Weapon
of Choice: The Digital Sampler
A
sampler is an electronic music instrument closely
related to a synthesizer. Instead of generating sounds from scratch,
however, a sampler starts with multiple recordings (or “samples”)
of different sounds, and then plays each back based on how the instrument
is configured. Because these samples are usually stored in RAM,
the information can be quickly accessed.
Unlike traditional digital audio playback, each sample is associated
with a set of synthesis parameters, and can thus be modified in
many different ways.
Most samplers have polyphonic capabilities: they are able to play
more than one note at the same time. Many are also multitimbral:
they can play back different sounds at the same time.
Usually a sampler is controlled from an attached music keyboard,
or from an external MIDI source. Each note value input into the
sampler then accesses a particular sample. Often, multiple samples
are arranged across the musical range, and assigned to a group of
notes. If keyboard tracking is enabled, then the sample is shifted
in pitch by an appropriate amount. 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. When a note value
is input to the sampler, it looks at the value, and plays back the
sample associated with that note.
Samplers have more uses than just instruments and can play
back any type of recorded audio. This makes them very powerful
tools for sound effects, experimental or unusual instruments.
In general samplers will have editing facilities to accommodate
editing and processing of the sounds on it. To be able to apply
effects etc on the sounds it stores.
Hierarchy
A sampler is organized into a hierarchy of progressively more complicated
data structures.
At the bottom lie the samples. Samples are individual
recordings of any imaginable sound. Each will have been recorded
at a particular sample rate and resolution. It is convenient, if
the sample is pitched, that a reference center pitch is included.
This pitch indicates the actual frequency of the recorded note.
Samples may also have loop points, that indicate where a repeated
section of the sample starts and ends. This allows a relatively
short sample to play endlessly. In some cases, a loop crossfade
is also indicated, which allows for more seamless transitions at
the loop point by fading the end of the loop out while simultaneously
fading the beginning of the loop in.
The samples are arranged into keymaps, or collections
of samples distributed across the range of notes. Each sample placed
into a keymap region should then reference which note value will
play back the sample at original pitch.
These keymaps are arranged into instruments. At
the instrument level, additional parameters may be added to define
how the keymaps are played. For example, filters can be applied
to change the color, low frequency oscillators and envelope generators
can shape the amplitude, pitch, filter, or other parameter. Instruments
may or may not have multiple layers of keymaps. A multilayer instrument
will be able to play more than one sample at the same time. Often
each keymap layer has a different set of parameters, so that the
input effects each layer differently. For example, two layers may
have different velocity sensitivity, and thus a note with a high
velocity may accentuate one layer over another.
At this level, there are two basic approaches to sampler organization.
In a bank approach, each MIDI channel is assigned
a different instrument. Multiple banks can then be stored to reconfigure
the sampler.
A different, and more powerful approach is to associate each instrument
with a patch number or ID. Then, each MIDI channel can be configured
separately by sending patch change information to the individual
channel. This allows much more flexibility in how the sampler is
configured.
Historical Overview
The emergence of the digital sampler made sampling far more practical,
and as samplers added progressively more digital processing to their
recorded sounds, they began to merge into the mainstream of modern
digital synthesizers. The first digital sampling synthesizer was
the Computer Music Melodian which was first available
in 1976. The first polyphonic digital sampling synthesizer was the
Australian-produced Fairlight CMI which was first
available in 1979.
Prior to computer memory-based samplers, musicians used tape replay
keyboards, which stored recordings of musical instrument notes and
sound effects on analog tape.
Modern digital samplers use mostly digital technology to process
the samples into interesting sounds. Akai pioneered
many processing techniques, such as Crossfade Looping to eliminate
glitches and Time Stretch which allows for shortening or lengthening
of samples without affecting pitch and vice versa.
During the early 1990s hybrid synthesizers began
to emerge that utilized very short samples of natural sounds
and instruments (usually the attack phase of the instrument)
along with digital synthesis to create more realistic instrument
sounds. Examples of this are Korg M1, Korg O1W
and the later Korg Triton and Korg Trinity series,
Yamaha's SY series and the Kawai K series of instruments.
The modern-day music workstation usually features an element of
sampling, from simple playback to complex editing that matches all
but the most advanced dedicated samplers.
Samplers, together with traditional Foley artists, are the mainstay
of modern sound effects production.
Examples of digital samplers
Computer Music Melodian
Computer Music Inc. was started in New Jersey USA in 1972 by Harry
Mendell and Dan Coren. The company was established to develop and
market musical instruments based on computer software.
The Melodian was based on the Digital Equipment Corporation
PDP-8 computer and hand wired D/A and A/D conversion and tracking
anti-aliasing filters. The Melodian was first used by Stevie Wonder
in the "Secret Life of Plants" (1979). The Melodian was
a monophonic synth with 12 bit A/D and sampling rates up to 22 kHz.
It was designed to be compatible with analog synthesizers and had
a feature where it would sync to the pitch of an analog synth, such
as an Arp 2600. This means the Melodian captured all of the frequency
modulation effects, including the touch ribbon control. It also
could trigger of the ARPs keyboard so it could almost be thought
of as a hybrid sampler/analog synth, making best use of the technology
that was available at the time.
