Categories of Effects

Hello, I am Carlos Devizia a musician from Argentina. Today I will write about Categories of effects, giving small definitions of each one and providing some audio clips as examples of how they work. Please note that these examples are not intended to be musical, but they aim to show the effect itself clearly. Also be aware that, depending on how you tweak the parameters of the effects processors, you may obtain results drastically different.  And that´s a great advantage in the creative field, if we know how to use it.

We can associate different effects to different principles of sound.

Dynamic Effects

These effects are related to amplitude and they can control volume in different ways.

 In this category we find: compressors, limiters, gates and expanders.

Compressor

Essentially, this effect reduces the dynamic range of a piece by reducing the volume when it gets too loud. In this case "too loud" is related to a point called threshold or ceiling. Everything that goes above that will be reduced in a desired amount.

Limiter

This is basically a compressor with a fast attack and a high ratio.

Gate

Also known as noise gate, this effect attenuates any signal below a determined point. We also can say that basically a gate allows a signal to flow only when it is above certain level, stoping everything that is below that level.

Expander

This effect increases the difference between the loud parts and the quiet parts in an audio signal.

In the following example you´ll hear the clean sound and then processed with a compressor, a limiter, a gate and expander (in that order)

Delay Effects

These ones add slight delays to the signal and they are used to represent a space the listener is inside. In this category we find: delays, flangers, phasers, choruses and reverbs.

Delay

This effect takes an audio signal and reproduces it a certain time later, mixing it with the original signal. The amount and strength of repetitions can be adjusted by the musician, producer or sound engineer.

Flanger

This effect is achieved by taking to identical signals of audio, leaving one of them intact while delaying the second one by a gradually changing period.

Phaser

It is very similar to flanger, in the fact that this effect takes two signals leaving one untouched while processing the other one with a small delay and altering the phase of it. When both signals are mixed the frequencies that are out of phase cancel each other.

Chorus

Once again we have two similar signals. One of them is slightly delayed and usually modulated with an LFO. This gives the impression of a thicker sound and we can perceive some kind of movement in the resulting sound.

Reverb

This effect is related to the reflections of sound in various surfaces before reaching the ear´s listener. With our reverb units (hardware or software) we can re-create an existing space, enhance certain sounds (like a vocal performance, for example) or create a totally weird ambience.

Now you´ll hear the audio processed  with delay, flanger, phaser, chorus and reverb (in taht order)

Filter Effects

These effects control the timbre of sound. Among them we find : high pass, low pass, band pass and EQs.

High pass filter

This filter allows, as it is suggested by its name, to pass frequencies that are over a determined one.

Low pass filter

It is exactly the opposite of the High pass filter. It allows to pass the frequencies that are below a certain point, attenuating the ones that are over that point.

Band pass filter

It allows to pass the frequencies that are in a determined band of frequencies, attenuating those that are below or above that range.

EQ

The EQ affects the timbre of the sound by enhancing or attenuating certain frequencies (boosting or lowing frequencies). It is a vital part of the music production. It can be used both as a corrective tool and as a creative tool. You can find different types of equalizers: graphic equalizers, parametric equalizers and paragraphic equalizers.

In the following example you´ll hear the audio processed with a high pass filter, a low pass filter, a band pass filter and an EQ filter (in that order).

Conclusion

As musicians, producers or sound engineers, it is vital for us to understand each category of effects, how they are produced and which impact they have on an audio source. This will give us the opportunity to use them in a creative way, knowing exactly what we are doing and achieving the results we want to achieve instead of random results.