Videomaker – Learn video production and editing, camera reviews › Forums › Technique › Sound › Wireless Lavalier Mics › The fact nowadays is that
The fact nowadays is that good quality UHF radio systems can be made very very cheaply, and the Fender and many others are budget priced systems that don’t let the side down – UNTIL you start working in places where other radio systems are in operation. The cheap systems have good signal to noise ratio, a wide audio frequency response and are ok. The snag is that to cut costs, receiver design has little or sometimes no in-built provision to filter out rf on nearby channels. Every transmitter has a deviation either side of the operating frequency, some designs a bit more than others – and having another transmitter ‘next door’ means that without good quality filtering, it will interfere. Here in the UK we have a license free band that most semi-pro and amateur level equipment works in without the bother of getting a license. Most brands let you have 4 systems that work together happily – but the cheaper brands often generate complaints of interference. I read a post recently on an audio forum from a guy who bought 4 identical systems and discovered that at best he got two working together – no hope with three or four – even though the units had switches stating clearly ch 1,2,3,4. Poor filtering makes them unusable together – and that is what the spec never makes clear. So the cheap ones work very well – on their own. However, a DJ in the Karaoke room next door, or another camera crew with their own radio gear on nearly the same channel could wipe them out.
So don’t dismiss or accept kit as being rubbish because it’s cheap and probably made in China – just consider how you will use it, and the need for reliability. I have Shure, Sennheiser, Trantec and AKG radio kit here – and the AKG, despite being a well known quality brand is a cheaper product, and has little filtering. The others are better, being designed and sold to be used in multi-channel systems, so far more immune to interference. If you never work with any other radio kit nearby, the cheap ones are fine – but add a few other users and you may be very annoyed with the performance!
As for using two mics, the usual snag is if one is using the transmitter to get it’s power – so you end up splitting the audio feed and the power – with variable results. I’ve a colleague who has two small lavs wired in parallel, and they share the power and the audio is fine. However – it took him some experimentation to find mic elements that worked this way properly – some he tried took too much power, and the DC voltage dropped below what was needed, producing very hissy results, a pair of Audio Technica’s he tried seems to oscillate oddly. He ended up using two very cheap electret element mics and it works – but the real solution is a cheap mixer, and the added complication of powering the mics. Generally the usual advice is one mic – one transmitter pack and one receiver. Want more mics? Buy more systems!