Korg OASYS

The HD-1 is a sample+synthesis engine with a two "oscillator" structure. In addition to the two "oscillators," an HD-1 Program contains a Vector Envelope, Common LFO (per-program as opposed to per-voice, similar to the modulation LFOs in some early polyphonic analog synths), two common key tracking generators, KARMA settings, and effects.

Each "oscillator" consists of a sample playback oscillator, dual multimode filter, nonlinear "drive" and low boost section, amp, and pan. The sample playback oscillator has four velocity zones, each of which can play a mono or stereo sample or a Wave Sequence. Velocity zones can overlap or crossfade. Korg claims very low aliasing distortion, due to the use of band limited interpolation.

Wave Sequences were first introduced on Korg's Wavestation synthesizer, released in 1990. Wave Sequences allow a single note to play through a list of samples, one after the other, with or without crossfades, with other associated parameters changing for each sample, as listed below. This can create smooth, evolving timbres, or rhythmic effects. Internally, Wave Sequences are implemented by using two voices; voice A plays the first sample, voice B plays the second sample, voice A plays the third sample, and so on. Other synthesizers have featured concepts which are similar in some aspects, such as PPG, Waldorf, and Access Virus wavetables, Synclavier resynthesis, and Ensoniq Transwaves and Hyperwaves (see the Ensoniq TS 10).

In the lists below, features new to the OASYS (in comparison to the Wavestation) are noted.

OASYS Wave Sequences include, for each step:

• The sample to play (mono or stereo)
• Sample start offset
• Reverse on/off
• The length of the step, in milliseconds or rhythmic value
• The crossfade time into the next step, in milliseconds
• Crossfade fade-in shape (256 steps, from log to exp)
• Crossfade fade-out shape (as above)
• Volume
• Transpose and fine-tune
• Two modulation ("AMS") value outputs, to control any assignable parameters of the synthesizer in the rest of the Program (e.g. filter cutoff or resonance, LFO speeds, etc.)

And, for the sequence as a whole:

• Time/Tempo mode (determines whether step durations will be in milliseconds or rhythmic values)
• Run on/off (enables and disables programmed durations and crossfades altogether; modulation from other sources can control the sequence directly)
• Key sync on/off (determines whether each note's Wave Sequence runs independently, or whether all notes sync together for lock-step rhythms)
• Swing and swing resolution
• Quantize Triggers on/off (adjusts note start times to match current KARMA/Sequence)
• Start step and start step modulation
• End step
• Loop start, end, and direction (forwards, backwards/forwards, backwards)
• Loop repeats
• Note-on advance (increments the start step for each played note)
• Position modulation (sweeps through the sequence manually)
• Duration modulation (changes the step durations)

Additions to the original Wavestation implementation include time/tempo modes, sample-locked tempo sync, constant-time crossfades in tempo mode, fade-in and fade-out shapes, swing, trigger quantization and key sync, note advance, real-time duration modulation, control of reverse and sample start point per step, and modulation outputs.

EXs is a Korg acronym for "EXpansion Sample". They are sample sounds that come pre-loaded with OASYS. EXs-1 is a sample library with acoustic instruments including guitars, brass, piano, strings, beside others. EXs-2 is a grand piano sampled in each key with 4 velocity levels plus damper. The 1G RAM of OASYS only permits to load 1 EXs at a time, but the user can expand it to have both working at the same time.

EXs3 ($149) includes over 700 MB of brass and woodwind samples, perfect for orchestral and pop productions. Recorded using world-class instruments and players, the collection features piccolo, flute, alto flute, clarinet, bass clarinet, oboe, English horn, bassoon, contrabassoon, soprano sax, alto sax, tenor sax, baritone sax, trumpet, piccolo trumpet, cornet, flugelhorn, trombone, French horn, bass tuba, contrabass tuba, dual-trumpets, dual-trombones, and brass ensemble. Designed to be richly expressive, the samples include multiple dynamics, straight and vibrato versions, breathy and overblown tones, legato, staccato, trills, flutter, growl, sforzando, glissando up/down, falls, doits, voice, breath, attack elements, grace notes, and key noise elements. 128 Programs and 64 Combinations take full advantage of the new sounds.

EXi is a Korg acronym for "EXpansion Instrument". It refers to all OASYS synth models other than the HD-1, including the AL-1, CX-3, etc.

This is the Program structure for playing EXi. It is similar to that of the HD-1, but differs slightly in a few ways, such as:

• Allows selection of any two EXi for layering or splitting
• Adds a "Common" step sequencer, shared by all voices in the Program
• Adds audio input selection for each of the two EXi (currently used by MS-20EX and MOD-7)
• Adds transposition for each EXi

Virtual analog synth engine.

• Two main oscillators with analog-style FM and sync
  • Korg claims proprietary anti-aliasing technology, for no audible aliasing over standard 88-note range, with sync (but with drive and ring-mod off)
  • Waveforms: Saw, Pulse, Saw/Pulse, Double Saw, Detuned Saw 1, Detuned Saw 2, Triangle, Square/Triangle
  • Wave Morph and Pulse Width/Phase/Detune
• Sub-oscillator
• Audio input
• Noise generator with saturation and dedicated filter
• Ring modulation (Ring Mod, AM, Rectify, Clip)
• Mixer provides modulatable volume and filter A/B pan for osc 1, osc 2, sub osc/audio input, noise generator, and ring mod
• Per-voice, modulatable Drive (nonlinear distortion) and Low Boost (low EQ)
• Dual resonant multimode filters, including "multifilter"
  • Multifilter provides two separate sets of gain controls for LB, HP, BP, and dry signals, with modulatable crossfade between the two sets
• 4 EGs
• 4 LFOs
• 2 "AMS Mixers" (modulation signal processors)
• Per-voice step sequencer

A modeled tonewheel organ based on Korg's dedicated CX-3 organ keyboard. This organ mimics and in many ways enhances the sound of the Hammond organ and Leslie speaker with amplifier simulation and other enhancements.

A plucked string physical model that allows you to pluck, strike, scrape, or otherwise "excite" the string with 16 different "pluck" types, noise, or any of the onboard or RAM-based PCM waveforms.[7]

The optional LAC-1 Legacy Analog Collection($249.00) EXi adds the MS-20EX and PolysixEX virtual analog synthesizers.

• MS-20EX Runs in demo mode until activated.
• PolysixEX Runs in demo mode until activated.

The MOD-7 ($249.00) includes six oscillators which combine simultaneous VPM (aka FM), Waveshaping, and ring modulation, plus a PCM oscillator, noise generator, audio input, two multi-mode filters, three 2-in/1-out mixers, and an input main mixer – with a patch panel for routing them together.

Note: The MOD-7 and PolysixEX/MS-20EX plug-ins are only available from www.korguser.net. Owners must register their Oasys at the site in order to purchase them. This includes providing the Public ID and serial numbers of their unit.