Modulating delay lines

One of the most important building blocks of digital signal processing is the delay line. Combined with basic arithmetic operations like addition and multiplication, we can make a large variety of filters.

«A digital filter is a computational process or algorithm by which a digital signal or sequence of numbers (acting as input) is transformed into a second sequence of numbers termed the output digital signal” (Rabiner et al. 1972)»

In daily parlor we tend to call many of the processes we apply to a signal «an effect». However, it is just as correct to call it a filter, since any process that changes the signal can be termed a filter.

In this lesson we will be looking at effects based on a delay line with a continuously varying delay time. With this simple arcitecture we can build effects like Chorus and Flanger. We will also be looking a the Phaser effect, since it's sound is somewhat similar to the Flanger. The Chorus and Flanger effects are very similar in architecture, but the Phaser effect is constructed differently.

Lesson subjects:

• Chorus
• Flanger
• Phaser