In the beginning it was just a channel, then 2, later 4, then they added a channel of effects of bass sounds and became 4.1 and we reached standardization of the well-known 5.1... Now there is talk of 7.1 and up to 10.2!!!
These systems of playback based on a given number of channels, they only try to recreate effects of movements and environments, the which very rarely have to do with the actual sound that we listen daily in different places and situations.
When we talk about sound for television, video or audiovisual productions, we can not forget about what we have learned in the cinema since the 30s. For manage to capture and mix a sound in 5.1 channels or more, there are to resort to certain techniques and special microphones that we provide a better acoustic representation of the event or program that we are recording or transmitting. Normally, the most used these days are wireless microphones with capsules of the lavalier type carried by the actors and / or announcers, and the famous shotguns or superdirectional microphones.
In all these cases the best thing is mix the audio in a commensurate control room, which must have at least one 5.1 system installed and calibrated. The engineer must be familiar with mixtures multichannel, as well as with the different effects that will use to enrich the acoustic scene, be these reverbs, compressors, limiters, etc.; which shall, in the possible, also be of the multichannel type.
Now, when we should perform sound recording with very high quality and reliability of what really sounds live and acoustic, we we find the doubt of how to do it and what microphones to use. There are a variety of stereo microphones on the market or multichannel, which can help us in these situations so Particular.
My recommendation is to use it add a binaural system and complement it with microphones of the hypercardioid and cardioid type for posterior canals and the central channel. At the beginning of July of this year, I had to perform a multichannel audio recording, for a video of tango that would be released in HD-DVD and BLU-RAY DISC format in the city of Buenos Aires, Argentina. The video was recorded in format HDV and audio in 24-bit and 96 Khz sampling rate.
For that occasion, I used to the right and left frontal canals, a binaural sphere BS-3D model of THE; for the center channel, a microphone cardioid model KR-2C with a KA-04 preamplifier of the same enterprise. For the rear channels I used a head binaural Aachen Head of German origin. For the bass, we installed a KR-1F omnidirectional microphone with a KA-04 preamplifier from the same company THE (www.theaudio.com).
The result was excellent as all the instruments were acoustic, and the female voice did not have no sound reinforcement; she was only accompanied by a piano, double bass, guitar, bandoneon and drums. What needs to be done To emphasize is that the environment was controlled and it was required that the three video cameras and their operators, will perform the minimum of noise possible.
In short, to get a very good sound capture for later use in a mixture 5.1, it is necessary to take into account the quality and form of microphone pickup (polar response or polar diagram), and its location on set. Therefore, the technique is very important to use and take into account that normally the channels fronts carry the bulk of information, and that the rear are most commonly used to recreate an environment or movement determined from a sound source.
Let's not forget that we have only a screen or monitor for the image, but for the audio we have 5 channels and one more of bass or subwoofer, and that we can do a lot with them to impress the audience or the viewer.
