Effects, Part 2

INSERT EFFECTS

Whether you’re using a hardware recording setup or a computer-based multitrack, each audio track in your recorder will normally have its own channel in the mixer. The simplest way to use an effect is to insert it in the signal path of a mixer channel. When used in this way, an effect processor is called an insert effect, or just an insert.

A good DAW (digital audio workstation) program will allow you to insert a number of effects on each channel, as shown in Figure 1. For instance, you might insert a compressor to tame the dynamic peaks in the signal, followed by a chorus to fatten the sound and a reverb to give it a sense of space.

The order in which effects are inserted can make a big difference in the resulting sound. For instance, effects that adjust the level of the signal, such as compressors, should usually process the dry signal before it’s passed on to any other effects. But this is not a hard-and-fast rule. By experimenting with effect order, you may be able to create a unique sound that will give your mix extra life and energy.

Some effects, such as filtering, can radically increase the level of the signal. If you’re hearing a distorted signal, try switching off (bypassing) the insert effects one by one to isolate the problem. You may be able to tame the overload by reducing the input level or output level of the offending effect.

When effects are used as inserts, you have maximum sonic control over the sound in each mixer channel. However, each effect that you add will increase the load on your computer’s CPU. If your recording has a lot of tracks, you may find that using a lot of inserts taxes the CPU, resulting in pops, crackles, and other nasty stuff.

SEND EFFECTS

A more efficient way to use effects is to create a separate mixer channel called an aux send, and put the effects on this channel. For instance, if you want to apply the same type of concert-hall reverb to half a dozen channels, you can use a single reverb effect on an aux send. Some computer recorders have a fixed set of aux send channels; others let you create as many aux sends as you might need.

Each mixer channel will have send outputs for routing signal to the aux buses. To use an aux send effect, you assign a send on the mixer channel to the aux bus. You then load an effect into the aux bus and adjust the send on each channel to the desired level. For instance, you might want a lot of reverb on the snare drum, but only a little on the guitar. In this case, you would put the reverb on an aux bus, set the send level on the snare channel to a high level, and set the send level on the guitar channel to a lower level.

When you use a send on a channel, the signal passing through the channel is split. The signal goes directly to the mixer’s main output, as usual. In addition, it goes to the aux send bus. Because of this, the wet/dry balance parameter of send effects is generally set to 100% wet. That is, only the output of the effect is heard on this channel; the dry (incoming) signal is completely suppressed. In contrast, the wet/dry mix of an insert effect is often set to an intermediate value such as 30% wet.

Usually, sends are post-fader, which means that if you turn down the channel’s main level control (the fader), the amount of signal going to the send will also decrease. That’s normally what you want: The channel’s fader should control the entire sound of the signal coming from that channel. In a few situations, though, it’s useful to set a send to pre-fader. When you do this, you can lower the level of the channel itself in the mix (using the fader) and still hear the signal as it emerges from the send bus. For example, if you want to crossfade from a full-frequency modern mix to a tinny “old-fashioned phonograph” mix created with a bandpass filter, you might put the filter on an aux send, make the channel sends pre-fader, and then fade out the channels while bringing up the level of the aux bus.

If that sounds like a lot of work — lowering half a dozen faders at once while also raising another fader — then you’re ready for the next What’s This For, when we unveil the basics of mixer automation.

JARGON JOCKEY

DSP:
Digital signal processing (DSP) is a general term for what happens inside a computer or a stand-alone piece of digital audio hardware as signals are being processed and/or routed from place to place.

Wet/Dry Mix:
The parameter in an effect that controls the balance between the wet (effect-processed) signal and the dry (unprocessed) signal. A few effects have separate controls for the wet and dry outputs, but most combine the two in a single wet/dry crossfade parameter. When wet/dry is set to 100% wet and 0% dry, only the processed signal is heard; when it’s set to 0% wet and 100% dry, the effect is bypassed.