Fairlight Instruments
Fairlight Instruments was started in Sydney Australia in 1975
by Peter Vogel and Kim Ryrie. The company was originally established
as a manufacturer and retailer of video special effects equipment.
The Fairlight CMI or Computer Music Instrument, released in (1979),
started life as the QASAR M8. The M8 was hand wired and legend has
it that it took 2 hours to boot up. The CMI was
the first commercially available digital sampling instrument. The
original Fairlight CMI sampled using a resolution of 8-bits at a
rate of 10 kHz and was comprised of two 8-bit Motorola 6800 processors,
which were later upgraded to the more powerful 16/32-bit Motorola
68000 chips. It was equipped with two six-octave keyboards, an alphanumeric
keyboard, and an interactive video display unit (VDU) where sound
waves could be edited or even drawn from scratch using a light pen.
Software allowed for editing, looping, and mixing of sounds which
could then be played back via the keyboard or the software-based
sequencer. It retailed for around US$25,000.
In 1982, Fairlight released the Series II which doubled the sampling
rate to 16 kHz. The Series IIx was released in 1983 and was the
first to feature basic MIDI functionality. 1985 saw the release
of the Series III which upped the sampling resolution to 16-bits.
SMPTE was also added in this final version. Notable users of the
Fairlight CMI include Peter Gabriel, Trevor
Horn, Art of Noise, Yello, Pet Shop Boys,
Jean-Michel Jarre,and Kate Bush.
E-mu Systems
E-mu Emulator (1981) was E-mu Systems initial foray into sampling,
and saved the company from financial disaster after the complete
failure of the Audity due to a price tag of $70,000!
The name 'Emulator' came as the result of leafing through a thesaurus
and matched the name of the company perfectly. The Emulator came
in 2-, 4-, and 8-note polyphonic versions, the 2-note being dropped
due to limited interest, and featured a maximum sampling rate of
27.7 kHz, a four-octave keyboard and 128 kB of memory.
E-mu Emulator II (1985) was designed to bridge the gap between the
Fairlight CMI and Synclavier and the Ensoniq Mirage.
It featured 8-bit sampling, up to 1 MB of sample memory, an 8-track
sequencer, and analog filtering. With the addition of the hard disk
option, the Emulator II was comparable to samplers released 5 years
later.
E-mu Emulator III (1987) was a 16-bit stereo digital sampler with
16-note polyphony, 44.1 kHz maximum sample rate and had up to 8
MB of memory. It featured a 16 channel sequencer, SMPTE and a 40
MB hard disk.
E-mu SP-1200 was, and still is, one of the most highly regarded
samplers for use in hip-hop related production. Its 12-bit sampling
engine gave a desirable warmth to instruments and a gritty punch
to drums. It featured 10 seconds of sample time spread across four
2.5-second sections.
Akai
Akai entered the electronic musical instrument world in 1984
with the first in a series of affordable samplers the S612, an 8bit
digital sampler module. The S612 was superseded in 1986 by the 12
bit S900.
The Akai S900 (1986) was the first truly
affordable digital sampler. It was 8-note polyphonic and
featured 12-bit sampling with a frequency range up to 40 kHz and
up to 750 kB of memory that allowed for just under 12 seconds
at the best sampling rate. It could store a maximum of 32 samples
in memory. The operating system was software based and allowed for
upgrades that had to be booted each time the sampler was switched
on.
The Akai MPC60 Digital Sampler/Drum Machine and
MIDI Sequencer (1987) was the first non rack mounted model released.
It is also the first time a sampler with touch sensitive trigger
pads was produced by AKAI.
The Akai S950 (1988) was an improved version of the S900, with a
maximum sample frequency of 48 kHz and some of the editing features
of the contemporary S1000.
The Akai S1000 (1988) was possibly the most popular
16-bit 44.1 kHz stereo sampler of its time. It featured 16-voices,
up to 32 MB of memory, and 24-bit internal processing, including
a digital filter (18dB/octave), an LFO, and two ADSR envelope generators
(for amplitude and filtering). The S1000 also offered up to 8 different
loop points. Additional functions included Auto looping, Crossfade
Looping, Loop in Release (which cycles through the loop as the sound
decays), Loop Until Release (which cycles through the loop until
the note begins its decay), Reverse and Time Stretch (version 1.3
and higher).
Other samplers released by AKAI include the MPC1000, MPC2000, MPC2000XL,
MPC3000, MPC3000XL, MPC3000LE and the MPC4000.
Software Based Samplers
Recently, the incredible increases in computer speed and power have
made it possible to develop software applications that can produce
the same level of performance and capability as hardware-based units.
The ease of modification and the elimination of the issues involved
with hardware development have created an environment where the
benefits of software-based sampling far outweigh those of hardware
solutions. A list of popular software applications follows:
Digidesign Samplecell - Hybrid system that relied
on a dedicated card (originally NuBus, then PCI), along with software.
TASCAM Gigastudio - Originally Gigasampler
Native Instruments Kontakt
Logic Pro EXS Sampler
Reason
Emu Emulator X2
Steinberg HALion
Mark of the Unicorn Mach 5
-- courtesy of wikipedia
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