of wireless microphones and has emerged as one of the leaders in the US and throughout the world in the fight to protect the spectrum for wireless microphones. In India the microphones are marketed by Sun Infonet Private Limited. The company is finding major success with its PG27USB and PG42USB condenser USB mics.

At IBC, Amsterdam, Sennheiser has scheduled the launch of its MKH 800 TWIN. Sound engineers in broadcasting, studio recording, film scoring and location/mobile recording can now also benefit from the advantages of the MKH 800 TWIN, dual-capsule microphone in a fully digital environment. A special adaptor cable is now available to connect the TWIN with the AES42 digital module of the MKH 8000 series.

AKG by Harman has created a full spectrum of studio, broadcast and recording microphones with components designed specifically for the most demanding instrument and vocal performance situations. In India the microphones have been used by several leading recording and broadcast studios, C&S channels (both regional and national) and other pro audio segments like musicians, tour sound/ sound rental companies.

Sanken is one of the oldest professional microphone manufacturers, established in Japan in 1925. Its Lavalier microphones for live broadcasting, location recording and studio applications, and CU range of capsule condenser microphones for professional recording are extremely popular. AGIV (India) Pvt. Limited is the exclusive authorized distributor in India.

Coles Electroacoustics has manufactured the superb BBC-designed ribbon microphones in the UK for over 30 years. Originally designed for radio and television broadcast, Coles ribbon mics have become one of the primary tools of choice throughout the sound recording industry. In India, Coles is marketed by Deepjyot Electronics, their sales and service distributor for the Asian region. In 2009-10, the company was awarded orders by Doordarshan and Zoom Communications.

Dynamic Microphones

Judging by their numbers, dynamic microphones are the most popular type of microphone, and for good reason: they are cheap and very robust. The most recognizable brand is Shure dynamic microphones

The dynamic microphone functions like a speaker in reverse. Imagine the speaker cone as the diaphragm and the attached coil is within the magnetic housing. Instead of an alternating current being supplied to cause a magnetic field that attracts and repels the cone, the diaphragm acts as a generator of alternating current but at a much lower power level than that necessary to power a speaker.

The dynamic microphone has also gained popularity because it requires no external power supply (the energy comes from the movement of air) and it is virtually immune to distortion, making it a convenient and reliable tool.

The downsides of dynamic microphones. Dynamic microphones have two downsides: their poor high frequency response, and a low output level. The former is caused by the relatively large mass of the diaphragm with its attached coil, along with the effects of magnetic damping. The latter is due to the small current that is produced.

These faults of a dynamic microphone dictate its usage considerably. It can only be effectively used in situations where its typical upper limit of 15khz frequency response doesn't matter e.g. the human voice doesn't go up to 20khz (which is considered the maximum limit of human hearing), and within close proximity to the sound source.

Popular uses of dynamic mics. Dynamic microphones are used frequently as radio microphones because they don't require any power, so the batteries are used just for the transmitter. These can be headset microphones or handheld microphones.

They can also be used as video microphones when plugged into the external microphone input of the camera, during an interview for instance, either in the form of clip microphones (sometimes called lapel microphones or lavalier microphones), handheld microphones, or as desktop mics.

Condenser Microphones.

Condenser microphones (or Capacitor) are generally considered to be of the highest quality and are used as recording microphones in recording studios and in the television industry where a wide frequency response, high sensitivity, and high electrical output are all required.

The wide frequency response is needed to record all instruments and natural sounds that the human ear can perceive; the high sensitivity allows a wide dynamic range to be recorded (the quiet to loud sounds); and the high electrical output avoids having to add more gain in the audio mixer, which would result in unwanted audible hiss.

The diaphragms used in condenser mics are not very robust and need careful handling. Therefore, normally they don't get used in a live situation except when a wide frequency response is needed.

Condenser microphones used to be considered too delicate to use in a live pop/rock concert situation, however new manufacturing techniques and new manufacturers have enabled them to become cheaper and more rugged.

Condenser microphones require a power source. Most modern day condenser microphones (non-valve) get their power from a three pin XLR plug that sends the signal from the microphone to the mixer. The so called Phantom power is supplied by the mixer and does not affect the audio signal going in the opposite direction.

A power source is needed to supply a polarizing voltage between a fixed plate and the diaphragm, the movement of the diaphragm with respect to the plate creates a change in capacitance, this signal goes to the pre-amplifier which is incorporated into the body of the microphone, and that requires power as well.

Large or small diaphragm condenser microphones. Historically, condenser microphones had large diaphragms of about one inch in diameter. Strictly speaking, these are more prone to resonance at some frequencies i.e. they tend to boost lower mid frequencies. These microphones are appreciated for their capability to warm up vocals.

The smaller diaphragm microphones that were introduced in the 1960s are used where a more faithful i.e. level frequency response is required.

Particularly with vocal recording, there are no absolute rights or wrongs in microphone choice. Different microphones should be auditioned for each singer to achieve the desired sound.

The longest established condenser microphone manufacturers include Neumann microphones (e.g. U87), AKG microphones (e.g. C414) and Sennheiser microphones (e.g. 416).

Ribbon Microphones

Many of the properties of ribbon microphones are similar to those of condenser microphones, except for their high electrical output (so they generally are not used as ambient microphones positioned far away from the sound source), and also because they are less robust.

The ribbon microphone consists of a very lightweight, metal foil diaphragm suspended in a high powered horse shoe shaped magnet (which is actually powerful enough to erase an audio tape when left in close proximity). The movement of the foil acts much like a dynamic microphone diaphragm and generates a low level alternating electrical current. The metal foil is very delicate and constantly requires an excellent integral windshield to prevent the foil from literally being blown away or deformed.

