Mutable Instruments Streams

Streams provides two channels of extremely flexible signal dynamics manipulation.

Each channel consists of an analog voltage-controlled filter and amplifier (VCFA). The response curve of the amplifier section is continuously variable from exponential to linear. The amplifier gain is directly controllable from a CV input, through an attenuator. But what makes Streams truly unique is the multi-purpose EXCITE input. The signal routed to this input is analyzed by a micro-controller and translated into internal control voltages for the VCFA, turning Streams into a very versatile signal contouring tool:

Envelope generator

The EXCITE input can work as a trigger input, triggering an internal AD or AR envelope routed to the gain and the filter cutoff (in variable amount). With only 6-HP of space, you can shape an oscillator or noise source into a full-bodied sound.

Vactrol curve generator The EXCITE input is processed by a digital model of a resistive opto-isolator (Vactrol), controlling the gain and the filter cutoff (in variable amount). The digital emulation allows the modification of properties of opto-isolators – such as response time – which are otherwise difficult to control. The virtual vactrol response can be either optimized for processing CVs, or triggers (for “plucked” sounds).

Amplitude and frequency content follower

The envelope and cutoff of the EXCITE signal is measured, and applied to the signal on the VCFA input.

Compressor/limiter

Streams’ VCF is disabled, and the VCA is used to control the dynamics of the input signal. An intuitive control scheme allows the compressor to be used either for peak reduction/limiting operation; or for boosting signal levels with soft-limiting. The EXCITE input can be used as a side chain.

Specifications

Dual analog VCA and 2-pole VCF, with digital control path. The control voltages for these two analog circuits are digitally generated, by “reacting to,” “following” or “listening to” a multi-purpose input called EXCITE.

Digital control modes

• AD or AR envelope generator.
• Vactrol response generator – gated or pinged/struck.
• Amplitude and cutoff follower.
• Compressor.

I/O (per channel)

• Multi-purpose EXCITE input.
• DC-coupled Audio/CV input (normalized to +5V constant voltage).
• VCA gain CV (normalized to +8V constant voltage).
• Output.

Controls (per channel)

• Digital control mode selection.
• Response time / compression threshold.
• Modulation amount / compression ratio and makeup gain.
• VCA gain CV input attenuator.
• VCA exponential to linear response curve.

Technical characteristics

• Analog signal path.
• All inputs DC-coupled.
• 12-bit, 31kHz EXCITE signal acquisition (for metering and following).
• 16-bit, 31kHz control voltage generation.
• Cortex-M3 ARM processor.
• Open-source hardware and firmware.
• 12-HP.
• Easy firmware updates through an audio interface.
• Current consumption: +12V: 100mA ; -12V: 30mA.