Free running oscillators in Thor

Sometimes when I’m messing about with Thor in Reason I find myself wishing it had free-running oscillators. In an analogue modular synth the oscillators are “always on” — if you connect the sine wave output from an oscillator to an audio playback output you will hear a steady tone playing indefinitely. While this is not what you want for most sounds, it is a mode that makes it a lot easier to hear and understand what filtering and various modulations, such as AM; FM or sync, do to the sound. Without this I find myself having to trigger notes all the time to hear what I’m doing which is both a bother and something that affects the sound since it re-triggers the envelopes.

Now Thor apparently has free-running oscillators in the sense that their cycles are not restarted when it receives a gate signal. I think this is to avoid having several oscillators starting in phase if they are triggered by a note simultaneously. So the Thor oscillators are “running” all the time, but they are not playing if they are not getting a gate signal. What’s worse: the amplitude envelope does not have an infinite release time. The maximum release time is 30 seconds so you will definitely hear it decaying. Fortunately, Thor’s awesome modulation matrix can come to the rescue!

The solution I came up with (and I’m sure there are many, many others) goes like this :

1. Go to the modulation matrix and route “Shaper” to “Audio Out1” as well as to “Audio Out2”.  Set the amount to 100%. This bypasses the amplitude envelope (and everything after it).

routing_matrix

2. Disable “Gate trig” on the amplitude envelope. This stops the envelope from affecting the sound.

amp_env

3. Go to the Thor sequencer. Set the mode to “Repeat” and the number of steps to 1. Use the edit knob to select “Gate len” and turn the knob above the active step fully to the right (100%). This causes the sequencer to generate a continuous note when it is running.

seq_mode

seq_steps

4. Press “RUN” in the sequencer section and start twiddling.

This seems to work pretty well. It doesn’t have any external dependencies so it works on the iPad version of Thor as well. The downside is that both the third filter and the chorus and delay blocks are bypassed. Still, whenever I’m programming a pad or drone sound, or if I’m just experimenting, I find it useful to start a patch this way and only activate the amplitude envelope once I’m happy with the basic sound.

Here’s hoping the Propellerheads adds an envelope disable option to the amplitude envelope in Thor in a future release!

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