CHAPTER 5 Mixers facilities. Occasionally multitrack recordings are edited or compiled ("comped") early on during a recording session to assemble an acceptable backing track from a number of takes, after which further layers are added. Considerable use may be made of computer-sequenced electronic instruments, under MIDI control, often in conjunction with multitrack disk recording. The computer controlling the elec- tronic instruments is synchronized to the recording machine using time code and the outputs of the instruments are fed to the mixer to be combined with the non-sequenced sources. Once the session is completed, the multitrack recording is mixed down. This is often done somewhere different from the original session, and involves feeding the outputs of each track into individual inputs of the mixer, treating each track as if it were an original source. The balance between the tracks, and the positioning of the tracks in the stereo image, can then be carried out at leisure (within the budget con- straints of the project!), often without all the musicians present, under control of the producer. During the mixdown, further post-production takes place such as the addition of effects from outboard equip- ment to enhance the mix. An automation system is often used to memorize fader and mute movements on the console, since the large number of channels involved in modern recording makes it difficult if not impossible for the engineer to mix a whole song correctly in one go. Following mixdown, the mas- ter that results will be edited very basically, in order to compile titles in the correct order for the produc- tion master. The compiled tape will then be mastered for the various distribution media. BASIC OPERATIONAL TECHNIQUES Level setting If one is using a microphone to record speech or classical music then normally a fairly high input gain setting will be required. If the microphone is placed up against a guitar amplifier then the mic's output