ARP Synthesizers Omni by lucasasdelli
The ARP Omni was an hybrid string machine, like some others from same time. It had a string section, a "synth" section and a bass mono section. Its main feature was the ensemble generator, a three-BBD delay unit derived from Eminent organs string units. Its sound was lush and full, very famous and rich of harmonics.
The generation was a "top octave divide down" schema, like combo organs.
The "synth" section was simply a low-pass 4-pole VCF with ADSR and an LFO. The bass line did work only on left one and a half octave, by selecting the lowest note and it had a dedicated filter and envelope.
The ARP Omni had a quite complex VCA envelope section, that allowed separate note decay for each section and to avoid unwanted retriggers. A big limitation was the attack, that did work as single for the whole keyboard, thus resetting all notes when activated.
It is known for being one of the most ARP products prone to failures: the key voices were controlled via low-quality tantalum capacitors, that quite often did short; the power supply did generate some transients that did break some CMOS ICs; the voice select switches were really fragile and no replacement is available on market.
My suggestion is NOT to implement ARP mod to power supply: to avoid CMOS damage, the mod adds two 15V zener diodes to outputs, but when they burn to protect the ICs, the line transformer burns as well! Alternatey, insert a couple of fuses just after the AC transformer.
Apart from those technical issues, its known beautiful sound remembers lots of '70 classics.