4, 5-string · Bolt-on or neck-through
Sivcak's flagship series, developed in collaboration with bassist Oskar Rozsa and Tibor Borsky. Mike Pope active electronics with Nordstrand or Delano pickups, 22-fret graphite-reinforced neck. Offered in OSC II and higher-tier OSC III forms, 4- and 5-string plus fretless (OSC 5F); the OSC III adds an instrument weight-balancing system (up to 403 g). Handcrafted by Sivcak Guitars, a family workshop in Northern Slovakia (est. 1992), aiming for 'uncompromising instruments in tone and detail.' Necks carry a dual-action truss rod reinforced with graphite rods; instruments are highly configurable (woods, colour, electronics, bridge, string count). Custom-order. About EUR 1,820-3,220 ($1,966-3,478).
| Construction | Bolt-on or neck-through |
| Strings | 4, 5 |
| Body | Premium configurable tonewoods |
| Neck | Maple with graphite reinforcement |
| Neck Pickup | Nordstrand or Delano |
| Bridge Pickup | Nordstrand or Delano |
| Controls | Mike Pope active preamp |
| Made In | Slovakia |