LIBRARY: Tutorials Reviews Interviews Editorials Features Business Authors RSS Feed

Why Use a Mixer?

A Creative Cow Feature Article


Why use a mixer?
Brandt Sleeper Brandt Sleeper
Ingram, Texas USA
©2008 Brandt Sleeper and CreativeCOW.net. All rights reserved.

Article Focus:
Want to know why you should be using a mixer and an external mic instead of your camera's onboard mic? After years shooting for clients including National Geographic, NFL Film and Oprah, as well as production for his own company, he'll give you the background you need to make your work sound its best.


Over the years, many a newcomer to the industry has asked: Why do I need a mixer to do audio? Well, the answer is quite simple: For the same reason that we need to use lights for image.

They appear to understand until I tell them that lighting is all about creating shadows and contrast, not light.

Lighting adds depth, as in film noir

Huh?

Next I explain that manipulation of these two elements, combined with a few others, helps to create the illusion of 3-D space in the two-dimensional world of the mono-optical camera lens. Without shadows and contrast the image would appear flat and separation of the subject from the background is almost impossible.

OK, I think I understand now, but what does that have to do with sound?

Well, in order for our audience to hear what is important, we need to suppress background ambiance. But much like the depth perception problem of the single lens, a microphone cannot distinguish desired sound from ambient noise.

Field microphoneUse of a mixer in tandem with the microphone allows us to maintain a high level of desired signal while minimizing the noise floor, which is commonly referred to as a good signal-to-noise ratio. This allows the listener to separate the dialog (or other focal audio content) from the background.

So the bottom line with both tools is that they give you control over the environment.

Now that we have established the need to have control, let’s see how a mixer can help us.

First and foremost, even with the most complete set of onboard audio features imagineable, the controls on a camera can't be adjusted when the camera is in use. These controls are inaccessible while the camera is in motion, and when static, any attempt to adjust levels might bump the camera giving the appearance of an earthquake on the screen.

Use of automatic gain control on the camera may not work well enought either because these devices cause dramatic fluctuations in the signal and with it the noise floor. When you get into the editing room, the audio edit may not work because the noise level in one shot does not match the noise level in the cut. Use of a mixer allows us to gradually and smoothly manipulate the levels in relation to the signal; this minimizes pumping of that noise floor. But this is just part of the picture.

Mixers are devices dedicated to sound and as such manufacturers put their money into the electronics that will guarantee quality audio: the preamps on mixers are typically of much greater quality that those on a camera. The preamps take the signal from microphone-level to line-level.

Once this is done, we would prefer to stay at line level; again because the signal-to-noise ratio of line-level is substantially better than mic-level. So, we run at line-level output from the mixer to line-level input at the camera.

Mystere audio mixder

Mystere ENG audio mixer

Mixers also have additional features such as high-pass filters and limiters. The high-pass filter can cut much of the low frequency noise present in all environments. Reduced noise enhances clarity of the signal. Limiters allow us to inhibit over-modulation of the signal that might clip the signal or introduce analog distortion.

Now, let’s add to this the bonus of confidence monitoring which allows us to audition either the mixer or the camera so we can isolate any problems in the signal by more easily determining the source.

Oh, and did I mention that we could have more than two inputs? Yes, even ENG mixers these days provide as many as six inputs. All these features combined make mixers a powerful tool for ensuring usable audio.

And, it only takes one time in the editing room trying to salvage bad audio to realize that the cost of a mixer is nominal in relation to the ongoing expense of audio post due to poor production sound.

 

 

 

Comments

Re: Why Use a Mixer?
by Gerard Richardson
Very Informative Brandt I like your comparison to light on that one.

Gerard "Gripp" Richardson


Related Articles / Tutorials:
Audio Professionals
Prince: Musician

Prince: Musician

There are almost too many stories to tell about Prince Rogers Nelson and his sudden passing at age 57. Stories of the dazzling star selling 100 million records, the explosive entertainer, the incendiary guitarist, the prolific composer, and more. Instead, we focus on a story too easily lost in all this: a man who was all about the music, 24 hours a day. Remarkable previously unseen footage of a playful Prince at an Osaka soundcheck in 1990 by Chainsaw Post GM Steve Purcell, who worked with Prince for 6 years, sheds entirely new light on an artist you only thought you knew.

