History and Evolution of Sample-Based Synthesis

In the early days of electronic music, pioneers strived to create convincing reproductions of real-world acoustic instruments. However, the technology of the time was restrictive, and the methods utilized, such as subtractive synthesis and FM synthesis, were imperfect in achieving accurate musical imitations.

Amid the development of subtractive synthesis in the 1950s and 1960s, the idea of using recorded samples or 'sampling' as a synthesis method was recognized. Despite this, sample-based synthesis didn't truly hit the mainstream until the late 1980s. This shift was a result of a decrease in the cost of RAM and processing power, enabling more samplers to enter the market.

As high-capacity memory and direct-from-disk sample streaming became available, the constraints of dedicated hardware samplers were overcome. This innovation allowed for the production of comprehensive sample sets that encompassed the most delicate aspects of an instrument's sound. Today, advanced software samplers like Native Instruments' Kontakt and Steinberg HALion have achieved the potential of sample-based synthesis, creating detailed and authentic replications of acoustic instruments.

Introduction to Sample-Based Synthesis

Sample-based synthesis is a distinctive form of audio synthesis that employs sampled sounds or instruments, unlike other synthesis forms such as subtractive synthesis or additive synthesis, which utilize fundamental waveforms like sine and saw waves.

Sample-and-synthesis (S&S) synths emerged in the mid-1980s and are a specific type of sample-based instruments. These are essentially samplers with preset, fixed samples, also known as ROMplers. They are renowned for convincingly mimicking real-world acoustic instruments.

For beginners in sample-based synthesis, various plugins may prove useful. IK Multimedia's Sampletank is a notable S&S plugin, although the boundary between S&S and a true sampler is increasingly blurred. Many instruments referred to as S&S synths are, in fact, sample banks constructed on top of a fully-equipped software sampler like Native Instruments' Kontakt or Steinberg's HALion.

To navigate the vast world of audio synthesis, beginners should first grasp the basic components that govern most synths. This understanding can facilitate exploration of the myriad types of synthesis available.

The Mechanics of Sample-Based Synthesis

Sample-based synthesis uses sampled sounds or instruments as the foundation for its sounds, contrasting with the fundamental waveforms such as sine and saw waves employed in other synthesis types. The process entails recording (or sampling) a sound into digital memory.

A sampler, a more versatile design of sample-based synthesis, permits the user to record arbitrary waveforms to form a sound's fundamental timbre. Although early samplers were rather expensive and had low sample rates and bit depth leading to grainy and aliased sound, samplers since the late 1980s have showcased specifications as good as, if not better than, CDs.

Looping, pitch shifting, and data reduction are the three core concerns in sample-based synthesis. Looping extends the shortest possible samples, pitch shifting facilitates variations when spreading one sample across several notes, and data reduction aids in managing memory and storage.

Sample-based synthesis can be accomplished through different machines. Samplers can convert a continuous analog sound into the digital realm, allowing it to be processed and played back. ROMplers, such as drum machines and synthesizers, offer similar sound design capabilities but only with pre-loaded sampled sounds. Hybrid synthesizers offer a mix of digital sampled waveforms and analog subtractive synthesis.

Subtractive synthesis and additive synthesis are two other prevalent forms of synthesis. Subtractive synthesis begins with a harmonically rich sound and then removes harmonics from it using a filter and volume with an envelope. Conversely, additive synthesis uses numerous harmonic partials of sine waves that, when combined, create harmonically rich sounds.

Sample-based synthesis can authentically replicate real-world acoustic instruments with minimal user input. However, it provides less control over the sound's timbre compared to other synthesis methods. This is because the sound source in sample-based synthesis is recorded samples, arranged on a keyboard in different zones. Each sample is pitch-shifted to span approximately five notes until a new sample is needed.