794 Chapter 27
on screen, by dragging them with a mouse. Another more drastic solution, and one that
has many adherents on sound quality grounds alone, is to use motorized faders as part of
the control system. In this case the faders act electrically as they do in a nonautomated
mixer, carrying the audio signal itself. The control system loop is restricted to reading
and “ recreating ” operator fader physical movements. Apart from providing unrivalled
operator feedback (and the quite thrilling spectacle of banks of faders moving as if
under the aegis of ghostly hands!), the advantage of this type of automation system is the
lack of VCAs in the signal path. VCA circuits are necessarily complicated and their
operation is beset with various defi ciencies, mostly in the areas of insuffi cient dynamic
range and control signal breakthrough. These considerations have kept motorized
faders as favorites among the best mixer manufacturers, despite their obvious complexity
and cost.
27.7.1 Time Code
Time code is the means by which an automation system is kept in step with the music
recorded onto tape. Normally, a track of the multitrack tape is set aside from audio use
and is devoted to recording a pseudo audio signal composed of a serial digital code.
ΣΣXXXXAudio 1Audio 1Audio 2Audio 2Fader control 1Fader control 2MixMixdacMicro
controllerTimecodeAnalogue
control busManual mixer using VCAsMixer with automation
Figure 27.23 : Fader automation system.