Cynthia is a free Windows VSTi/VST inspired by the classic EMS Synthi A.

Specifications (like Synthi A):

• 3 oscillators with controls for shape and level of the waveforms
  • OSC1: Range from 0.6 Hz to 16 kHz, sine and triangle
  • OSC2: Range from 0.6 Hz to 16 kHz, square and triangle
  • OSC3: Range from 0.015 Hz to 500 Hz, square and triangle
• Noise generator
• Two audio inputs so you can modify the sound of a guitar or your voice
• A nasty filter that can go into self-oscillation
• An attack-hold-decay(-repeat) envelope controlling the volume, and doubling as an envelope generator with a freely assignable output
• Ring modulator
• Spring reverb
• Joystick for extra control
• Stereo outputs with extra filters, pan and volume control
• A 16 x 16 routing matrix, where you can connect everything at will
• 2 pairs of stereo outputs
• Direct out
• Speaker (simulating the sound of a pair of canny speakers)

Additional Features in Cynthia:

• Each OSC can be synced and phase shifted (0-180 degrees) at will.
• A delay module with delay time in the range 0-0.1 seconds or 1-10 seconds. This allows you to delay not only audio, but also phase shift it or delay control voltages.
• More advanced modifications of envelope control voltage as you can add bias, invert it and adjust its level independently.
• Inversion of each individual connection you make in the matrix
• A simple 8 step control voltage sequencer, that allows you to make a sequence of notes, but also filter frequency, amplification or what ever you feel like.
• Adjustable portamento time, so you can make nice glides.
• A build in tuner, so you can tune each OSC by ear.
• 3 extra matrix rows for the build in CV sequencer, and host MIDI pitch and velocity.
• A collection of nice presets to get you started (thanks HSkovlund)
• And of course: MIDI cc’s can be assigned at your command to any knob!