Noise VCA with state variable VCF and VCA - minijack version

Noise Generator with state-variable VCF and VCA

The NoiseVCA is a complete noise-'voice' with integrated VCF and VCA. But the possible applications are much more versatile.
Instead of the internal noise source an external signal can be used as input for the VCF and the VCA.
In standard operation the noise generator feeds the VCF and this feeds the VCA.
The untreated white noise signal, a subfrequent random voltage and the VCF signal are available as direct outputs too.
The state-variable VCF can be operated in highpass, bandpass or lowpass mode. The cutoff frequency is controllable by the big scale knob (and/or CV), and resonance is adjustable by knob 'Q' up to self-oscillation. The filter is providing a very good 1V/oct. tracking.
Optionally, one can add an external signal to the filter's input or replace the white noise completely by that.
For modulating the cutoff frequency, the VCF has an 1V/oct. input and 2nd one which is adjustable by a potentiometer and which polarity can be inverted by a switch.
The VCA's input source can be chosen between 'White Noise', 'Sub F' or 'VCF'.
Its control characteristic can be switched between linear and exponential, in middle position of the switch the VCA will be completely muted.
By using the polarizer-knob 'CV in', the control voltage for the VCA can be adjusted and inverted. Knob 'Offset' is adding an offset voltage in the range from ca. -5V to +5V to the CV signal. Thus, the VCA's zero point may be shifted in positive or negative direction - determing where the VCA is starting (e.g. with a triangle-wave as CV); or just to turn it loud, if there is no CV.

• Width: 10 HP
• 3 direct Outputs: 
  - White Noise (Transistor noise source)
  - Sub F (Random CV)
  - VCF Out
• Switchable VCF characteristic:
  - Highpass (12dB)
  - Bandpass (6dB)
  - Lowpass (12dB)
• Adjustable filter resonance (Q)
• Switchable 2nd VCF signal input:
  - White noise only
  - White noise & external signal combined
  - External signal only
• VCA with switchable CV mode:
  - linear CV
  - 0 (mute)
  - exponential CV
• Dimensions: 128,5 x 50,5 mm; Depth: ca. 40mm
• Power consumption: ca. 42 mA (positive rail)