How do you use filters and envelopes to create contrast and interest in your arrangements?

1 Filter types

A filter is a device or a plugin that modifies the frequency spectrum of a sound, allowing some frequencies to pass through and attenuating or blocking others. There are different types of filters, such as low-pass, high-pass, band-pass, and notch filters, each with a different effect on the sound. For example, a low-pass filter lets the low frequencies pass through and cuts off the high frequencies, creating a darker or muffled sound. A high-pass filter does the opposite, letting the high frequencies pass through and cutting off the low frequencies, creating a thinner or brighter sound. A band-pass filter lets a specific range of frequencies pass through and cuts off the rest, creating a narrow or focused sound. A notch filter cuts off a narrow band of frequencies, creating a notch or a dip in the spectrum, which can be useful for removing unwanted noises or resonances.

2 Filter parameters

Each filter has some parameters that you can adjust to control how the filter affects the sound. The most common parameters are cutoff frequency, resonance, and slope. The cutoff frequency is the point where the filter starts to attenuate or block the frequencies. The resonance is the amount of boost or emphasis that the filter applies around the cutoff frequency, creating a peak or a ring in the spectrum. The slope is the steepness or the rate of attenuation or blocking that the filter applies beyond the cutoff frequency, measured in decibels per octave (dB/oct). For example, a 12 dB/oct slope means that the filter reduces the level of the frequencies by 12 dB for every octave away from the cutoff frequency.

3 Envelope basics

An envelope is a device or a plugin that controls how the level or the amplitude of a sound changes over time, following a specific shape or curve. An envelope has four stages: attack, decay, sustain, and release, also known as ADSR. The attack is the time it takes for the sound to reach its maximum level from silence. The decay is the time it takes for the sound to drop from its maximum level to its sustain level. The sustain is the level that the sound maintains while the note is held. The release is the time it takes for the sound to fade out from its sustain level to silence after the note is released.

4 Envelope types

There are different types of envelopes that can control different aspects of the sound, such as volume, pitch, filter, or modulation. For example, a volume envelope controls how loud or soft the sound is over time, creating different dynamics and expressions. A pitch envelope controls how high or low the sound is over time, creating different pitches and glides. A filter envelope controls how the cutoff frequency of a filter changes over time, creating different timbres and colors. A modulation envelope controls how a modulation source, such as an LFO or an oscillator, changes over time, creating different effects and movements.