Plan B For Quality: Using Miniature Mics To Back Up Critical Performances

Developing a back-up plan for seamlessly reacting when something goes wrong

By Omer Inan April 1, 2013

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High-end audio equipment manufacturers pride themselves on consistently delivering robust products that hold up to rough treatment.

Unfortunately, the success of any live performance depends on more than just the products themselves: many complex environmental, human, and unknown factors can cause a performance to fail.

Radio frequency (RF) interference can compromise the transmission, causing the audio to drop out. The presenter can lean in and nearly swallow the gooseneck microphone head, creating loud pops and bass boost. A drop of sweat can cover the tip of the mic, muffling the audio.

There are endless possibilities for what can go wrong, and unfortunately, no possibility of going back and fixing things afterwards.

This is why it’s so important to prepare in advance for these situations by developing a back-up plan for seamlessly reacting when something goes wrong. With the right plan, you can instantly transition to your “plan B” with no indication to the audience of what happened.

Insuring The Experience
In the past 20 years, with the invention of ultra-miniature lavalier, earset, and headset microphones, audiences have been spoiled: they expect highly intelligible and natural sound pick-up from nearly invisible microphones, allowing complete immersion in the production with no distractions. This immersive experience should always be preserved when using back-up mics.

Fortunately, mics keep getting smaller: the smallest lavalier available today is only 0.1-inch (2.5 mm) in diameter, more than twice as small as its predecessors from a decade earlier. This means that two of these mics can be fit together while still maintaining a very small overall profile.

With all of the following techniques, provided by veteran audio engineers, it’s important to consider: 1) What types of failure can be expected; 2) How to seamlessly switch from one mic to the second without changing the audio quality or the character of the background noise; and 3) How to mount the two mics together without the overall assembly being distracting.

As Seen On TV
The most commonly used double miking technique involves positioning two omnidirectional lavalier mics on a double tie clip. This is seen regularly on TV for newscasters or other live broadcast productions. Only one lavalier is turned “on” at any given time, and if something goes wrong with that channel, the audio is immediately switched to the second lavalier. Since the two mics are positioned close together, and the sound engineer has taken the time to match the gain of the two channels, this switch can be executed successfully and seamlessly.

Audio mixer Ed Greene uses another double miking technique for critical performances: pairing one cardioid lavalier with one omnidirectional lav in a dual tie clip. When the audience gets loud, he uses the cardioid; when things get quieter, he moves to the omni for more open sound. This is also ideal when there are two desired outputs, one for the live audience that requires maximum gain-before-feedback and one for the broadcast feed where the objective is maximum transparency and rejection of cable noise or other unwanted directional microphone characteristics.

If mics need to be out of sight, they can be hidden in the knot of a tie. In this case, make sure that the mic heads are not touching or rubbing against each other to avoid noise. Also, use omnidirectional elements since the mics will be pointing downward away from the user’s mouth.

On The Inside
There are so many ways that a gooseneck mic can be misused that I couldn’t hope list them all here. Perhaps the most common issue is when the presenter gets too close to the mic in some kind of effort to be “heard.” The first instinct is to then pull back on the fader – unfortunately, while this certainly helps, it’s not enough. It will not prevent pops and distortion, and the voice will be boomy due to the proximity effect.

A gooseneck podium mic with lavalier back-up (see the cable?). (click to enlarge)

As part of his approach at the Nobel Prize banquet each year, sound engineer Lars Wern hides a tiny omnidirectional lavalier inside of the windscreen of the hypercardioid gooseneck mic. For this approach, select a miniature lavalier with an extremely small and lightweight cable, and simply use a few narrow pieces of black tape along the gooseneck for attachment. Position the lavalier cable under the gooseneck, on the side facing away from the audience and the cameras.

If the presenter gets too close to the microphone, simply fade out the gooseneck mic and fade in the lavalier. The omni lavalier will not exhibit the same bass-boosting properties as the hypercardioid gooseneck microphone and will be much less susceptible to breath pops.

Some engineers hardwire both the gooseneck mic and the lavalier to separate XLR connectors inside of the podium base; others connect the lavalier to a wireless transmitter pack inside of the podium instead. Using a wireless link for the lavalier could simplify installation since most podiums only provide one XLR connector for the mic.

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