A-130 Linear Voltage Controlled Amplifier

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The A-130 Voltage Controlled Amplifier is a (very well-equipped) linear VCA. The “sibling module” A-131 works with exponential characteristics, but is otherwise identically equipped.

It has already been shown with the mixers A-138a (linear) and A-138b (exponential) that an exponential characteristic of the amplification comes closer to our psychophysiological feeling of a “perceived linear” volume control.

Therefore, the linear amplifier A-130 is preferred for control voltages.

User interface

Inputs:

  1. CV1: Control voltage input for modulating gain (without attenuator).
  2. CV2: Control voltage input for modulating the gain (with attenuator “CV2”).
  3. Audio In 1: Input for audio signals or control voltages, which are amplified according to the control voltage at “CV1” and “CV2”.
  4. Audio In 2: Additional input for audio signals or control voltages, which are amplified according to the control voltage at “CV1” and “CV2”. The module has a small “internal mixer” – luxurious!

Outputs:

  1. Audio Out: Output for the amplified signal from “Audio In 1” and “Audio In 2”.

Controls:

  1. Gain: Manual controller for the gain (setting a continuous level).
  2. CV2: Attenuator for the control voltage input “CV2”.
  3. In1: Attenuator for the audio/control voltage input “Audio In 1”.
  4. In2: Attenuator for the audio/control voltage input “Audio In 2”.
  5. Out: Attenuator for the “Audio Out” sum output.

Control voltages

Two control voltages from an A-145 LFO are mixed in the A-130 and modulated in amplitude by a second LFO.

The module is ideal for amplifying/attenuating control voltages.

If you have several LFOs or LFO and ADSR available, you can easily create more complex modulations.

“Smoother” volume gradients for audio

If you need a slightly less “pointed/jagged” volume curve for audio signals, it’s definitely worth trying a linear VCA instead of the usual exponential variant (like the A-131). Incidentally, the effect of a linear VCA cannot be replaced by longer decay etc. times in the ADSR generator – the two modules behave differently with the same control voltages and thus change the characteristics of the gain curve.

Technical specifications

Width8 HP
Depth45 mm
Power requirements20 mA (+12V) / -10 mA (-12V)