After Later Audio COCO modules, create your own complex oscillator

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After Later Audio has released the COCO system, a new series of modules that allows you to create your own Eurorack complex oscillator. 

Complex oscillators are super versatile sound generators. Often inspired by the west-coast Buchla world. In addition to classic waveforms, they shine in the creation of very deep and wild sounds with just a few twists. You get basically a lab for wacky, unique waveforms. A disadvantage of such modules is their size.

To accommodate the many features, they have large faceplates that take up a lot of space in the case. There is hope: the last Superbooth editions also showed that there are smaller and smaller complex oscillators optimized for compact systems. After Later Audio from the US takes a completely different approach with its COCO system and series of modules. They leave it up to the users how big the Complex Oscillator should be.

After Later Audio COCO Cascades Brooks

After Later Audio COCO Modules

COCO is a new series of modules that can be combined into one large complex oscillator outputting super rich tones full of overtones. What is special about the COCO series is that the modules can be used standalone or in combination. Cascades, Brooks, Canyon, and Valley are part of this series as well as a new utility module.


It is a new 8HP SSI2230 chip based through zero FM analog oscillator and is the main oscillator core of the COCO system. It offers CV-controllable waveform morphing (triangle, saw, and pulse waves), PWM, sync, amplitude modulation (AM), and linear/exponential FM.

FM, PWM, and morph come with a dedicated attenuator for precise CV control. The amplitude has either offset or full wave rectification for the modulating wave. There is an octave switch for simplified tuning. Cascades supports both VCO and LFO ranges giving you a rich-sounding VCO or alternatively a complex LFO.

Connection side, you get individual waveform outputs, a cosine and morph output, sub out, and various CV inputs including a 1V/octave socket.


Brooks is another thru-zero oscillator but this time in just 4HP. You can use it standalone as a classic oscillator or as a second or third in the COCO system. Also, Brooks uses the SSI2130 chip in its core. It offers both a tuning knob (4-octave ranges) and switch enabling ranges of 0V, 3V, and 6V.

Then, it has FM as well as hard and soft sync (time reverse) on board. Brooks also supports both VCO and LFO ranges. The signals can be output via individual outputs (square, sine, saw, triangle). Brooks is a more simple oscillator but offers a lot on only 4HP.

After Later Audio COCO Canyon Valley


The third module in the COCO system is Canyon a new sub-harmonics generators consisting of two sections powered by two different clock sources. The first section offers odd sub harmonics, dividing the clocks by 1, 3, 5, and 7 while the second gives you even sub harmonics (clock divisions 2, 4, 6, 8).

Each side of Canyon can also be operated independently using different clock signals. With the built-in voltage-controlled crossfade, you can mix both section outputs together. And the output can be used for creating rich sounds or as slow evolving CV sources.


The strength of each complex oscillator is the variety of ways to manipulate the sounds. That with waveshaper, wavefolder, FM, etc. And the fourth module from the COCO series offers exactly this. It’s a combination of a mixer/crossfader and wavefolder that can be used standalone or in conjunction with the other modules.

Valley has two inputs to which the five-stage wavefolder can be applied. You can crossfade between the inputs and the crossfader gives you dedicated outputs for the fundamentals and folded signal. You can work with odd and even harmonics, all controllable with CVs. Further, there are also tuning and sync controls for the connected COCO oscillators.


Last but not least, we have a new utility module called SUM/INV which is basically a summarizer and inverter module. You get 4 ins/4 outs split into two sections. The first is the summarizer where the first output sums the two inputs at unity while the second output gives you an inverted sum at unity.

The second block is identical to the first channel but it normals channel one summed output to the first input. This enables a 3:1 configuration with both a summed and inverted output.

Complex oscillators are usually very large modules that offer a lot. Breaking this concept down into different possibilities and giving you the ability to design your own oscillator is an interesting concept.

The new After Later Audio COCO modules are available now: Cascades for $149 USD, Brooks for $119 USD, Canyon for $99 USD, and Valley for $99 USD.

More information here: After Later Audio

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