Delay effects – The flanger and phaser

Hello, I am Brandon Fallout from Seattle, WA in the USA. This lesson is for week 5 of Introduction To Music Production at Coursera.org. I will talk about two delay effects, the flanger and the phaser. If you missed last weeks post on Ableton Live 9 – Adding and using a compressor on a track , you can find it here.

 

The Flanger

The flanger is actually the name of an effects unit that produces a flanging effect. This flanging effect is created by mixing two identical audio signals together. One of the signals is delayed a small amount and is gradually changed over time, usually under 20ms of Delay Time. This creates a sweeping comb filter effect.

The comb filter effect consists of peaks and valleys in the resulting frequency spectrum. These peaks and valleys are related to each other in a linear harmonic series. By varying the time delay, they will sweep up and down the frequency spectrum.  This can be controlled via a modulating LFO.

Here are some good examples of the flanging effect in use. Many large bands use this effect for a variety of reasons. One very popular use of a flanger is to get a jet plane noise or that white noise rush that’s ever so popular in Trance music.

Credit for image to soundsonsound.com
This is a flanger circuit. The delay portion of the circuit applies equally to the entirety of the signal it receives.

 

 

The Phaser

What can be said about the flanger in many circumstances can also be said about a phaser. Two of the key differences however, consist of the All-Pass filters and the type of comb filter that it can produce.  It’s also worth noting that phasers typically exclude devices where the all-pass section is a delay line. Those devices would usually fall under the flanger category above.

The part of the signal that is fed into the all-pass filter has it’s amplitude preserved but it’s phase altered.  The amount of change in phase depends on the frequency. Depending on the amount of All-Pass filters, you can affect several different frequency ranges at once. Once the processed signal gets mixed back in with the original signal, the frequencies that are out of phase will cancel each other out. This will create a comb filter.

The comb filter of a phaser, unlike a flanger, tends to have less uniformly-spaced peaks and valleys. The overall amount of these teeth in the signal tend to be smaller as well and less numerous throughout the mix. They also tend to be unevenly spaced and vary depending on the manufacture of the plugin or hardware.

The phaser effect is popularly used with the electric guitar to create otherworldly sounds. You can find a lot of phaser usage in styles such as Reggae, Funk and even 80’s Big Rock.

Credit for image goes to soundsonsound.com
This is a four-stage phaser. It utilizes four all-pass filters to delay different frequencies in the original signal by varying amounts.

 

 

Dry/Wet, feedback and the LFO

By utilizing a feedback function, part of the output signal is routed back into the input. This will produce a resonance effect that can further enhance the intensity of the peaks and valleys in the signal.

The dry/wet setting in your effects unit shifts the output of the signal from output = input at 100% dry to output = fully processed signal at 100% wet and any place in between. For example, a 50/50 mix of dry/wet would mix 50% of the original signal with 50% of the delayed or processed signal.

The LFO for the flanger and phaser works as a modulator. The flanger LFO can modulate the delay to create a sweeping like sensation. The LFO modulator sweeps those notches and peaks up and down the frequency range  by tweaking the All-Pass filters. This can create a spacey whoosh and swirl-like sound.

 

That’s all today kids, thanks for reading!

 

 

Credit goes to wikipedia and soundonsound.com for research and base material.

 

 

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