Special Stage Oscillographic Block (OB) is the ultimate chip-audio workstation and combines three digital synthesizer voices with integrated function generators, preset memory, algorithmic patch generators and CV control. The module is designed for maximum flexibility - the OB is able to create any sound from arcade impacts and abstract 8-bit drums to musical sequences and multi-timbral soundscapes.
The module is based on the SN76489 chip, a digital sound generator manufactured by Texas Instruments during the early 80´er years. Better known as the "PSG" chip, SN76 offers two square wave channels, a noise channel with 4-bit amplifiers. The SN76 has a characteristically rich, dark sound and has been installed in many popular video games and in various consoles such as the Sega Master System, Sega Game Gear, ColecoVision, BBC Micro and IBM PCjr.
The OB combines the simple, nostalgic sounds of the SN76 with a profound and innovative control matrix. Each SN76 channel is linked to two associated function generators for pitch and amplitude control, resulting in a total of six function generators per preset. In standard mode, the function generators use discrete values; in interpolation mode, the values glide smoothly, resulting in continuous characteristics similar to an LFO waveform. Various standard characteristics are available, but intrepid researchers will quickly create their own custom characteristics with the graphical envelope curve interface. In combination with the extremely wide range of speed levels, the function generators can create everything from short drum sounds and 1-shot effects to slowly developing textures and sequences.
The resulting patches can be stored in one of the eight preset slots. Each module parameter is stored and written to an SD card for easy data management and transport. The presets can be switched immediately via the centrally placed CV & Gate inputs. When percussive 1-shot sounds are loaded into each slot, the sounds can be triggered via the eight gate inputs like a drum machine, while the preset CV inputs can be used to switch through the presets via control voltage. Presets can also be randomly generated using three individual algorithms:
Four freely assignable CV inputs allow external control over pitch, amplitude, or the speed of each SN76 channel. Each input addressing routing is stored in a preset, allowing dramatic modulations to be implemented without having to physically patch the inputs again.