Sampler (musical instrument)
A sampler is an electronic musical instrument that records and plays back samples. Samples may comprise elements such as rhythm, melody, speech, sound effects or longer portions of music.
The mid-20th century saw the introduction of keyboard instruments that played sounds recorded on tape, such as the Mellotron. As technology improved, cheaper standalone samplers with more memory emerged, such as the E-mu Emulator, Akai S950 and Akai MPC.
Samples may be loaded or recorded by the user or by a manufacturer. The samples can be played back by means of the sampler program itself, a MIDI keyboard, sequencer or another triggering device. Because these samples are usually stored in digital memory, the information can be quickly accessed. A single sample may be pitch-shifted to different pitches to produce musical scales and chords.
Often samplers offer filters, effects units, modulation via low frequency oscillation and other synthesizer-like processes that allow the original sound to be modified in many different ways. Most samplers have Multitimbrality capabilities – they can play back different sounds simultaneously. Many are also polyphonic – they are able to play more than one note at the same time.
History
Prior to computer memory-based samplers, musicians used tape replay keyboards, which store recordings on analog tape. When a key is pressed the tape head contacts the moving tape and plays a sound. The Mellotron was the most notable model, used by a number of groups in the late 1960s and the 1970s, but such systems were expensive and heavy due to the multiple tape mechanisms involved, and the range of the instrument was limited to three octaves at the most. To change sounds a new set of tapes had to be installed in the instrument. The emergence of the digital sampler made sampling far more practical.The earliest digital sampling was done on the EMS Musys system, developed by Peter Grogono, David Cockerell and Peter Zinovieff at their London Studio c. 1969. The system ran on two mini-computers, Digital Equipment PDP-8's. These had a pair of fast D/A and A/D converters, 12,000 bytes of core memory, backed up by a hard drive of 32k and by tape storage. EMS equipment was used to control the world's first digital studio, and their earliest digital sampling was done on that system during 1971–1972 for Harrison Birtwistle's "Chronometer" released in 1975.
Image:Fairlight green screen.jpg|thumb|152px|Fairlight CMI
The first commercially available sampling synthesizer was the Computer Music Melodian by Harry Mendell, while the first polyphonic digital sampling synthesizer was the Australian-produced Fairlight CMI, first available in 1979. These early sampling synthesizers used wavetable sample-based synthesis. The Fairlight CMI played and recorded low quality samples at 8-bit audio depth and 824 kHz sampling rate.
In 1981, Toshiba introduced the LMD-649 in Japan. It was an early digital sampler that played and recorded high quality pulse-code modulation samples at 12-bit audio depth and 50 kHz sampling rate, stored in 128 KB of dynamic RAM. It was created by engineer Kenji Murata for Japanese electronic music band Yellow Magic Orchestra, who used it for extensive sampling and looping in their 1981 album Technodelic. The LMD-649 was also used by other Japanese synthpop artists in the early 1980s, including Chiemi Manabe and Logic System.
Sampling keyboards were notable for their high price which was out of reach for the majority of working musicians – with the early Fairlight starting at $30,000. The E-mu Emulator brought the price down to under $10,000 but it was not until the mid-1980s that genuinely affordable keyboard samplers began to hit the market with the Ensoniq Mirage in 1985 and the E-mu Emax the following year, which had a sub-$2000 price point. The Korg DSS-1 and Roland's S-Series followed shortly afterwards.
During the 1980s, hybrid synthesizers began to utilize short samples along with digital synthesis to create more realistic imitations of instruments than had previously been possible. Examples are the Korg M1, Roland U-110, Yamaha's SY series, and the Kawai K series of instruments. Limiting factors at the time were the cost of physical memory and the limitations of external data storage devices, and this approach made best use of the tiny amount of memory available to the design engineers.
The E-mu SP-1200 percussion sampler, upon its release in August 1987, popularized the use of digital samplers within hip hop music in the late 1980s. Akai pioneered many processing techniques, such as crossfade looping and "time stretch" to shorten or lengthen samples without affecting pitch and vice versa. The Akai MPC60, released in 1988, went on to become the most influential sampler in hip hop music. That same year, the Ensoniq EPS – the successor to the Mirage – was launched and was the first sampling keyboard which was designed specifically for live performance rather being a purely studio based tool as most samplers had been hitherto.
