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Why you need Multichannel Wireless Audio - Part 1

By Mark Thorn

This is our first blog since we launched AirLinc V2.0.1 with Multichannel capability.

In this 2-part blog, AirLinc co-founder Mark Thorn compares the new AirLinc Multichannel system to other solutions currently on the market.

The ideal location audio kit

When I started recording location audio back in the 80’s most News and Current Affairs audio kits were put together around 3 factors: portability, reliability and flexibility.

Nagra 4 analogue location recorder
Nagra 4 analogue location recorder

Recording was always handled by the ultra reliable Nagra 4 analogue location recorder which committed the proceedings onto quarter inch magnetic tape.

We generally had a selection of Sennheiser shotgun mic’s including the legendary 406 ‘mini shotgun’ for everyday ‘run and gun’ interviews and the industry standard 806 shotgun for situations where more ‘reach’ was required. A ‘fish-pole’ boom was standard for when you needed to get in over the top of the frame for wider framing.

Nowadays, a location sound kit might have a Digital Audio Recorder such as a Tascam DR 60 or a Zoom H6 to replace the Nagra and the shotgun might be a Rode NTG 2. Almost certainly there will also be a few lavalier microphones, along with a variety of high quality cables of varying length, and a good set of headphones.

audio guy

So the technology for recording the audio has changed, there are some new additions in the form of lavalier microphones, but the fundamentals of portability, reliability and flexibility are still adhered to.

But above that, the physics of getting good location audio - whilst ensuring the camera person has the freedom to get the best framing for the shot - has definitely not changed.

Getting close, but not in shot

mic in shot

Microphone distance from the talent is always a trade-off between the sound person and the cameraperson, because in order to capture quality voice audio, you need your microphone to be as close to the subject as possible, without restricting the camera person’s freedom to re-frame to a wider shot and not see a microphone in shot.

Multi-person interviews and moving talent - the sound person’s worst nightmares

The day of reckoning will come in every location sound person’s life when you get a seated group interview and an interviewer (on or off-camera).

Even with a shotgun mic on a fish-pole, you’re going to miss it when the conversation swings from one person to another. You can always stay wide to avoid being in shot, but when a fridge or an air conditioner kicks in you’re toast because, at that distance, the external noise will overwhelm the speaker’s voice (especially if the fridge is behind the person speaking).

Add to that a noisy location (sometimes this can’t be avoided when you’re in a run and gun situation) and one of three is inevitable:

  • Your cameraperson will stay on a wide shot and you’ll get your mic in shot
  • You will stay wide with your mic to avoid getting in shot and the audio will be borderline unusable
  • Your cameraperson be accommodating and zoom in to a close-up, but not all camera people are going to restrict their shot for the sake of audio.

The problem with cables

problem with cables

This is where lavalier microphones come into their own. They are small enough to appear in shot and not be too noticeable. And if you’ve got a Digital Audio Recorder that can accept several channels then you can wire your lavalier mic’s into your DAR and off you go. One problem - what about cables? Nobody wants to see cables in shot and with a multi-person interview your camera person will generally want to get a wide-shot when unsure of who’s going to speak next. And what happens if the interview happens on the move? Cables are a real hassle in these situations.

This is where wireless microphones become invaluable, and why we produced our AirLinc smartphone wireless mic system.

So how would you use AirLinc for a multi person or mobile interview?

Our new AirLinc Multichannel release allows you to mic up to 6 (or more) on-camera presenters using either iPhones or iPod touches as the transmitters. To get professional results, we recommend your transmitter devices are connected to good lav mic’s that come with TRRS or Lightning connectors (RODE SmatLav+ or Sennheiser MKE2 or ClipMic). You can always use older iPhones or iPod Touches as transmitters since these are generally cheap to acquire - or you might have a few hanging around. Technically, they work just as well as newer iOS devices, but just be sure they can run iOS 9 or above.

Your receiver device can be either an iPhone, iPad or iPod touch. (iPads are great as receiver devices, since they have larger screens and can therefore display more mic inputs). You will also need a good pair of headphones. Bluetooth headphones are a good choice if you’re using iPhone 7 or above since these phones only come with a Lightning connector for monitoring and you will need that connector for your mic input.

personal hotspot

But one of the hidden treasures of iPhones that make all this goodness possible in a run and gun, external environment, is Personal Hotspot. This great feature is generally used to tether your devices so you can have a travelling internet connection, but AirLinc uses it as a way of connecting phones wirelessly without the need for a wireless router, internet connection or even a mobile connection. So basically, none of your transmitter devices need SIM cards, which will limit your expenditure when purchasing multiple phones.

Another great feature of AirLinc that can be a real lifesaver on location is our fail-safe recording on the transmitter devices. Once you finish a take, not only do all your transmitter devices automatically sync their tracks back to the master (receiver) device, but they also store the original track locally. This is a very handy fail-safe if, for instance, your master device is lost or the sync process doesn’t work for some reason (unlikely, but may happen under some circumstances). So your precious tracks are always kept safe (and you get to keep your job!)

clapper boy

Oh... and before I forget - since AirLinc is best used in the double-system mode (you record the audio separately to the video and post-sync), then one of the best things you can invest in is a clapper board. This way you can have an easily-identifiable sync point during the post-syncing process.

In the next part of this blog, I discuss what other solutions are available that allow you the same flexibility of AirLinc for recording and monitoring multichannel audio, but take a different approach. Please leave your comments and feedback below!