Modular Diary

A few details on Rob Hordijk’s Dual Fader and my Audulus recreation of it: Hordijk makes clever use of normalized inputs and outputs to achieve a wide range of possibilities with only a few inputs and outputs:

  • Crossfading: 2 input signals, 1 output signal
  • Panning: 1 input signal, 2 output signals
  • Ducking: 2 input signals, 2 output signals

Since normalized1 inputs and outputs aren’t (yet) a viable possibility in Audulus I’ve simply included an extra output for the crossfaded signals. Another feature of Hordijk’s module is a 20db Gain control on two of the inputs to enable using external signals within the modular system. That isn’t something that needs to be thought of within the Audulus context, but those controls can also be used to introduce clipping distortion, so I’ve kept that as a feature. 2

Hordijk also includes a switch that changes between the crossfade output of channel A being routed to:

  • Both inputs of channel B
  • Only input 1 of channel B
  • Both inputs of channel B, but with input 2 inverted. That means that when fader B is set precisely to its center, the two signals cancel each other out resulting in silence. However if that fader is modulated at audio rates a type of Ring Modulation is heard, with a particular quality that is the result of the RMS curves.

I put together a simple demo.

I’m impressed by Hordijk’s take on a simple mixing module, both the way in which distinctions between levels and placement are eased, and just how much can be gotten out of what is essentially two crossfaders – especially when modulation is introduced.


  1. Normalized connections are ‘behind the panel’ connections that don’t require patch cables. However should a cable be connected the hardwired connection is broken and the patch cable connection takes over.  

  2. Soft clipping in my case, but that could be adjusted. 

Modular Diary: A few details on Rob Hordijk’s Dual Fader and my @Audulus recreation of it: Hordijk makes clever use of normalized inputs and outputs to achieve a wide range of possibilities with only a few inputs and outputs… rdgr.me/u/osqxsi

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Rudiger Meyer is a composer interested in the play between traditional concert music and new media.


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