Linear Arithmetic Synthesis
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Linear arithmetic synthesis, or LA synthesis, is a means of
sound synthesis A synthesizer (also synthesiser or synth) is an electronic musical instrument that generates audio signals. Synthesizers typically create sounds by generating waveforms through methods including subtractive synthesis, additive synthesis an ...
invented by the
Roland Corporation is a Japanese multinational manufacturer of electronic musical instruments, electronic equipment, and software. It was founded by Ikutaro Kakehashi in Osaka on 18 April 1972. In 2005, its headquarters relocated to Hamamatsu in Shizuoka Prefect ...
when they released their D-50 synthesizer in April 1987.


Overview

LA synthesis combines traditional
subtractive synthesis Subtractive synthesis is a method of sound synthesis in which Harmonic_series_(music)#Partial.2C_harmonic.2C_fundamental.2C_inharmonicity.2C_and_overtone, overtones of an audio signal are attenuated by a audio filter, filter to alter the timbre of ...
with
PCM Pulse-code modulation (PCM) is a method used to Digital signal (signal processing), digitally represent analog signals. It is the standard form of digital audio in computers, compact discs, digital telephony and other digital audio application ...
-based samples. The term ''linear arithmetic'' refers to synthesis that puts sounds together in a timeline. Typically a PCM transient begins a note, which is then continued with a subtractive synthesis prolongation. Roland did not use the term ''additive'', as
additive synthesis Additive synthesis is a sound synthesis technique that creates timbre by adding sine waves together. The timbre of musical instruments can be considered in the light of Fourier series, Fourier theory to consist of multiple harmonic or inharmoni ...
already refers to a different synthesis method. This technology first appeared in 1987, in the
Roland D-50 The Roland D-50 is a synthesizer produced by Roland and released in April of 1987. Its features include digital sample-based subtractive synthesis, on-board effects, a joystick for data manipulation, and an analog synthesis-styled layout desig ...
synthesizer. At the time, re-synthesizing samplers were very expensive, so Roland set out to produce a machine that would be easy to program, sound realistic, and still sound like a synthesizer. Also, Yamaha had previously gained world market lead with their DX7 FM synth, which excelled at metallic, percussive sounds—something that Roland's synths using subtractive synthesis were less good at. Roland understood that their subtractive synthesis method had to change. One of the more complex parts of a sound to program is the attack
transient Transience or transient may refer to: Music * ''Transient'' (album), a 2004 album by Gaelle * ''Transience'' (Steven Wilson album), 2015 * Transience (Wreckless Eric album) Science and engineering * Transient state, when a process variable or ...
, so Roland added a suite of sampled attack transients to subtractive synthesis. As well as the attack transients, Roland added a suite of single-cycle sampled waveforms that could be continuously looped. Sounds could now have three components: An attack, a body made from a subtractive synth sound (saw or pulse wave through a filter) and an "embellishment" of one of many looped samples. (The looped samples also contained a collection of totally synthetic waves derived from additive synthesis, as well as sequences of inharmonic wave cycles. Thus, LA synthesis offered the realistic sounds of a sampler with the control and creativity of a synthesizer.) The PCM waveforms could be modified with a pitch envelope and a time-variant amplifier. Waveforms from the sound wave generators could be further modified with time-variant filters for cutoff frequency and resonance. These modified waveforms were called "partials". Two partials grouped together created a ''tone''. Tones could be modified using up to three
low-frequency oscillator Low-frequency oscillation (LFO) is an electronic frequency that is usually below 20  Hz and creates a rhythmic pulse or sweep. This is used to modulate musical equipment such as synthesizers to create audio effects such as vibrato, tremolo ...
s, a pitch envelope, a programmable equalizer, and on-board effects such as reverberation and chorus. Two tones grouped together created a patch.


Hardware

**
Roland CM-32L The Roland MT-32 Multi-Timbre Sound Module is a MIDI synthesizer module first released in 1987 by Roland Corporation. It was originally marketed to amateur musicians as a budget external synthesizer with an original list price of $695. However, ...
** Roland CM-32LN ** Roland CM-64 ** Roland CM-500 ** Roland D-05 ** Roland D-10 ** Roland D-110 ** Roland D-20 **
Roland D-50 The Roland D-50 is a synthesizer produced by Roland and released in April of 1987. Its features include digital sample-based subtractive synthesis, on-board effects, a joystick for data manipulation, and an analog synthesis-styled layout desig ...
** Roland D-550 ** Roland E-10http://cdn.roland.com/assets/media/pdf/E-10_OM.pdf ** Roland E-15 ** Roland E-20 ** Roland E-30 ** Roland Pro-E ** Roland JD-800 ** Roland LAPC-I ** Roland LAPC-N **
Roland MT-32 The Roland MT-32 Multi-Timbre Sound Module is a MIDI synthesizer module first released in 1987 by Roland Corporation. It was originally marketed to amateur musicians as a budget external synthesizer with an original list price of $695. However, ...
** Roland MT-100 ** Roland RA-50


Similar concepts

Yamaha's SY77, its rack-mount equivalent TG77, and successor SY99 introduced Advanced Wave Memory 2 (AWM2), enabling playback and digital filtering of samples. Notably, these also let AWM2 samples be used as transients to Advanced FM (AFM) synth sounds, as looped oscillators in their own right, or even as modulators of AFM carriers. This, like LA, enabled more realistic modeling of physical instruments, and in combination with FM, new possibilities for synthesis. The SY99 seemed to be the last FM workstation by Yamaha, and the later FM synth FS1R did not feature AWM — so SY99 was seemingly the last synthesizer to combine AWM with fully-fledged FM. This was until the Montage in 2016, which combines a later version of AWM2 with FM-X (an offshoot of the FM engine from FS1R, without the latter's Formant Synthesis) - though without letting samples be used as modulators, as the 77/99 series did. In any case, AWM sampling on its own has become a mainstay of subsequent flagship Yamaha products, such as the Yamaha EX5, Motif, and Montage lines — which still use the umbrella term AWM2, though the engine's details have changed many times.
Casio is a Japanese multinational electronics manufacturing corporation headquartered in Shibuya, Tokyo, Japan. Its products include calculators, mobile phones, digital cameras, electronic musical instruments, and analogue and digital watches. It ...
has also developed a similar synthesis system known as ''Advanced and High Quality Large Waveform'', better known as AHL, for use on their portable keyboard line. Earlier Casio keyboard models instead use ZPI, a similar but more advanced system. AHL was originally a simplified version of the previous ZPI, in which both are mostly optimized for acoustic instrument samples. Ensoniq with the SQ-80 called the same technique Cross Wave Synthesis. Kawai with the K4 called the same technique Digital Multi Spectrum. Korg's Modwave engine was designed to do both the morphing wavetable and sample synthesis, along with the usage of MS-20 filters due to its slope, which makes it closer to Roland's D-50 / D-550 / D-05 LA synthesizers. Some features are limited to layers instead of individual oscillators (e.g. filters).


References


External links


ROLAND D-110 HOMEPAGE - A Website Dedicated To The D-110 Synth Module - Patches, Tones, Utilities, Info, DIY's, Reference Materials
{{Sound synthesis types Sound synthesis types