Monitoring the Soundtrack - The Boom

Booming00Last month, Fred Ginsburg talked to us about the importance of monitoring the sound track during our shoot. This month, we continue with the special needs of the boom operator.

The boom operator also needs to hear the soundtrack, though not as critically as the Sound Mixer. Because a boom operator is in the middle of the set, his headphone volume may be set lower. Sometimes a boomperson needs to be able to hear possible warnings on the set from other crew members (watch out for the dolly, etc.).

Too often, novice soundpeople restrict the boomperson's headphone feed to only hear what the boom mic is picking up. That is a bad practice and should be avoided. What the boomperson NEEDS to hear is the boom mic along with all othermics that are in play on the set.

On most shoots, a professional sound mixer will use more than one mic in order to cover distance across the set, or to solve boom shadow issues close to walls, etc. But when two mics (recording to the same audio channel) are open at the same time, and can pickup the same sound, a phasing issue occurs that causes the audio to become very hollow and thin. One of the offending mics must be faded down; and the other mic needs to compensate. Or, one of the mics (the boom) needs to be angled away from the other mic.

The boom operator must be able to hear the presence of any other open mics, so that he or she does not accidentally "double mic" the actor in question. (And some folks believe that being a boomperson is brainless.)

AudioPlugs

Left: The end of a custom built Duplex Cable, made by PSC.

Specialized mixing panels used for film and video production may offer a dedicated headphone output for the boom operator. Most of the time, though, the less expensive (but still good quality) mixing panels from Mackie or Behringer do not have a special headphone output separate from the soundmixer's own headphone connection. But they DO have Aux outputs for monitor mixes.

Plug the headphone extension cable (feeding your boomperson) into the post-fader Aux Send of the mixing board. Most boards have a "master" Aux Send volume control, which you can use as a de-facto headphone volume control for your boom operator. Note that the Aux Send connection is usually ¼-inch MONO, so make sure you have the necessary mono-stereo adapter plug or a custom cable to keep audio in both sides of the headphones.

In addition to the master Aux Send volume control, there are individual Aux controls for every input. Normally, just set these to the default detent or middle position. Some inputs, such as an external tone generator, audience mics, or SFX mics do NOT need to be monitored by the boomperson. You can turn the Aux controls for those inputs to the low end. But make sure that the mics on the set affecting dialogue are sent out to his headphones.

MonitorinBoomsOn a mixing board, you will see two types of Aux Send. It may a switch, or there may be more than one Aux Send with labels. Pre-Fader Aux Send means that the only knob affecting the monitoring is the individual Aux knob on each input. What that means is that it does not matter whether or not the main faders for a given mic is open or closed down; the only knob that controls the audio flow to the monitor (Aux Send) is the Aux knob. If the Aux knob is open, that mic is open in the headphones. If the Aux knob is closed, then that mic will not be heard in the headphones. It matters not what you are doing in the main mix. It is as every mic had a Y cable connecting two separate mixing boards on your cart; they function completely independent of each other.

As you can imagine, sending the boomperson a Pre-Fader Aux Send would be quite distracting, since every mic on the set would be "open" at all times, even if the Sound Mixer was not deploying it.

When Post-Fader Aux Send is selected, the only sound that makes it up to the Aux Send controls is what passes out of the controlled fader of each input. If the sound mixer closes a mic, then no signal is allowed to enter the Aux Send. When that mic is open, then only that relative amount of volume is sent to the Aux.

Think of your home sprinkling system. If the main water valve is closed, then no water reaches the sprinklers, irregardless of whether the sprinkler valve is open or not. Open the main valve, and then the knob on the sprinkler determines the water flow.

Post-Fader Aux Send allows the boom operator to hear the live mix. When needed, the version of the live mix going to the boomperson can be modified by the individual Aux controls, such as keeping the non-important (to the boomperson) audio minimized. On the other hand, the sound mixer can wig-wag the Aux volume of a particular mic to call the boomperson's attention to it, perhaps to warn him of a hidden mic in the set.