Illustrate a detailed workflow for effective sound design using a subtractive synthesizer, emphasizing the manipulation of oscillators, filters, and envelopes to create a specific, evolving sound texture.

A detailed workflow for effective sound design using a subtractive synthesizer revolves around a systematic approach to manipulating its core components—oscillators, filters, and envelopes—to craft a specific, evolving sound texture. Subtractive synthesis, as the name suggests, begins with a harmonically rich sound source (the oscillator) and then shapes it by filtering and modifying it with envelopes and other modulation sources.

The first step involves selecting the oscillators. Most subtractive synthesizers have multiple oscillators that can be set to various waveforms, such as sine, triangle, square, and sawtooth. Each of these waveforms has a unique harmonic content that affects the overall timbre. For instance, a sine wave produces a pure tone with no harmonics, whereas a sawtooth wave is rich in both even and odd harmonics, making it suitable for creating bright, buzzing sounds. The choice of oscillator waveform will be fundamental to the sound we will make. It would make sense to pick a richer waveform such as a sawtooth if we want a more prominent or aggressive sound, or a sine wave if we want a purer, more subdued one. A simple example might include combining a sawtooth wave for a main aggressive tone, and a triangle wave pitched an octave higher for a gentler supporting one. Sometimes tuning the oscillators away from each other will provide phasing or chorus type effects making the tone thicker.

Next, oscillator tuning, including coarse and fine tuning, and the use of unison or detune features, contribute to the overall texture. A slightly detuned unison can give the sound a "thick" and lush feeling, ideal for pads and leads. A saw wave detuned in a unison with several voices is a very common element in trance. This allows for a wide, rich texture that is characteristic of the genre. In the same way, different waveforms combined and detuned give the sound character. After having the sound source, we need to modify it.

The filter section is where subtractive synthesis comes to life. The filter removes specific frequencies from the oscillator's sound based on user input. A low-pass filter allows low frequencies to pass while attenuating higher frequencies, resulting in a warmer, more mellow tone. A high-pass filter does the opposite, allowing higher frequencies through and making the sound thinner and brighter. Band-pass filters allow a range of frequencies and attenuate frequencies outside the range and can achieve a sound with a sharp and resonant quality. The most important parameter in a filter is the cutoff frequency; when it is manipulated, it can create movement and animation. The resonance parameter is also very important and boosts frequencies around the cutoff point, enhancing the filter's effect and causing it to scream when high.

For example, to create a synth bass, we can start with a sawtooth wave and then use a low-pass filter to cut out the harsh high frequencies, which will give the sound more body and low-end warmth. Then we will add resonance to emphasize the harmonics and make it a more prominent bass. If we wanted a more high-frequency aggressive tone we might use a high-pass filter to emphasize the harmonics of a saw wave. The key idea here is to carefully shape the harmonic content that we got from the oscillators by using the filter.

Envelopes provide a dynamic way to modulate various parameters over time. An ADSR (Attack, Decay, Sustain, Release) envelope is the most common type. The attack controls how fast the parameter reaches its peak, decay controls how quickly it falls from peak to sustain, sustain controls how long it stays at that level, and release controls how quickly it fades back to zero. Envelopes can be assigned to the filter cutoff, amplifier volume, or pitch to add movement and expression to a sound.

For example, to create a pluck sound we can use an envelope assigned to the filter cutoff. We might set the attack to zero, decay to a fast rate, sustain to a low or non-existent level, and release to a fast rate. This gives the sound a sharp attack and a quick decay, simulating a plucked string. We might also apply the envelope to the amplifier, again giving the sound a quick attack and a quick fade to zero. On the other hand if we wanted a pad sound we could have very slow attack and decay stages for all our parameters.

Now to put it all together. Imagine creating a pad sound. We might use two detuned sawtooth waves with slightly different octaves. We will add a low pass filter, and modulate its cut-off frequency with an envelope with slow attack and decay times, allowing the filter to open slowly and close slowly. Then, we will modulate the filter cutoff also with a slow LFO (low frequency oscillator) to add some movement and variation. We might also add a bit of delay and reverb to give it spatial character. This makes a slow evolving pad.

Finally, experimentation is key. Sometimes, deliberately making unconventional decisions will lead to unique textures and sounds. This workflow focuses on the deliberate and controlled manipulation of oscillators, filters, and envelopes, to allow the producer to create a focused and professional sound. By understanding how each component interacts, producers can transform simple waveforms into complex, textured soundscapes that are unique and evolving.