In 1989, Keyboard Magazine published a comparison of samplers from Akai, Casio, E-MU, Ensoniq, Fairlight, Korg, Kurzweil, New England Digital, Oberheim, Roland, Sequential, Simmons, WaveFrame, and Yamaha. Prices ranged from $800 - $250,000.
The 2010s-era music workstation usually uses sampling, whether simple playback or complex editing that matches all but the most advanced dedicated samplers, and also includes features such as a sequencer. Samplers, together with traditional Foley artists, are the mainstay of modern sound effects production. Using digital techniques various effects can be pitch-shifted and otherwise altered in ways that would have required many hours when done with tape.
Elements
Interface
Usually a sampler is controlled by an attached music keyboard or other external MIDI controller or source. Each note-message received by the sampler accesses a particular sample. Often multiple samples are arranged across the keyboard, each assigned to a note or group of notes. Keyboard tracking allows samples to be shifted in pitch by an appropriate amount, typically in semitones and tones. Each group of notes to which a single sample has been assigned is often called a "keyzone", and the resultant set of zones is called a keymap.For example, in Fig 1, a keymap has been created with four different samples. Each sample, if pitched, should be associated with a particular center pitch. The first sample is distributed across three different notes, G2, G#2, and A2. If the note G#2 is received the sampler will play back the Violin G#2 sample at its original pitch. If the note received is G2 the sampler will shift the sample down a semitone while the note A2 will play it back a semitone tone higher. If the next note is input the sampler will select the Violin B2 sample, playing it a semitone lower than its center pitch of B2.
In general, samplers can play back any kind of recorded audio. Most samplers offer editing tools that allow the user to modify and process the audio and apply a wide range of effects. This makes the sampler a powerful and versatile musical tool.
Hierarchy
A sampler is organized into a hierarchy of progressively more complicated data structures. At the bottom lie samples, individual recordings of any sound, recorded at a particular sample rate and resolution. While a common sound to sample is a musical instrument being played, a sample could be any sound, including "non-musical" sounds such as a typewriter clacking or a dog barking. A reference center pitch indicates the actual frequency of the recorded note. Samples may also be "looped" by defining points at which a repeated section of the sample starts and ends, allowing a relatively short sample to play endlessly. In some cases, a "loop crossfade" is indicated, allowing less obvious transitions at the loop point by fading the end of the loop out while fading its beginning in.Keymaps are arranged into instruments. At this level parameters may be added to define how the keymaps are played. Filters can be applied to change the sound-color while low frequency oscillators and envelope generators can shape the amplitude, pitch, filter or other parameters of the sound. Instruments may have multiple layers of keymaps to play more than one sample at the same time and each keymap may have a different set of parameters so that the incoming note-events affect each layer differently. For example, two layers may have a different sensitivity to the velocity of the incoming note, altering the resulting timbre according to how hard the note is played.
At this level, there are two basic approaches to sampler organization. In a bank approach, each instrument is assigned to a different MIDI channel and multiple banks can be stored to reconfigure the sampler. A different and more powerful approach is to associate each instrument with a patch number or ID so that each MIDI channel can be configured separately by sending controller information on the individual channel.
Types
Many samplers work as described above: the keymapping system "spread out" a sample over a certain range of keys. This has side-effects that may be desirable in some contexts, such as speeding up or slowing down drum loops. However, the higher and lower-pitched parts of such a keymap may sound unnatural. For example, if a harpsichord is sampled in its lower register and then the samples are moved up to very high pitches, the high notes may not sound natural and authentic. When arranging a pitched instrument over several keymaps, the transition from one to another may be too noticeable for realistic imitation of the instrument – the art is to make transitions as smooth as possible.Some phrase samplers are more optimised for triggering single "one-shot" sounds such as drum hits. Each keymap spans only a single key, requiring a large number of zones, each with its own settings. "Phrase sampling" aims to simplify this, particularly on interfaces such as the 16 pads on the Akai MPC series: the fact that each pad is actually a note is hidden from the user. The sampling engine does not re-pitch samples, it only plays them back. The user interface is simplified. Phrase samplers often have a groovebox format, which makes them lightweight, easy to operate and light to carry.