Audio Mixer Tips
Onsite audio mixing is one of the most important positions on a film production set, yet it is usually one of the first to be looked over. This is usually because what it takes to be a live audio mixer is somewhat mysterious to most people and they usually will just rely on the camera operator taking double duty to monitor the sound. Here is the basic workflow and some tips for working as the live audio mixer on a film or digital video production, as well as some of the different specifics it takes.
Your Audio Recording Device
If you are using a digital field recorder or some sort, such as a DAT or 702 kit, then the sound mixer will be mounted on that. The first thing that you have to do is to separate the sound mixer from the rest of the production. They need to get a clear line as to what sound is actually being recorded, so that means they need to only be exposed to the sound that is coming from the microphones. If they are in the same room they will get poisoned by the onsite sound and will not be able to report exactly how the sound is being recorded.
Audio Production for Video
On the digital field recorder that they are using they will adjust the gain, inputs, and other factors according to the needs of the scene. They will likely set up the different files for each audio clip that will then be uploaded to the post-production workflow. This requires a very strict adherence to the device that the sound mixer is using, so they must do audio tests with it the same way the camera operator and second camera person does camera tests.
Audio Log and Audio Playback
The onsite sound mixer will be the person in charge of keeping the audio log in place so that they will list exactly how long the tracks are, their quality, and any scene information that is relevant for them. This will be important as it is used to give to the editor and director for post-production so they know exactly the quality of the audio they are going for. In this way the audio sheet is comparable to the camera report. After each take the sound mixer will also communicate with the assistant director and director about the quality of the audio that was just received. They may have to play back the audio, so they must remain organized as to how to get back to where they need to be.
Listening and VU Meter
Though the audio mixer should be listening to the sounds that are coming in from the production to make assessments, they also need to be looking at the VU meter the entire time. This way you can tell if there was clear clipping instead of just trying to deduce it from the sounds they are hearing. The levels should be check and addressed for each change in set up on set. To do this correctly the audio mixer needs to initiate a rehearsal for each set up so that they can get levels. This should be a full rehearsal so that the actors can use it to get ready and the audio mixer has a real set up from which they can get a clear reading of the sound levels so they can make appropriate adjustments.
Proper labeling of each file if you are using a digital storage mixer is going to be key. This is for a couple different reasons. First, you are going to want to have this when you are on set so that you can look and find things easily and make sure that you are not recording over or deleting any important file. Second, you are going to need these clear when you are going through post-production workflows.
The onsite audio mixer is going to be responsible for setting up tone in the beginning. This means initiating the process on the device that puts in the base tone and then adjusting it so that it is at -20dB, or another preference as set by the audio post-production person. Make sure you get twenty to thirty seconds of this tone. You will also need to remind the production staff to get room tone when on set for background noise, but you will not have to be in charge of this as the assistant director should take the reins on this. These tones will be labeled specifically and out of the scheme set up for the rest of the takes.
Directly Into the Camera
If you are recording audio directly into the camera you have a different process all together. The boom microphone operator will be monitoring the sound through the pre-amp, but you will be monitoring it on the camera. This means that you should have an external monitor so that you can see the audio levels without having to crowd the camera operator and assistant camera person on the camera.