This lesson covers many different examples of using delay for music production and sound transformation. Many references can be found in Max and on the internet but also you can find them well explained in Cipriani’s volume n.2, pages 206-304 (available a library, and also as ebook – cheaper than paperback).
Filter or Echo
The first important distinction when working with delayed signal lines is between filter and echo. Following up from
Following up from Lesson 7, by creating a copy of a signal and playing it back with a slight delay to the original would produce to our ears a number of acoustic effects. The first ones are those of filtration. More technically, with the term ‘filtration’ I refer to the acoustic phenomena of constructive and destructive interference. At the ears, the merging of the two copies (the original and the delayed) of the signals causes an increase in amplitude at certain frequencies and a reduction in amplitude of other frequencies.
Over a certain amount of delay, filtration effects are no more as the ear starts clearly distinguishing two identical but distinct sounds. When two distinct sounds are heard that is what we call ‘echo‘. The echo threshold greatly depends on the type of sound, its attack and release transients and body. Usually, for a short percussive sound, an echo is heard quite sooner than for a violin bow sound, for example.
The most common echo effects are the slapback, the multitap delay, ping pong delay. There is also a multiband slap delay, which features an interesting process of band separation with the Max object cross~.
For filtration effects, it is important to distinguish between fixed delay windows and changing delay windows. Comb and all-pass filters use fixed delay windows although arranged in a specific way, but flanger and the chorus, are effects that act on very small delay window that changes in time.
Other important effects can be produced with the feedback technique, as it pairs the power of creating delay windows and interferences between sounds with the control of its total duration, adjusting the amount of repetition of the interferences.
In Lesson 7, the flanger and chorus effects have been already discussed in detail. Here in Lesson 8 will follow the detailed description of some of the mentioned effects.