A means of generating a control signal based on how much pressure is applied to the keys of a MIDI keyboard. Most instruments that support this do not have independent pressure sensing for all keys, but rather detect the overall pressure by means of a sensing strip running beneath the keys. Aftertouch may be used to control such functions as vibrato depth, filter brightness, loudness and so on....
Omni-2
"The ARP Omni-2 is an improved version of the popular Omni. It features all-
electronic switching, single/multiple triggering and a separate bass synthesizer.
The Omni-2 is actually three separate instruments in one package - 1) a highly
evolved string chorus, 2) polyphonic synthesizer section and 3) separate bass
synthesizer. All three sections can be played simultaneously for impressively-rich
orchestral effects....The Omni-2 has controls to balance the volume of each
section, selectable waveforms and chorus phaser controls. Each section has its
own output so that the Omni-2 can be played in stereo or even dramatic
'triphonic.'"----[from ARP's promotional Omni-2 brochure courtesy of Kevin
Lightner]
The Omni keyboards are string synthesizers with four separate voices (bass,
cello, viola, violin, each independently switchable) and a bass/synthesizer
section. The string section has its own variable speed LFO, and attack/release
envelopes. The synthesizer section has a VCF and its own ADSR envelope. The
bass/synthesizer split is set to the lower one and a half octaves.
The Omni (model 2300) was ARP's best selling intstrument. Unlike the original,
the Omni-2 has single triggering so that when any note is held down the VCF and
VCA envelopes will not re-trigger. The original Omni had multiple triggering so
that every time a key was depressed the envelopes were triggered.