WIRELESS MICROPHONES
Posted on Fri 12 August 2011 in entries
This is a feature taken from Issue 7 of our brochure, written by Rob Speight...
Having spent the last 23 years honing his sound engineering skills, Rob is MD of Outpost Sound offering recording, mixing, post-production and sound design services to music professionals.
GOING WIRELESS
Engineer and recording expert Rob Speight delves deep into the whys and wherefores of wireless microphones…
From Beyoncé and Take That to West End stage shows, over-enthusiastic preachers and Tom Cruise-style public speakers (think Magnolia), the wireless microphone is a must-have in many a situation where trailing cables just won’t do. I mean, can you imagine the lead actress in Les Mis suddenly stumbling over a wire in the middle of the heart-rending Castle On A Cloud?! A wireless microphone will definitely give you greater flexibility of movement but get it wrong and you could land yourself with a whole lot of problems.
However, if you take time to work out exactly what you need and have some sort of idea of the environment in which you are likely to be using your new wireless microphone, then the whole process can be very liberating...
HEAD OR HAND
If you are in an energetic dance band or you’re involved with putting on stage shows, then a headset microphone may be the way forward. If, however, you just want the freedom to run all over the stage and not worry about getting tangled in a mass of cables, a handheld may be the right option.
If foldback is an issue then you could consider in-ear monitors, which also run wirelessly. Of course, you can make pretty much anything wireless with the right piece of kit, including guitars, keyboards and even brass, but make sure you know what you need and why you need it before you go shopping!
FREAKY FREQUENCIES
The most important things to consider when buying a radio solution of any kind are frequency range and agility. At present the UK is undergoing digital switchover. You can read more about this in the information box below ('About That Switchover Thing'), but essentially a lot of our analogue frequencies are being reallocated, as analogue television and eventually radio broadcasts get switched off.
The problem is that in amongst those frequencies are the channels commonly used for radio mics and talkback systems. So, when buying a new system, make sure that it will work legally now and after the digital switchover is complete in 2012. Luckily, most wireless mic manufacturers are now labelling their wireless systems as '2012-ready' or 'switchover-friendly', but if you need any advice, give our sales team a call on 01202 597180 (or use our online Live Chat service) to talk through your options.
CROSSING THE CHANNELS
At the moment, most ‘old-school’ wireless systems operate on channels 68 and 69 (requiring a license) and 70 (de-regulated). From 2012 the frequency range from 790 to 862MHz (covering Channels 68 and 69) will be switched off. If you’re using channel 70, you’ll be fine as this is already free to use and will continue to be so after the switchover. This is fine for small set-ups but if you’re running multiple systems or you’re on 68 and 69, it’s time for a change!
Channel 68 and 69 users are being advised to change to equipment suitable for use on Channel 38 (606 to 614MHz). This is currently used by radio astronomy boffins, but they’ll be kicked off by the end of 2011. As Channels 37 and 39 are still being used for analogue TV in some parts of the country, channel 38 won’t be available nationwide until late in 2011.
GO FOR GIGAHERTZ
Another option is to use a wireless system that transmits in the 2.4GHz frequency band. This band is also deregulated (so you don’t need a licence) and hence it is often used for other devices such as cordless phones and wireless computer networks.
'That's a lot of traffic' you might think and you’re right! However, systems such as the Line 6 XD-V30 digital wireless mic system (available in handheld or lavalier versions for the same price) use proprietary processing and encoding to ensure crystal clear, interference-free transmission up to 100 feet.
Unlike analogue systems, digital wireless mics have the advantage of not featuring a compander (which essentially is a compressor on the transmitter and an expander on the receiver) meaning that your audio will have been through much less processing by the time it reaches your mixing console. Nevertheless, you must bear in mind that digital systems need time (albeit it microseconds) to do the analogue-to-digital and digital-to-analogue sampling before and after the audio is transmitted and this introduces latency. This in itself is not necessarily a problem as the time delay introduced on a Line 6 system, for example, is less than four milliseconds. However, if you start then putting the signal into a digital desk, doing some digital processing then sending it out via a digital snake to digital amplifiers… well, that latency will soon add up!