The pickup pattern of ribbon microphones is always figure of eight which makes them useful for ignoring sound sources to their sides. They make good audience microphones since they can be placed next to P.A. speakers, which they won't pick up very well, but the audience's laughter and applause will still be recorded well.

The tone of ribbon microphones. Ribbon microphones have always been appreciated by certain recorders for their natural tone and they are currently experiencing a revived interest, however their fragile nature means they tend to be used only in a recording studio.

Ribbon mics have high impedance as well, so it is necessary to ensure that a microphone preamplifier can handle such impedances to avoid losing bass response. It is also wise to switch off any phantom power on a ribbon microphone channel since it can cause loud noises when patching on a jackfield or potentially damage the ribbon.

The frequency response of ribbon microphones gently rolls off at higher frequencies along a similar curve to that of human hearing so they are considered to have a pleasant warm sound.

Nowadays the main manufacturers of ribbon microphones are Coles, Royer, Audio Engineering Associates (AEA) and Beyer Dynamic.

Technology advancements

Digital Microphones

Recent advances in technology have enabled microphone manufacturers to incorporate the analog to digital converter into the microphone itself. The advantage of this is that there is no quality loss due to impedance and induced distortion artifacts. It can operate on standard 75 ohm XLR cables up to 100 metres and up to 400 metres on 110 ohm (AES 3) cable.

An added benefit of this system is that it is possible to remotely control all the functions of the microphone from the mixer or recorder. Additionally, information such as the microphone's manufacturer, model, serial number, software version installed and a list of control functions are displayed. Also the sound source can be named for that microphone.

The technology that supports this remote control is the AES 42 protocol. This is an agreed standard, approved by the Audio Engineering Society, which any manufacturer of digital microphones is required to conform to.

The digital microphone has a three pin XLR connector. However, unlike an analog microphone this connector handles a bi-directional signal (AES 42) which takes a balanced audio feed from the microphone and supplies phantom power, the remote control data stream, and a synchronizing signal from the master clock to the microphone. Unlike analog systems, digital systems require a master clock to keep all the packets of digital information in the correct sequence.

Mode 1 and Mode 2 operation

AES 42 has two modes of synchronizing digital microphones with the controller.

Mode 1 operates asynchronously, i.e. the microphone generates its own internal clock and a sample rate converter in the controller matches the sample rates and timing of each microphone's signals.

In Mode 2 the controller sends timing (frequency and phase) information to each microphone to control the internal quartz oscillator in each microphone.

Mode 2 is the preferred option since mode 1 can impair the signal quality in terms of dynamic range and latency times.

Currently there are only a few manufacturers making digital microphones using AES 42 technology, these include Neumann with their KM-D range and Schoeps with their Colette range.

USB Microphones

Although technically these are digital microphones, they are not as versatile as AES42 types and some care needs to be taken with their gain structure (particularly those with 16 bit convertors) to avoid hiss and distortion. Gain has to be set at the microphone itself and the signal cannot travel very long distances without employing USB powered hubs to amplify the signal.

However, they are a compact and lightweight solution for transmitting audio into a computer since they do not require a separate pre-amplifier and analog to digital convertor.

When using many microphones, a mixer (analog or digital) is ideal because it avoids the issue of running out of the necessary number of USB ports.

Examples of USB microphones are Audio Technica's AT2020-USB, Rode's Podcaster and Samson's G Track SA-GM1U.

Also in this category is the HHB DRM 85 which has a built-in Flash Ram recorder that can be connected to the DAW (Digital Audio Workstation), after recording, is finished, for editing.

Frequency and the future

A major issue confronting the industry is that multiple government ad¬?ministrations throughout Asia, includ¬?ing Singapore, Australia, New Zealand, the Asia-Pacific Telecommunity and others, are currently taking into account the frequencies used for wireless microphone transmis¬?sion in their review of what spectrum could be taken over for rapidly expand¬?ing wireless data and voice services use.

Wireless microphone transmission typically has received relatively little attention for a variety of reasons. Since they have really only been widely used for a decade or two, and often oper¬?ate on an unlicensed basis, they have largely operated under the radar.

However, a big event like the Commonwealth Games might well require more than 50 separate wireless microphones transmission channels, each capable of handling multiple microphones, just to link on-field an¬?nouncers to the transmission trucks. As each channel is at least 200kHz, and sometimes as much as 6OOkHz, this adds up to a lot of spectrum.

In many cases, that spectrum is the so-called white spaces-portions of the UHF TV band that are not currently being used for actual TV broadcasts. As wireless microphone transmissions may travel as little as 100m, their operation on those bands causes no appreciable interference to other TV broadcasters. However, following the DTV tran¬?sition, most Asian governments are looking at ways to convert the digital dividend of freed-up TV spectrum, including the white spaces, for other uses.

Transducer technology has certainly come a long way over the past several decades, with more transparent mics, handling greater dynamic range than in the past, including a number of quality options at ever more popular price points. But have we achieved perfection? Likely not.

Transducers are indeed better than ever, be the elements ribbons, conventional dynamic designs or condenser mics. The internal electronics of modern mics have benefited from technical progress (while at the same time, many chase the allure of the legendary mics of old with approaches like incorporating NOS tube preamp stages). The performance obtainable by today's microphones is light years beyond that of the original crystal mics. That said, the capture capabilities of microphones are not the same as our ears. And then there's the fact that we judge the performance of microphones through yet another set of transducers–loudspeakers of various ilk and headphones. Arguably, speaker technology (though, again, better than ever) is less advanced than microphone technology, yet that stage of the reproduction chain can hardly be avoided until we all get USB7-to-brain implants in our heads.