ABSTRACT
Looking back at the internal architecture of a gate in Figure 18.2, all that needs to be done to turn a gate into a ducker is to swap the threshold outputs (above and below). Indeed, duckers offer exactly the same controls as gates and work in a similar way. The sole difference between the two is that while a gate attenuates signals below the threshold, a ducker attenuates signals above the threshold. Put another way, once the signal overshoots the threshold, it is attenuated (ducked). The amount of attenuation is fixed and determined by the range. Figure 20.2 illustrates the transfer function of a ducker.
The rationale for attenuating a signal by a fixed amount once it exceeds a certain threshold is yet to be discovered. But there are many reasons for attenuating a signal once a different signal exceeds a certain threshold like in the radio example above, where we want the music attenuated when the DJ speaks. To achieve this we use the key input – the ducked signal (e.g., the music) is fed into the ducker’s input, and the ducking signal (e.g., the voice) is fed into the key input. Whenever the voice exceeds the ducker’s threshold, the music will be attenuated. Figure 20.3 illustrates this arrangement, and Figure 20.4 shows it in action. Ducking applications always make use of the key input in a ducked/ducking arrangement.