Feature, People / Interview
Tim Wilson
Audio Professionals
The Trouble With Rain: Designing the Sounds of Noah

The Trouble With Rain: Designing the Sounds of Noah

To add new dimensions to the soundscapes of Darren Aronofsky's Noah, Supervising Sound Editor Craig Henighan took advantage of the new Dolby Atmos mixing stage at Deluxe New York to place movie audiences in the middle of the storm.

Editorial, Feature, People / Interview
Tim Wilson
Audio Professionals
Skywalker Sound's Randy Thom Awarded for Career Achievement

Skywalker Sound's Randy Thom Awarded for Career Achievement

Randy Thom, Director of Sound Design at Skywalker Sound, received the Motion Picture Sound Editors Career Achievement Award at the 61st MPSE Golden Reel Award ceremony on February 16th, 2014. Thom, a two-time Academy Award-winner (The Right Stuff, The Incredibles) and a 14-time Oscar nominee, has contributed to more than 100 films as a sound designer and re-recording mixer. Star Wars creator George Lucas presented the annual MPSE Career Achievement Award to Randy.

Editorial, Feature, People / Interview
Debra Kaufman
Audio Professionals
Remembering Ray Dolby: A Life of Invention

Remembering Ray Dolby: A Life of Invention

Ray Dolby gave his talents and his name to the most significant advances in audio recording, for both the professional film/TV/music industries and consumer products. On the occasion of his death, at age 80, Creative COW tells the story of his life, his engineering achievements and the impact he has had on the creative people in our industry.

Editorial, Feature, People / Interview
Debra Kaufman
Audio Professionals
The Art of Foley: John Roesch Honored by MPSE

The Art of Foley: John Roesch Honored by MPSE

John Roesch is one of the most accomplished Foley artists in the motion picture industry, with contributions to more than 400 films in a three decade-spanning career. He is the recipient of two MPSE Golden Reel Awards (The Dark Knight, The Matrix) alongside more than a dozen nominations. He has worked on 16 films that have won Academy Awards for Best Sound or Best Sound Editing. John Roesch spoke to Creative COW about the art of Foley and his extensive experience in creating sound effects.

Editorial, Feature, People / Interview
John Roesch
Audio Professionals
Soundelux's Wilhoit Recreates Sonic World for End of Watch

Soundelux's Wilhoit Recreates Sonic World for End of Watch

Michael D. Wilhoit, supervising sound editor at Soundelux, collaborated with director David Ayers on the sound track for End of Watch, a critically acclaimed police thriller that takes viewers into the lives of two policemen who become the targets of a dangerous Mexican drug cartel. The movie is stylistically "found footage," and Wilhoit's challenge was to create a soundtrack that matched the movie's gritty immediacy and realism.

Feature, People / Interview
Debra Kaufman
Audio Professionals
Technicolor Opens Sound Facility on Paramount Lot

Technicolor Opens Sound Facility on Paramount Lot

These two companies structure a partnership to benefit clients and their own ecosystems by opening gleaming new mixing stages for Technicolor on the Paramount lot.

Feature
Debra Kaufman
Audio Professionals
Drive garners Oscar Nom for Soundelux's Lon Bender and Victor Ennis Garner

Drive garners Oscar Nom for Soundelux's Lon Bender and Victor Ennis Garner

Oscar nominated Soundelux Supervising Sound Editors Lon Bender and Victor Ray Ennis & team take the audience of "Drive" on an aural trip.

Feature, People / Interview
Debra Kaufman
Audio Professionals
A Look at Alan Parsons Art & Science of Sound Recording

A Look at Alan Parsons Art & Science of Sound Recording

If you are one of the many people working in film and broadcast that has been wanting to sharpen your skills in audio production -- or just become more aware of its principles and dynamics -- Creative COW's Ronald Lindeboom points to a series that is near to guaranteed to expand your working knowledge of audio.

Review
Ronald Lindeboom
Audio Professionals
sE Electronics' USB2200a and Reflexion Filter

sE Electronics' USB2200a and Reflexion Filter
  Play Video
Sam McGuire demonstrates the quality and effectiveness of two sE Electronics' products. The USB2200a is a USB/XLR hybrid microphone which is extremely low noise (I didn't believe it until I heard it.) The "Reflexion Filter" is an acoustics baffle used to create a studio environment in any room. For a combined price of under $600 this is a relatively affordable, portable, and high quality solution for all of your VO needs.

Review, Tutorial, Video Tutorial
Sam McGuire
MORE
© 2016 CreativeCOW.net All Rights Reserved
[TOP]