UNDERSTANDING SOUND & SYNTHESIS

Exploring the Minimoog Model D App can be a rewarding experience, regardless of your level of synthesizer expertise. But to understand the synthesizer, it's a good idea to know a few things about sound, too.

UNDERSTANDING SOUND

The sounds we hear are vibrations in the air, caused by a vibrating source such as the string of a guitar, the reed of a clarinet, or the column of air in a flute. One of the things that makes each sound different is the speed at which it vibrates; this frequency determines the pitch of the sound, or the note. Now, obviously a flute and a guitar and a clarinet playing the same note at the same frequency don’t all sound alike, so there is more to it than that.

In addition to pitch, another factor is how the sound behaves over time. A note played on the guitar will begin to die away almost immediately. The flute and the clarinet will continue to sound as long as the player breathes air into the instrument. And while the guitar can continue to sound as it dies away, the flute and clarinet cease to sound right as the airflow stops. This change in dynamics over time is referred to as the loudness contour.

The last thing we can look at is the tonal content of the sound itself. In musical terms, this is called the timbre (pronounced tam’–br, as in tambourine, not tim’–br, as in a tree falling). Each instrument produces a different waveform, and different waveforms carry a different harmonic content. The flute in our example is very close to a pure sine wave, with little or no overtones. But the clarinet and guitar each have a much more complex waveform, with a distinctive harmonic content. By understanding the pitch, the contour, and the harmonic content of a sound, we can learn how to use the synthesizer more effectively.

UNDERSTANDING THE SYNTHESIZER

Every synthesizer – even an integrated synthesizer such as the Minimoog Model D App – is at heart a collection of individual modules. Each module contains specific circuitry to control a certain aspect of the sound being created.

Oscillators

The sound-generating circuitry has no physical moving parts like a guitar string or a clarinet reed. Instead, the Minimoog Model D App oscillators create an electronic signal that changes direction very rapidly. Connected to a loudspeaker, that electronic voltage moves the speaker to create the sound we hear. How smoothly the signal changes direction determines the waveform, or wave shape, which in turn determines the harmonic content.

The Filter

Minimoog Model D App uses a low-pass “ladder” filter design. Even though each waveform has a distinct harmonic content, using the filter changes that content by selectively removing some of the upper harmonics, which carry a higher frequency. Lowering the Cutoff Frequency of the Filter will cause more upper harmonic content to be filtered out.

Contour Controls (Envelope Generators)

The Contour controls determine how the sound changes over time. The Loudness Contour determines how the amplitude, or volume, of the sound changes over time – how fast the sound comes on (Attack Time); how fast the sound falls (Decay Time) to a preset level (Sustain Level) and how the sound dies out after the key, or note is released. The Filter Contour has the same parameters, but they are used to control the Cutoff Frequency of the Filter over time, and not the amplitude.

Modulation

Modulation paths allow the synthesizer modules to interact with one another to create more complex sounds. In addition, dedicated Modulation sources can be assigned to the Modulation wheel, and freely introduced as part of a performance.

Block Diagram Of The 2016 Minimoog Model D Hardware Synthesizer

This illustration shows the major synthesizer components, plus the audio and control pathways between them.