Sound Design Tutorial - Subtractive Synthesis

Summary

This video explains the core techniques of sound synthesis, focusing on additive and subtractive methods. Additive synthesis involves layering frequencies to build complex sounds, while subtractive synthesis removes unwanted frequencies using filters. The video covers key concepts such as filter types (low-pass, high-pass, band-pass), pulse width modulation (PWM), resonance, and key tracking. By exploring both approaches, the tutorial provides practical tips for sound design, emphasizing how filters and modulation shape the tonal quality of sounds. Whether using filters for sculpting or adding harmonics through modulation, the video demonstrates essential tools for crafting unique sounds.

Takeaways

• 😀 Additive synthesis involves adding frequencies to a basic waveform like a sine wave to create a more complex sound.
• 😀 Subtractive synthesis involves removing frequencies from a waveform, such as a saw wave, to shape the sound.
• 😀 Additive synthesis is likened to painting, where frequencies are added to a sound, while subtractive synthesis is compared to sculpting, where frequencies are removed using tools like filters.
• 😀 Filters are essential tools in subtractive synthesis, used to remove or attenuate specific frequency ranges, shaping the sound.
• 😀 The most common types of filters are low-pass (allowing low frequencies to pass), high-pass (allowing high frequencies to pass), and band-pass (allowing a specific range of frequencies to pass).
• 😀 The filter cutoff frequency controls the point where filtering starts, and the slope (e.g., 12 dB or 24 dB per octave) defines how quickly the frequencies are attenuated beyond the cutoff point.
• 😀 Resonance can boost frequencies near the cutoff point, adding emphasis to certain harmonics or giving a more pronounced effect.
• 😀 Key tracking ensures that the filter cutoff moves according to the pitch of the note being played, maintaining consistent harmonic content across different pitches.
• 😀 Pulse Width Modulation (PWM) can be used to create variations in a waveform's harmonics, such as removing every second, third, or fourth harmonic, shaping the timbre of the sound.
• 😀 Filters like comb and phaser filters can produce unique effects, such as emulating vowel sounds or creating metallic, bell-like textures in the sound.
• 😀 Synthesizers like the Yamaha DX7 introduced additive synthesis techniques like frequency modulation, which can generate complex and unique sounds even from simple sine waves.

Q & A

What is the main difference between additive and subtractive synthesis?

Additive synthesis involves adding frequencies to a basic waveform (such as a sine wave) to create more complex sounds, whereas subtractive synthesis starts with a rich waveform (like a saw wave) and removes frequencies using filters to shape the sound.

How does subtractive synthesis work in sound design?

In subtractive synthesis, we use filters to remove certain frequencies from a waveform, sculpting the sound. Common filters include low-pass (cuts high frequencies), high-pass (cuts low frequencies), and band-pass (cuts both extremes). The result is a more refined and controlled sound.

What role do filters play in subtractive synthesis?

Filters are used to attenuate or eliminate unwanted frequencies, allowing sound designers to shape the overall character of the sound. They can remove high or low frequencies or target specific frequency ranges, providing greater control over the sound's tonal balance.

What is key tracking, and how does it affect the sound?

Key tracking is a feature that adjusts the cutoff frequency of a filter based on the pitch of the note being played. This ensures that the harmonic content of the sound remains consistent across the keyboard, particularly when using filters to shape the sound.

What is pulse width modulation (PWM), and how does it affect a waveform?

Pulse width modulation (PWM) is a technique primarily used with square waves. By modulating the pulse width (the duration of the wave), certain harmonics are removed, which alters the timbre. This technique can create evolving and dynamic changes in the sound.

What is the significance of the resonance control in a filter?

Resonance controls the boost of frequencies at the cutoff point of a filter, emphasizing specific harmonic content and adding emphasis or sharpness to the sound. Increasing resonance can create a more pronounced filter effect and can even result in a ringing sound at the cutoff frequency.

How does a low-pass filter differ from a high-pass filter?

A low-pass filter allows low frequencies to pass through while attenuating higher frequencies, effectively 'cutting off' the high-end. In contrast, a high-pass filter allows high frequencies to pass through while cutting off lower frequencies.

What is the effect of the 'cutoff' parameter in a filter?

The cutoff parameter determines the frequency at which a filter begins to attenuate the signal. For example, a low-pass filter will allow frequencies below the cutoff point to pass through, while frequencies above the cutoff will be reduced or removed.

How can you combine filters in a synthesizer to achieve different sounds?

Filters can be combined in series (where one filter processes the signal and the output is sent to another filter) or in parallel (where multiple filters process the signal simultaneously). This allows for more complex and layered filtering effects, enabling a wider range of tonal possibilities.

What is the difference between a band-pass filter and a band-stop filter?

A band-pass filter allows a specific range of frequencies to pass through while filtering out frequencies outside of that range. A band-stop filter, on the other hand, removes a specific range of frequencies and allows frequencies outside that range to pass through.