The Sirius is a keyboard "groove-synth," featuring a subtractive hybrid-tone-generation synthesizer referred to as DTE ('Difficult To Explain') synthesis introduced in 1997 by Quasimidi. The unit featured both real-time and step sequencers with pattern- and song-modes, capable of acting basic drum machine, groove-box, or sound-module.
Track/voice structure was organized as follows:
- Kick drum - 1 voice sample through synthesis chain
- Snare drum - 1 voice sample through synthesis chain
- Hi-Hat - 2 voice samples (open/closed) through synthesis chain
- Percussion drum kit - 12 samples through common synthesis chain
- (chromatic) Synth 1
- (chromatic) Synth 2
- (chromatic) Synth 3
...where the first 4 tracks can only load patches from 2 banks (1 ROM and 1 User) of 96 User patches of that instrument, but all 3 (chromatic) synth parts can load from a common pool of 4 banks (3 ROM and 1 User) of 96 keyboard patches.
The onboard pattern sequencer allows for storage of 1600 motifs (MIDI sequence only) to freely assign to sound within Patterns, holding 142 ROM and 100 User Patterns (assignments between motif and Program). The Sirius can store holds 16 Songs, where each Song assigns
- 8 patterns
- 4 breaks (fills pattern to change all parts)
- 4 special loop tracks (momentary-action fill for single Part)
- settings for 2 bus effect
- settings for vocoder