Frequency Modulation [Pulveriser]

Note that these modulation inputs accept audio rate signals, which is really cool!

(quote from the Operation Manual of Reason)

A super interesting but not yet super famous feature of the Pulveriser can be found at the back of this device.

modulation-input

The Pulveriser accepts Audio Inputs for modulating. Audio modulating audio, which is indeed really cool!

Frequency Modulation: radio en FM synthesis

I grew up listening to radio. FM radio that is. Frequency Modulated signals floating through air. And the first synth I’ve bought was using Frequency Modulation for generating sounds: the Yamaha DX100 which I still own, use and love.

FM in simple words

Frequency Modulation (FM) works by using an audio signal to modulate another audio signal. This proces creates the signal to shift in frequency while a relatively constant amplitude (volume) remains.

Watch this video for a simple explanation of what FM is and looks like:

In FM synthesis this is done by using one oscillator (called the carrier) for generating sound and using another one (called the modulator) to modulate that carrier. Sometimes even more modulators are used to modulate the carrier which can create very complex waveforms with high overtones that way.

How to do this in Pulveriser

The Operation Manual of Reason is not very clear on how the Pulveriser uses Frequency Modulation:

Use this for dynamically changing the Frequency parameter from an external audio signal. The result of this modulation is Filter FM.

From what I’m feeling (and hearing) is that the Filter Frequency will respond to the Modulation Input and change it’s values dynamically. But it doesn’t sound like a WahWah for example, so the modulation process is a true carrier/modulator kind of process.

To make the Pulveriser modulate the input signal do the following:

  • use the Pulveriser as an insert effect and make sure the Filter is not set on Bypass
  • connect a modulator sound source (can be anything: a synth, a sampler, or route an audio track into it) to the Filter Frequency of the Audio Modulation Input

This works great in a Combinator. For example using a synth or sampler as a carrier and another one for the modulation like I’m using in this demo:

You hear a simple Malström sound using one Square*4 oscillator for the first 4 bars and then 4 bars with the modulator (using one Triangle oscillator). So what you’re hearing is just one oscillator which gets modulated by another oscillator.

But you might as well use a Dr. Octo Rex Loop as carrier and modulate it with a sharp sounding SubTractor patch for example. You can really “play” the modulation effect this way by manually changing the filters on the SubTractor and changing its Volume output. The Pulveriser Filter will respond to the frequencies and loudness of those frequencies send to the Filter Frequency of the Audio Modulation Input. So changing those will have a huge effect on the modulated sound.

Devote some time for experimenting with this. Hopefully you will be able to create anything from very subtle modulations to stuff which sounds very lofi and broken (the sound of a radio which is incorrectly adjusted for example – which is kinda fun :D).

And remember: I’m sending some examples and files in the Newsletter this weekend.

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