Portabellabz The Sister Card for EMS Synthi A / AKS / VCS3

Portabellabz Sister Card expansion for the legendary EMS Synthi A / AKS.

The Sister Card greatly expands the modulation possibilities of the Synthi without requiring any permanent modification to the instrument. It plugs directly into the Synthi’s 8-pin Jones keyboard socket and is powered by the Synthi itself, making it an extremely clean and convenient way to add a substantial amount of modulation and control.

Designed especially with experimental sound design in mind, the Sister Card can produce everything from extremely slow evolving modulation to audio-rate effects, rhythmic sequences, sample-and-hold patterns, unusual CV interactions, and classic sci-fi / “droid” style sounds.

Features include:

• Two independent LFOs
• Triangle and square wave outputs
• Continuously variable waveform shape / fine tuning
• High and low frequency ranges
• LFO cycles ranging from approximately 25 seconds up to 90 Hz
• Sample & Hold clockable from either LFO
• Sample input through the Synthi meter column
• Slew limiter with adjustable rate
• Linear / logarithmic slew response
• Normal and slewed CV outputs
• Two independent CV modulation buses
• Individual level controls for LFO and S&H outputs
• CV routing directly to Synthi input channels 1 and 2
• CV inversion
• Two attenuverter inputs for scaling and inverting signals
• Gate output capable of triggering the Synthi envelope generator
• LED indication for frequency, clock, and modulation level

One of the coolest expansion options available for the Synthi platform, particularly for anyone interested in generative patches, complex modulation, sequencing, drones, experimental synthesis, or pushing the Synthi beyond its original control architecture.

Designed primarily for the EMS Synthi A and Synthi AKS. It can also be used with a VCS3 with the appropriate Jones connector / adapter configuration.

Important: Power consumption is approximately 50mA on each -9V/+12V rail. This is near the stated limit of the original MK1 Synthi/VCS3 power supply, so owners of early MK1 instruments should confirm their power supply is suitable before use.

A rare and extremely useful companion for an EMS Synthi.