Siel Opera 6
The Opera 6 is a classic, early eighties analog 6-voice polyphonic synthesizer that was in the same class as the Roland Juno series. The Opera 6 came in three versions as it was developing during its lifetime. First there was a totally analog version with an Oberheim-style pin-stripe control panel and one modulation wheel. A matrix of push-buttons enabled program selection. The later versions replaced the VCOs with DCOs. This meant more stable tuning without compromising the analog sound. Then, MIDI was also added (with velocity response ability). Also onboard the Opera were 3 LFOs for lots of modulation and effects. Its design was intuitive, but quirky - ie: the Pitch/Mod wheels are far away from the keyboard.
A working Juno-106 will smoke the Opera 6 when it comes to features and MIDI, but sometimes the alternative (Italian) sound of the Opera 6 may be what you need. It's great for swooshy pads, analog strings, and analog effects. Bass is OK, brass is "iffy", lead sounds are pretty weak as well are percussive/noise sounds and effects. Unfortunately, there are no effects, not even a Chorus to thicken up your sounds. MIDI is only 1-part multitimbral and always in OMNI mode, so it's quite limited. But the velocity responsiveness can control the VCF or ADSR. In the end it makes a nice piece of collector's kit and can offer some unique analog pads and sounds - that don't sound like the common Juno!