Week 5: Modulated Short Delay Effects (Flanger, Phaser, and Chorus)

This week we explored filter and delay effects. It was probably the most important week for practical knowledge. Understanding how filters work depends mainly on our capacity to experience these plug-ins, and being aware of the changing properties of the signal. 

However, the theory part of that knowledge is fundamental in the process of understanding it. While you probably had the opportunity to explore the characteristics of your specific plug-in, I think theory might get a little bit ignored. So I'll talk about the modulated short delay effects, and describe their function and how they work. 

Modulation effects are very helpful when trying to add dimension and depth to the signal. These effects are, actually, delays, but their delay time response is only a few milliseconds, and they use a low frequency oscillator (LFO), so it can't be perceived as such by our ears. That means these effects do not feature repetition of their signal, but rather they combine the original signal (dry) with the altered one (wet). That's what modulation means: by duplicating a signal with a particular alteration, the effect "modulates", changes a particular kind of adjustment of the original signal. 

I want to explore two of those modulation effects: Flanger and Chorus.

Flanger:
I did say this was a theory post. But to understand a good use of flanging, you should probably start by listening to the best Beatles album (yeah, the best, you heard me!): Revolver. It is said that it was John Lennon who named the effect. "Tomorrow never knows" is probably one of the best songs to demonstrate an awesome use of a flanger effect:



Do you hear it? Flanger could be described as the sound of a jet engine. It has a certain metallic quality to it...
Flanger is a Comb filtering effect, placed in motion. It means it is a delayed version of a signal added to itself. As a result, the frequency response consists of a series of spaced spikes, that simulate a comb. This is how it looks through a spectrum analyzer:

Flanger controls: In order to be a flanger, the Delay time has to be very short (pictured as "Rate", in the Logic effect panel). Being a modulated effect, both the original and edited signal should be present, so the Dry/Wet controller should feature both signals. (A 100% mix in the example means all wet, so 50% could be a standard). The amount of Feedback, how much the signal is sent back to itself, can give the effect more tonal presence, or make the sweeping more pronounced. 

Chorus:


Have you ever experienced listening to a choir? Well, that is literally what happens when you use this effect: there is more than one similar sound source, sounding almost at once, and almost at the same timbre. The little discrepancies between a group of singers is what makes you hear something and say, ok, that's a choir. Let's get out before communion starts. Chorus can give depth to a clean guitar, offering certain echo quality. It is featured, for example, in Nirvana's "Come as You Are":





Sorry to remind you of your 15 year old self. Yeah, this song has been more overplayed than O.J Simpson's race card, but still, such a good song. And the chorus effect helps to that: the opening rhythm guitar has some depth to it, like if there were several guitars playing at the same time. The effect is also heard when that high, piercing chord explodes just before Kurt starts the "Memori--a" bit, right under the minute mark of the video. 

Chorus works by passing the dry signal through the effect, which duplicates it and very slightly changes its pitch and playback speed. Again, being a modulated effect, you need the original signal, so having the effect with only the wet signal might give you an out-of-tune sound. 

Chorus controls: 
 Delay should be higher than the one in a Flanger, but not high enough to be an echo. Somewher between 15-30 ms is a good idea. Again, as a modulated effect, the Dry/Wet controller should feature both signals. The Frequency of the signal is determined by the Rate knob.In the Logic plugin, the Intensity slider sets the modulation amount of the chorus. 

There you have it. These effects add a very interesting effect to your signals, and are usually very helpful to create a very vivid environment. If you want to explore the effects, open your music library. I bet that, if you pay attention, you'll find cases where you can hear both of these effects in motion. 

Thanks for reading!