West Cat Oscillator

West Cat Oscillator

The WCO is a complex oscillator that started off as my riff on West Coast Synthesis for @biminiroad’s live stream. Afterwards I tweaked and refined the knob values and wave shaping to create something unique.

There is a modulating oscillator which can modulate the amplitude, phase, and frequency of the carrier oscillator. The Carrier oscillator has some wave shaping options over the symmetry and smoothness of the wave but also had a special “squelch” wave shaper instead of a wave folder. The squelch can completely silence the signal or add progressive harmonics that become erratic and unstable creating a distinctive squelchy character.

Squelch behaves almost like unstable resonance even at low frequencies when turned up all the way and can be used almost like a Rungler for making generative atonal melodies.


Input Signal Range Notes
56%20PM58x57 -10 to 4 Because of the squelch waveshaper, the WCO still makes audible sounds at LFO rates.

Output Signal Range Notes
02%20PM58x59 -1 to 1 Modulator oscillator output
13%20PM58x56 -.5 to .5 Responds to phase and frequency modulation, handy for syncing oscilloscopes
17%20PM66x60 -1 to 1 Final waveform output


Knob, Button Function Notes
29%20PM106x97 Symmetry Controls the slope of the waveform rom ramp to triangle to saw
17%20PM116x139 Modulating Oscillator Frequency Sweeps a set of fixed ratios that the modulator oscillator can be set to.
34%20PM108x95 Amplitude Modulation index
39%20PM108x93 Phase Modulation Index
48%20PM108x96 Frequency Modulation Index Does not pass below 0 Hz
54%20PM87x76 Hard Sync Mode Carrier is synced to Modulator
58%20PM83x69 Sync Type
17%20PM116x139 Carrier Frequency Sets an unquantized ratio of the carrier oscillator with incoming 1/oct signals.
31%20PM109x92 Smoothness Shapes the wave from a triangle to a distorted sine.
36%20PM112x103 Squelch Creates unstable resonant harmonics


Meter Displays Notes
46%20PM110x113 Modulator to Carrier Frequency Ratio
53%20PM120x79 Which type of sync is enabled in sync mode

Version History

Revision File Date Notes
2.0 WCO V2.0.audulus (152.2 KB) 06/20/2018 Initial Upload

I’m excited to play with this kitty!


This module is a lot of fun.

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I’ve recently been enjoying Forms 1 – Benge’s Buchla 100 album, and this module is definitely good for producing those west coast sounds.

Interesting interpolations of the square root and 2*pi in the modulation ratios – those are perhaps the most fun.

Nice UI too!


That is quite an entertaining listen! I can only aspire to the crazy textures on that album :heart_eyes:

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This track is built around this oscillator

Definitely in the same space as my DPO . Lovely


Wow, I’m actually pretty blown away! I love the bucephalus percussion and and the atmospheric drones. Great stuff!


I guess Windows users have to wait for updates - those custom icons doesnt show up - so as knobs ;(((

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Ok, I’ll see what I can do. I am really hoping that the windows version sees an update soon (I own it also, but haven’t been using it) but I can retrofit this to run on windows.


WCO 2.0 - pc friendly.audulus (154.4 KB)

Let me know if that works or if I missed a clamped knob somewhere. My apologies for the delay :neutral_face:


Sweet! Works like charm. Thank you! Also I noticed that your The Garbler PLL module doesnt have knobs, any chance you could take look at it as well? Thank you!


Curse of the Clamped Knobs!




@futureaztec Here’s the West Cat Oscillator @robertsyrett was talking about in the other post.


Yeah I really like this one. I didn’t realize it was inspired by the Make Noise DPO. I do notice that there is no “strike” jack, which I think adds some interesting possibilities to the HBO/DPO.


Great track! Is that all Audulus?

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I have been watching some of Todd Barton’s excellent Buchla Easel tutorials demonstrations in trying to understand the components of some of the sounds that he and Alessandro Cortini use and figure out how I might re-create them in Audulus. I appreciate the fine work that has gone into West Cat Oscillator and Rasmus but am having trouble getting some of the sounds that I seek to create.

I am hoping to figure out (but I am a total newb and DSP idiot) how to re-purpose some of the pieces you have all built (and will share back if I manage to come up with anything),

I was wondering if anyone here has a precise understanding of the Music Easel’s signal flow.

Does the modulating oscillator modulate the Complex oscillator after the wavefolding or before it.

I.e. if the modulator is set to do AM and the complex oscillator is set to a sine wave, is the modulator amplitude modulating the CO’s sine wave with the result going through the wavefolder. Or is the wavefolding applied to the CO’s sine wave with the resulting waveform being amplitude-modulate.

Did the question make sense?


Looks like to me that waveshaping comes after. Would make sense because if you had one on the mod oscillator and pnly jad a little bit of modulation coming in, it would’t do much. So it’s mod->osc->waveshaper. Usually if something is laid out on a front panel, that hints at the underlying signal flow left to right.


If you haven’t checked out Todd Barton on Buchla stuff, you should! He’s got great tutorials on West Coast synthesis. :metal:

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Yes, Todd’s videos are great. (I guess you missed my remark up-thread about my studying his videos is what is leading me to figure this out – as there are some great timbres that he demonstrates that I haven’t succeeded in coaxing out of WestCat or Rasmus. So, I am trying to figure out how to do that.

I agree about the panel being a place to look, but I think we are looking at it and drawing different conclusions. On the easel, the mod oscillator is color-coded blue. The complex oscillator is coded red. Timbre (wavefolding) is part of that red grouping. To me, that implies (not definitively, though) that timbre is integral to the CO and that it is the CO’s output stage.

I infer from the front panel that the signal flow is something like below.

(COMPLEX OSCILLATOR–wavefolding integrated internally and applied to the complex oscillator output)

as opposed to

(MODULATING OSCILLATOR) MODULATES (CO’s pre-timbre waveform) -> wavefolder (Timbre)

By the way, the sounds that I am trying to coax out of Audulus include the type of timbres heard here:

As I have been playing with some waveshaping/folding software, I am getting the sense (I could be wrong) that what can sound like subtle differences in waveshaping algos can have a big impact on the final sound when it is combined with AM or FM. It seems like Buchla spent a lot of time experimenting with designs.

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The complex oscillator is the combination of the modulating oscillator and the oscillator you actually hear.

Also, what you’re describing here is actually the same thing, just talked about in two different ways.

There is a signal flow but not an order of operations - it all happens simultaneously.

Think of of it this way - would it sound different if you wired a modulator into an oscillator then into a wavefolder vs wiring an oscillator into a wavefolder, then modulating that oscillator with another?

Or another way - if you plugged your guitar into your delay pedal first, then into your amp, would it sound different if you first plugged the delay into your amp, then plugged your guitar into your delay pedal?

As to how to get these timbres - the reverb is also a big part of the sound you linked to there. It helps smear the thing together and at right settings adds a lot of magic.

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