Using Portable Sound Mixers
Continued from Using Portable Audio Mixers Part 1
You might wonder, "Why use a field audio mixer for one microphone?"
Portable audio / ENG mixers - the good ones at least - don't just allow you to control audio volume levels, they also have a metering system that lets you set consistent levels without having to guess. The good portable audio mixers will also have controls that let you change the tone a bit to compensate for things like room ambience (for instance you might be a big echoey room and need to reduce the bass - the low tones - a bit). The professional quality mixers will also have circuits to help even out the audio a bit (compressor/limiter circuits) and the mixers even generate a tone that can be recorded to tape to help you set levels later during the editing process.
Another thing good portable audio mixers have is a battery. There are so-called "passive" field audio mixers that don't need batteries. They have their place and can be good values when starting out in video production, but they will not provide the kind of robust audio mixing you get from the circuits in powered mixers. A powered portable audio mixer can also provide "phantom power" which is power used by certain types of microphones.
So, you can see that portable audio mixers can do a lot even without doing any actual sound "mixing." But what about mixing, is that something you need?
First of all, as we said, you do not want to use a camcorder's built-in microphone, so that means at least one mic plugged into the field mixer. For many types of video, a good choice is a so-called "shotgun mic" which can mount on the camcorder. These mics are designed to have a rather narrowly focused pickup area: they might not capture too much audio from the right or the left, but they can do a very good job with stuff in the middle. These can be a very good choice when you want to record someone who is always facing the video camera and is within 10 feet or so of the camera lens.
Now let's suppose you want to interview that person. This is when it's time to plug a second mic into the mixer. You could use one of those headsets that has a microphone on a little boom: this would let you monitor the camcorder audio and have a convenient mic. The portable audio mixer will let you adjust the levels of that mic and the shotgun mic (or other external microphone) so that they are equal.
While we're mentioning headsets, one very important rule for getting good audio for video: always use a headset to monitor your camcorder's audio, whether you use a portable audio mixer or not. Everything can look okay, and the mixers meters might show proper audio levels, but things like audio cables and connectors can go bad or microphones can pick up hum from nearby electrical equipment. Monitoring the audio during shooting will let you hear any problems. More than one videomaker has had their day/week/month ruined when they sat down to edit their video and discovered there was, for example, a hum through all of it.
Back to multiple mics.
The highly directional shotgun mic is a good first choice for an external microphone. You can mount it on the camcorder, use it handheld, or mount it on the end of a pole ("boom") and have an assistant hold it above the subject, out of camera range, of course.
Another good choice is a wireless microphone system and in fact, if you shoot, for example, weddings, you might want to start with two or more of these and a portable audio mixer. Weddings really demand the use of more than one microphone and it's not uncommon to see three or more used: one for the preacher, one on the groom to capture his and the bride's voices, and a third, perhaps an omnidirectional mic to capture the ambiance of the room and the sound of the piano, organ or other music. Since camcorders generally only let you record two audio tracks at a time (left and right stereo) a portable audio mixer is a must to mix three or more mics to two channels.
Some field portable audio mixers will let you "pan" the audio so you can send a particular mixer channel to the left or right channel or to both. In a wedding you might send the room/music mic to both channels and then send the preacher's mic to the left channel and the bride/groom mic(s) to the right channel.
If you're just starting out in video, the temptation is to set a budget and then go spend it all on a camcorder.
Instead, spend part of that budget on good audio gear: mics, mixer, cables, etc. even if it means you have to go a down a step in your choice of camcorders. A $500 DV camcorder and $700 of audio gear can produce better videos than a $1,200 camcorder using just the internal microphone. Good audio gear will last you through several camcorders: microphones and portable audio mixers that help make great audio on that $500 DV camcorder and help make great audio on that $5,000 HD camcorder or whatever else lies in the future.
As with camcorders, good audio gear has become more affordable. The ENG audio mixers most popular among TV news crews for so many years could easily cost $2,000 and up and until recently you could not find decent field portable sound mixers for much less than that. Today though you can get full-featured portable sound mixers for about 25% of that cost, and there are some very good shotgun mics retailing for about $200. Wireless microphone systems are available with more options than ever before and - once again - quality systems are more affordable than ever, so there's no excuse for not having good audio on your video.
ENG-44 Portable Audio Mixer
Article © copyright 2006 by Bob