OSCILLOGRAPHIC BLOCK

Description

This unique module is designed by SPECIAL STAGE SYSTEMS (sadly defunct) and now sold out at the manufacturer – this is the last unit we have, so grab it whilst you can! We’re placing them under the MHI moniker as manufactured and distributed by Darkplace.

Welcome to the ultimate chip-audio workstation. The Oscillographic Block (OB) combines a three channel digital synthesizer voice with integrated function generators, preset memory, algorithmic patch generators, and CV control. Designed for maximum flexibility, the OB can generate everything from arcade impacts and abstract 8-bit drums to looping musical sequences and multi-timbral soundscapes.

The module utilizes the SN76489 chip, a digital sound generator manufactured by Texas Instruments during the early 1980’s. Better known as the “PSG” chip, the SN76 features two square wave channels, a noise channel, and dedicated 4-bit amplifiers. The SN76 possesses a characteristically rich, dark sound, and was used in a number of beloved videogame and computer systems, including the Sega Master System, Sega Game Gear, ColecoVision, BBC Micro, and IBM PCjr.

The OB pairs the simple, nostalgic tones of the SN76 with a deep and innovative control system. Each SN76 channel is paired with two dedicated function generators for controlling pitch and amplitude, for a total of six function generators per preset. In standard mode, the function generators snap to discreet values; in interpolation mode, they smoothly glide between values, generating continuous LFO-like waveforms. A number of standard shapes are provided, but intrepid explorers will find themselves programming custom shapes via the powerful Envelope Graph interface. Combined with their extremely wide speed deltas, the function generators can be used to create anything from short drum sounds and 1-shot effects to slowly moving textures and sequences.

The resulting patches can be saved to any of the OB’s eight preset slots. Presets store virtually every module parameter, and are written to an SD Card for easy management and portability. Each preset is instantly recallable using the Preset CV input or the dedicated gate inputs running along the center of the module. By storing a 1-shot percussive sound in each slot, the eight gate inputs can be used to trigger each preset drum-machine-style, while the preset CV input can be used to sequence or sweep through presets with control voltage. Presets can also be algorithmically generated using the RANDOM button according to three distinct modes: Drum Mode, which generates bass drums, snares, hats, cymbals, and effects; Envelope Mode, which randomizes the function generator shapes; and Sequence Mode, which generates full looping patches and sequences.

Four assignable CV inputs allow for external control over pitch, amplitude, or speed on any SN76 channel. Each input’s assigned routing is stored along with the preset system, allowing for dramatic modulation permutations without physically re-patching the inputs.

• Direct CV control over a physical SN76489AN sound chip, with 4-bit amplitude and 1V/Oct-scaled 10-bit pitch
• 2 square wave channels and one dual-mode (white and periodic) noise wave channel
• 6 programmable function generators per preset create both smooth waves and stepped sequences, and operate across a wide range of speeds suitable for percussive effects, looping melodies, slowly evolving structures, and pure bug music
• 4 user-assignable CV inputs for controlling pitch, amplitude, and function speed
• Unique preset system allows eight patches to be stored to SD Card and instantly recalled (no audible gap) via CV and gate inputs
• Built-in algorithmic patch generator with Drum, Envelope, and Sequence modes
• Dedicated Chip Clock and Fine Tune controls extend the SN76’s frequency range
• Low resolution (not V/Oct) envelope + gate outputs for driving external modules
• Advanced functionality accessible via Shift button combinations, including overall channel volume, alternate display mode, shape macros, copy / paste, envelope synchronization, and full-bank preset randomization