Parallel processing is one of the two main ways of adding affects to a chain. However, before delving into what it consists on, we need to explain its counterpart.
Adding Effect to a Chain
As mentioned previously, there are two main way of adding effects to a chain. The first approach is serial processing and it works by interrupting the dry audio signal by using an insert slot. When doing this, the dry signal is fed to the processor. Consequently, it feeds the processed result to the next processor, and so on. In other words, the chain of effects runs in series from one to the next.
Parallel processing tends to enhance or enlarge the outcome. Within this effect, the original audio signal uses an auxiliary track that remains untouched before the second audio feed offers a second audio stream. The auxiliary buses are places where one can add diverse spacial effects. Some of the most common spacial effects are reverb and delay. Producers usually blend in these effects with the dry signal to achieve a balance between the clarity of the original effect and the desired one.
When used accurately, the reverb effect tends to enhance and support a vocal track. This effect is quite useful for vocals recorded inside a highly absorbent room with a close mic. A magical dust can enable the vocal to glide into the mix to create an emotional presence. When this unique quality appears, the human ear is able to hear both the original audio signal and the output of the reverb.
Another way in which the parallel processing is common is dynamic processing. By setting up the dynamic processor as an auxiliary effect, it is viable to equalize its return channel to customize the specific processed tone. The fast attack/fast release compressor that works in a parallel configuration can emphasize the overall sustain, whereas a low shelving cut to the return signal can direct that sustain towards an upper-frequency zone.