IT TAKES TWO
Of course, the wireless system you decide to go with is only as good as the microphone that is attached to it. You can have the best transmitter and receiver technology in the world, but if your microphone is cheap and cheerful then your audio will sound the same. Buy the best you can afford or a system that is upgradeable. Again, ask the Absolute Music experts for advice on flexible systems that can grow with you and your career.
GENTLY, GENTLY...
One final thing you will want to consider is the use of headsets and lavalier (or clip-on) microphones. These microphones are very sensitive and therefore need to be treated differently when used in a live situation. They can also be very ‘lively’ in the feedback department, especially if you have a number of open mics on stage or have a lot of level coming through your foldback. Therefore, they often need a fair bit of tweaking with EQ to get them sounding just right, although the more expensive ones are often tuned considerably to allow for their position.
If you are in a band, my advice is simple: don’t use a lavalier, it will cause you no end of problems. Get a headset microphone instead. With your headset mic, try to get the microphone as close to your mouth as possible, although men (and possibly some women!) should be aware that stubble and beards can often be heard a-rustlin’ every time you open your mouth!
GET READY, GET ADVICE
Ultimately, wireless microphones are incredibly useful and give great flexibility. However, they will take more time to set up and you must remember that you either need a licence or you will have to be aware of other users. Weigh up exactly what works for you, get advice and try before you buy.
MINI-GLOSSARY - WHAT IT ALL MEANS
• COMPANDER – a device in two parts that compresses the signal picked up by the transmitter (the mic) and expands it on arrival in the receiver. This means the audio has been doubly processed before it’s even reached your mixer.
• FOLDBACK – a method to play the music back towards (usually) a lead singer in a band or a main performer on stage, normally done by means of rear-facing loudspeakers or in-ear monitors.
• LATENCY – slight delay introduced into an audio signal, often through converting a digital signal to analogue or vice versa.
• LAVALIER – named after a style of necklace worn by Louis XIV’s mistress, Duchesse de la Vallière, this is a small microphone that clips to a collar, tie or neckline and connects via a small cable to a beltpack transmitter.
• SWITCHOVER (DSO) – the point in 2012 when analogue radio and TV channels in the UK will be turned off and digital-only transmissions will be made.
ABOUT THAT SWITCHOVER THING
In 2012 the 800MHz band will be cleared and unavailable for use, specifically channels 61, 62 and 69 in UHF bands IV and V.
• Ofcom has released Channel 38 specifically for what are known as PSME or Programme Makers and Special Events. This channel is not available across the whole of the UK until digital switchover (DSO) is complete and therefore access to channels 39 and 40 will remain available in certain areas until then.
• Channels 69 (current), 38, 39 & 40 are shared channels without priority, so it is important that your wireless gear has the agility to be able to find a clear frequency and the flexibility to be used both now and after digital switchover in 2012.
• More information can be found at www.jfmg.co.uk (Joint Frequency Management Group), www.ofcom.org.uk (Office of Communications) and www.beirg.co.uk (British Entertainment Industry Radio Group). Or read more on our News page.
WE RECOMMEND
• Samson Micro Airline Ear
A completely portable, rechargeable system with a headworn mic that'll save you a fortune in batteries.
• Line 6 XD-V30
Available in handheld and lavalier versions, this sub-£300 system uses a clever channel-hopping technique to avoid interference.
You may also want to look at the Line 6 XD-V70 in either handheld or lavalier models.
• Shure PGX24/SM58
This combination of PGX24 receiver and SM58-style transmitter (mic) is totally 2012-switchover-ready!
A true performer's mic with a supercardioid transmitter and flexible receiver with five-band equaliser.
You may also want to check out the Sennheiser EW135 G3 system.
READ MORE
We've put together a complete guide to the 2012 digital switchover and rounded up even more wireless mics for you to choose from! CLICK HERE!